CHROMATIN REGULATORY EVENTS UNDERLYING HEART REGENERATION

描述(由申请人提供)：斑马鱼在严重的心脏损伤后具有非凡的再生新心肌的能力。因此，它们是发现心肌梗死后心肌细胞恢复机制的重要模式生物。在斑马鱼中，再生是通过成熟心肌细胞的去分化和随后的增殖进行的。尽管一些对胚胎心脏发育至关重要的因子在心脏再生过程中重新表达，但尚不清楚去分化是如何实现的，胚胎程序是如何重新激活的。染色质组织是导致分化改变的主要机制，但染色质结构是否改变以促进心脏再生尚未得到研究。在初步研究中，我观察到在心脏组织大规模损伤后的第一天，染色质结构发生了广泛的重排。 心室部。更多的初步数据表明，核小体周转可能是再生过程中这些早期大规模变化的一个特征。这项建议的目的是探索核小体组织的变化如何在心脏再生期间的关键调控事件中起基础作用。首先，我将使用核小体周转作为一个标记，以揭示基因组中正在重排的区域。1)在心肌细胞启动去分化的早期再生阶段，我将检测核小体周转和异染色质结构的变化。2)我将发现在再生过程中特异激活的基因调控位。活性基因及其调节域是核小体快速更新的区域。因此，核小体更替的区域可以指向产生新的心肌细胞所必需的基因程序。利用核小体更替，我将检验这一假设，即在斑马鱼心脏再生过程中，染色质结构的再生特异性变化是心肌细胞分化变化的基础。最终，这些发现将有助于确定可用于促进哺乳动物等再生能力较弱生物的心肌细胞恢复的过程和信号通路。

DESCRIPTION (provided by applicant): Zebrafish have a remarkable capacity to regenerate new heart muscle after major cardiac damage. Therefore, they represent an important model organism to discover mechanisms for cardiomyocyte recovery after myocardial infarction. In zebrafish, regeneration proceeds by dedifferentiation and subsequent proliferation of mature cardiomyocytes. Although some factors important for embryonic heart development are re-expressed during heart regeneration, it is unclear how dedifferentiation is achieved and how embryonic programs are reactivated. Chromatin organization is a principal mechanism to institute changes in differentiation, but whether chromatin structure changes to facilitate heart regeneration has not been examined. In preliminary studies, I have observed widespread rearrangement of chromatin structure in cardiac tissue in the first day after massive injury to the cardiac ventricle. Additional preliminary data suggest that nucleosome turnover may be a feature of these early large-scale changes during regeneration. The goal of this proposal is to explore how changes in nucleosome organization underlie key regulatory events during heart regeneration. Primarily, I will use nucleosome turnover as a marker to uncover regions of the genome undergoing rearrangement. 1) I will examine changes in nucleosome turnover and heterochromatin structure during early regeneration stages, when cardiomyocytes initiate dedifferentiation. 2) I will uncover gene regulatory loci activated specifically during regeneratio. Active genes and their regulatory domains are regions of rapid nucleosome turnover. Therefore, regions of nucleosome turnover can point to gene programs necessary for the production of new cardiomyocytes. Using nucleosome turnover, I will test the hypothesis that regeneration-specific alterations of chromatin structure underlie changes in cardiomyocyte differentiation during zebrafish heart regeneration. Ultimately, these findings will help identify processes and signaling pathways that may be exploited to promote recovery of cardiomyocytes in less regenerative organisms like mammals.