MBNL1's function in myofibroblast transformation and fibrosis

MBNL1 在肌成纤维细胞转化和纤维化中的功能

基本信息

批准号：
8719166
负责人：
Jennifer Michelle Davis
金额：
$ 13.11万
依托单位：
CINCINNATI CHILDRENS HOSP MED CTR
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-08-09 至 2015-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8719166
关键词：
Accounting Address Adult Affect Alternative Splicing Automobile Driving Binding Cardiac Cardiomyopathies Cell physiology Cells Cessation of life Chronic Cicatrix Clinical Clinical Management Contracts Cytokine Signaling Data Development Disease Embryo Environment Event Extracellular Matrix Fibroblasts Fibrosis Gene Expression Profile Gene Targeting Genes Genetic Heart Heart Diseases Heart failure Hybrids Hypertrophic Cicatrix Immunoprecipitation In Vitro Injury Intervention Knock-in Mouse Knockout Mice Laboratories Link Mechanical Stress Mechanics Mediating Mediator of activation protein Messenger RNA Modeling Molecular Molecular Genetics Mus Muscle Cells Myocardial Myocardial Infarction Myocardium Myofibroblast Myotonic Dystrophy Nodal Pathway interactions Phenotype Positioning Attribute Process Protein Isoforms Proteins Proteome Proteomics RNA RNA Binding RNA Splicing RNA-Binding Proteins Regulation Role Secretory Cell Signal Pathway Signal Transduction Smooth Muscle Myocytes Subcellular Fractions Sudden Death Testing Tissues Transcript Transgenic Organisms Treatment Efficacy United States Variant Wound Healing base defined contribution design drug discovery genetic activator genome wide association study improved in vivo injured mouse model novel overexpression periostin prevent programs remediation repaired research study response response to injury tissue repair tool

项目摘要

DESCRIPTION (provided by applicant): Cardiac fibrosis has rapidly emerged as one of the biggest problems affecting the clinical management of heart disease to date because current treatments only delay rather than prevent fibrotic remodeling and heart failure. Fibrosis results from an unrestrained tissue repair response orchestrated predominantly by the myofibroblast. Myofibroblasts are highly specialized cells characterized by a hybrid fibroblast/smooth muscle cell phenotype, as they can contract, migrate, and secrete vast amounts of extracellular matrix. The healthy heart is normally devoid of myofibroblasts, but injury-induced alterations of the mechanical and neurohumoral environment induce fibroblasts to transform into myofibroblasts. Initially, myofibroblast function is critical to the repair process as its contractile function and matrix secretion provides structural support to the injured myocardium; however, chronic myofibroblast activity eventually causes hypertrophic scarring and cumulative fibrosis, which is not only deleterious to cardiac function but creates a highly arrhythmogenic substrate. Due to the lack of genetic tools for specifically manipulating the fibroblast in vivo, the contribution ofthe fibroblast and myofibroblast to tissue repair and fibrotic disease has not been clearly defined. This proposal features two newly developed fibroblast-specific Cre knockin mouse models for delineating the fibroblast's role in myocardial repair and fibrosis and to identify the molecular regulators of the fibroblast-dependent fibrotic response. Currently, most studies examining the regulatory networks in myofibroblast transformation have been solely focused on TGF? signaling due to its central role in initiating myofibroblast transformation and fibrosis, providin a very limited scope of the regulatory networks driving the fibrotic process. This prompted us to perform a genome-wide screen for new molecular regulators of fibroblast to myofibroblast conversion from which we identified the gene for the RNA-binding protein muscleblind-like splicing regulator 1 (MBNL1). To date MBNL1 function has never been linked to tissue repair or fibrosis, but our preliminary data in primary fibroblasts (cardiac and MEFs) demonstrates that MBNL1 is both necessary and sufficient for inducing fibroblast to myofibroblast transformation, suggesting that MBNL1 is a primary mediator of fibrotic disease. Thus, this proposal is designed (1) to directly examine the mechanism by which injury induced changes in MBNL1's regulation of transcript abundance and alternative splicing alters the fibroblast's proteome to functionally transform into a myofibroblast and (2) to directly examine the role programmed fibroblast transformation by MBNL1 has in tissue repair and fibrotic disease. By defining the regulatory networks directing fibroblast to myofibroblast transformation this proposal will further delineate the cellular and molecular underpinnings for fibrotic disease which in turn should yield new invention points for developing targeted interventions and drug discovery as many of these molecular regulators should be amenable to pharmacologic remediation.

描述（由申请人提供）：心脏纤维化已迅速成为迄今为止影响心脏病临床治疗的最大问题之一，因为目前的治疗只能延迟而不是预防纤维化重塑和心力衰竭。纤维化是由主要由肌成纤维细胞协调的不受限制的组织修复反应引起的。肌成纤维细胞是高度特化的细胞，其特征是混合成纤维细胞/平滑肌细胞表型，因为它们可以收缩、迁移和分泌大量细胞外基质。健康的心脏通常缺乏肌成纤维细胞，但损伤引起的机械和神经体液环境的改变会诱导成纤维细胞转化为肌成纤维细胞。最初，肌成纤维细胞功能对于修复过程至关重要，因为其收缩功能和基质分泌为受损心肌提供结构支撑；然而，慢性肌成纤维细胞活性最终会导致肥厚性疤痕和累积性纤维化，这不仅损害心脏功能，而且会产生高度致心律失常的基质。由于缺乏体内特异性操纵成纤维细胞的遗传工具，成纤维细胞和肌成纤维细胞对组织修复和纤维化疾病的贡献尚未明确定义。该提案采用了两种新开发的成纤维细胞特异性 Cre 敲入小鼠模型，用于描述成纤维细胞在心肌修复和纤维化中的作用，并确定成纤维细胞依赖性纤维化反应的分子调节因子。目前，大多数研究肌成纤维细胞转化调控网络的研究都只关注 TGF？信号传导由于其在启动肌成纤维细胞转化和纤维化中的核心作用，提供了驱动纤维化过程的非常有限的调节网络范围。这促使我们对成纤维细胞向肌成纤维细胞转化的新分子调节因子进行全基因组筛选，从中我们鉴定出了 RNA 结合蛋白肌盲样剪接调节因子 1 (MBNL1) 的基因。迄今为止，MBNL1 功能从未与组织修复或纤维化相关，但我们在原代成纤维细胞（心脏和 MEF）中的初步数据表明，MBNL1 对于诱导成纤维细胞向肌成纤维细胞转化是必要且充分的，这表明 MBNL1 是纤维化的主要介质疾病。因此，该提案的目的是（1）直接检查损伤诱导MBNL1转录丰度调节变化的机制，以及选择性剪接改变成纤维细胞的蛋白质组以功能性转化为肌成纤维细胞，以及（2）直接检查程序化成纤维细胞转化的作用MBNL1 具有组织修复和纤维化疾病的作用。通过定义引导成纤维细胞向肌成纤维细胞转化的调控网络，该提案将进一步描绘纤维化疾病的细胞和分子基础，这反过来又应该为开发有针对性的干预措施和药物发现产生新的发明点，因为许多这些分子调节因子应该适合药物治疗。