AUTHOR=Anna Geo , John Maria , Kannan Nisha N. 

TITLE=miR-277 regulates the phase of circadian activity-rest rhythm in Drosophila melanogaster

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1082866

DOI=10.3389/fphys.2023.1082866

ISSN=1664-042X

ABSTRACT=<p>Circadian clocks temporally organize behaviour and physiology of organisms with a rhythmicity of about 24 h. In <italic>Drosophila</italic>, the circadian clock is composed of mainly four clock genes: <italic>period</italic> (<italic>per</italic>)<italic>, timeless</italic> (<italic>tim</italic>)<italic>, Clock</italic> (<italic>Clk</italic>) and <italic>cycle</italic> (<italic>cyc</italic>) which constitutes the transcription-translation feedback loop. The circadian clock is further regulated via post-transcriptional and post-translational mechanisms among which microRNAs (miRNAs) are well known post-transcriptional regulatory molecules. Here, we identified and characterized the role of miRNA-277 (miR-277) expressed in the clock neurons in regulating the circadian rhythm. Downregulation of miR-277 in the pacemaker neurons expressing circadian neuropeptide, pigment dispersing factor (PDF) advanced the phase of the morning activity peak under 12 h light: 12 h dark cycles (LD) at lower light intensities and these flies exhibited less robust rhythms compared to the controls under constant darkness. In addition, downregulation of miR-277 in the PDF expressing neurons abolished the <italic>Clk</italic> gene transcript oscillation under LD. Our study points to the potential role of miR-277 in fine tuning the <italic>Clk</italic> expression and in maintaining the phase of the circadian rhythm in <italic>Drosophila</italic>.</p>