Journal Article

A direct regulatory link between microRNA-137 and SHANK2: implications for neuropsychiatric disorders

de Sena Cortabitarte, Ana, Cristian, Flavia-Bianca, Fischer, Christine, Berkel, Simone, Rappold, Gudrun A.

2018

Overview

Background Mutations in the SHANK genes, which encode postsynaptic scaffolding proteins, have been linked to a spectrum of neurodevelopmental disorders. The SHANK genes and the schizophrenia-associated microRNA-137 show convergence on several levels, as they are both expressed at the synapse, influence neuronal development, and have a strong link to neurodevelopmental and neuropsychiatric disorders like intellectual disability, autism, and schizophrenia. This compiled evidence raised the question if the SHANKs might be targets of miR-137. Methods In silico analysis revealed a putative binding site for microRNA-137 (miR-137) in the SHANK2 3′UTR, while this was not the case for SHANK1 and SHANK3 . Luciferase reporter assays were performed by overexpressing wild type and mutated SHANK2-3′UTR and miR-137 in human neuroblastoma cells and mouse primary hippocampal neurons. miR-137 was also overexpressed or inhibited in hippocampal neurons, and Shank2 expression was analyzed by quantitative real-time PCR and Western blot. Additionally, expression levels of experimentally validated miR-137 target genes were analyzed in the dorsolateral prefrontal cortex (DLPFC) of schizophrenia and control individuals using the RNA-Seq data from the CommonMind Consortium. Results miR-137 directly targets the 3′UTR of SHANK2 in a site-specific manner. Overexpression of miR-137 in mouse primary hippocampal neurons significantly lowered endogenous Shank2 protein levels without detectable influence on mRNA levels. Conversely, miR-137 inhibition increased Shank2 protein expression, indicating that miR-137 regulates SHANK2 expression by repressing protein translation rather than inducing mRNA degradation. To find out if the miR-137 signaling network is altered in schizophrenia, we compared miR-137 precursor and miR-137 target gene expression in the DLPFC of schizophrenia and control individuals using the CommonMind Consortium RNA sequencing data. Differential expression of 23% (16/69) of known miR-137 target genes was detected in the DLPFC of schizophrenia individuals compared with controls. We propose that in further targets (e.g., SHANK2 , as described in this paper) which are not regulated on RNA level, effects may only be detectable on protein level. Conclusion Our study provides evidence that a direct regulatory link exists between miR-137 and SHANK2 and supports the finding that miR-137 signaling might be altered in schizophrenia.

• Publisher: BioMed Central,BioMed Central Ltd,BMC
• Subject: 3' Untranslated Regions / Animals / Autism / Binding Sites / Biomedical and Life Sciences / Biomedicine / Cell Line, Tumor / Development and progression / Gene Expression Regulation / Genetic aspects / Hippocampus - metabolism / Human Genetics / Humans / Intellectual disability / Mice / MicroRNA / MicroRNAs - chemistry / MicroRNAs - metabolism / miR-137 / Nerve Tissue Proteins - chemistry / Nerve Tissue Proteins - metabolism / Nervous system diseases / Neurology / Neurons - metabolism / Neuropsychology / Neurosciences / Pediatrics / Physiological aspects / Prefrontal Cortex - metabolism / Primary Cell Culture / Psychiatry / Risk factors / Schizophrenia / Schizophrenia - genetics / Schizophrenia - metabolism / SHANK2