Getting a damaged optic nerve to regenerate is vital to restoring vision in people blinded through nerve trauma or disease. A variety of growth-promoting factors have been shown to help the optic nerve’s retinal ganglion cells regenerate their axons, but we are still far from restoring vision. A new study published yesterday in Neuron underscores the complexity of the problem.
A research team led by Fengfeng Bei, PhD, of Brigham and Women’s Hospital, Zhigang He, PhD, and Michael Norsworthy, PhD, of Boston Children’s Hospital, and Giovanni Coppola, MD, of UCLA conducted a screen for transcription factors that regulate the early differentiation of RGCs, when axon growth is initiated. While one factor, SOX11, appeared to be critical in helping certain kinds of RGCs regenerate their axons, it simultaneously killed another type — alpha-RGCS (above)— when tested in a mouse model.
At least 30 types of retinal ganglion cell message the brain via the optic nerve. “The goal will be to regenerate as many subtypes of neurons as possible,” says Bei. “Our results here suggest that different subtypes of neurons may respond differently to the same factors.”
The ongoing opioid epidemic underscores the dire need for new pain medications that aren’t addicting. New research published today in Nature Medicine suggests a possible avenue of relief for people with chronic pain: simply getting more sleep, or, failing that, taking medications to promote wakefulness.
In an unusually rigorous mouse study, either approach relieved pain better than ibuprofen or even morphine. The findings reveal an unexpected role for alertness in setting pain sensitivity. …
A study of tuberous sclerosis, a syndrome associated with autism, suggests a new treatment approach that could extend to other forms of autism.
The genetic disorder tuberous sclerosis complex (TSC) causes autism in about half of the children affected. Because its genetics are well defined, TSC offers a window into the cellular and network-level perturbations in the brain that lead to autism. A study published today by Cell Reports cracks the window open further, in an intriguing new way. It documents a defect in a basic housekeeping system cells use to recycle and renew their mitochondria.
Mitochondria are the organelles responsible for energy production and metabolism in cells. As they age or get damaged, cells digest them through a process known as autophagy (“self-eating”), clearing the way for healthy replacements. (Just this month, research on autophagy earned the Nobel Prize in Physiology or Medicine.)
Mustafa Sahin, MD, PhD, Darius Ebrahimi-Fakhari, MD, PhD, and Afshin Saffari, in Boston Children’s Hospital’s F.M. Kirby Neurobiology Center now report that autophagy goes awry in brain cells affected by TSC. But they also found that two existing medications restored autophagy: the epilepsy drug carbamazepine and drugs known as mTOR inhibitors. The findings may hold relevance not just for TSC but possibly for other forms of autism and some other neurologic disorders. …
A quick look at recent research Vector finds noteworthy.
Tracking infants’ microbiomes
Microbiome studies are blooming as rapidly as bacteria in an immunocompromised host. But few studies have been done in children, whose microbiomes are actively forming and vulnerable to outside influences. Two studies in Science Translational Medicine on June 15 tracked infants’ gut microbiomes prospectively over time. The first, led by researchers at the Broad Institute and Massachusetts General Hospital, analyzed DNA from monthly stool samples from 39 Finnish infants, starting at 2 months of age. Over the next three years, 20 of the children received at least one course of antibiotics. Those who were repeatedly dosed had fewer “good” bacteria, including microbes important in training the immune system. Overall, their microbiomes were less diverse and less stable, and their gut microbes had more antibiotic resistance genes, some of which lingered even after antibiotic treatment. Delivery mode (cesarean vs. vaginal) also affected microbial diversity. A second study at NYU Langone Medical Center tracked 43 U.S. infants for two years and similarly found disturbances in microbiome development associated with antibiotic treatment, delivery by cesarean section and formula feeding versus breastfeeding. …
To the eye, nervous systems look like a tangled mess of neurons and their tree-like branches known as dendrites, but it’s really organized chaos. How the system finds order has intrigued but eluded scientists. In the worm C. elegans, Max Heiman, PhD and graduate student Candice Yip found an elegant system to help explain how neurons each maintain their own space.
Normally, worms have just one neuron of a certain type on either side of their bodies. Yip did a “forward genetic screen” — mutating genes at random to find factors important for neuron wiring. One mutation caused the worm to grow not one set of neurons but five. By engineering the neurons to make a color-changing signal — as shown above — Yip showed that these extra neurons didn’t overlap with each other, but instead carved out discrete territories — a phenomenon known as tiling. How?
Acting on a hunch, Yip and Heiman, of Harvard Medical School and Boston Children’s Hospital’s Division of Genetics and Genomics, showed that C. elegans, faced with an increase in neurons, pressed a molecule called netrin into service to enforce boundaries between them. Netrin is better known for helping nerve fibers navigate to their destinations. When Yip took netrin out of action, the dendrites from the five neurons crossed the invisible borders and grew entangled.
The findings, published today in Cell Reports, could provide insight into neuropsychiatric diseases, believes Heiman, also part of Boston Children’s F.M. Kirby Neurobiology Center. “It’s fundamental to neuropsychiatric disease to make sure brain wiring goes right,” he says. “This is also story about how new features evolve, and how you can form something as complicated as a nervous system. There are pathways that bring everything into order.”
Nine-year-old Haley Hilt has had intractable seizures all her life. Though she cannot speak, she communicates volumes with her eyes. Using a tablet she controls with her gaze, she can tell her parents when her head hurts and has shown that she knows her letters, numbers and shapes.
Haley is one of a growing group of children who are advancing the science around CDKL5 epilepsy, Haley’s newly recognized genetic disorder. When Boston Children’s Hospital geneticist Joan Stoler, MD, diagnosed Haley in 2009, there were perhaps 100 cases known in the world; today, there are estimated to be a few thousand. Haley’s neurologist, Heather Olson, MD, leads a CDKL5 Center of Excellence at the hospital that is bringing the condition into better view. …
A deep genetic analysis, involving nearly 65,000 people, finds a surprising risk factor for schizophrenia: variation in an immune molecule best known for its role in containing infection, known as complement component 4 or C4.
The findings, published this week in Nature, also support the emerging idea that schizophrenia is a disease of synaptic pruning, and could lead to much-needed new approaches to this elusive, devastating illness. …
When Zhigang He, PhD, started a lab at Boston Children’s Hospital 15 years ago, he hoped to find a way to regenerate nerve fibers in people with spinal cord injury. As a proxy, he studied optic nerve injury, which causes blindness in glaucoma — a condition affecting more than four million Americans — and sometimes in head trauma.
By experimenting with different growth-promoting genes and blocking natural growth inhibitors, he was able to get optic nerve fibers, or axons, to grow to greater and greater lengths in mice. But what about vision? Could the animals see? …
As far back as she can remember, neuroscientist Beth Stevens, PhD, of the Boston Children’s Hospital Department of Neurology and the F.M. Kirby Neurobiology Center, has loved science. The concept of a career in the field began to take root in high school, nurtured in part by her biology teacher — a scientist on the side — who was both encouraging and inspiring.
Today, Stevens, winner of the 2015 MacArthur “genius” grant for her groundbreaking research on microglia cells, is doing her part to inspire a new generation of scientists and show them, as she says, “Scientists aren’t just nerdy guys in white coats.”
Hover over the objects in Stevens’s office to learn more about her work, life and innovations, and read more about her science.
When 2015 MacArthur “genius” grant winner Beth Stevens, PhD, began studying the role of glia in the brain in the 1990s, these cells—“glue” from the Greek—weren’t given much thought. Traditionally, glia were thought to merely protect and support neurons, the brain’s real players.
But Stevens, from the Department of Neurology and the F.M. Kirby Neurobiology Center at Boston Children’s Hospital, has made the case that glia are key actors in the brain, not just caretakers. Her work—at the interface between the nervous and immune systems—is helping transform how neurologic disorders like autism, amyotrophic lateral sclerosis (ALS), Alzheimer’s disease and schizophrenia are viewed. …