New research led by King’s College London has discovered that thousands of DNA sequences originating from ancient viral infections are expressed in the brain, some of which contribute to susceptibility for psychiatric disorders such as schizophrenia, bipolar disorder, and depression. These sequences, known as Human Endogenous Retroviruses (HERVs), were previously thought to be junk DNA but are now understood to play a role in the body. This study, funded by the National Institute for Health and Care Research (NIHR) Maudsley Biomedical Research Centre and the US National Institutes of Health (NIH), is the first to show that specific HERVs expressed in the human brain are linked to psychiatric disorder susceptibility.
Advances in genomics research have enabled scientists to identify where in our DNA these ancient viral sequences are located, providing insights into when they are expressed and what functions they may have. By analyzing data from large genetic studies and autopsy brain samples, the researchers found that some genetic risk variants associated with psychiatric disorders impact the expression of HERVs. The study reported five HERV expression signatures associated with psychiatric disorders, including two linked to schizophrenia, one to both bipolar disorder and schizophrenia, and one to depression.
Dr. Timothy Powell, co-senior author and Senior Lecturer at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London, emphasized the importance of this study’s novel approach to assessing how genetic susceptibility for psychiatric disorders influences the expression of ancient viral sequences in the human genome. The research suggests that these viral sequences may play a more significant role in the human brain than previously believed, with specific HERV expression profiles being associated with an increased susceptibility to certain psychiatric disorders. Despite not yet fully understanding how these HERVs affect brain cells to confer risk, the findings highlight the importance of regulating their expression for brain function.
Dr. Rodrigo Duarte, first author and Research Fellow at the IoPPN, King’s College London, highlighted the genetic component of psychiatric disorders and the incremental contribution of various parts of the genome to susceptibility. The study’s exploration of HERVs led to the identification of five sequences relevant to psychiatric disorders. While the exact mechanisms through which these HERVs affect brain cells are not clear, the study’s results suggest that their expression regulation is crucial for brain function. Dr. Douglas Nixon, co-senior author and researcher at the Feinstein Institutes for Medical Research at Northwell Health in the US, stressed the need for further research to understand the exact functions of HERVs identified in the study and their potential to revolutionize mental health research and improve treatment or diagnosis of psychiatric conditions.