Biology subjects

Poilbout, C.

Publications and source records attributed to Poilbout, C..

3 recordsLinked to original sources

bioRxiv2024

Prefrontal gamma oscillations and fear extinction learning require early postnatal interneuron-oligodendroglia communication

Emerging evidence links oligodendrocyte (OL) lineage cells and myelin to cognitive processes, yet the role of myelination in shaping neuronal networks critical for cognitive tasks remains unknown. We demonstrate in mice that early postnatal GABAergic signaling between interneurons and oligodendrocyte precursor cells (OPCs) is crucial for myelination of parvalbumin (PV) interneurons, which facilitates in vivo low-gamma oscillations in the medial prefrontal cortex (mPFC) and supports fear extinction learning. Disruption of this signaling results in PV interneuron dysmyelination, decreases low-gamma power, and impairs tone fear extinction. These deficits are specific to PV interneuron dysmyelination, as mPFC myelination, high-gamma oscillations and contextual fear extinction are not significantly altered. Increasing PV interneuron activity or enhancing myelination do not reverse the deficits, indicating the long-term consequences of these early myelination impairments. Our findings reveal the role of OPC GABAergic signaling in PV interneuron myelination and mPFC circuit maturation, with lasting impacts on gamma rhythms and cognition. Brief SummaryEarly postnatal interneuron-oligodendroglia communication may shape neuronal networks underlying cognition. Here, the authors show that disrupting this signaling in mice impairs interneuron myelination, gamma rhythms, and fear-related learning.

neuroscience↗

bioRxiv2024

Circadian regulation of CaV1.2 expression by RORalpha in the mouse heart

BackgroundIn addition to show autonomous beating rhythmicity, the physiological functions of the heart present daily periodic oscillations. Notably the ventricular repolarization itself varies throughout the circadian cycle which was mainly related to the periodic expression of K+ channels. However, the involvement of the L-type Ca2+ channel (CaV1.2 encoded by Cacna1c gene) in these circadian variations remains elusive. MethodsWe used a transgenic mouse model (PCa-luc) that expresses the luciferase reporter under the control of the cardiac Cacna1c promoter and analyzed promoter activity by bioluminescent imaging, qPCR, immunoblot, Chromatin immunoprecipitation assay (ChIP) and CaV1.2 activity. ResultsUnder normal 12:12h light-dark cycle, we observed in vivo a biphasic diurnal variation of promoter activities peaking at 9 and 19.5 Zeitgeber time (ZT). This was associated with a periodicity of Cacna1c mRNA levels preceding 24-h oscillations of CaV1.2 protein levels in ventricle (with a 1.5 h phase shift) but not in atrial heart tissues. The periodicity of promoter activities and CaV1.2 proteins, which correlated with biphasic oscillations of L-type Ca2+ current conductance, persisted in isolated ventricular cardiomyocytes from PCa-Luc mice over the course of the 24-h cycle, suggesting an endogenous cardiac circadian regulation. Comparison of 24-h temporal patterns of clock gene expressions in ventricles and atrial tissues of the same mice revealed conserved circadian oscillations of the core clock genes except for the retinoid-related orphan receptor gene (ROR), which remained constant throughout the course of a day in atrial tissues. In vitro we found that ROR is recruited to two specific regions on the Cacna1c promoter and that incubation with specific ROR inhibitor disrupted 24-h oscillations of ventricular promoter activities and CaV1.2 protein levels. Similar results were observed for pore forming subunits of the K+ transient outward currents, KV4.2 and KV4.3. ConclusionsThese findings raise the possibility that the ROR-dependent rhythmic regulation of cardiac CaV1.2 and KV4.2/4.3 throughout the daily cycle may play an important role in physiopathology of heart function.

physiology↗

bioRxiv2022

Versatile and automated workflow for the analysis of oligodendroglial calcium signals in preclinical mouse models of myelin repair

Intracellular Ca2+ signals of oligodendroglia, the myelin-forming cells of the central nervous system, regulate vital cellular processes including myelination. However, studies on oligodendroglia Ca2+ signal dynamics are still scarce, especially during myelin repair, and there are no software solutions to properly analyze the unique Ca2+ signal characteristics in these cells. Here, we provide a comprehensive experimental and analytical workflow to acquire and analyze Ca2+ imaging data of oligodendroglia at the population and single-cell levels in preclinical mouse models of myelin repair. We report diverse ex vivo and in vivo experimental protocols to obtain reproducible Ca2+ imaging data from oligodendroglia in demyelinated lesions. Importantly, we provide an analytical pipeline containing two free, open source and cross-platform software programs, Occam and post-prOccam, that enable the fully automated analysis of one- and two-photon Ca2+ imaging datasets from oligodendroglia obtained by either ex vivo or in vivo Ca2+ imaging techniques. This versatile and accessible experimental and analytical framework, which revealed significant but uncorrelated spontaneous Ca2+ activity in oligodendroglia inside demyelinated lesions, should facilitate the elucidation of Ca2+-mediated mechanisms underlying remyelination and therefore help to accelerate the development of therapeutic strategies for the many myelin-related disorders, such as multiple sclerosis.

neuroscience↗