Tag Archive for: gene

Yuan Zhu

Study suggests glioblastoma tumors originate far from resulting tumors

Yuan Zhu

“The more we continue to learn about glioblastoma,” Yuan Zhu, Ph.D., says, “the more hope we can give to these patients who currently have few effective options.”

A pre-clinical model of glioblastoma, an aggressive type of cancer that can occur in the brain, suggests that this recalcitrant cancer originates from a pool of stem cells that can be a significant distance away from the resulting tumors. The findings of a new study, led by Children’s National Hospital researchers and published July 22 in the journal Nature Communications, suggest new ways to fight this deadly disease.

Despite decades of research, glioblastoma remains the most common and lethal primary brain tumor in adults, with a median survival of only 15 months from diagnosis, says study leader Yuan Zhu, Ph.D., the scientific director and endowed professor of the Gilbert Family Neurofibromatosis Institute at Children’s National. Unlike many cancers, which start out as low-grade tumors that are more treatable when they’re caught at an early stage, most glioblastomas are almost universally discovered as high-grade and aggressive lesions that are difficult to treat with the currently available modalities, including surgery, radiation and chemotherapy.

“Once the patient has neurological symptoms like headache, nausea, and vomiting, the tumor is already at an end state, and disease progression is very rapid,” Dr. Zhu says. “We know that the earlier you catch and treat cancers, the better the prognosis will be. But here, there’s no way to catch the disease early.”

However, some recent research in glioblastoma patients shows that the subventricular zone (SVZ) – an area that serves as the largest source of stem cells in the adult brain – contains cells with cancer-driving mutations that are shared with tumors found in other often far-distant brain regions.

To see if the SVZ might be the source for glioblastoma tumors, Dr. Zhu and his colleagues worked with pre-clinical models that carried a single genetic glitch: a mutation in a gene known as p53 that typically suppresses tumors. Mutations in p53 are known to be involved in glioblastoma and many other forms of cancer.

Using genetic tests and an approach akin to those used to study evolution, the researchers traced the cells that spurred both kinds of tumors back to the SVZ. Although both single and multiple tumors had spontaneously acquired mutations in a gene called Pten, another type of tumor suppressor, precursor cells for the single tumors appeared to acquire this mutation before they left the SVZ, while precursor cells for the multiple tumors developed this mutation after they left the stem cell niche. When the researchers genetically altered the animals to shut down the molecular pathway that loss of Pten activates, it didn’t stop cancer cells from forming. However, rather than migrate to distal areas of the brain, these malignant cells remained in the SVZ.

Dr. Zhu notes that these findings could help explain why glioblastoma is so difficult to identify the early precursor lesions and treat. This work may offer potential new options for attacking this cancer. If new glioblastoma tumors are seeded by cells from a repository in the SVZ, he explains, attacking those tumors won’t be enough to eradicate the cancer. Instead, new treatments might focus on this stem cell niche as target for treatment or even a zone for surveillance to prevent glioblastoma from developing in the first place.

Another option might be to silence the Pten-suppressed pathway through drugs, a strategy that’s currently being explored in various clinical trials. Although these agents haven’t shown yet that they can stop or reverse glioblastomas, they might be used to contain cancers in the SVZ as this strategy did in the pre-clinical model — a single location that might be easier to attack than tumors in multiple locations.

“The more we continue to learn about glioblastoma,” Dr. Zhu says, “the more hope we can give to these patients who currently have few effective options.”

Other Children’s National researchers who contributed to this study include Yinghua Li, Ph.D., Wei Li, Ph.D., Yuan Wang, Ph.D., Seckin Akgul, Ph.D., Daniel M. Treisman, Ph.D., Brianna R. Pierce, B.S., Cheng-Ying Ho, M.D. /Ph.D.

This work is supported by grants from the National Institutes of Health (2P01 CA085878-10A1, 1R01 NS053900 and R35CA197701).

Vittorio Gallo

Special issue of “Neurochemical Research” honors Vittorio Gallo, Ph.D.

Vittorio Gallo

Investigators from around the world penned manuscripts that were assembled in a special issue of “Neurochemical Research” that honors Vittorio Gallo, Ph.D., for his leadership in the field of neural development and regeneration.

At a pivotal moment early in his career, Vittorio Gallo, Ph.D., was accepted to work with Professor Giulio Levi at the Institute for Cell Biology in Rome, a position that leveraged courses Gallo had taken in neurobiology and neurochemistry, and allowed him to work in the top research institute in Italy directed by the Nobel laureate, Professor Rita Levi-Montalcini.

For four years as a student and later as Levi’s collaborator, Gallo focused on amino acid neurotransmitters in the brain and mechanisms of glutamate and GABA release from nerve terminals. Those early years cemented a research focus on glutamate neurotransmission that would lead to a number of pivotal publications and research collaborations that have spanned decades.

Now, investigators from around the world who have worked most closely with Gallo penned tributes in the form of manuscripts that were assembled in a special issue of “Neurochemical Research” that honors Gallo “for his contributions to our understanding of glutamatergic and GABAergic transmission during brain development and to his leadership in the field of neural development and regeneration,” writes guest editor Arne Schousboe, of the University of Copenhagen in Denmark.

Dr. Gallo as a grad student

Vittorio Gallo, Ph.D. as a 21-year-old mustachioed graduate student.

“In spite of news headlines about competition in research and many of the negative things we hear about the research world, this shows that research is also able to create a community around us,” says Gallo, chief research officer at Children’s National Hospital and scientific director for the Children’s National Research Institute.

As just one example, he first met Schousboe 44 years ago when Gallo was a 21-year-old mustachioed graduate student.

“Research can really create a sense of community that we carry on from the time we are in training, nurture as we meet our colleagues at periodic conferences, and continue up to the present. Creating community is bi-directional: influencing people and being influenced by people. People were willing to contribute these 17 articles because they value me,” Gallo says. “This is a lot of work for the editor and the people who prepared papers for this special issue.”

In addition to Gallo publishing more than 140 peer-reviewed papers, 30 review articles and book chapters, Schousboe notes a number of Gallo’s accomplishments, including:

  • He helped to develop the cerebellar granule cell cultures as a model system to study how electrical activity and voltage-dependent calcium channels modulate granule neuron development and glutamate release.
  • He developed a biochemical/neuropharmacological assay to monitor the effects of GABA receptor modulators on the activity of GABA chloride channels in living neurons.
  • He and Maria Usowicz used patch-clamp recording and single channel analysis to demonstrate for the first time that astrocytes express glutamate-activated channels that display functional properties similar to neuronal counterparts.
  • He characterized one of the spliced isoforms of the AMPA receptor subunit gene Gria4 and demonstrated that this isoform was highly expressed in the cerebellum.
  • He and his Children’s National colleagues demonstrated that glutamate and GABA regulate oligodendrocyte progenitor cell proliferation and differentiation.
Purkinje cells

Purkinje cells are large neurons located in the cerebellum that are elaborately branched like interlocking tree limbs and represent the only source of output for the entire cerebellar cortex.

Even the image selected to grace the special issue’s cover continues the theme of continuity and leaving behind a legacy. That image of Purkinje cells was created by a young scientist who works in Gallo’s lab, Aaron Sathyanesan, Ph.D. Gallo began his career working on the cerebellum – a region of the brain important for motor control – and now studies with a team of scientists and clinician-scientists Purkinje cells’ role in locomotor adaptive behavior and how that is disrupted after neonatal brain injury.

“These cells are the main players in cerebellar circuitry,” Gallo says. “It’s a meaningful image because goes back to my roots as a graduate student and is also an image that someone produced in my lab early in his career. It’s very meaningful to me that Aaron agreed to provide this image for the cover of the special issue.”

bacterial extracellular vesicle

Once overlooked cellular messengers could combat antibiotic resistance

bacterial extracellular vesicle

Children’s National Hospital researchers for the first time have isolated bacterial extracellular vesicles from the blood of healthy donors. The team theorizes that the solar eclipse lookalikes contain important signaling proteins and chromatin, DNA from the human host.

Children’s National Hospital researchers for the first time have isolated bacterial extracellular vesicles from the blood of healthy donors, a critical step to better understanding the way gut bacteria communicate with the rest of the body via the bloodstream.

For decades, researchers considered circulating bacterial extracellular vesicles as bothersome flotsam to be jettisoned as they sought to tease out how bacteria that reside in the gut whisper messages to the brain.

There is a growing appreciation that extracellular vesicles – particles that cells naturally release – actually facilitate intracellular communication.

“In the past, we thought they were garbage or noise,” says Robert J. Freishtat, M.D., MPH, associate director, Center for Genetic Medicine Research at Children’s National Research Institute. “It turns out what we throw away is not trash.”

Kylie Krohmaly, a graduate student in Dr. Freishtat’s laboratory, has isolated from blood, extracellular vesicles from Escherichia coli and Haemophilus influenzae, common bacteria that colonize the gut, and validated the results via electron microscopy.

“The images are interesting because they look like they have a bit of a halo around them or penumbra,” Krohmaly says.

The team theorizes that the solar eclipse lookalikes contain important signaling proteins and chromatin, DNA from the human host.

“It’s the first time anyone has pulled them out of blood. Detecting them is one thing. Pulling them out is a critical step to understanding the language the microbiome uses as it speaks with its human host,” Dr. Freishtat adds.

Krohmaly’s technique is so promising that the Children’s National team filed a provisional patent.

The Children’s research team has devised a way to gum up the cellular works so that bacteria no longer become antibiotic resistant. Targeted bacteria retain the ability to make antibiotic-resistance RNA, but like a relay runner dropping rather than passing a baton, the bacteria are thwarted from advancing beyond that step. And, because that gene is turned off, the bacteria are newly sensitive to antibiotics – instead of resistant bacteria multiplying like clockwork these bacteria get killed.

“Our plan is to hijack this process in order to turn off antibiotic-resistance genes in bacteria,” Dr. Freishtat says. “Ultimately, if a child who has an ear infection can no longer take amoxicillin, the antibiotic would be given in tandem with the bacteria-derived booster to turn off bacteria’s ability to become antibiotic resistant. This one-two punch could become a novel way of addressing the antibiotic resistance process.”

ISEV2020 Annual Meeting presentation
(Timing may be subject to change due to COVID-19 safety precautions)
Oral with poster session 3: Neurological & ID
Saturday May 23, 2020, 5 p.m. to 5:05 p.m. (ET)
“Detection of bacterial extracellular vesicles in blood from healthy volunteers”
Kylie Krohmaly, lead author; Claire Hoptay, co-author; Andrea Hahn, M.D., MS, infectious disease specialist and co-author; Robert J. Freishtat, M.D., MPH, associate director, Center for Genetic Medicine Research at Children’s National Research Institute and senior author.

Hepatocytes

H-IPSE internalized by just a limited range of cells

Hepatocytes

A team led by Children’s National Hospital found that H-IPSE is internalized by just a limited range of cells, including hepatocytes.

Schistosoma mansoni is a parasite that hides out in snails, breaks free into waterways, and then infects humans, spending much of its life inside blood vessels, laying eggs and jeopardizing public health when those eggs are excreted in urine or feces. As parasitic diseases go, the ailment it causes, Schistosomiasis, is second only to malaria in global impact, according to the Centers for Disease Control and Prevention.

In order to elude the human host’s defenses, S. mansoni uses self-defense tactics that researchers are trying to better understand in order to outmaneuver the parasite. A research team led by Children’s National Hospital is trying to tease out the multiple steps that enable this parasite to reproduce and generate millions of eggs without killing its host.

The parasite’s eggs secrete a number of proteins, with IPSE as one of the most abundant, the team recently presented during the American Society of Tropical Medicine and Hygiene 2019 annual meeting. That protein binds immunoglobulin, which induces basophils and mast cells to release IL-4. After sequestering chemokines, H-IPSE infiltrates the cell nucleus (thus H-IPSE is called an infiltrin), modulating gene expression.

“H-IPSE tips the immune system balance, making it more likely to trigger a Th2 anti-inflammatory response,” says Michael Hsieh, M.D., Ph.D., director of transitional urology at Children’s National and the research project’s senior author. “It downregulates pro-inflammatory pathways, but we wanted to know more about which specific human cells it targets.”

Using Trypan Blue, a stain that selectively colors certain cells bright blue, they solved the mystery, finding that H-IPSE is internalized by just a limited range of cells. What’s more, some cell types, like urothelial cells and hepatocytes (the liver’s chief functioning cells, which activate innate immunity), are more susceptible than neurons, endothelial cells or immature dendritic cells.

In addition to Dr. Hsieh, presentation co-authors include Olivia Lamanna, Evaristus Mbanefo and Kenji Ishida, all of Children’s National; Franco Falcone, of University of Nottingham; and Theodore Jardetzky and Luke Pennington, of Stanford University.

mitochondria

Molecular gatekeepers that regulate calcium ions key to muscle function

mitochondria

Controlled entry of calcium ions into the mitochondria, the cell’s energy powerhouses, makes the difference between whether muscles grow strong or easily tire and perish from injury, according to research published in Cell Reports.

Calcium ions are essential to how muscles work effectively, playing a starring role in how and when muscles contract, tap energy stores to keep working and self-repair damage. Not only are calcium ions vital for the repair of injured muscle fibers, their controlled entry into the mitochondria, the cell’s energy powerhouses, spells the difference between whether muscles will be healthy or if they will easily tire and perish following an injury, according to research published Oct. 29, 2019, in Cell Reports.

“Lack of the protein mitochondrial calcium uptake1 (MICU1) lowers the activation threshold for calcium uptake mediated by the mitochondrial calcium uniporter in both, muscle fibers from an experimental model and fibroblast of  a patient lacking MICU1,” says Jyoti K. Jaiswal, MSc, Ph.D., a principal investigator in the Center for Genetic Medicine Research at Children’s National Hospital and one of the paper’s corresponding authors. “Missing MICU1 also tips the calcium ion balance in the mitochondria when muscles contract or are injured, leading to more pronounced muscle weakness and myofiber death.”

Five years ago, patients with a very rare disease linked to mutations in the mitochondrial gene MICU1 were described to suffer from a neuromuscular disease with signs of muscle weakness and damage that could not be fully explained.

To determine what was going awry, the multi-institutional research team used a comprehensive approach that included fibroblasts donated by a patient lacking MICU1 and an experimental model whose MICU1 gene was deleted in the muscles.

Loss of MICU1 in skeletal muscle fibers leads to less contractile force, increased fatigue and diminished capacity to repair damage to their cell membrane, called the sarcolemma. Just like human patients, the experimental model suffers more pronounced muscle weakness, increased numbers of dead myofibers, with greater loss of muscle mass in certain muscles, like the quadriceps and triceps, the research team writes.

“What was happening to the patient’s muscles was a big riddle that our research addressed,” Jaiswal adds. “Lacking this protein is not supposed to make the muscle fiber die, like we see in patients with this rare disease. The missing protein is just supposed to cause atrophy and weakness.”

Patients with this rare disease show early muscle weakness, fluctuating levels of fatigue and lethargy, muscle aches after exercise, and elevated creatine kinase in their bloodstream, an indication of cell damage due to physical stress.

“One by one, we investigated these specific features in experimental models that look normal and have normal body weight, but also show lost muscle mass in the quadriceps and triceps,” explains Adam Horn, Ph.D., the lead researcher in Jaiswal’s lab who conducted this study. “Our experimental model lacking MICU1 only in skeletal muscles responded to muscle deficits so similar to humans that it suggests that some of the symptoms we see in patients can be attributed to MICU1 loss in skeletal muscles.”

Future research will aim to explore the details of how the impact of MICU1 deficit in muscles may be addressed therapeutically and possible implications of lacking MICU1 or its paralog in other organs.

In addition to Jaiswal and Horn, Children’s National Hospital Center for Genetic Medicine Research co-authors include Marshall W. Hogarth and Davi A. Mazala. Additional co-authors include Lead Author Valentina Debattisti, Raghavendra Singh, Erin L. Seifert, Kai Ting Huang, and Senior Author György Hajnóczky, all from Thomas Jefferson University; and Rita Horvath, from Newcastle University.

Financial support for research described in this post was provided by the National Institutes of Health under award numbers R01AR55686, U54HD090257 and RO1 GM102724; National Institute of Arthritis and Musculoskeletal and Skin Diseases under award number T32AR056993; and Foundation Leducq.

Andrea Gropman

$5M in federal funding to help patients with urea cycle disorders

Andrea Gropman

Andrea L. Gropman, M.D.: We have collected many years of longitudinal clinical data, but with this new funding now we can answer questions about these diseases that are meaningful on a day-to-day basis for patients with urea cycle disorders.

An international research consortium co-led by Andrea L. Gropman, M.D., at Children’s National Hospital has received $5 million in federal funding as part of an overall effort to better understand rare diseases and accelerate potential treatments to patients.

Urea cycle disorder, one such rare disease, is a hiccup in a series of biochemical reactions that transform nitrogen into a non-toxic compound, urea. The six enzymes and two carrier/transport molecules that accomplish this essential task reside primarily in the liver and, to a lesser degree, in other organs.

The majority of patients have the recessive form of the disorder, meaning it has skipped a generation. These kids inherit one copy of an abnormal gene from each parent, while the parents themselves were not affected, says Dr. Gropman, chief of the Division of Neurodevelopmental Pediatrics and Neurogenetics at Children’s National. Another more common version of the disease is carried on the X chromosome and affects boys more seriously that girls, given that boys have only one X chromosome.

Regardless of the type of urea cycle disorder, when the urea cycle breaks down, nitrogen converts into toxic ammonia that builds up in the body (hyperammonemia), particularly in the brain. As a result, the person may feel lethargic; if the ammonia in the bloodstream reaches the brain in high concentrations, the person can experience seizures, behavior changes and lapse into a coma.

Improvements in clinical care and the advent of effective medicines have transformed this once deadly disease into a more manageable chronic ailment.

“It’s gratifying that patients diagnosed with urea cycle disorder now are surviving, growing up, becoming young adults and starting families themselves. Twenty to 30 years ago, this never would have seemed conceivable,” Dr. Gropman says. “We have collected many years of longitudinal clinical data, but with this new funding now we can answer questions about these diseases that are meaningful on a day-to-day basis for patients with urea cycle disorders.”

In early October 2019, the National Institutes of Health (NIH) awarded the Urea Cycle Disorders Consortium for which Dr. Gropman is co-principal investigator a five-year grant. This is the fourth time that the international Consortium of physicians, scientists, neuropsychologists, nurses, genetic counselors and researchers has received NIH funding to study this group of conditions.

Dr. Gropman says the current urea cycle research program builds on a sturdy foundation built by previous principal investigators Mendel Tuchman, M.D., and Mark Batshaw, M.D., also funded by the NIH. While previous rounds of NIH funding powered research about patients’ long-term survival prospects and cognitive dysfunction, this next phase of research will explore patients’ long-term health.

Among the topics they will study:

Long-term organ damage. Magnetic resonance elastrography (MRE) is a state-of-the-art imaging technique that combines the sharp images from MRI with a visual map that shows body tissue stiffness. The research team will use MRE to look for early changes in the liver – before patients show any symptoms – that could be associated with long-term health impacts. Their aim is spot the earliest signs of potential liver dysfunction in order to intervene before the patient develops liver fibrosis.

Academic achievement. The research team will examine gaps in academic achievement for patients who appear to be underperforming to determine what is triggering the discrepancy between their potential and actual scholastics. If they uncover issues such as learning difficulties or mental health concerns like anxiety, there are opportunities to intervene to boost academic achievement.

“And if we find many of the patients meet the criteria for depression or anxiety disorders, there are potential opportunities to intervene.  It’s tricky: We need to balance their existing medications with any new ones to ensure that we don’t increase their hyperammonemia risk,” Dr. Gropman explains.

Neurologic complications. The researchers will tap continuous, bedside electroencephalogram, which measures the brain’s electrical activity, to detect silent seizures and otherwise undetectable changes in the brain in an effort to stave off epilepsy, a brain disorder that causes seizures.

“This is really the first time we will examine babies’ brains,” she adds. “Our previous imaging studies looked at kids and adults who were 6 years and older. Now, we’re lowering that age range down to infants. By tracking such images over time, the field has described the trajectory of what normal brain development should look like. We can use that as a background and comparison point.”

In the future, newborns may be screened for urea cycle disorder shortly after birth. Because it is not possible to diagnose it in the womb in cases where there is no family history, the team aims to better counsel families contemplating pregnancy about their possible risks.

Research described in this post was underwritten by the NIH through its Rare Diseases Clinical Research Network.

allopregnanolone molecule

Autism spectrum disorder risk linked to insufficient placental steroid

allopregnanolone molecule

A study led by Children’s National Hospital and presented during Neuroscience 2019 finds that loss of allopregnanolone, a key hormone supplied by the placenta, leads to long-term structural alterations of the cerebellum – a brain region essential for smooth motor coordination, balance and social cognition – and increases the risk of developing autism.

An experimental model study suggests that allopregnanolone, one of many hormones produced by the placenta during pregnancy, is so essential to normal fetal brain development that when provision of that hormone decreases – as occurs with premature birth – offspring are more likely to develop autism-like behaviors, a Children’s National Hospital research team reports at the Neuroscience 2019 annual meeting.

“To our knowledge, no other research team has studied how placental allopregnanolone (ALLO) contributes to brain development and long-term behaviors,” says Claire-Marie Vacher, Ph.D., lead author. “Our study finds that targeted loss of ALLO in the womb leads to long-term structural alterations of the cerebellum – a brain region that is essential for motor coordination, balance and social cognition ­– and increases the risk of developing autism,” Vacher says.

According to the Centers for Disease Control and Prevention, about 1 in 10 infants is born preterm, before 37 weeks gestation; and 1 in 59 children has autism spectrum disorder.

In addition to presenting the abstract, on Monday, Oct. 21, Anna Penn, M.D., Ph.D., the abstract’s senior author, will discuss the research with reporters during a Neuroscience 2019 news conference. This Children’s National abstract is among 14,000 abstracts submitted for the meeting, the world’s largest source of emerging news about brain science and health.

ALLO production by the placenta rises in the second trimester of pregnancy, and levels of the neurosteroid peak as fetuses approach full term.

To investigate what happens when ALLO supplies are disrupted, a research team led by Children’s National created a novel transgenic preclinical model in which they deleted a gene essential in ALLO synthesis. When production of ALLO in the placentas of these experimental models declines, offspring had permanent neurodevelopmental changes in a sex- and region-specific manner.

“From a structural perspective, the most pronounced cerebellar abnormalities appeared in the cerebellum’s white matter,” Vacher adds. “We found increased thickness of the myelin, a lipid-rich insulating layer that protects nerve fibers. From a behavioral perspective, male offspring whose ALLO supply was abruptly reduced exhibited increased repetitive behavior and sociability deficits – two hallmarks in humans of autism spectrum disorder.”

On a positive note, providing a single ALLO injection during pregnancy was enough to avert both the cerebellar abnormalities and the aberrant social behaviors.

The research team is now launching a new area of research focus they call “neuroplacentology” to better understand the role of placenta function on fetal and newborn brain development.

“Our team’s data provide exciting new evidence that underscores the importance of placental hormones on shaping and programming the developing fetal brain,” Vacher notes.

  • Neuroscience 2019 presentation
    Sunday, Oct. 20, 9:30 a.m. (CDT)
    “Preterm ASD risk linked to cerebellar white matter changes”
    Claire-Marie Vacher, lead author; Sonia Sebaoui, co-author; Helene Lacaille, co-author; Jackie Salzbank, co-author; Jiaqi O’Reilly, co-author; Diana Bakalar, co-author; Panagiotis Kratimenos, M.D., neonatologist and co-author; and Anna Penn, M.D., clinical neonatologist and developmental neuroscientist and senior author.
tube labeled "CRISPR"

$2M from NIH to extract meaningful data from CRISPR screens

tube labeled "CRISPR"

Protein-coding genes comprise a mere 1% of DNA. While the other 99% of DNA was once derided as “junk,” it has become increasingly apparent that some non-coding genes enable essential cellular functions.

Wei Li, Ph.D., a principal investigator in the Center for Genetic Medicine Research at Children’s National in Washington, D.C., proposes to develop statistical and computational methods that sidestep existing hurdles that currently complicate genome-wide CRISPR/Cas9 screening. The National Institutes of Health has granted him $2.23 million in funding over five years to facilitate the systematic study of genes, non-coding elements and genetic interactions in various biological systems and disease types.

Right now, a large volume of screening data resides in the public domain, however it is difficult to compare data that is stored in one library with data stored at a different library. Over the course of the five-year project, Li aims to:

  • Improve functional gene identification from CRISPR screens.
  • Develop new analyses algorithms for screens targeting non-coding elements.
  • Study genetic interactions from CRISPR screens targeting gene pairs.

Ultimately, Li’s work will examine a range of disease types. Take cancer.

“There is abundant information already available in the public domain, like the Project Achilles  from the Broad Institute. However, no one is looking to see what is going in inside these tumors,” Li says. “Cancer is a disease of uncontrolled cell growth that makes tumors grow faster.”

Li and colleagues are going to ask which genes control this process by looking at genes that hit the brakes on cell growth as well as genes that pump the gas.

“You knock out one gene and then look: Does the cell grow faster or does it grow more slowly? If the cell grows more slowly, you know you are knocking out a gene that has the potential to stop tumor growth. If cells are growing faster, you know that you’re hitting genes that suppress cancer cell growth.”

In a nutshell, CRISPR (clustered regularly interspaced short palindromic repeats) screens knock out different genes and monitor changes in corresponding cell populations. When CRISPR first became popular, Li decided he wanted to do something with the technology. So, as a Postdoc at Harvard, he developed comprehensive computational algorithms for functional screens using CRISPR/Cas9.

To reach as many people as possible, he offered that MAGeCK/MAGeCK-VISPR software free to as many researchers as possible, providing source code and offering internet tutorials.

“So far, I think there are quite a lot of people using this. There have been more than 40,000 software downloads,” he adds. “It’s really exciting and revolutionary technology and, eventually, we hope the outcomes also will be exciting. We hope to find something really helpful for cancer patients.”

Research reported in this publication was supported by the National Human Genome Research Institute of the National Institutes of Health under award number R01HG010753.

little boy using asthma inhaler

Searching for the molecular underpinnings of asthma exacerbations

little boy using asthma inhaler

It’s long been known that colds, flu and other respiratory illnesses are major triggers for asthma exacerbations, says asthma expert Stephen J. Teach, M.D., MPH. Consequently, a significant body of research has focused on trying to figure out what’s happening on the cellular or molecular level as these illnesses progress to exacerbations.

People with asthma can be indistinguishable from people who don’t have this chronic airway disease – until they have an asthma attack, also known as an exacerbation. During these events, their airways become inflamed and swollen and produce an abundance of mucus, causing dangerous narrowing of the bronchial tubes that leads to coughing, wheezing and trouble breathing. These events are a major cause of morbidity and mortality, leading to the deaths of 10 U.S. residents every day, according to the Centers for Disease Control and Prevention.

It’s long been known that colds, flu and other respiratory illnesses are major triggers for asthma exacerbations, says Children’s National in Washington, D.C., asthma expert Stephen J. Teach, M.D., MPH. Consequently, a significant body of research has focused on trying to figure out what’s happening on the cellular or molecular level as these illnesses progress to exacerbations. Targeted searches have identified several different molecular pathways that appear to be key players in this phenomenon. However, Dr. Teach says researchers have been missing a complete and unbiased snapshot of all the important pathways in illness-triggered exacerbations and how they interrelate.

To develop this big picture view, Dr. Teach and  Inner-City Asthma Consortium colleagues recruited 208 children ages 6-17 years old with severe asthma – marked by the need for daily doses of inhaled corticosteroids, two hospitalizations or systemic corticosteroid treatments over the past year, and a high concentration of asthma-associated immune cells – from nine pediatric medical centers across the country, including Children’s National. (Inhaled corticosteroids are a class of medicine that calms inflamed airways.) The researchers collected samples of nasal secretions and blood from these patients at baseline, when all of them were healthy.

Then, they waited for these children to show symptoms of respiratory illnesses. Within six days of cold symptoms, the researchers took two more samples of nasal secretions and blood. They also administered breathing tests to determine whether these respiratory illnesses led to asthma exacerbations and recorded whether these patients were treated with systemic corticosteroids to stem the associated respiratory inflammation.

The researchers examined nasal fluid samples for evidence of viral infection during illness and used analytical methods to identify the causative virus. They analyzed all the samples they collected for changes in concentrations of various immune cells. They also looked globally in these samples for changes in gene expression compared with baseline and between the two collection periods during respiratory illness.

Together, this information told the molecular story about what took place after these children got sick and after some of them developed exacerbations. Of the 208 patients recruited, 106 got respiratory illnesses during the six-month study period, leading to a total of 154 illness events. Of those, 47 caused exacerbations, and 107 didn’t.

About half the exacerbations appeared to have been triggered by a rhinovirus, a cause of common colds, the research team reports in a study published online April 8, 2019, in Nature Immunology. The other children’s cold-like symptoms could have been triggered by pollution, allergens or other irritants.

In most exacerbations, virally triggered or not, the researchers saw early activation of a network of genes that appeared to be associated with SMAD3, a signaling molecule already known to be involved in airway inflammation. At the same time, genes that control a set of immune cells known as lymphocytes were turned down. However, as the exacerbation progressed and worsened, the researchers saw gene networks turned on that related to airway narrowing, mucus hypersecretion and activation of other immune cells.

Exacerbations triggered by viruses were associated with multiple inflammatory pathways, in contrast to those in which viruses weren’t found, which were associated with molecular pathways that affected cells in the airway lining.

The researchers validated these findings in 19 patients who each got respiratory illnesses at least twice during the study period but only developed an exacerbation during one of these episodes, finding the same upregulated and downregulated molecular pathways in these patients as in the study population as a whole. They also identified a set of molecular risk factors in patients at baseline – signatures of gene activation that appeared to put patients at risk for exacerbations when they got sick. When patients were treated with systemic corticosteroids during exacerbations, these medicines appeared to restore only some of the affected molecular pathways to normal, healthy levels. Other molecular pathways remained markedly changed.

Each finding could represent a new target for drugs that could prevent or more effectively treat exacerbations, keeping more patients with asthma healthy and out of the hospital.

“Our consortium study found increased gene expression of enzymes that produce molecules that contribute to narrowed airways and dilated blood vessels,” Dr. Teach adds. “This is especially intriguing because drugs that target kallikreins or bradykinin may help treat asthma attacks that aren’t caused by viruses.”

In addition to Dr. Teach, study co-authors include Lead Author Matthew C. Altman, University of Washington; Michelle A. Gill, Baomei Shao and Rebecca S. Gruchalla, all of University of Texas Southwestern Medical Center; Elizabeth Whalen and Scott Presnell of Benaroya Research Institute; Denise C. Babineau and Brett Jepson of Rho, Inc.; Andrew H. Liu, Children’s Hospital Colorado; George T. O’Connor, Boston University School of Medicine; Jacqueline A. Pongracic, Ann Robert H. Lurie Children’s Hospital of Chicago; Carolyn M. Kercsmar and Gurjit K. Khurana Hershey, , Cincinnati Children’s Hospital; Edward M. Zoratti and Christine C. Johnson, Henry Ford Health System; Meyer Kattan, Columbia University College of Physicians and Surgeons; Leonard B. Bacharier and Avraham Beigelman, Washington University, St. Louis; Steve M. Sigelman, Peter J. Gergen, Lisa M. Wheatley and Alkis Togias, National Institute of Allergy and Infectious Diseases; and James E. Gern, William W. Busse and Senior author Daniel J. Jackson, University of Wisconsin School of Medicine and Public Health.

Funding for research described in this post was provided by the National Institute of Allergy and Infectious Diseases under award numbers 1UM1AI114271 and UM2AI117870; CTSA under award numbers UL1TR000150, UL1TR001422 and 5UL1TR001425; the National Institutes of Health under award number UL1TR000451;  CTSI under award number 1UL1TR001430; CCTSI under award numbers UL1TR001082 and 5UM1AI114271; and NCATS under award numbers UL1 TR001876 and UL1TR002345.

ID-KD vaccine induced T-cell cytotoxicity

Fighting lethal cancer with a one-two punch

The immune system is the ultimate yin and yang, explains Anthony D. Sandler, M.D., senior vice president and surgeon-in-chief of the Joseph E. Robert Jr. Center for Surgical Care at Children’s National in Washington, D.C. With an ineffective immune system, infections such as the flu or diarrheal illness can run unchecked, causing devastating destruction. But on the other hand, excess immune activity leads to autoimmune diseases, such as lupus or multiple sclerosis. Thus, the immune system has “checks and balances” to stay controlled.

Cancer takes advantage of “the checks and balances,” harnessing the natural brakes that the immune system puts in place to avoid overactivity. As the cancer advances, molecular signals from tumor cells themselves turn on these natural checkpoints, allowing cancers to evade immune attack.

Several years ago, a breakthrough in pharmaceutical science led to a new class of drugs called checkpoint inhibitors. These medicines take those proverbial brakes off the immune system, allowing it to vigorously attack malignancies. However, Dr. Sandler says, these drugs have not worked uniformly and in some cancers, they barely work at all against the cancer.

One of these non-responders is high risk neuroblastoma, a common solid tumor found outside the skull in children. About 800 U.S. children are diagnosed with this cancer every year. And kids who have the high-risk form of neuroblastoma have poor prognoses, regardless of which treatments doctors use.

However, new research could lead to promising ways to fight high-risk neuroblastoma by enabling the immune system to recognize these tumors and spark an immune response. Dr. Sandler and colleagues recently reported on these results in the Jan. 29, 2018, PLOS Medicine using an experimental model of the disease.

The researchers created this model by injecting the preclinical models with cancer cells from an experimental version of neuroblastoma. The researchers then waited several days for the tumors to grow. Samples of these tumors showed that they expressed a protein on their cell surfaces known as PD-L1, a protein that is also expressed in many other types of human cancers to evade immune system detection.

To thwart this protective feature, the researchers made a cancer vaccine by removing cells from the experimental model’s tumors and selectively turning off a gene known as Id2. Then, they irradiated them, a treatment that made these cells visible to the immune system but blocked the cells from dividing to avoid new tumors from developing.

They delivered these cells back to the experimental models, along with two different checkpoint inhibitor drugs – antibodies for proteins known as CLTA-4 and PD-L1 – over the course of three treatments, delivered every three days. Although most checkpoint inhibitors are administered over months to years, this treatment was short-term for the experimental models, Dr. Sandler explains. The preclinical models were completely finished with cancer treatment after just three doses.

Over the next few weeks, the researchers witnessed an astounding turnaround: While experimental models that hadn’t received any treatment uniformly died within 20 days, those that received the combined vaccine and checkpoint inhibitors were all cured of their disease. Furthermore, when the researchers challenged these preclinical models with new cancer cells six months later, no new tumors developed. In essence, Dr. Sandler says, the preclinical models had become immune to neuroblastoma.

Further studies on human patient tumors suggest that this could prove to be a promising treatment for children with high-risk neuroblastoma. The patient samples examined show that while tumors with a low risk profile are typically infiltrated with numerous immune cells, tumors that are high-risk are generally barren of immune cells. That means they’re unlikely to respond to checkpoint inhibiting drugs alone, which require a significant immune presence in the tumor microenvironment. However, Dr. Sandler says, activating an immune response with a custom-made vaccine from tumor cells could spur the immune response necessary to make these stubborn cancers respond to checkpoint inhibitors.

Dr. Sandler cautions that the exact vaccine treatment used in the study won’t be feasible for people. The protocol to make the tumor cells immunogenic is cumbersome and may not be applicable to gene targeting in human patients. However, he and his team are currently working on developing more feasible methods for crafting cancer vaccines for kids. They also have discovered a new immune checkpoint molecule that could make this approach even more effective.

“By letting immune cells do all the work we may eventually be able to provide hope for patients where there was little before,” Dr. Sandler says.

In addition to Dr. Sandler, study co-authors include Priya Srinivasan, Xiaofang Wu, Mousumi Basu and Christopher Rossi, all of the Joseph E. Robert Jr. Center for Surgical Care and The Sheikh Zayed Institute for Pediatric Surgical Innovation (SZI), at Children’s National in Washington, D.C.

Financial support for research described in this post was provided by the EVAN Foundation, the Catherine Blair foundation, the Michael Sandler Research Fund and SZI.

ID-KD vaccine induced T-cell cytotoxicity

Mechanism of Id2kd Neuro2a vaccination combined with α-CTLA-4 and α-PD-L1 immunotherapy in a neuroblastoma model. During a vaccine priming phase, CTLA-4 blockade enhances activation and proliferation of T-cells that express programmed cell death 1 (PD1) and migrate to the tumor. Programmed cell death-ligand 1 (PD-L1) is up-regulated on the tumor cells, inducing adaptive resistance. Blocking PD-L1 allows for enhanced cytotoxic effector function of the CD8+ tumor-infiltrating lymphocytes. Artist: Olivia Abbate

DNA strands on teal background

NUP160 genetic mutation linked to steroid-resistant nephrotic syndrome

DNA strands on teal background

Mutations in the NUP160 gene, which encodes one protein component of the nuclear pore complex nucleoporin 160 kD, are implicated in steroid-resistant nephrotic syndrome, an international team reports March 25, 2019, in the Journal of the American Society of Nephrology. Mutations in this gene have not been associated with steroid-resistant nephrotic syndrome previously.

“Our findings indicate that NUP160 should be included in the gene panel used to diagnose steroid-resistant nephrotic syndrome to identify additional patients with homozygous or compound-heterozygous NUP160 mutations,” says Zhe Han, Ph.D., an associate professor in the Center for Genetic Medicine Research at Children’s National and the study’s senior author.

The kidneys filter blood and ferry waste out of the body via urine. Nephrotic syndrome is a kidney disease caused by disruption of the glomerular filtration barrier, permitting a significant amount of protein to leak into the urine. While some types of nephrotic syndrome can be treated with steroids, the form of the disease that is triggered by genetic mutations does not respond to steroids.

The patient covered in the JASN article had experienced persistently high levels of protein in the urine (proteinuria) from the time she was 7. By age 10, she was admitted to a Shanghai hospital and underwent her first renal biopsy, which showed some kidney damage. Three years later, she had a second renal biopsy showing more pronounced kidney disease. Treatment with the steroid prednisone; cyclophosphamide, a chemotherapy drug; and tripterygium wilfordii glycoside, a traditional therapy, all failed. By age 15, the girl’s condition had worsened and she had end stage renal disease, the last of five stages of chronic kidney disease.

An older brother and older sister had steroid-resistant nephrotic syndrome as well and both died from end stage kidney disease before reaching 17. When she was 16, the girl was able to receive a kidney transplant that saved her life.

Han learned about the family while presenting research findings in China. An attendee of his session said that he suspected an unknown mutation might be responsible for steroid-resistant nephrotic syndrome in this family, and he invited Han to work in collaboration to solve the genetic mystery.

By conducting whole exome sequencing of surviving family members, the research team found that the mother and father each carry one mutated copy of NUP160 and one good copy. Their children inherited one mutated copy from either parent, the variant E803K from the father and the variant R1173X, which causes truncated proteins, from the mother. The woman (now 29) did not have any mutations in genes known to be associated with steroid-resistant nephrotic syndrome.

Some 50 different genes that serve vital roles – including encoding components of the slit diaphragm, actin cytoskeleton proteins and nucleoporins, building blocks of the nuclear pore complex – can trigger steroid-resistant nephrotic syndrome when mutated.

With dozens of possible suspects, they narrowed the list to six variant genes by analyzing minor allele frequency, mutation type, clinical characteristics and other factors.

The NUP160 gene is highly conserved from flies to humans. To prove that NUP160 was the true culprit, Dr. Han’s group silenced the Nup160 gene in nephrocytes, the filtration kidney cells in flies. Nephrocytes share molecular, cellular, structural and functional similarities with human podocytes. Without Nup160, nephrocytes had reduced nuclear volume, nuclear pore complex components were dispersed and nuclear lamin localization was irregular. Adult flies with silenced Nup160 lacked nephrocytes entirely and lived dramatically shorter lifespans.

Significantly, the dramatic structural and functional defects caused by silencing of fly Nup160 gene in nephrocytes could be completely rescued by expressing the wild-type human NUP160 gene, but not by expressing the human NUP160 gene carrying the E803K or R1173X mutation identified from the girl’s  family.

“This study identified new genetic mutations that could lead to steroid-resistant nephrotic syndrome,” Han notes. “In addition, it demonstrates a highly efficient Drosophila-based disease variant functional study system. We call it the ‘Gene Replacement’ system since it replaces a fly gene with a human gene. By comparing the function of the wild-type human gene versus mutant alleles from patients, we could determine exactly how a specific mutation affects the function of a human gene in the context of relevant tissues or cell types. Because of the low cost and high efficiency of the Drosophila system, we can quickly provide much-needed functional data for novel disease-causing genetic variants using this approach.”

In addition to Han, Children’s co-authors include Co-Lead Author Feng Zhao, Co-Lead Author Jun-yi Zhu, Adam Richman, Yulong Fu and Wen Huang, all of the Center for Genetic Medicine Research; Nan Chen and Xiaoxia Pan, Shanghai Jiaotong University School of Medicine; and Cuili Yi, Xiaohua Ding, Si Wang, Ping Wang, Xiaojing Nie, Jun Huang, Yonghui Yang and Zihua Yu, all of Fuzhou Dongfang Hospital.

Financial support for research described in this post was provided by the Nature Science Foundation of Fujian Province of China, under grant 2015J01407; National Nature Science Foundation of China, under grant 81270766; Key Project of Social Development of Fujian Province of China, under grant 2013Y0072; and the National Institutes of Health, under grants DK098410 and HL134940.

Nichole Jefferson and Patrick Gee

African American stakeholders help to perfect the APOLLO study

Nichole Jefferson and Patrick Gee

Nichole Jefferson and Patrick O. Gee

African Americans who either donated a kidney, received a kidney donation, are on dialysis awaiting a kidney transplant or have a close relative in one of those categories are helping to perfect a new study that aims to improve outcomes after kidney transplantation.

The study is called APOLLO, short for APOL1 Long-Term Kidney Transplantation Outcomes Network. Soon, the observational study will begin to enroll people who access transplant centers around the nation to genotype deceased and living African American kidney donors and transplant recipients to assess whether they carry a high-risk APOL1 gene variant.

The study’s Community Advisory Council – African American stakeholders who know the ins and outs of kidney donation, transplantation and dialysis because they’ve either given or  received an organ or are awaiting transplant – are opening the eyes of researchers about the unique views of patients and families.

Already, they’ve sensitized researchers that patients may not be at the same academic level as their clinicians, underscoring the importance of informed consent language that is understandable, approachable and respectful so people aren’t overwhelmed. They have encouraged the use of images and color to explain the apolipoprotein L1 (APOL1) gene. The APOL1 gene is found almost exclusively in people of recent African descent, however only 13 percent of these people carry the high-risk APOL1 variant that might cause kidney problems.

One issue arose early, during one of the group’s first monthly meetings, as they discussed when to tell patients and living donors about the APOLLO study. Someone suggested the day of the transplant.

“The Community Advisory Council told them that would not be appropriate. These conversations should occur well before the day of the transplant,” recalls Nichole Jefferson.

“The person is all ready to give a kidney. If you’re told the day of transplant ‘we’re going to include you in this study,’ that could possibly stop them from giving the organ,” Jefferson says. “We still remember the Tuskegee experiments. We still remember Henrietta Lacks. That is what we are trying to avoid.”

Patrick O. Gee, Ph.D., JLC, another Community Advisory Council member, adds that it’s important to consider “the mental state of the patient and the donor. As a patient, you know you are able to endure a five- to eight-hour surgery. The donor is the recipient’s hero. As the donor, you want to do what is right. But if you get this information; it’s going to cause doubt.”

Gee received his kidney transplant on April 21, 2017, and spent 33 days in the hospital undergoing four surgeries. His new kidney took 47 days to wake up, which he describes as a “very interesting journey.” Jefferson received her first transplant on June 12, 2008. Because that kidney is in failure, she is on the wait list for a new kidney.

“All I’ve ever known before APOLLO was diabetes and cardiovascular issues. Nobody had ever talked about genetics,” Gee adds. “When I tell people, I tread very light. I try to stay in my lane and not to come off as a researcher or a scientist. I just find out information and just share it with them.”

As he spoke during a church function, people began to search for information on their smart phones. He jotted down questions “above his pay grade” to refer to the study’s principal investigator. “When you start talking about genetics and a mutated gene, people really want to find out. That was probably one of the best things I liked about this committee: It allows you to learn, so you can pass it on.”

Jefferson’s encounters are more unstructured, informing people who she meets about her situation and kidney disease. When she traveled from her Des Moines, Iowa, home to Nebraska for a transplant evaluation, the nephrologist there was not aware of the APOL1 gene.

And during a meeting at the Mayo Clinic with a possible living donor, she asked if they would test for the APOL1 gene. “They stopped, looked at me and asked: ‘How do you know about that gene?’ Well, I’m a black woman with kidney failure.”

Patrick O. Gee received his kidney transplant on April 21, 2017, and spent 33 days in the hospital undergoing four surgeries. His new kidney took 47 days to wake up, which he describes as a “very interesting journey.”

About 100,000 U.S. children and adults await a kidney transplant. APOLLO study researchers believe that clarifying the role that the APOL1 gene plays in kidney-transplant failure could lead to fewer discarded kidneys, which could boost the number of available kidneys for patients awaiting transplant.

Gee advocates for other patients and families to volunteer to join the APOLLO Community Advisory Council. He’s still impressed that during the very first in-person gathering, all researchers were asked to leave the table. Only patients and families remained.

“They wanted to hear our voices. You rarely find that level of patient engagement. Normally, you sit there and listen to conversations that are over your head. They have definitely kept us engaged,” he says. “We have spoken the truth, and Dr. Kimmel is forever saying ‘who would want to listen to me about a genotype that doesn’t affect me? We want to hear your voice.’ ”

(Paul L. Kimmel, M.D., MACP, a program director at the National Institute of Diabetes and Digestive and Kidney Diseases, is one of the people overseeing the APOLLO study.)

Jefferson encourages other people personally impacted by kidney disease to participate in the APOLLO study.

“Something Dr. Kimmel always says is ‘You’re in the room.’ We’re in the room while it’s happening. It’s a line from Hamilton. That’s a good feeling,” she says. “I knew right off, these are not necessarily improvements I will see in my lifetime. I am OK with that. With kidney disease, we have not had advances in a long time. As long as my descendants don’t have to go through the same things I have gone through, I figure I have done my part. I have done my job.”

dystrophin protein

Experimental drug shows promise for slowing cardiac disease and inflammation

dystrophin protein

Duchenne muscular dystrophy (DMD) is caused by mutations in the DMD gene, which provides instructions for making dystrophin, a protein found mostly in skeletal, respiratory and heart muscles.

Vamorolone, an experimental medicine under development, appears to combine the beneficial effects of prednisone and eplerenone – standard treatments for Duchenne muscular dystrophy (DMD) – in the heart and muscles, while also showing improved safety in experimental models. The drug does so by simultaneously targeting two nuclear receptors important in regulating inflammation and cardiomyopathy, indicates a small study published online Feb. 11, 2019, in Life Science Alliance.

DMD is a progressive X-linked disease that occurs mostly in males. It is characterized by muscle weakness that worsens over time, and most kids with DMD will use wheelchairs by the time they’re teenagers. DMD is caused by mutations in the DMD gene, which provides instructions for making dystrophin, a protein found mostly in skeletal, respiratory and heart muscles.

Cardiomyopathy, an umbrella term for diseases that weaken the heart, is a leading cause of death for young adults with DMD, causing up to 50 percent of deaths in patients who lack dystrophin. A collaborative research team co-led by Christopher R. Heier, Ph.D., and Christopher F. Spurney, M.D., of Children’s National Health System, is investigating cardiomyopathy in DMD. They find genetic dystrophin loss provides “a second hit” for a specific pathway that worsens cardiomyopathy in experimental models of DMD.

“Some drugs can interact with both the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) since these two drug targets evolved from a common ancestor. However, we find these two drug targets can play distinctly different roles in heart and skeletal muscle. The GR regulates muscle inflammation, while the MR plays a key role in heart health,” says Heier, an assistant professor at Children’s National and lead study author. “In our study, the experimental drug vamorolone safely targets both the GR to treat chronic inflammation and the MR to treat the heart.”

After gauging the efficacy of various treatments in test tubes, the study team looked at whether any could mitigate negative impacts of the MR on heart health. Wild type and mdx experimental models were implanted with pumps that activated the MR. These models also received a daily oral MR antagonist (or inhibitor) drug, and either eplerenone, spironolactone or vamorolone. Of note:

  • MR activation increased kidney size and caused elevated blood pressure (hypertension).
  • Treatment with vamorolone maintained normal kidney size and prevented hypertension.
  • MR activation increased mdx heart mass and fibrosis. Vamorolone mitigated these changes.
  • MR activation decreased mdx heart function, while vamorolone prevented declines in function.
  • Daily prednisone caused negative MR- and GR-mediated side effects, such as hyperinsulinemia, whereas vamorolone safely improved heart function without these side effects.

“These findings have the potential to help current and future patients,” Heier says. “Clinicians already prescribe several of these drugs. Our new data support the use of MR antagonists such as eplerenone in protecting DMD hearts, particularly if patients take prednisone. The experimental drug vamorolone is currently in Phase IIb clinical trials and is particularly exciting for its unique potential to simultaneously treat chronic inflammation and heart pathology with improved safety.”

In addition to Heier and senior author Spurney, study co-authors include Qing Yu, Alyson A. Fiorillo, Christopher B. Tully, Asya Tucker and Davi A. Mazala, all of Children’s National; Kitipong Uaesoontrachoon and Sadish Srinivassane, AGADA Biosciences Inc.; and Jesse M. Damsker, Eric P. Hoffman and Kanneboyina Nagaraju, ReveraGen BioPharma.

Financial support for research described in this report was provided by Action Duchenne; the Clark Charitable Foundation; the Department of Defense under award W81XWH-17-1-047; the Foundation to Eradicate Duchenne; the Intellectual and Developmental Disabilities Research Center under award U54HD090257 (through the National Institutes of Health’s (NIH) Eunice Kennedy Shriver National Institute of Child Health and Human Development); and the NIH under awards K99HL130035, R00HL130035, L40AR068727 and T32AR056993.

Financial disclosure:  Co-authors employed by ReveraGen BioPharma were involved in creating this news release.

DNA moleucle

PAC1R mutation may be linked to severity of social deficits in autism

DNA moleucle

A mutation of the gene PAC1R may be linked to the severity of social deficits experienced by kids with autism spectrum disorder (ASD), finds a study from a multi-institutional research team led by Children’s National faculty. If the pilot findings are corroborated in larger, multi-center studies, the research published online Dec. 17, 2018, in Autism Research represents the first step toward identifying a potential novel biomarker to guide interventions and better predict outcomes for children with autism.

As many as 1 in 40 children are affected by ASD. Symptoms of the disorder – such as not making eye contact, not responding to one’s name when called, an inability to follow a conversation of more than one speaker or incessantly repeating certain words or phrases – usually crop up by the time a child turns 3.

The developmental disorder is believed to be linked, in part, to disrupted circuitry within the amygdala, a brain structure integral for processing social-emotional information. This study reveals that PAC1R is expressed during key periods of brain development when the amygdala – an almond-shaped cluster of neurons – develops and matures. A properly functioning amygdala, along with brain structures like the prefrontal cortex and cerebellum, are crucial to neurotypical social-emotional processing.

“Our study suggests that an individual with autism who is carrying a mutation in PAC1R may have a greater chance of more severe social problems and disrupted functional brain connectivity with the amygdala,” says Joshua G. Corbin, Ph.D., interim director of the Center for Neuroscience Research at Children’s National Health System and the study’s co-senior author. “Our study is one important step along the pathway to developing new biomarkers for autism spectrum disorder and, hopefully, predicting patients’ outcomes.”

The research team’s insights came through investigating multiple lines of evidence:

  • They looked at gene expression in the brains of an experimental model at days 13.5 and 18.5 of fetal development and day 7 of life, dates that correspond with early, mid and late amygdala development. They confirmed that Pac1r is expressed in the experimental model at a critical time frame for brain development that coincides with the timing for altered brain trajectories with ASD.
  • They looked at gene expression in the human brain by mining publicly available genome-wide transcriptome data, plotting median PAC1R expression values for key brain regions. They found high levels of PAC1R expression at multiple ages with higher PAC1R expression in male brains during the fetal period and higher PAC1R expression in female brains during childhood and early adulthood.
  • One hundred twenty-nine patients with ASD aged 6 to 14 were recruited for behavioral assessment. Of the 48 patients who also participated in neuroimaging, 20 were able to stay awake for five minutes without too much movement as the resting state functional magnetic resonance images were captured. Children who were carriers of the high-risk genotype had higher resting-state connectivity between the amygdala and right posterior temporal gyrus. Connectivity alterations in a region of the brain involved in processing visual motion may influence how kids with ASD perceive socially meaningful information, the authors write.
  • Each child also submitted a saliva sample for DNA genotyping. Previously published research finds that a G to C single nucleotide polymorphism, a single swap in the nucleotides that make up DNA, in PAC1R is associated with higher risk for post traumatic stress disorder in girls. In this behavioral assessment, the research team found children with autism who carried the homozygous CC genotype had higher scores as measured through a validated tool, meaning they had greater social deficits than kids with the heterozygous genotype.

All told, the project is the fruit of six years of painstaking research and data collection, say the researchers. That includes banking patients’ saliva samples collected during clinical visits for future retrospective analyses to determine which genetic mutations were correlated with behavioral and functional brain deficits, Corbin adds.

Lauren Kenworthy, who directs our Center for Autism Spectrum Disorders, and I have been talking over the years about how we could bring our programs together. We homed in on this project to look at about a dozen genes to assess correlations and brought in experts from genetics and genomics at Children’s National to sequence genes of interest,” he adds. “Linking the bench to bedside is especially difficult in neuroscience. It takes a huge amount of effort and dozens of discussions, and it’s very rare. It’s an exemplar of what we strive for.”

In addition to Corbin, study co-authors include Lead Author Meredith Goodrich and Maria Jesus Herrero, post-doctoral fellow, Children’s Center for Neuroscience Research; Anna Chelsea Armour and co-Senior Author Lauren Kenworthy, Ph.D., Children’s Center for Autism Spectrum Disorders; Karuna Panchapakesan, Joseph Devaney and Susan Knoblach, Ph.D., Children’s Center for Genetic Medicine Research; Xiaozhen You and Chandan J. Vaidya, Georgetown University; and Catherine A.W. Sullivan and Abha R. Gupta, Yale School of Medicine.

Financial support for the research described in this report was provided by DC-IDDRC under awards HD040677-07 and 1U54HD090257, the Clinical and Translational Science Institute at Children’s National, The Isidore and Bertha Gudelsky Family Foundation and the National Institutes of Health under awards MH083053-01A2 and MH084961.

Andrew Dauber

Andrew Dauber, M.D., joins Children’s National as Chief of Endocrinology

Andrew Dauber

“Researchers, clinicians and medical trainees are pressed for time,” says Andrew Dauber, M.D. “Merging these three arenas into a joint infrastructure powers institutional collaboration and fuels transformative, cutting-edge care.”

Imagine an endocrinology division staffed with endowed researchers, clinicians and specialists, that serves as an engine of innovation, making it easy for pediatricians to make the right referrals, based on the best research, to endocrinologists who can provide families with cutting-edge care.

Andrew Dauber, M.D., MMSc, the new chief of endocrinology at Children’s National, is turning this dream into a reality. Over the next few years, Dr. Dauber will work with a nationally-ranked endocrinology and diabetes center to build a clinical endocrinology research program, housing specialty clinics for Turner’s syndrome, thyroid care and growth disorders, amongst others.

“Researchers, clinicians and medical trainees are pressed for time,” notes Dr. Dauber. “Merging these three arenas into a joint infrastructure powers institutional collaboration and fuels transformative, cutting-edge care.”

To put his real-life hypothesis of providing an engine for innovation into practice, Dr. Dauber led the interdisciplinary growth center at Cincinnati Children’s Hospital Medical Center and organized a Genomics First for Undiagnosed Diseases Program to study genetic clues for undiagnosed diseases. At Boston Children’s Hospital, he was the assistant medical director for the clinical research unit and held academic appointments with Harvard Medical School.

Dr. Dauber finds it’s critically important to merge clinical practice with research and education. He received his medical degree and a Master’s of Medical Sciences in Clinical Investigation from Harvard Medical School. He has published more than 65 studies examining genetic clues to endocrine disorders, with a focus on short stature and growth disorders.

Dr. Dauber conducted the majority of his research – ranging from studying genetic clues for rare growth disorders and causes of precocious puberty to genes that regulate the bioavailability of IGF1, insulin-like growth factor – while counseling patients, advising students and fellows, managing grants, reviewing studies and speaking at international pediatric endocrinology conferences.

He’s harnessing this data by combining genomic insights with electronic health records and patient registries. While some of this information can be used immediately to identify a high-risk patient, other conditions may take years to understand. Dr. Dauber views this as an investment in the future of pediatric endocrinology.

“I’m excited to join Children’s National and to work in Washington, where we can power our city and the nation with premier partnerships and collaboration,” adds Dr. Dauber. “In addition to using genetic clues to investigate growth disorders, we’re just as enthusiastic about investing in and expanding access to youth-focused diabetes education and care.”

The Division of Diabetes and Endocrinology works with the National Institutes of Health, conducts independent research and received support from the Washington Nationals Dream Foundation for its diabetes program, the largest pediatric diabetes program in the region, which provides community education and counsels 1,800 pediatric patients each year.

Cleft lip and palate: caught in the web of genetic interactions

Children’s National research scientists are working to unravel the complicated web of genetic interactions that lead children to develop cleft lip and palate.

On June 26, 2000, scientists around the world hailed the first draft of the human genetic code as a scientific milestone that eventually would revolutionize the practice of medicine. By knowing the approximately 20,000 protein-coding genes for humans, many speculated that researchers and doctors eventually might elucidate the unique factors that influence thousands of diseases—and, someday, make it easier to find custom ways to treat these conditions.

“It is humbling for me and awe inspiring to realize that we have caught the first glimpse of our own instruction book, previously known only to God,” said Francis S. Collins, M.D., Ph.D., who directed the international effort to sequence the human genome and who now directs the National Institutes of Health.

Nearly two decades later, actually using this wealth of information has proven exceedingly more complicated than many envisioned. While some genetic diseases like Huntington’s disease or sickle cell anemia follow a simple pattern in which variations in a single gene lead to deleterious effects, the vast majority of other genetic health problems result from the interaction of multiple genes, from a handful to hundreds.

One condition that has proven especially tricky to understand on the genetic level is cleft lip and palate (CLP), says Youssef A. Kousa, D.O., Ph.D., a pediatric neurology resident at Children’s National Health System who has made human development a central focus of his research program. CLP, which affects about 1 in 1,000 babies born worldwide, can be devastating, Kousa explains. At some point between 6 and 12 weeks gestation, the palate and lip fail to close in some fetuses. Those children are born with a fissure that can significantly impair eating and speaking and that can complicate social interactions.

While researchers have linked some genes to CLP, Kousa says it has become increasingly clear that these genes do not exert their influence in isolation. In a review paper published recently in Developmental Dynamics, he and Brian C. Schutte, Ph.D., of Michigan State University, detail the story of three of those genes. The trio plays a role in CLP but also is implicated in another devastating congenital problem, neural tube defects.

One of these genes is IRF6, which scientists tagged as the gene responsible for inherited forms of CLP called van der Woude syndrome and popliteal pterygium syndrome more than a decade ago. In the interim, research has shown IRF6 also appears to be important in orofacial clefting that occurs independently of these syndromes. Estimates suggest that mutations in IRF6 increase the risk for CLP by 12 percent to 18 percent.

That means at least 80 percent of the risk for clefting is caused by different genes. Kousa and Schutte write that one of these is GRHL3, which also can cause van der Woude syndrome if it is mutated. GRHL3 is regulated by IRF6, Kousa explains. So, if IRF6 does not work properly, neither does GRHL3.

But what regulates IRF6? Upstream of this important gene is another called TFAP2A. The healthy operation of TFAP2A is key for IRF6 and orofacial clefting. Complicating the scenario further, several studies also have shown that TFAP2A is essential for normal development of the palate and neural tube, the embryo’s precursor to the central nervous system that eventually develops into the brain and spinal cord.

To shed light on the interplay of the full array of genes involved CLP, Kousa and colleagues recently published a paper in Birth Defects Research in which they use computer programs to analyze datasets on all genes identified thus far that are involved in orofacial and neural tube development and which molecules these genes produce and target. Their analyses showed that many of these genes are linked in associated pathways that influence vast realms of development, risk of cancer and folate metabolism. (Women who take folic acid supplements before getting pregnant and during pregnancy can reduce birth defect risks.)

By better understanding how these genes are connected into networks, Kousa says, researchers may be able to reduce the risk of both CLP and neural tube defects with a single intervention. However, like the study of genetic diseases itself, finding the right intervention might not be so simple. A drug or supplement that can alleviate one condition might exacerbate others, based on the complicated web of genetic interactions, he says.

“That’s why work from our lab and others is so important,” Kousa says. “It adds layers and layers of knowledge that, eventually, we’ll be able to put together to help prevent these devastating problems.”

Why subtle cellular changes can result in dramatically different genetic disorders

cellular_changes

PDF Version

What’s Known
One single gene, lamin A/C, is to blame for a multitude of genetic disorders, such as premature aging and problems with nerves, the heart, and muscles. Uncertainties linger in the scientific and medical community about why subtle changes of this gene cause such dramatically different disorders, such as Emery-Dreifuss muscular dystrophy, a condition that can lead to progressive muscle weakness in childhood and heart problems by adulthood.

What’s New
The nuclear envelope is where attached regions are pulled from genetic circulation never to be used again. The process of attachment signals which parts of the genome the cell no longer considers useful. Discarding superfluous DNA keeps the cell focused on what matters more: Its future role. Proper cell differentiation hinges on “the coordinated execution of three key cellular programs,” the study authors write. Pluriopotency programs, which give primitive cells the remarkable ability to generate any cell type in the body, are inactivated. Exit from the cell cycle occurs, and cells stop dividing. Myogenesis is induced, ushering in formation of muscle tissue. Mutations in lamin A/C can disrupt this careful choreography with the cumulative effect of slowing exit from cell cycle, slowing exit from pluripotency programs, and poorly coordinating induction of terminal differentiation programs.

Questions for Future Research
Q: What are the regions of human genome that become attached to the nuclear envelope during the development of tissues other than muscle (such as fat, nerve, and heart)?
Q: Can medicines that influence epigenetic pathways help to reverse the inappropriate DNA-lamin associations in Emery-Dreifuss muscular dystrophy?
Q: Can the new knowledge of DNA-lamin associations during muscle cell differentiation help to inform stem cell therapies?

Source:Laminopathies Disrupt Epigenomic Developmental Programs and Cell Fate.” J. Perovanovic, S. Dell’Orso, V.F. Gnochi, J. K. Jaiswal, V. Sartorelli, C. Vigouroux, K. Mamchaoui, V. Mouly, G. Bonne, and E. P. Hoffman. Science Translational Medicine. April 20, 2016.