Transcriptional targets of the schizophrenia risk gene MIR137

Genome-wide association studies (GWAS) have strongly implicated MIR137 (the gene encoding the microRNA miR-137) in schizophrenia. A parsimonious hypothesis is that a pathway regulated by miR-137 is important in the etiology of schizophrenia. Full evaluation of this hypothesis requires more definitive knowledge about biological targets of miR-137, which is currently lacking. Our goals were to expand knowledge of the biology of miR-137 by identifying its empirical targets, and to test whether the resulting lists of direct and indirect targets were enriched for genes and pathways involved in risk for schizophrenia. We overexpressed miR-137 in a human neural stem cell line and analyzed gene expression changes at 24 and 48 h using RNA sequencing. Following miR-137 overexpression, 202 and 428 genes were differentially expressed after 24 and 48 h. Genes differentially expressed at 24 h were enriched for transcription factors and cell cycle genes, and differential expression at 48 h affected a wider variety of pathways. Pathways implicated in schizophrenia were upregulated in the 48 h findings (major histocompatibility complex, synapses, FMRP interacting RNAs and calcium channels). Critically, differentially expressed genes at 48 h were enriched for smaller association P-values in the largest published schizophrenia GWAS. This work provides empirical support for a role of miR-137 in the etiology of schizophrenia.