Targeting Cbl for Cardiac Repair Post-Myocardial Infarction

心力衰竭(HF)是全球发病率和死亡率的主要原因。在缺乏有意义的 成年哺乳动物的心脏在心肌梗死(MI)后经历病理性重塑。 这对高频的发展做出了贡献。相比之下，新生儿的心脏在受伤后可以再生，例如 MI，主要是因为新生心肌细胞(CMS)对增殖信号有反应。出生后，浩瀚的 大多数CMS在损伤后退出细胞周期，失去完全再生心肌的能力。 最近的证据表明，成年哺乳动物的CMS具有可测量但有限的增殖潜力。这个 CMS增殖和再生新生儿心脏的能力表明有明显的分子和细胞特征 随着CMS向成年期过渡，这一点在很大程度上消失了。对CM细胞周期调控机制的认识 在成人心脏中观察到的发育阶段和无法分裂是一种挑战，但可能会 成人心脏再生策略的发展。最近，我们为Proto确定了一个新的角色- 癌基因Casitas b系淋巴瘤(CBL)在CM生存和死亡中的作用Cbl丢失功能与 减少CM死亡率，增加血管生成，改善心脏收缩功能，显示出 Cbl在心脏保护中的作用初步数据显示，Cbl缺乏与CM增加有关 心肌梗死后成年小鼠的增殖，表明Cbl在心脏再生中的作用尚未被认识。分析 新生小鼠心脏的CM增殖进一步支持了这一假说，并显示出显著增加的 Cbl基因敲除小鼠与野生型(WT)小鼠的CMS循环率比较。CBL功能依赖于激活 其E3泛素连接酶活性，负向调节受体酪氨酸激酶(RTK)信号，和/或 它的接头功能介导Cb1与包括磷脂酰肌醇-3激酶在内的几个分子的相互作用 (PI3K)。我们对Cbl激活的分析表明，Cbl结构域在调节CM增殖或 对外界刺激的反应而死亡。基于这些初步数据，我们假设异常激活 Cbl E3泛素连接酶活性对受体酪氨酸激酶信号转导和CM的负性调节 Cbl与PI3K相互作用增强可促进CM存活和增殖并改善其功能 心脏再生和功能。在目标1中，我们将确定Cbl增益函数和Cbl损耗函数对CM的影响 出生后心脏发育过程中的增殖。在目标2中，我们将研究Cbl表达对 新生和成年小鼠心肌梗死后CM增殖。最后，目标3将定义分子机制 Cb1通过影响新生和成人心脏的CM增殖和心脏再生。建议数 实验将提供对Cb1调节CM增殖和 心肌梗死后新生儿和成人心脏的区别及用我们对Cbl功能的新认识揭示新的 加强心肌梗死后心脏修复/再生的方法。

Heart failure (HF) is a leading cause of morbidity and mortality worldwide. In the absence of meaningful regeneration, the adult mammalian heart undergoes pathological remodeling after myocardial infarction (MI), which contributes to the development of HF. In contrast, the neonatal heart can regenerate after injury such as MI, primarily because neonatal cardiomyocytes (CMs) respond to proliferative signaling. After birth, the vast majority of CMs withdraw from the cell cycle and lose the ability to fully regenerate the myocardium after injury. Recent evidence shows that adult mammalian CMs harbor measurable, but limited, proliferative potential. The ability of CMs to proliferate and regenerate the neonatal heart suggests a distinct molecular and cellular signature that is largely lost as CMs transition to adulthood. Understanding the mechanisms regulating CM cell cycle during developmental stages and inability to divide as observed in the adult heart represents a challenge, but may allow development of strategies for adult heart regeneration. Recently, we have identified a novel role for proto- oncogene Casitas b-lineage lymphoma (Cbl) in CM survival and death. Loss-of-Cbl function was associated with decreased CM death, increased angiogenesis and improved cardiac contractile function, demonstrating a role of Cbl in cardioprotection. Preliminary data shows that Cbl deficiency is associated with increased CM proliferation in adult mice after MI, suggesting an unrecognized role of Cbl in cardiac regeneration. Analysis of CM proliferation in neonatal mouse heart further supports this hypothesis and shows a marked increase in the rate of cycling CMs in Cbl knockout compared to wild-type (WT) mice. Cbl function is dependent on the activation of its E3 ubiquitin ligase activity, which negatively regulates receptor tyrosine kinase (RTK) signaling, and/or on its adaptor functions that mediate Cbl interaction with several molecules including phosphoinositide-3 kinase (PI3K). Our analysis of Cbl activation suggests a differential role of Cbl domains in regulating CM proliferation or death in response to external stimuli. Based on these preliminary data, we hypothesize that aberrant activation of Cbl E3 ubiquitin ligase activity negatively regulates receptor tyrosine kinase (RTK) signaling and CM proliferation, while increased Cbl interaction with PI3K mediates CM survival and proliferation and improves cardiac regeneration and function. In aim 1, we will determine the effects of gain- and loss-of-Cbl function on CM proliferation during post-natal heart development. In aim 2, we will investigate the impact of Cbl expression in CM proliferation following MI in both neonate and adult mice. Finally, aim 3 will define the molecular mechanisms by which Cbl affects CM proliferation and cardiac regeneration in neonatal and adult heart. The proposed experiments will provide new insights into the mechanisms whereby Cbl modulates CM proliferation and differentiation in neonatal and adult heart after MI and use our new understanding of Cbl function to uncover new approaches to enhance cardiac repair/regeneration post-MI.