Nav: Home

Study may explain gene's role in major psychiatric disorders

April 26, 2016

A new study shows the death of newborn brain cells may be linked to a genetic risk factor for five major psychiatric diseases, and at the same time shows a compound currently being developed for use in humans may have therapeutic value for these diseases by preventing the cells from dying.

In 2013, the largest genetic study of psychiatric illness to date implicated mutations in the gene called CACNA1C as a risk factor in five major forms of neuropsychiatric disease -- schizophrenia, major depression, bipolar disorder, autism, and attention deficit hyperactivity disorder (ADHD). All the conditions also share the common clinical feature of high anxiety. By recognizing an overlap between several lines of research, scientists at the University of Iowa and Weill Cornell Medicine of Cornell University have now discovered a new and unexpected role for CACNA1C that may explain its association with these neuropsychiatric diseases and provide a new therapeutic target.

The new study, recently published in eNeuro, shows that loss of the CACNA1C gene from the forebrain of mice results in decreased survival of newborn neurons in the hippocampus, one of only two regions in the adult brain where new neurons are continually produced - a process known as neurogenesis. Death of these hippocampal neurons has been linked to a number of psychiatric conditions, including schizophrenia, depression, and anxiety.

"We have identified a new function for one of the most important genes in psychiatric illness," says Andrew Pieper, MD, PhD, co-senior author of the study, professor of psychiatry at the UI Carver College of Medicine and a member of the Pappajohn Biomedical Institute at the UI. "It mediates survival of newborn neurons in the hippocampus, part of the brain that is important in learning and memory, mood and anxiety."

Moreover, the scientists were able to restore normal neurogenesis in mice lacking the CACNA1C gene using a neuroprotective compound called P7C3-A20, which Pieper's group discovered and which is currently under development as a potential therapy for neurodegenerative diseases. The finding suggests that the P7C3 compounds may also be of interest as potential therapies for these neuropsychiatric conditions, which affect millions of people worldwide and which often are difficult to treat.

Pieper's co-lead author, Anjali Rajadhyaksha, associate professor of neuroscience in Pediatrics and the Feil Family Brain and Mind Research Institute at Weill Cornell Medicine and director of the Weill Cornell Autism Research Program, studies the role of the Cav1.2 calcium channel encoded by the CACNA1C gene in reward pathways affected in various neuropsychiatric disorders.

"Genetic risk factors that can disrupt the development and function of brain circuits are believed to contribute to multiple neuropsychiatric disorders. Adult newborn neurons may serve a role in fine-tuning rewarding and environmental experiences, including social cognition, which are disrupted in disorders such as schizophrenia and autism spectrum disorders," Rajadhyaksha says. "The findings of this study provide a direct link between the CACNA1C risk gene and a key cellular deficit, providing a clue into the potential neurobiological basis of CACNA1C-linked disease symptoms."

Several years ago, Rajadhyaksha and Pieper created genetically altered mice that are missing the CACNA1C gene in the forebrain. The team discovered that the animals have very high anxiety.

"That was an exciting finding, because all of the neuropsychiatric diseases in which this gene is implicated are associated with symptoms of anxiety," says Pieper who also holds appointments in the UI Departments of Neurology, Radiation Oncology, Molecular Physiology and Biophysics, the Holden Comprehensive Cancer Center, and the Iowa City VA Health Care System.

By studying neurogenesis in the mice, the research team has now shown that loss of the CACNA1C gene from the forebrain decreases the survival of newborn neurons in the hippocampus - only about half as many hippocampal neurons survive in mice without the gene compared to normal mice. Loss of CACNA1C also reduces production of BDNF, an important brain growth factor that supports neurogenesis.

The findings suggest that loss of the CACNA1C gene disrupts neurogenesis in the hippocampus by lowering the production of BDNF.

Pieper had previously shown that the "P7C3-class" of neuroprotective compounds bolsters neurogenesis in the hippocampus by protecting newborn neurons from cell death. When the team gave the P7C3-A20 compound to mice lacking the CACNA1C gene, neurogenesis was restored back to normal levels. Notably, the cells were protected despite the fact that BDNF levels remained abnormally low, demonstrating that P7C3-A20 bypasses the BDNF deficit and independently rescues hippocampal neurogenesis.

Pieper indicated the next step would be to determine if the P7C3-A20 compound could also ameliorate the anxiety symptoms in the mice. If that proves to be true, it would strengthen the idea that drugs based on this compound might be helpful in treating patients with major forms of psychiatric disease.

"CACNA1C is probably the most important genetic finding in psychiatry. It probably influences a number of psychiatric disorders, most convincingly, bipolar disorder and schizophrenia," says Jimmy Potash, MD, professor and DEO of psychiatry at the UI who was not involved in the study. "Understanding how these genetic effects are manifested in the brain is among the most exciting challenges in psychiatric neuroscience right now."
-end-
In addition to Pieper and Rajadhyaksha, the research team included Anni Lee, Hector De Jesus-Cortes, Zeeba Kabir, Whitney Knobbe, Madeline Orr, Caitlin Burgdorf, Paula Huntington, Latisha McDaniel, Jeremiah Britt, Franz Hoffmann, and Daniel Brat.

The research was supported in part by grants from The Hartwell Foundation, and Weill Cornell Autism Research Program.

University of Iowa Health Care

Related Autism Articles:

Autism risk estimated at 3 to 5% for children whose parents have a sibling with autism
Roughly 3 to 5% of children with an aunt or uncle with autism spectrum disorder (ASD) can also be expected to have ASD, compared to about 1.5% of children in the general population, according to a study funded by the National Institutes of Health.
Adulthood with autism
The independence that comes with growing up can be scary for any teenager, but for young adults with autism spectrum disorder and their caregivers, the transition from adolescence to adulthood can seem particularly daunting.
Brain protein mutation from child with autism causes autism-like behavioral change in mice
A de novo gene mutation that encodes a brain protein in a child with autism has been placed into the brains of mice.
Autism and theory of mind
Theory of mind, or the ability to represent other people's minds as distinct from one's own, can be difficult for people with autism.
Potential biomarker for autism
A study of young children with autism spectrum disorder published in JNeurosci reveals altered brain waves compared to typically developing children during a motor control task.
Autism often associated with multiple new mutations
Most autism cases are in families with no previous history of the disorder.
State laws requiring autism coverage by private insurers led to increases in autism care
A new study led by researchers at the Johns Hopkins Bloomberg School of Public Health has found that the enactment of state laws mandating coverage of autism spectrum disorder (ASD) was followed by sizable increases in insurer-covered ASD care and associated spending.
Autism's gender patterns
Having one child with autism is a well-known risk factor for having another one with the same disorder, but whether and how a sibling's gender influences this risk has remained largely unknown.
Pinpointing the origins of autism
The origins of autism remain mysterious. What areas of the brain are involved, and when do the first signs appear?
Genes, ozone, and autism
Exposure to ozone in the environment puts individuals with high levels of genetic variation at an even higher risk for developing autism than would be expected just by adding the two risk factors together, a new analysis shows.
More Autism News and Autism Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.