Circadian clocks control the timing of animal behavioral and physiological rhythms. Fruit flies anticipate daily environmental changes and exhibit two peaks of locomotor activity around dawn and dusk. microRNAs are small non-coding RNAs that play important roles in post-transcriptional regulation. Here we identify Drosophila miR-210 as a critical regulator of circadian rhythms. Under light-dark conditions, flies lacking miR-210 ( miR-210 KO ) exhibit a dramatic 2 hrs phase advance of evening anticipatory behavior. However, circadian rhythms and molecular pacemaker function are intact in miR-210 KO flies under constant darkness. Furthermore, we identify that miR-210 determines the evening phase of activity through repression of the cell adhesion molecule Fasciclin 2 (Fas2) . Ablation of the miR-210 binding site within the 3’ UTR of Fas2 ( Fas2 ΔmiR-210 ) by CRISPR-Cas9 advances the evening phase as in miR-210 KO . Indeed, miR-210 genetically interacts with Fas2 . Moreover, Fas2 abundance is significantly increased in the optic lobe of miR-210 KO . In addition, overexpression of Fas2 in the miR-210 expressing cells recapitulates the phase advance behavior phenotype of miR-210 KO . Together, these results reveal a novel mechanism by which miR-210 regulates circadian locomotor behavior.
The thioredoxin system, including NADPH, thioredoxin (Trx), and thioredoxin reductase (TrxR), plays significant roles in maintaining intracellular redox homeostasis and protecting organisms against oxidative damage. In this study, the characteristics and functions of H. armigera HaTrx2 and HaTrxR1 were identified. Sequence analysis showed that HaTrx2 and HaTrxR1 were both highly conserved and shared high sequence identity with other insect counterparts. The mRNA of HaTrx2 was expressed the highest in 5th instar 96 h and was mainly detected in heads and epidermis. The expression of HaTrxR1 was highly concentrated in 5th instar 72 h and 96 h, and higher in malpighian tube, midgut and hemocyte than other examined tissues. HaTrx2 and HaTrxR1 were markedly induced by various types of stress. HaTrx2- or HaTrxR1-knockdown increased ROS production in hemocytes and also increased the lipid damage in NPV infected H. armigera larvae. Furthermore, interference with expression of HaTrx2 or HaTrxR1 transcripts in H. armigera larvae resulted in increased sensitivity to NPV infection and shortened LT50 values. Our findings indicated that HaTrx2 and HaTrxR1 contribute to the susceptibility of H. armigera to NPV and also provided the theoretical basis for the in-depth study of insect thioredoxin system.
: 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.
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