Mechanisms of regulating cardiomyocyte chromatin dynamics and regenerative transitions by Tbx20

Tbx20调节心肌细胞染色质动力学和再生转变的机制

• 批准号: 10311171
• 负责人: Stephanie L Padula
• 金额: $ 5.35万
• 依托单位: CINCINNATI CHILDRENS HOSP MED CTR
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2022-07-15
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10311171
• 关键词: Adult; Binding; Birth; Cardiac Myocytes; Cardiomegaly; Cardiovascular Diseases; Caring; Cause of Death; Cell Cycle; Cell Cycle Arrest; Cell Cycle Proteins; Cell Proliferation; Characteristics; Chromatin; Chromatin Remodeling Factor; Co-Immunoprecipitations; Data; Development; ERBB2 gene; Embryo; Excision; Failure; Family suidae; Fetal Heart; Gene Expression; Genes; Genetic Transcription; Heart; Heart Diseases; Heart Injuries; Heart failure; Human; Hypertrophy; Impairment; Injury; Laboratories; Lead; Mediating; Metabolic; Mitotic; Modeling; Mus; Muscle Cells; Myocardial Infarction; Myocardial dysfunction; Natural regeneration; Neonatal; Newborn Infant; Pathologic; Pathology; Patient-Focused Outcomes; Phenotype; Physiological; Proliferating; Protein Isoforms; Regenerative capacity; Regenerative response; Regulator Genes; SMARCA4 gene; SWI/SNF Family Complex; Technology; Testing; Tetracyclines; Therapeutic; Tissues; United States; Zebrafish; cardiac repair; chromatin remodeling; conditional knockout; fetal; heart function; improved; improved outcome; in vivo; injured; mouse model; multiple omics; neonatal mice; novel; overexpression; postnatal; postnatal period; preadolescence; programs; regeneration potential; regenerative; regenerative repair; transcription factor

Project Summary/Abstract Cardiovascular disease is the leading cause of death in the world, and an adult’s ability to recover after a cardiac injury, such as myocardial infarction (MI) is hindered by the quiescent state of cardiomyocytes (CMs). Anecdotal evidence suggests that pre-adolescent humans can replenish CMs after injury by proliferation of resident CMs. Fetal and neonatal mice can also regenerate CMs after injury, but regenerative potential is lost beyond the first postnatal week. Failed attempts to promote regenerative proliferation in adult mouse CMs by activating robust cell cycle effectors have led to pathological hypertrophy and reduced cardiac function. In contrast, our laboratory demonstrated that conditional induction of Tbx20- a transcription factor critical for fetal CM proliferation- promotes fetal characteristics and restrained proliferation in normal and post-MI adult CMs without impairing cardiac function. While this finding has enormous therapeutic relevance, the mechanism underlying this is unknown, particularly because Tbx20 function throughout CM maturation and regenerative transitions are currently ill-defined. Moreover, increasing evidence suggests that Tbx20 interacts with the SWI/SNF chromatin remodeling component BRG1 to promote the expression of genes related to cell cycle activity in fetal and neonatal CMs, providing another facet to the gene regulatory actions of Tbx20. We hypothesize that Tbx20 cooperates with BRG1 to promote proliferation and fetal characteristics in adult CMs by remodeling CM chromatin into a more immature, fetal-like state, and by opening chromatin regions associated with fetal Tbx20 transcriptional targets. We propose two separate Aims to elucidate the mechanism by which Tbx20 promotes proliferation and fetal reversion in adult CMs. In Aim 1, will utilize an integrative multiomics approach to identify how Tbx20 dynamically regulates gene expression throughout normal CM development and regenerative transitions, including its binding targets and effect on chromatin changes (Aim 1.1). We will characterize the reversibility of this regenerative phenotype using a transient model of Tbx20 induction (Aim 1.2). This will determine whether proliferative, fetal-like CMs can mature into adult CMs following the removal of Tbx20, which is necessary to accommodate the metabolic demands of the adult heart. In Aim 2, we will utilize co-immunoprecipitation and CHIP-qPCR to elucidate whether an interaction between Tbx20 and BRG1 occurs in immature CMs (Aim 2.1). We will also utilize conditional mouse models of Tbx20 induction and Brg1 deletion to determine whether Tbx20 induction after MI promotes proliferation, fetal characteristics, and improved cardiac function via a BRG1-dependent mechanism (Aim 2.2). Understanding gene regulatory mechanisms during CM maturation will advance therapeutic strategies aimed at reactivating fetal gene programs, promoting CM regeneration, and improving cardiac function post-MI. The Aims in this proposal seek to elucidate this in the context of Tbx20, with BRG1 as a potential novel partner in directing the fetal gene program during normal development and regenerative repair.

项目总结/摘要 心血管疾病是世界上死亡的主要原因，成年人在心脏病后恢复的能力 心肌细胞（CM）的静止状态阻碍了心肌损伤，如心肌梗死（MI）。轶事 有证据表明，青春期前的人在受伤后可以通过固有CM的增殖来补充CM。 胎儿和新生小鼠在损伤后也可以再生CM，但再生潜力在第一次损伤后丧失。 产后一周在成年小鼠CM中，通过激活强有力的 细胞周期效应物导致病理性肥大和降低的心脏功能。相比之下，我们的实验室 证明了Tbx 20-一种对胎儿CM增殖至关重要的转录因子-的条件诱导， 促进胎儿特征，抑制正常和MI后成人CM的增殖， 心脏功能虽然这一发现具有巨大的治疗意义，但其背后的机制是 未知，特别是因为Tbx 20在整个CM成熟和再生过渡中的功能是未知的。 目前定义不清。此外，越来越多的证据表明Tbx 20与SWI/SNF染色质相互作用 重塑成分BRG 1，以促进与胎儿细胞周期活性相关的基因表达， 新生儿CM，提供了Tbx 20基因调控作用的另一个方面。我们假设Tbx 20 与BRG 1合作，通过重塑CM促进成人CM的增殖和胎儿特征 通过打开与胎儿相关的染色质区域， Tbx 20转录靶标。我们提出了两个不同的目的，以阐明机制，Tbx 20 促进成人CM的增殖和胎儿逆转。 在目标1中，将利用整合的多组学方法来确定Tbx 20如何动态调节基因 在整个正常CM发育和再生过渡中表达，包括其结合靶点， 对染色质变化的影响（目标1.1）。我们将使用以下方法来表征这种再生表型的可逆性： Tbx 20诱导的瞬态模型（目标1.2）。这将决定是否增殖，胎儿样CM可以 在去除Tbx 20后成熟为成年CM，Tbx 20是调节代谢所必需的。 成人的心的要求。在目标2中，我们将利用免疫共沉淀和CHIP-qPCR来阐明是否 Tbx 20和BRG 1之间的相互作用发生在未成熟的CM中（Aim2.1）。我们还将使用条件 Tbx 20诱导和Brg 1缺失的小鼠模型，以确定MI后Tbx 20诱导是否促进 通过BRG 1依赖性机制促进细胞增殖、胎儿特征和改善心脏功能（目的2.2）。 了解CM成熟过程中的基因调控机制将推进治疗策略 旨在重新激活胎儿基因程序，促进CM再生，并改善MI后的心脏功能。 本提案中的目的旨在Tbx 20的背景下阐明这一点，BRG 1作为潜在的新伙伴 在正常发育和再生修复过程中指导胎儿基因程序。