Background The neonatal heart maintains its entire regeneration capacity within days after birth. Using quantitative phosphoproteomics technology, we identified that SGK3 (serine/threonine‐protein kinase 3) in the neonatal heart is highly expressed and activated after myocardial infarction. This study aimed to uncover the function and related mechanisms of SGK3 on cardiomyocyte proliferation and cardiac repair after apical resection or ischemia/reperfusion injury. Methods and Results The effect of SGK3 on proliferation and oxygen glucose deprivation/reoxygenation– induced apoptosis in isolated cardiomyocytes was evaluated using cardiomyocyte‐specific SGK3 overexpression or knockdown adenovirus5 vector. In vivo, gain‐ and loss‐of‐function experiments using cardiomyocyte‐specific adeno‐associated virus 9 were performed to determine the effect of SGK3 in cardiomyocyte proliferation and cardiac repair after apical resection or ischemia/reperfusion injury. In vitro, overexpression of SGK3 enhanced, whereas knockdown of SGK3 decreased, the cardiomyocyte proliferation ratio. In vivo, inhibiting the expression of SGK3 shortened the time window of cardiac regeneration after apical resection in neonatal mice, and overexpression of SGK3 significantly promoted myocardial repair and cardiac function recovery after ischemia/reperfusion injury in adult mice. Mechanistically, SGK3 promoted cardiomyocyte regeneration and myocardial repair after cardiac injury by inhibiting GSK‐3β (glycogen synthase kinase‐3β) activity and upregulating β‐catenin expression. SGK3 also upregulated the expression of cell cycle promoting genes G1/S‐specific cyclin‐D1, c‐myc (cellular‐myelocytomatosis viral oncogene), and cdc20 (cell division cycle 20), but downregulated the expression of cell cycle negative regulators cyclin kinase inhibitor P 21 and cyclin kinase inhibitor P 27. Conclusions Our study reveals a key role of SGK3 on cardiac repair after apical resection or ischemia/reperfusion injury, which may reopen a novel therapeutic option for myocardial infarction.

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Abnormalities in programmed cell death (PCD) signaling cascades can be observed in the development and progression of various cardiovascular diseases, such as apoptosis, necrosis, pyroptosis, ferroptosis, and cell death associated with autophagy. Aberrant activation of PCD pathways is a common feature leading to excessive cardiac remodeling and heart failure, involved in the pathogenesis of various cardiovascular diseases. Conversely, timely activation of PCD remodels cardiac structure and function after injury in a spatially or temporally restricted manner and corrects cardiac development similarly. As many cardiovascular diseases exhibit abnormalities in PCD pathways, drugs that can inhibit or modulate PCD may be critical in future therapeutic strategies. In this review, we briefly describe the process of various types of PCD and their roles in the occurrence and development of cardiovascular diseases. We also discuss the interplay between different cell death signaling cascades and summarize pharmaceutical agents targeting key players in cell death signaling pathways that have progressed to clinical trials. Ultimately a better understanding of PCD involved in cardiovascular diseases may lead to new avenues for therapy.

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Purpose This research aimed to investigate the correlation between androgenic alopecia (AGA) and coronary artery disease (CAD) and analyze its value in predicting the severity of coronary atherosclerosis in the Han Chinese male population. Patients and Methods A total of 402 Han Chinese male patients aged 28–75 years were enrolled and performed coronary angiography (CAG) after admission. According to the BASP classification, the participants were divided into mild, moderate and severe AGA. CAD was determined via CAG and defined as stenosis of ≥50% in at least one major coronary artery, and the Gensini score was calculated to evaluate the severity of coronary atherosclerosis. Results In this study, CAD status ( P = 0.002), dyslipidemia status ( P = 0.002), age ( P = 0.003) and coronary atherosclerosis severity ( P < 0.001) were different in patients with different levels of AGA. Multivariate logistic regression analysis revealed that severe AGA was independently correlated to CAD risk (OR, 2.111; 95% CI 1.152 to 3.870, P = 0.016), while the relative CAD risk of early-onset AGA was 2.292 (OR, 2.292; 95% CI 1.132 to 4.640, P = 0.021). AGA status (OR, 2.247; 95% CI 1.396 to 3.617, P = 0.001), severe AGA (OR, 2.360; 95% CI 1.506 to 3.699, P < 0.001) and early-onset AGA (OR, 3.474; 95% CI 2.069 to 5.832, P < 0.001) were all independently associated with the severity of coronary atherosclerosis. The area under the receiver operating characteristic (ROC) curve plotted using severe AGA was 0.601, which is predictive of severe coronary atherosclerosis. Moreover, the presence of severe AGA increases the risk of developing CAD associated with obesity (SI = 1.663, SIM = 1.222, AP = 0.289), diabetes (SI = 2.239, SIM = 1.149, AP = 0.503) and dyslipidemia (SI = 1.062, SIM = 0.646, AP = 0.045). Conclusion This study suggested that AGA is independently associated with CAD in a Han Chinese male population. AGA may be a simple and feasible method for screening CAD and indicative of the severity of coronary atherosclerosis.

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The mammalian heart possesses entire regeneration capacity after birth, which is lost in adulthood. The role of the kinase network in myocardial regeneration remains largely elusive. SGK3 (threonine-protein kinase 3) is a functional kinase we identified previously with the capacity to promote cardiomyocyte proliferation and cardiac repair after myocardial infarction. However, the upstream signals regulating SGK3 are still unknown. Based on the quantitative phosphoproteomics data and pulldown assay, we identified cyclin-dependent kinase 9 (CDK9) as a novel therapeutic target in regeneration therapy. The direct combination between CDK9 and SGK3 was further confirmed by co-immunoprecipitation (Co-IP). CDK9 is highly expressed in the newborn period and rarely detected in the adult myocardium. In vitro, the proliferation ratio of primary cardiomyocytes was significantly elevated by CDK9 overexpression while inhibited by CDK9 knockdown. In vivo, inhibition of CDK9 shortened the time window of cardiac regeneration after apical resection (AR) in neonatal mice, while overexpression of CDK9 significantly promoted mature cardiomyocytes (CMs) to re-enter the cell cycle and cardiac repair after myocardial infarction (MI) in adult mice. Mechanistically, CDK9 promoted cardiac repair by directly activating SGK3 and downstream GSK-3β/β-catenin pathway. Consequently, our study indicated that CDK9 might be a novel target for MI therapy by stimulating myocardial regeneration.

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