Biology subjects

Koike, N.

Publications and source records attributed to Koike, N..

3 recordsLinked to original sources

bioRxiv2021

Non-coding enhancer RNA regulates NPAS4 in the mPFC to control chronic stress-induced anhedonia-like behavior

Chronic stress can produce reward system deficits (i.e. anhedonia) and other common symptoms associated with depressive disorders, as well as neural circuit hypofunction in the medial prefrontal cortex (mPFC). However, the molecular mechanisms by which chronic stress promotes depressive-like behavior and hypofrontality remain unclear. We show here that the neuronal activity-regulated transcription factor, NPAS4, in the mPFC is regulated by chronic social defeat stress (CSDS), and its required in this brain region for CSDS-induced changes in sucrose preference and natural reward motivation. Interestingly, NPAS4 is not required for CSDS-induced social avoidance or anxiety-like behavior. We also find that mPFC NPAS4 is required for CSDS-induced reduction of pyramidal cell dendritic spine density, revealing a relationship between mPFC dendritic spine changes and anhedonia-like behavior, but not social avoidance behavior. Finally, transcriptomic analysis from the mPFC revealed that NPAS4 influences expression of numerous genes linked to glutamatergic synapses and ribosomal function, as well as many dysregulated genes observed in common neuropsychiatric disorders, including depression. Together our findings reveal an essential role for the activity-regulated transcription factor, NPAS4, in chronic stress-induced mPFC hypofunction and anhedonia.

neuroscience↗

bioRxiv2020

CLOCK/BMAL1 interferes with segmentation clock oscillation in mouse embryonic organoids

In mammals, circadian clocks are strictly suppressed during early embryonic stages as well as pluripotent stem cells, by the lack of CLOCK/BMAL1 mediated circadian feedback loops. During ontogenesis, the innate circadian clocks emerge gradually at a late developmental stage, then, with which the circadian temporal order is invested in each cell level throughout a body. Meanwhile, in the early developmental stage, a segmented body plan is essential for an intact developmental process and somitogenesis is controlled by another cell-autonomous oscillator, the segmentation clock, in the posterior presomitic mesoderm (PSM). In the present study, focusing upon the interaction between circadian key components and the segmentation clock, we investigated the effect of the CLOCK/BMAL1 on the segmentation clock Hes7 oscillation, revealing that the expression of functional CLOCK/BMAL1 severely interferes with the ultradian rhythm of segmentation clock in induced PSM and gastruloids. RNA sequencing analysis showed that the premature expression of CLOCK/BMAL1 affects the Hes7 transcription and its regulatory pathways. These results suggest that the suppression of CLOCK/BMAL1-mediated transcriptional regulation during the somitogenesis may be inevitable for intact mammalian development.

developmental biology↗

bioRxiv2020

Natural Antisense Transcript of Period2, Per2AS, regulates the amplitude of the mouse circadian clock

Circadian transcriptome studies identified a novel transcript at the Period2 (Per2) locus, which we named Per2AS. Per2AS is a long non-coding RNA transcribed from the antisense strand of Per2, and is expressed rhythmically and anti-phasic to Per2 mRNA. Previously, we mathematically tested the hypothesis that Per2AS and Per2 mutually inhibit each others expression by forming a double negative feedback loop, and found that Per2AS expands the oscillatory domain. In this study, we have experimentally tested this prediction by perturbing the expression of Per2AS in mouse fibroblasts. We found that Per2AS represses Per2 pre-transcriptionally in cis and regulates the amplitude of the circadian clock, but not period or phase. Unexpectedly, we also found that Per2 positively regulates Per2AS post-transcriptionally, indicating that Per2AS and Per2 form a single negative feedback loop. Because knock-down of Per2 does not recapitulate the phenotypes of Per2AS perturbation and Per2AS also activates Bmal1 in trans, we propose that Per2AS regulates the amplitude of the circadian clock without producing a protein by rewiring the molecular clock circuit.

molecular biology↗