Project description:Rev-erbα/β are druggable components of the molecular circadian clock. Rev-erb agonists can mitigate pressure overload-induced cardiac hypertrophy and myocardial infarction in mice, while Rev-erb antagonist increases myocardial ischemia-reperfusion tolerance ex vivo at the sleep-to-wake transitionHow cardiac Rev-erb regulates heart function has not been studied in vivo. ChIP-seq of Rev-erbα in the heart confirmed the robust diurnal rhythmicity of Rev-erbα genome binding with about 5 times more binding at ZT9 than at ZT21.
Project description:Myocardial ischemia-reperfusion injury (MIRI) is a major threat to heart functional integrity and pharmacological means to achieve cardioprotection are sorely needed. The sequential hypoxic/normoxic status of the cardiac tissue triggers life-threatening damages through the activation of multiple intra-cellular pathways. Heart tolerance to MIRI varies according to a day-night cycle and is regulated by components of the molecular clock such as the transcriptional repressor and nuclear receptor REV-ERBα. Timed REV-ERBα antagonism alleviates sensitivity to myocardial infarction in mice. Here we show that timed administration of digoxin is cardioprotective by triggering REV-ERBα protein degradation. Kinomics and transcriptomic assays revealed that in several cardiomyocyte cellular models, digoxin and other cardiotonic steroids induced multiple signaling pathways. Pharmacological inhibition and knockdown approaches revealed that inhibition of the Src tyrosine-kinase partially alleviated digoxin-induced REV-ERBα degradation, which was fully prevented upon proteasome inhibition. REV-ERBα is increasingly ubiquitinylated in digoxin-treated cells, and its degradation depends on its ability to bind its natural ligand, heme. In unchallenged conditions, the proteasomal degradation of REV-ERBα is controlled by several known (HUWE1, FXW7, SIAH2) or novel (CBL, UBE4B)E3 ubiquitin ligases. Only SIAH2 together with the proteasome subunit PSMB5 were found tocontribute to the digoxin-induced degradation of REV-ERBα. Taken together, these results show that controlling REV-ERBα proteostasis is an appealing cardioprotective strategy, and bring further support to the rationale, timed use of CTS in prophylactic cardiac preconditioning to MIRI.
Project description:Myocardial ischemia-reperfusion injury (MIRI) is a major threat to heart functional integrity and pharmacological means to achieve cardioprotection are sorely needed. The sequential hypoxic/normoxic status of the cardiac tissue triggers life-threatening damages through the activation of multiple intra-cellular pathways. Heart tolerance to MIRI varies according to a day-night cycle and is regulated by components of the molecular clock such as the transcriptional repressor and nuclear receptor REV-ERBα. Timed REV-ERBα antagonism alleviates sensitivity to myocardial infarction in mice. Here we show that timed administration of digoxin is cardioprotective by triggering REV-ERBα protein degradation and involves the anti-apoptotic factor p21. Kinomics and transcriptomic assays revealed that in several cardiomyocyte cellular models, digoxin and other cardiotonic steroids induced multiple signaling pathways at subinotropic doses. Pharmacological inhibition and knockdown approaches revealed that inhibition of phosphatidylinositol 3- and of Src tyrosine-kinase partially alleviated digoxin-induced REV-ERBα degradation, which was fully prevented upon proteasome inhibition. REV44 ERBα is increasingly ubiquitinylated in digoxin-treated cells, and its degradation depends on its ability to bind its natural ligand, heme. In normal conditions, the proteasomal degradation of REV-ERBα is controlled by several known (HUWE1, FXW7, SIAH2) or novel (CBL, UBE4B) E3 ubiquitin ligases. Only SIAH2 together with the proteasome subunit PSMB5 contributed to the digoxin-induced degradation of REV-ERBα. Taken together, these results show that controlling REV-ERBα proteostasis is an appealing cardioprotective strategy, and bring further support to the rationale, timed use of CTS in prophylactic cardiac preconditioning to MIRI.
Project description:Myocardial ischemia-reperfusion injury (MIRI) is a major threat to heart functional integrity and pharmacological means to achieve cardioprotection are sorely needed. The sequential hypoxic/normoxic status of the cardiac tissue triggers life-threatening damages through the activation of multiple intra-cellular pathways. Heart tolerance to MIRI varies according to a day-night cycle and is regulated by components of the molecular clock such as the transcriptional repressor and nuclear receptor REV-ERBα. Timed REV-ERBα antagonism alleviates sensitivity to myocardial infarction in mice. Here we show that timed administration of digoxin is cardioprotective by triggering REV-ERBα protein degradation and involves the anti-apoptotic factor p21. Kinomics and transcriptomic assays revealed that in several cardiomyocyte cellular models, digoxin and other cardiotonic steroids induced multiple signaling pathways at subinotropic doses. Pharmacological inhibition and knockdown approaches revealed that inhibition of phosphatidylinositol 3- and of Src tyrosine-kinase partially alleviated digoxin-induced REV-ERBα degradation, which was fully prevented upon proteasome inhibition. REV44 ERBα is increasingly ubiquitinylated in digoxin-treated cells, and its degradation depends on its ability to bind its natural ligand, heme. In normal conditions, the proteasomal degradation of REV-ERBα is controlled by several known (HUWE1, FXW7, SIAH2) or novel (CBL, UBE4B) E3 ubiquitin ligases. Only SIAH2 together with the proteasome subunit PSMB5 contributed to the digoxin-induced degradation of REV-ERBα. Taken together, these results show that controlling REV-ERBα proteostasis is an appealing cardioprotective strategy, and bring further support to the rationale, timed use of CTS in prophylactic cardiac preconditioning to MIRI.
Project description:Agonists and antagonists of nuclear receptor Rev-erbα/β, key components of the circadian clock, can benefit the heart. Here, we show that mice with cardiomyocyte-specific knockout (KO) of Rev-erbα/β display progressive cardiac dilation and lethal heart failure. Inducible ablation of Rev-erbα/β in adult hearts causes similar phenotypes. Impaired fatty acid oxidation in the KO myocardium, particularly in the light cycle, precedes contractile dysfunctions with a reciprocal overreliance on carbohydrate utilization, particularly in the dark cycle. These findings delineate temporal coordination between clock-mediated anticipation and nutrient-induced response in myocardial metabolism.
Project description:Agonists and antagonists of nuclear receptor Rev-erbα/β, key components of the circadian clock, can benefit the heart. Here, we show that mice with cardiomyocyte-specific knockout (KO) of Rev-erbα/β display progressive cardiac dilation and lethal heart failure. Inducible ablation of Rev-erbα/β in adult hearts causes similar phenotypes. Impaired fatty acid oxidation in the KO myocardium, particularly in the light cycle, precedes contractile dysfunctions with a reciprocal overreliance on carbohydrate utilization, particularly in the dark cycle. These findings delineate temporal coordination between clock-mediated anticipation and nutrient-induced response in myocardial metabolism.
Project description:Alzheimer’s disease is associated with disrupted circadian rhythms and clock gene expression. REV-ERBα (Nr1d1) is a circadian transcriptional repressor involved in the regulation of lipid metabolism and macrophage function. While global REV-ERBα deletion increases microglial activation and mitigates amyloid plaque formation, the cell-autonomous effects of microglial REV-ERBα on tau pathology are unexplored. Here, we show that microglial REV-ERBα deletion enhances inflammatory signaling, disrupts lipid metabolic processes, and causes lipid droplet (LD) accumulation specifically in male microglia. Inflammation and LD accumulation combine to inhibit microglial tau phagocytosis, which can be partially rescued by blockage of lipid droplet formation. Microglial REV-ERBα deletion exacerbates tau aggregation and neuroinflammation in P301S and AAV-P301L tauopathy models in male, but not female mice. These data demonstrate the importance of microglial lipid droplets in tau accumulation and reveal REV-ERBα as a therapeutically accessible, sex-dependent regulator of microglial inflammatory signaling, lipid metabolism, and tauopathy.