Enhancing mammalian liver repair and regeneration

项目摘要/摘要 目前对肝硬变的发病机制及其调节机制的认识尚不完全。我们最近 发现ARID1A是SWI/SNFATP依赖的染色质重塑复合体的一个组成部分，在 在肝脏损伤和再生中起重要作用。我们发现肝脏特异的ARID1A基因敲除小鼠具有高度的 抵抗多种形式的化学损伤后的肝脏损伤和纤维化。这些老鼠也有更快的 肝部分切除后再生。ARID1A缺陷的肝脏表现为终末分化受抑和 损伤后增殖增加，导致更快和更彻底的组织修复，在某些情况下 提高了存活率。全身ARID1a缺陷小鼠的软组织和胰腺β细胞得到改善 再生。这些发现首次将染色质重塑机制与组织修复和 器官再生。这也表明存在再生抑制基因(类似于肿瘤 抑制物)，当被抑制或丢失时，在慢性肝病的背景下促进组织修复。vt.给出 SWI/SNF染色质重塑复合体中ARID1A的丢失改善了肝细胞在 不同的损伤，我们的中心假设是表观遗传变化对组织损伤和 在肝硬变进展过程中的修复，并可用于治疗。这一假设的几个关键方面 要求进一步调查。在目标1中，我们将对SWI/SNF复合体进行生化表征以及如何 在存在和不存在ARID1A的情况下，它们会影响其基因组靶标。在目标2中，我们将确定 如果在非恶性人类肝脏中出现染色质重塑基因突变，如ARID1A 疾病组织。然后，我们将评估小鼠模型中失活突变的功能影响 慢性肝病的进展。在AIM 3中，我们将确定Arid1b，一个与之密切相关的平行曲线 已观察到在结构上取代了ARID1A的络合物，是一种功能拮抗剂 ARID1a，因此负责增强获得和丧失功能的小鼠模型的再生。 用生化、细胞和遗传方法解决这些主要问题将增加我们的 了解SWI/SNF复合体如何影响器官再生和肝脏疾病的发病机制。 尽管目前尚不清楚抑制ARID1A或激活ARID1B在 治疗意识，在这一领域获得的知识有朝一日可能会导致新的战略来抵消或逆转 肝硬变的发展。

PROJECT SUMMARY/ABSTRACT There is incomplete understanding of liver cirrhosis pathogenesis and how it might be modulated. We recently discovered that Arid1a, a component of the SWI/SNF ATP-dependent chromatin-remodeling complex, plays potent roles in liver injury and regeneration. We found that liver-specific Arid1a knockout mice are highly resistant to liver damage and fibrosis after multiple forms of chemical injury. These mice also have faster regeneration after partial hepatectomy. Arid1a deficient livers show suppressed terminal differentiation and increased proliferation after injuries, leading to more rapid and complete tissue repair, and in some cases improved survival. Mice with whole-body Arid1a deficiency exhibit improved soft tissue and pancreatic β-cell regeneration. These findings for the first time connect chromatin-remodeling machinery with tissue repair and organ regeneration. This also suggests the existence of regeneration suppressor genes (analogous to tumor suppressors), that when repressed or lost, promote tissue repair in the context of chronic liver disease. Given that the loss of Arid1a from SWI/SNF chromatin-remodeling complexes improved hepatocyte fitness after diverse injuries, our central hypothesis is that epigenetic changes have a major impact on tissue damage and repair in cirrhosis progression and could be exploited for therapy. Several critical aspects of this hypothesis demand further investigation. In AIM 1, we will biochemically characterize SWI/SNF complexes and how they influence their genomic targets in the presence and absence of Arid1a. In AIM 2, we will determine if mutations in chromatin-remodeling genes such as ARID1A appear in non-malignant human liver disease tissues. We will then assess the functional impact of inactivating mutations in mouse models of chronic liver disease progression. In AIM 3, we will determine if Arid1b, a closely related paralog that has been observed to structurally substitute for Arid1a within complexes, is a functional antagonist of Arid1a, and is thus responsible for enhancing regeneration in gain and loss-of-function mouse models. Addressing these major questions with biochemical, cellular, and genetic approaches will increase our understanding of how the SWI/SNF complex influences organ regeneration and liver disease pathogenesis. Although it is not currently known if the suppression of ARID1A or activation of ARID1B will be practical in a therapeutic sense, knowledge gained in this area may one day lead to novel strategies to counteract or reverse the development of cirrhosis.