MiR-263b Controls Circadian Behavior and the Structural Plasticity of Pacemaker Neurons by Regulating the LIM-Only Protein Beadex.

Xiaoge Nian,Wenfeng Chen,Zhangwu Zhao,Weiwei Bai,Yong Zhang

doi:10.3390/cells8080923

Xiaoge Nian, Wenfeng Chen + Show 3 more

Open Access

https://doi.org/10.3390/cells8080923

Copy DOI

Abstract

Circadian clocks drive rhythmic physiology and behavior to allow adaption to daily environmental changes. In Drosophila, the small ventral lateral neurons (sLNvs) are primary pacemakers that control circadian rhythms. Circadian changes are observed in the dorsal axonal projections of the sLNvs, but their physiological importance and the underlying mechanism are unclear. Here, we identified miR-263b as an important regulator of circadian rhythms and structural plasticity of sLNvs in Drosophila. Depletion of miR-263b (miR-263bKO) in flies dramatically impaired locomotor rhythms under constant darkness. Indeed, miR-263b is required for the structural plasticity of sLNvs. miR-263b regulates circadian rhythms through inhibition of expression of the LIM-only protein Beadex (Bx). Consistently, overexpression of Bx or loss-of-function mutation (BxhdpR26) phenocopied miR-263bKO and miR-263b overexpression in behavior and molecular characteristics. In addition, mutating the miR-263b binding sites in the Bx 3′ UTR using CRISPR/Cas9 recapitulated the circadian phenotypes of miR-263bKO flies. Together, these results establish miR-263b as an important regulator of circadian locomotor behavior and structural plasticity.

Highlights

Circadian clocks are intracellular pacemakers that generate approximately 24-h rhythms of behavior and physiology in most organisms
To examine whether the impaired circadian locomotor rhythmicity in miR-263bKO flies is due to a defect in the molecular pacemaker or in the circadian output pathway, we examined the oscillation of the key pacemaker protein PER in days in constant darkness (DD) in three important groups of circadian neurons: small LNvs (sLNvs), LNds, and DN1s
To test the hypothesis that miR-263b controls the circadian plasticity of pigment dispersing factor (PDF)-positive projections, we examined the termini of sLNv dorsal projections in miR-263KO flies with a PDF-specific antibody at early day (Zeitgeber time 2 (ZT2), ZT0 is light on and ZT12 is light off) and early night (ZT14)

Summary

Introduction

Circadian clocks are intracellular pacemakers that generate approximately 24-h rhythms of behavior and physiology in most organisms. The core circadian oscillator consists of a conserved autoregulatory transcriptional–translational negative feedback loop [1,2,3]. The fruit fly, Drosophila melanogaster, serves as a great model in dissecting the molecular and neuronal mechanisms of circadian clocks [2,3,4]. In Drosophila, transcription factors CLOCK (CLK) and CYCLE (CYC). Activate the rhythmic transcription of clock-controlled genes. Is a key repressor in the core circadian negative feedback loop that inhibits CLK/CYC activity and represses per transcription. Post-translational modifications such as phosphorylation, glycosylation, and ubiquitination play important roles in setting the pace of circadian clock [2,5,6,7,8,9]

Objectives

Methods

Findings

Conclusion