MicroRNA-132-Dependent Post-Transcriptional Regulation of Clock Entrainment Physiology Via Modulation of Chromatin Remodeling and Translational Control Gene Targets

Abstract

Mammalian circadian rhythms of behaviour are synchronized to external time by daily resetting of the master pacemaker, the suprachiasmatic nucleus (SCN), in response to light, in a process known as light-induced clock entrainment. microRNA-132 (miR-132) is induced by light within the SCN via a MAPK-CREB-dependent mechanism and has the capacity to attenuate the entraining effects of light. However, the identity of the genes that miR-132 regulates and their roles in the light-entrainment process have not yet been characterized. This thesis describes that 2 gene clusters involved in chromatin remodeling (i.e. Mecp2, Ep300, Jarid1a) and translational control (i.e. Btg2, Paip2a) are under the regulation of miR-132 in the SCN and coordinated regulation of these genes underlies miR132-dependent modulation of mPeriod1 (mPer1) and mPeriod2 (mPer2) and the light-entrainment process. I find that the Period genes are bound and transcriptionally modulated by MeCP2. In addition, Paip2a acts as a repressor of Period translation. This work further proposes that miR-132 is enriched for chromatin and translation-associated target genes-and, thus, miR-132 is an important orchestrator of chromatin remodeling and protein translation within the SCN clock, thereby fine-tuning clock entrainment.