背景:新生哺乳动物心脏在通过心肌细胞增殖损伤后表现出相当大的再生潜力,而成熟的心肌细胞退出细胞周期并失去再生能力。因此,研究新生心肌细胞增殖和再生的潜在机制对于释放成年哺乳动物心脏修复损伤和心肌损伤后恢复收缩功能的再生潜力至关重要。
方法:制作了Tudor葡萄球菌核酸酶(Tudor-SN)转基因(TG)或心肌细胞特异性敲除小鼠(Myh6-Tudor-SN-/-),以研究Tudor-SN在心尖切除术(AR)后心肌细胞增殖和心脏再生中的作用。从新生小鼠分离的原代心肌细胞用于评估Tudor-SN对心肌细胞增殖的影响。使用亲和纯化和质谱来阐明潜在的机制。H9c2细胞和Tudor-SN过表达或敲除的小鼠心肌被用来评估其对Yes相关蛋白(YAP)磷酸化的影响,在体外和体内。
结果:我们以前确定Tudor-SN是一种细胞周期调节因子,在新生小鼠心肌中高表达,但在成人中下调。我们目前的研究表明,Tudor-SN的持续表达促进和延长新生心肌细胞的增殖,改善心脏功能,并增强新生小鼠左心室心尖部切除的修复能力。始终如一,心肌细胞特异性敲除Tudor-SN损害心脏功能并延迟损伤后恢复。都铎-SN与YAP有联系,在心脏发育和再生中起着重要作用,通过防止大肿瘤抑制因子1(LATS1)和YAP之间的关联来抑制Ser127和Ser397残基的磷酸化,相应地维持YAP的稳定性并促进其核易位,从而增强增殖相关基因的转录。
结论:Tudor-SN调节YAP的磷酸化,因此,在生理条件下增强和延长新生儿心肌细胞的增殖,促进新生儿心脏损伤后的再生。
BACKGROUND: The neonatal mammalian
heart exhibits considerable regenerative potential following injury through cardiomyocyte proliferation, whereas mature cardiomyocytes withdraw from the cell cycle and lose regenerative capacities. Therefore, investigating the mechanisms underlying neonatal cardiomyocyte proliferation and regeneration is crucial for unlocking the regenerative potential of adult mammalian
heart to repair damage and restore contractile function following myocardial injury.
METHODS: The Tudor staphylococcal nuclease (Tudor-SN) transgenic (TG) or cardiomyocyte-specific knockout mice (Myh6-Tudor-SN -/-) were generated to investigate the role of Tudor-SN in cardiomyocyte proliferation and
heart regeneration following apical resection (AR) surgery. Primary cardiomyocytes isolated from neonatal mice were used to assess the influence of Tudor-SN on cardiomyocyte proliferation in vitro. Affinity purification and mass spectrometry were employed to elucidate the underlying mechanism. H9c2 cells and mouse myocardia with either overexpression or knockout of Tudor-SN were utilized to assess its impact on the phosphorylation of Yes-associated protein (YAP), both in vitro and in vivo.
RESULTS: We previously identified Tudor-SN as a cell cycle regulator that is highly expressed in neonatal mice myocardia but downregulated in adults. Our present study demonstrates that sustained expression of Tudor-SN promotes and prolongs the proliferation of neonatal cardiomyocytes, improves cardiac function, and enhances the ability to repair the left ventricular apex resection in neonatal mice. Consistently, cardiomyocyte-specific knockout of Tudor-SN impairs cardiac function and retards recovery after injury. Tudor-SN associates with YAP, which plays important roles in
heart development and regeneration, inhibiting phosphorylation at Ser 127 and Ser 397 residues by preventing the association between Large Tumor Suppressor 1 (LATS1) and YAP, correspondingly maintaining stability and promoting nuclear translocation of YAP to enhance the proliferation-related genes transcription.
CONCLUSIONS: Tudor-SN regulates the phosphorylation of YAP, consequently enhancing and prolonging neonatal cardiomyocyte proliferation under physiological conditions and promoting neonatal
heart regeneration after injury.