Psychiatric risk geneNT5C2regulates protein translation in human neural progenitor cells

AbstractGenome-wide significant variants associated with combined risk for major psychiatric disorders on chromosome 10q24 affect the expression of the cytosolic 5’-nucleotidase II (NT5C2, cN-II) in population controls, implicating it as a psychiatric susceptibility gene. Risk alleles are associated with reduced expression of this gene in the developing and adult brain, but the resulting neurobiological risk mechanisms remain elusive. In this study, we provide further evidence for the association ofNT5C2with psychiatric disorders, and use a functional genetics approach to gain a deeper understanding of the function of this risk gene in the nervous system.NT5C2expression was significantly reduced in thepost-mortembrain of schizophrenia and bipolar disorder patients, and its protein predominately expressed in neurons within the adult brain. Using human neural progenitor cells (hNPCs), we found thatNT5C2expression peaked at the neural progenitor state, where the encoded protein was ubiquitously distributed through the cell.NT5C2knockdown in hNPCs elicited transcriptomic changes associated with protein translation, that were accompanied by regulation of adenosine monophosphate-activated protein kinase (AMPK) signalling and ribosomal protein S6 (rpS6) activity. To identify the effect of reduced neuronalNT5C2expression at a systems level, we knockdown its homologue,CG32549, inDrosophila melanogasterCNS. This elicited impaired climbing behaviour in the model organism. Collectively, our data implicateNT5C2expression in risk for psychiatric disorders and inDrosophila melanogastermotility, and further suggest that risk is mediated via regulation of AMPK signalling and protein translation during early neurodevelopment.