Fewer rhythmic genes were detected in mice subjected to long , with gene expression rhythms advanced by 4-6 hours.
The central in mammals is influenced by seasonal daylength through retinal input to the suprachiasmatic nuclei (SCN).
Long photoperiods significantly alter the timing and properties of the SCN clock and its driven rhythms.
RNA sequencing revealed changes in expression for several clock-associated genes and genes related to light responses, neuropeptides, and neurotransmitters.
Notable delays in gene expression were observed for a few specific genes, contrasting with the overall advancements in rhythmic gene expression timing.
Transcriptional changes in certain genes may support neural network reconfiguration in the SCN during photoperiodic entrainment.
The identified gene sets related to the SCN light response and neuropeptide signaling could provide insights into the molecular mechanisms of photoperiod plasticity.
Simplified
Seasonal daylength, or circadian , is a pervasive environmental signal that profoundly influences physiology and behavior. In mammals, the central resides in the suprachiasmatic nuclei (SCN) of the hypothalamus where it receives retinal input and synchronizes, or entrains, organismal physiology and behavior to the prevailing light cycle. The process of entrainment induces sustained plasticity in the SCN, but the molecular mechanisms underlying SCN plasticity are incompletely understood. Entrainment to different photoperiods persistently alters the timing, waveform, period, and light resetting properties of the SCN clock and its driven rhythms. To elucidate novel candidate genes for molecular mechanisms of photoperiod plasticity, we performed RNA sequencing on whole SCN dissected from mice raised in long (light:dark [LD] 16:8) and short (LD 8:16) photoperiods. Fewer rhythmic genes were detected in mice subjected to long photoperiod, and in general, the timing of gene expression rhythms was advanced 4-6 h. However, a few genes showed significant delays, including. There were significant changes in the expression of the clock-associated geneand in SCN genes related to light responses, neuropeptides, gamma aminobutyric acid (GABA), ion channels, and serotonin. Particularly striking were differences in the expression of the neuropeptide signaling genesand, as well as convergent regulation of the expression of 3 SCN light response genes,,, and. Transcriptional modulation ofandand phase regulation ofare compelling candidate molecular mechanisms for plasticity in the SCN light response through their modulation of the critical NMDAR-MAPK/ERK-CREB/CRE light signaling pathway in SCN neurons. Modulation ofandmay critically support SCN neural network reconfiguration during photoperiodic entrainment. Our findings identify the SCN light response and neuropeptide signaling gene sets as rich substrates for elucidating novel mechanisms of photoperiod plasticity. Data are also available at http://circadianphotoperiodseq.com/, where users can view the expression and rhythmic properties of genes across these photoperiod conditions. Gem Timeless Prokr2Cck Dusp4Rasd1Gem Dusp4Rasd1Gem Prokr2Cck
Key numbers
2488
Rhythmic Genes Detected
Out of 16,549 total transcripts analyzed.
1518
Differentially Expressed Genes
Between short and long .
4-6 h
Advanced Gene Expression Timing
In long compared to short.
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Conflict of interest statementThe authors have no potential conflicts of interest with respect to the research, authorship, and/or publication of this article
