BACKGROUND:Adult mammalian cardiomyocytes have limited proliferative capacity, but in specifically induced contexts they traverse through cell-cycle reentry, offering the potential for heart regeneration. Endogenous cardiomyocyte proliferation is preceded by cardiomyocyte dedifferentiation (CMDD), wherein adult cardiomyocytes revert to a less matured state that is distinct from the classical myocardial fetal stress gene response associated with heart failure. However, very little is known about CMDD as a defined cardiomyocyte cell state in transition.METHODS:Here, we leveraged 2 models of in vitro cultured adult mouse cardiomyocytes and in vivo adeno-associated virus serotype 9 cardiomyocyte–targeted delivery of reprogramming factors (Oct4, Sox2, Klf4, and Myc) in adult mice to study CMDD. We profiled their transcriptomes using RNA sequencing, in combination with multiple published data sets, with the aim of identifying a common denominator for tracking CMDD.RESULTS:RNA sequencing and integrated analysis identified Asparagine Synthetase (Asns) as a unique molecular marker gene well correlated with CMDD, required for increased asparagine and also for distinct fluxes in other amino acids. Although Asns overexpression in Oct4, Sox2, Klf4, and Myc cardiomyocytes augmented hallmarks of CMDD, Asns deficiency led to defective regeneration in the neonatal mouse myocardial infarction model, increased cell death of cultured adult cardiomyocytes, and reduced cell cycle in Oct4, Sox2, Klf4, and Myc cardiomyocytes, at least in part through disrupting the mammalian target of rapamycin complex 1 pathway.CONCLUSIONS:We discovered a novel gene Asns as both a molecular marker and an essential mediator, marking a distinct threshold that appears in common for at least 4 models of CMDD, and revealing an Asns/mammalian target of rapamycin complex 1 axis dependency for dedifferentiating cardiomyocytes. Further study will be needed to extrapolate and assess its relevance to other cell state transitions as well as in heart regeneration.

中文翻译：

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天冬酰胺合成酶标志着心肌细胞去分化的独特依赖性阈值

背景：成年哺乳动物心肌细胞的增殖能力有限，但在特定诱导的情况下，它们会经历细胞周期折返，从而提供心脏再生的潜力。内源性心肌细胞增殖先于心肌细胞去分化（CMDD），其中成年心肌细胞恢复到较不成熟的状态，这不同于与心力衰竭相关的经典心肌胎儿应激基因反应。然而，人们对 CMDD 作为一种确定的心肌细胞细胞状态转变知之甚少。 方法：在这里，我们利用了两种体外培养的成年小鼠心肌细胞模型和体内腺相关病毒血清型 9 心肌细胞靶向递送重编程因子（Oct4、Sox2、Klf4和Myc）在成年小鼠中研究 CMDD。我们使用 RNA 测序，结合多个已发表的数据集，对它们的转录组进行了分析，目的是确定追踪 CMDD 的共同点。 结果：RNA 测序和综合分析确定天冬酰胺合成酶( Asns ) 是一种独特的分子标记基因，与 CMDD 密切相关。 CMDD，是增加天冬酰胺以及其他氨基酸不同通量所必需的。尽管Asns在Oct4、Sox2、Klf4和Myc心肌细胞中过度表达增强了 CMDD 的特征，但Asns缺乏导致新生小鼠心肌梗死模型中的再生缺陷，培养的成年心肌细胞的细胞死亡增加，以及Oct4、Sox2、Klf4中的细胞周期缩短和Myc心肌细胞，至少部分是通过破坏雷帕霉素复合物 1 通路的哺乳动物靶点而实现的。结论：我们发现了一个新基因Asns，它既作为分子标记又作为重要介质，标记了至少 4 个共同出现的独特阈值。 CMDD 模型，并揭示了雷帕霉素复合物 1 轴依赖性的Asns /哺乳动物靶标对去分化心肌细胞的影响。需要进一步的研究来推断和评估其与其他细胞状态转变以及心脏再生的相关性。