Intermediate Filaments & Costamere Structure & Function

中间丝

基本信息

批准号：
7590621
负责人：
ROBERT J BLOCH
金额：
$ 38.54万
依托单位：
UNIVERSITY OF MARYLAND BALTIMORE
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-30 至 2011-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7590621
关键词：
Actins Address Affect Animals Anterior Behavior Binding Biomechanics Biopsy Cardiac Cell membrane Complex Creatine Kinase Desmin Dystrophin Elements Extracellular Matrix Fiber Figs - dietary Filament Generations Genetic Glycoproteins Heart Human In Situ Individual Injury Intermediate Filament Proteins Intermediate Filaments KRT19 gene Keratin Keratin-19 Knock-out Knockout Mice Lead Learning Ligands Link Measures Mechanics Membrane Microfilaments Mitochondria Molecular Morphology Mus Muscle Muscle Cells Muscle Fibers Muscular Dystrophies Mutant Strains Mice Mutation Myocardium Myofibrils Myopathy Nature Organelles Pathway interactions Physiology Play Predisposition Property Proteins Research Role Running Sarcolemma Sarcomeres Secure Serum Severity of illness Skeletal Muscle Skeletal muscle injury Striated Muscles Structure Surface System Testing Work base dystrobrevin flexor digitorum brevis homologous recombination mutant null mutation overexpression protein complex research study response skeletal syncoilin synemin

项目摘要

Costameres are structures at the surface of striated muscle that align the sarcolemma regularly with nearby myofibrils and transmit contractile force laterally, through the membrane to the extracellular matrix. Costameres must therefore be linked to nearby structures firmly enough to withstand the forces of contraction. Here we focus on links between costameres and myofibrils. Desmin-based and keratin-based intermediate filaments (IFs), as well as actin microfilaments, link superficial myofibrils to costameres at the sarcolemma. We postulate that IFs containing keratins 8 and 19 play an important role at costameres because, unlike desmin, they are found at all costameric structures. We have shown that K8/K19 IFs interact with the dystrophin- glycoprotein complex via K19, and that over-expression of K19 or elimination of K19 by homologous recombination disrupts costameres. The K19-null mutation in mice also leads to mitochondrial mislocalization, increased serum creatine kinase levels and reduced contractile force, suggesting that the absence of IFs containing K19 causes a mild skeletal myopathy. We now have mice in the same genetic background as the K19-null (FVB) that lack desmin, and that lack both K19 and desmin. Here we propose 5 aims to test the hypothesis that K19-based IFs together with desmin IFs form distinct but complementary links between the contractile apparatus and costameres in healthy muscle. We further propose that their absence either alone or together leads to a weakening of the links between costameres and the contractile apparatus, compromised muscle physiology, and increased susceptibility to injury induced by lengthening ("eccentric") contractions. Aim1 addresses the morphological changes in costameres, sarcomeres and intracellular organelles, including mitochondria, in K19-null, desmin-null, and double knock-out (DKO) mice. In Aim 2, we will characterize the contractile activity, running ability, and susceptibility to eccentric injury of the individual mutants and the DKO. Aim 3 addresses the biomechanical properties of muscles lacking K19, desmin or both IF proteins, by investigating the strength of connections between myofibrils, and between myofibrils and the sarcolemma. Our results should therefore elucidate the molecular pathways that transmit force in healthy muscle, and how the absence of IFs can lead to muscle disease.

肋节是横纹肌表面的结构，将肌膜与附近的肌原纤维定期对齐，并通过膜将收缩力横向传递到细胞外基质。因此，肋节必须与附近的结构足够牢固地连接，以承受收缩力。在这里，我们重点关注肋节和肌原纤维之间的联系。基于结蛋白和角蛋白的中间丝 (IF) 以及肌动蛋白微丝将浅表肌原纤维与肌膜处的肋节连接起来。我们假设含有角蛋白 8 和 19 的 IF 在肋节中发挥重要作用，因为与结蛋白不同，它们存在于所有肋节结构中。我们已经证明，K8/K19 IF 通过 K19 与肌营养不良蛋白-糖蛋白复合物相互作用，并且 K19 的过度表达或通过同源重组消除 K19 会破坏肋节。小鼠中的 K19 缺失突变还会导致线粒体错位、血清肌酸激酶水平升高和收缩力降低，这表明缺乏含有 K19 的 IF 会导致轻度骨骼肌病。我们现在拥有与 K19 缺失 (FVB) 具有相同遗传背景的小鼠，它们缺乏结蛋白，并且缺乏 K19 和结蛋白。在这里，我们提出 5 旨在检验以下假设：基于 K19 的 IF 与结蛋白 IF 一起在健康肌肉的收缩装置和肋肌之间形成独特但互补的联系。我们进一步提出，它们的单独或共同缺失会导致肋肌和收缩器官之间的联系减弱，肌肉生理机能受损，并增加对延长（“离心”）收缩引起的损伤的敏感性。 Aim1 解决了 K19 缺失、结蛋白缺失和双敲除 (DKO) 小鼠中肋节、肌节和细胞内细胞器（包括线粒体）的形态变化。在目标 2 中，我们将描述个体突变体和 DKO 的收缩活动、奔跑能力和对偏心损伤的敏感性。目标 3 通过研究肌原纤维之间以及肌原纤维与肌膜之间的连接强度，解决缺乏 K19、结蛋白或两种 IF 蛋白的肌肉的生物力学特性。因此，我们的结果应该阐明健康肌肉中传递力的分子途径，以及 IF 的缺失如何导致肌肉疾病。