MOLECULAR MECHANISMS OF CARDIAC DIFFERENTIATION

描述 （改编自申请人摘要）心室终末分化 肌细胞涉及谱系限制基因的协调表达， 永久性生长停滞 这种组织特异性的不可逆表达 基因和细胞周期退出排除了心肌再生作为治疗 在其他损伤的梗塞后机动。 的理解 导致心脏分化的分子事件将提供强有力的 科学基础，以实现未来的目标， 再生人类心肌的因子。 Rb，a的原型成员， 口袋蛋白家族，已被牵连在指导关键方面 通过与组织特异性转录的关联， 因子和正性细胞周期调节因子的失活。 一本小说， 以富有成效的方法确定和描述关键因素， 其他组织的终末分化利用了E1 A的能力， 选择性地结合并置换口袋中的内源性因子 导致组织限制性基因的下调，同时迫使细胞 循环再生 导师的实验室最近证明了 控制心脏特异性转录的口袋蛋白依赖性途径 和心肌细胞周期调节的重要性。 本申请 提出利用腺病毒E1 A蛋白的口袋结合特性 和两种Rb缺乏模型，以研究口袋蛋白在 终末心脏分化 根据骨骼肌的结果 可以设想几种机制来解释口袋蛋白依赖性 抑制心脏基因的途径。 他们从具体的基础 本提案的目的：1）E1 A是否通过以下方式改变心源性因子的活性： 直接结合和灭活心源性因子，降低表达 或DNA结合，抑制转录活性，2）心脏 类似于MyoD的转录因子需要与Rb或 其他口袋蛋白的转录活性; 3）是影响 E1 A是Rb释放E2 F的第二位; 4）E1 A是否增加 心肌细胞中cyclin/Cdk活性; 5）在体内研究， Rb在心脏限制性心肌细胞终末分化中的作用 同源重组 (End摘要）

DESCRIPTION (Adapted from applicant's abstract) Terminal differentiation of ventricular myocytes involves the coordinate expression of lineage-restricted genes and permanent growth arrest. This irreversible expression of tissue-specific genes and cell cycle exit precludes myocardial regeneration as therapeutic maneuver after infarction of other insult. An understanding of the molecular events leading to cardiac differentiation would provide a strong scientific foundation towards the future objective of manipulation of these factors to regenerate human myocardium. Rb, the protypical member of a family of pocket proteins, has been implicated in directing critical aspects of this process through its association with tissue-specific transcription factors and inactivation of positive cell cycle regulators. One novel and fruitful approach to identify and characterize critical factors mediating terminal differentiation in other tissues has been to exploit E1A's ability to selectively bind and displace endogenous factors from the pocket resulting in downregulation of tissue-restricted genes while forcing cell cycle reetry. The preceptor's lab has recently demonstrated evidence for a pocket protein-dependent pathway that governs cardiac-specific transcription and cell cycle regulation in cardiac muscle. The present application proposes to exploit the pocket-binding properties of adenoviral E1A proteins and two models of Rb deficiency to study the role of pocket proteins in terminal cardiac differentiation. Based on results from skeletal muscle several mechanisms can be envisioned to explain the pocket protein-dependent pathway repression of cardiac genes. They from the basis for the specific aims of this proposal: 1) Does E1A alter activity of cardiogenic factors by directly binding and inactivating cardiogenic factors, decreasing expression or DNA binding, repressing transcriptional activity, 2) Do cardiac transcription factors, analogous to MyoD, require association with Rb or other pocket proteins for transcriptional activity; 3) Are the effects of E1A are secondary to release of E2F from the Rb; 4) Does E1A increase cyclin/Cdk activity in cardiac myocytes; and 5) Investigate in vivo, the role of Rb in controlling terminal differentiation by cardiac-restricted homologous recombination. (End of abstract)