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Genetic disruption of the cardiomyocyte circadian clock differentially influences insulin-mediated processes in the heart
Journal article   Open access   Peer reviewed

Genetic disruption of the cardiomyocyte circadian clock differentially influences insulin-mediated processes in the heart

Graham R McGinnis, Yawen Tang, Rachel A Brewer, Manoja K Brahma, Haley L Stanley, Gobinath Shanmugam, Namakkal Soorappan Rajasekaran, Glenn C Rowe, Stuart J Frank, Adam R Wende, …
Journal of molecular and cellular cardiology, Vol.110, pp.80-95
09/2017
DOI: 10.1016/j.yjmcc.2017.07.005
PMCID: PMC5586500
PMID: 28736261
url
https://www.ncbi.nlm.nih.gov/pmc/articles/5586500View
Open Access

Abstract

Cardiovascular physiology exhibits time-of-day-dependent oscillations, which are mediated by both extrinsic (e.g., environment/behavior) and intrinsic (e.g., circadian clock) factors. Disruption of circadian rhythms negatively affects multiple cardiometabolic parameters. Recent studies suggest that the cardiomyocyte circadian clock directly modulates responsiveness of the heart to metabolic stimuli (e.g., fatty acids) and stresses (e.g., ischemia/reperfusion). The aim of this study was to determine whether genetic disruption of the cardiomyocyte circadian clock impacts insulin-regulated pathways in the heart. Genetic disruption of the circadian clock in cardiomyocyte-specific Bmal1 knockout (CBK) and cardiomyocyte-specific Clock mutant (CCM) mice altered expression (gene and protein) of multiple insulin signaling components in the heart, including p85α and Akt. Both baseline and insulin-mediated Akt activation was augmented in CBK and CCM hearts (relative to littermate controls). However, insulin-mediated glucose utilization (both oxidative and non-oxidative) and AS160 phosphorylation were attenuated in CBK hearts, potentially secondary to decreased Inhibitor-1. Consistent with increased Akt activation in CBK hearts, mTOR signaling was persistently increased, which was associated with attenuation of autophagy, augmented rates of protein synthesis, and hypertrophy. Importantly, pharmacological inhibition of mTOR (rapamycin; 10days) normalized cardiac size in CBK mice. These data suggest that disruption of cardiomyocyte circadian clock differentially influences insulin-regulated processes, and provide new insights into potential pathologic mediators following circadian disruption. •Cardiomyocyte clock disruption differentially influences insulin signaling proteins.•Cardiomyocyte clock disruption attenuates glucose utilization.•Cardiomyocyte clock disruption attenuates autophagy.•Cardiomyocyte clock disruption augments protein synthesis.
Metabolism Circadian rhythm Hypertrophy Insulin signaling

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