2008 NARSAD Independent Investigator Grantee Gustavo Turecki, M.D., Ph.D., of McGill University, led research that has determined that levels of a small molecule, a microRNA called miR-1202, that is only found in humans and other primates, is lower in the brains of depressed individuals as compared to healthy control subjects. MicroRNAs (miRNAs) are fragments of RNA that regulate gene expression, turning genes on and off.
The researchers, at McGill and the University of British Columbia, found that miR-1202 targets the gene encoding a protein called GRM4, which is involved in regulating neurotransmission—the process that enables communication between neurons in the brain—and whose malfunction has been implicated in anxiety-related disorders and depression.
At present, antidepressant treatment is a trial-and-error process. The Turecki team went on to establish that in patients given the antidepressant citalopram, changes in miR-1202 expression levels predicted treatment response. These findings suggest that miR-1202 levels may serve as a biomarker for predicting patient response to antidepressant medications.
“This study highlights the role of miRNAs in neuropsychiatric disorders,” said Dr. Turecki, Head of the Depressive Disorders Program at the Douglas Institute and Director of the McGill Group for Suicide Studies, “and provides further steps toward the development of early diagnostic tools, preventive strategies and effective pharmacological treatment for mood disorders.” The findings were published online on June 8th in Nature Medicine.