Nuclear envelope protein LEMD2 in heart

心脏中的核膜蛋白 LEMD2

基本信息

批准号：
10662287
负责人：
Ju Chen
金额：
$ 53.9万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN DIEGO
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-15 至 2025-07-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10662287
关键词：
Ablation Address Adult Affect Age Amino Acid Substitution Apoptosis Arginine Biological Process Birth Body Weight Cardiac Myocytes Cardiomyopathies Cell Nucleus Chromatin Cytoplasm Dilatation - action Disease Embryo Epigenetic Process Functional disorder Gene Expression Regulation Gene Silencing Genes Goals Heart Heart Abnormalities Heterochromatin Human Impairment Integral Membrane Protein Knock-in Mouse Knock-out Knockout Mice Knowledge Lamins Leucine Link Maintenance Mechanics Mediating Membrane Proteins Modeling Molecular Morphogenesis Mutant Strains Mice Mutation Myocardium Myosin Heavy Chains Nonmuscle Myosin Type IIA Nuclear Nuclear Envelope Nuclear Inner Membrane Nuclear Lamina Nucleoplasm Pattern Physiological Play Polymers Protein Family Proteins Regulation Reporting Role Shapes Structure System TNFSF5 gene Thick Thinness Ventricular Weight Xenopus laevis autosome clinically relevant emerin env Gene Products heart function histone modification induced pluripotent stem cell induced pluripotent stem cell derived cardiomyocytes insight man mouse model mutant myosin light chain 2 new therapeutic target

项目摘要

PROJECT SUMMARY Mutations in genes encoding nuclear envelope (NE) components cause an array of diseases referred to as nuclear envelopathies that often manifest as cardiomyopathies. The NE separates the nucleoplasm from cytoplasm and is composed of outer and inner nuclear membranes. The nuclear lamina (NL) is an extensive network of lamin polymers and associated proteins that are embedded in the inner nuclear membrane (INM). Functionally, NL and INM proteins not only provide mechanical stability to the nucleus but also serve as the anchoring point for chromatin at the nuclear periphery, playing a critical role in chromatin organization and regulation of gene expression via interaction with and modulation of epigenetic machinery components. The LAP2-Emerin-MAN1-domain (LEM-D) family of proteins play an important role in the association between the NL and chromatin. LEMD2 (LEM domain-containing protein 2), is a transmembrane protein located in the INM, involved in nuclear integrity and perinuclear tethering and transcriptional silencing of heterochromatin. Recently, it has been reported that a single amino acid substitution of leucine 13 to arginine (L13R) in LEMD2 leads to autosomal recessive human cardiomyopathy. However, despite its clinical relevance, little is known as to the specific role of LEMD2 in cardiomyocytes (CMs), and mechanisms by which the L13R mutation leads to cardiomyopathy. To address this gap in knowledge, we have generated three mouse models: constitutive CM- specific Lemd2 knockout (cKO), inducible CM-specific Lemd2 knockout (icKO), and LEMD2 L13R knock-in mice. We will also utilize a human induced pluripotent stem cell (iPSC)-derived CM model of the LEMD2 L13R mutation to address the impact of L13R mutation in LEMD2 on human CMs. Preliminary studies revealed that loss of LEMD2 in embryonic or adult CMs is detrimental, and LEMD2 L13R mutation affects cardiac function in a murine model, indicating that LEMD2 plays a critical role in maintaining normal CM structure and function in developing and adult hearts. Thus, we hypothesize that LEMD2-mediated maintenance of NE integrity and/or regulation of heterochromatin tethering and silencing is essential for CM structure and function, and LEMD2 L13R mutation impairs specific aspects of LEMD2 function leading to cardiomyopathy. Accordingly, Our Specific Aims are: 1. To determine the role of LEMD2 in the developing and adult myocardium by analyzing constitutive (cKO) and inducible (icKO) Lemd2 CM-specific knockout mice for heart morphogenesis, structure and function, and the progression of cardiomyopathy; and 2. To elucidate molecular mechanisms underlying cardiomyopathy consequent to the L13R mutation in LEMD2 by detailed analyses of LEMD2 L13R knock-in mice and human induced pluripotent stem cell (iPSC)-derived LEMD2 L13R mutant CMs.

项目概要编码核膜 (NE) 成分的基因突变会导致一系列疾病，称为核包膜病通常表现为心肌病。 NE 将核质与细胞质由外核膜和内核膜组成。核层（NL）是一个广泛的嵌入内核膜 (INM) 的核纤层蛋白聚合物和相关蛋白网络。从功能上讲，NL 和 INM 蛋白不仅为细胞核提供机械稳定性，而且还充当核周边染色质的锚定点，在染色质组织和染色质组织中发挥着关键作用通过与表观遗传机制成分的相互作用和调节来调节基因表达。这 LAP2-Emerin-MAN1 结构域 (LEM-D) 蛋白家族在 NL 和染色质。 LEMD2（含LEM结构域的蛋白2）是一种位于INM的跨膜蛋白，参与核完整性和核周束缚以及异染色质的转录沉默。最近，有报道称 LEMD2 中亮氨酸 13 被单氨基酸取代为精氨酸（L13R）导致常染色体隐性遗传人类心肌病。然而，尽管它具有临床相关性，但人们对其知之甚少。 LEMD2 在心肌细胞 (CM) 中的具体作用，以及 L13R 突变导致的机制心肌病。为了解决这一知识差距，我们生成了三种小鼠模型：组成型 CM- 特异性 Lemd2 敲除 (cKO)、诱导型 CM 特异性 Lemd2 敲除 (icKO) 和 LEMD2 L13R 敲入老鼠。我们还将利用 LEMD2 L13R 的人类诱导多能干细胞 (iPSC) 衍生的 CM 模型突变以解决 LEMD2 中 L13R 突变对人类 CM 的影响。初步研究表明胚胎或成人 CM 中 LEMD2 的缺失是有害的，并且 LEMD2 L13R 突变影响心脏功能小鼠模型，表明 LEMD2 在维持正常的 CM 结构和功能中发挥着关键作用发育中和成人的心脏。因此，我们假设 LEMD2 介导的 NE 完整性维持和/或异染色质束缚和沉默的调节对于 CM 结构和功能至关重要，而 LEMD2 L13R 突变损害 LEMD2 功能的特定方面，导致心肌病。因此，我们的具体目标是： 1. 通过分析确定 LEMD2 在发育中和成年心肌中的作用组成型 (cKO) 和诱导型 (icKO) Lemd2 CM 特异性敲除小鼠心脏形态发生、结构和功能以及心肌病的进展； 2. 阐明潜在的分子机制通过对 LEMD2 L13R 敲入的详细分析，了解 LEMD2 中 L13R 突变引起的心肌病小鼠和人诱导多能干细胞 (iPSC) 衍生的 LEMD2 L13R 突变体 CM。