Defining the mechanism of chromatin accessibility modifications in vertebrate appendage regeneration

项目总结 两栖动物能够在截肢后进行无疤痕的愈合和再生 附属物。通过阐明这种再生能力的细胞和分子基础，我们可以发展 改善人类再生愈合的治疗策略。两栖动物的成功再生 需要组蛋白脱乙酰酶(HDAC)的早期作用，组蛋白脱乙酰酶是一种作用于浓缩染色质并抑制 抄写。然而，在这种情况下，HDAC活性的基因组和转录靶标是未知的， 限制了我们在脊椎动物中形成表观遗传和转录重编程的机制模型的能力 再生。由于用于查询的资源很少，因此很难识别这些目标 再生脊椎动物组织中的染色质结构。我们已经克服了这一障碍，使用了一种新的检测方法 转座酶可及染色质(ATAC-Seq)在非洲爪哇尾部再生中的作用。我们发现， 截肢后6小时，数以千计的启动子区域迅速变得无法访问：完全相同 需要HDAC活动的时间。这些地区后来被重新开放。因此，我们的核心假设是 研究表明，hdac活性通过脱乙酰化作用，使这些启动子区域的染色质瞬间浓缩。 特定的核心组蛋白残基，并被组蛋白乙酰转移酶(HATS)的后期作用逆转。这里 将利用我们在基因组学和功能扰动方面的专业知识对这个系统进行简洁的功能 将检验这一假设的二次分析。我们将确定对病毒敏感的基因组区域 HDAC和HAT活性、靶向的特定残基以及组蛋白的时空分布 再生尾巴中的乙酰化。重要的是，我们还将为今后的工作奠定基础， HDAC活性如何与其他染色质重塑活动平衡以重新编程转录和细胞 再生早期的行为。 好了！

PROJECT SUMMARY Amphibians are able to undergo scarless healing and regeneration in response to amputation of their appendages. By articulating the cell and molecular basis for this regenerative capacity, we can develop therapeutic strategies to improve regenerative healing in humans. Successful regeneration in amphibians requires the early action of histone deacetylases (HDACs), enzymes that act to condense chromatin and inhibit transcription. However, the genomic and transcriptional targets of HDAC activity are unknown in this context, limiting our ability to form a mechanistic model of epigenetic and transcriptional reprogramming in vertebrate regeneration. It has been difficult to identify these targets because there are few resources for querying chromatin structure in regenerating vertebrate tissue. We have overcome this barrier by using a new assay for transposase accessible chromatin (ATAC-Seq) in Xenopus tropicalis tail regeneration. We have found that thousands of promoter regions are rapidly rendered inaccessible at 6 hours post amputation: the very same time that HDAC activity is required. These regions are later re-opened. Therefore, the central hypothesis of our study is that HDAC activity acts transiently to condense chromatin in these promoter regions by deacetylating specific core histone residues, and is reversed by the later action of histone acetyltransferases (HATs). Here will use our expertise in genomics and functional perturbations of this system to conduct a succinct functional secondary analysis that will test this hypothesis. We will identify the genomic regions that are sensitive to HDAC and HAT activity, the specific residues that are targeted, and the spatiotemporal distribution of histone acetylation in the regenerating tail. Importantly, we will also lay the foundation for future work that will establish how HDAC activity is balanced with other chromatin remodeling activities to reprogram transcription and cell behavior early in regeneration. !