A novel role for GSK3? as a modulator of Drosha microprocessor activity and MicroRNA biogenesis.

ABSTRACT: Regulation of microRNA (miR) biogenesis is complex and stringently controlled. Here, we identify the kinase GSK3? as an important modulator of miR biogenesis at Microprocessor level. Repression of GSK3? activity reduces Drosha activity toward pri-miRs, leading to accumulation of unprocessed pri-miRs and reduction of pre-miRs and mature miRs without altering levels or cellular localisation of miR biogenesis proteins. Conversely, GSK3? activation increases Drosha activity and mature miR accumulation. GSK3? achieves this through promoting Drosha:cofactor and Drosha:pri-miR interactions: it binds to DGCR8 and p72 in the Microprocessor, an effect dependent upon presence of RNA. Indeed, GSK3? itself can immunoprecipitate pri-miRs, suggesting possible RNA-binding capacity. Kinase assays identify the mechanism for GSK3?-enhanced Drosha activity, which requires GSK3? nuclear localisation, as phosphorylation of Drosha at S300 and/or S302; confirmed by enhanced Drosha activity and association with cofactors, and increased abundance of mature miRs in the presence of phospho-mimic Drosha. Functional implications of GSK3?-enhanced miR biogenesis are illustrated by increased levels of GSK3?-upregulated miR targets following GSK3? inhibition. These data, the first to link GSK3? with the miR cascade in humans, highlight a novel pro-biogenesis role for GSK3? in increasing miR biogenesis as a component of the Microprocessor complex with wide-ranging functional consequences.

SUBMITTER: Fletcher CE 

PROVIDER: S-EPMC5389555 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature