Novel cardioskeletal myopathy associated with MYL2

与 MYL2 相关的新型心脏骨骼肌病

基本信息

批准号：
9272949
负责人：
Danuta Szczesna-Cordary
金额：
$ 49.88万
依托单位：
UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-07-06 至 2019-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9272949
关键词：
3&apos Splice Site Address Affect Age of Onset Age-Months Applications Grants Arginine Aspartic Acid Benign Binding Sites Birth C-terminal Cardiac Cardiac Death Cardiomyopathies Cessation of life Complement DNA Disease Electron Microscopy Event Familial Hypertrophic Cardiomyopathy Family Fiber Foundations Functional disorder Genes Genetic study Glutamic Acid Glutamine Goals Head Heart Heart Abnormalities Heart Ventricle Heart failure Histopathology Human Hypertrophic Cardiomyopathy Induced Mutation Infant Kinetics Label Link Liquid Chromatography Lysine Malignant - descriptor Measurement Measures Molecular Mus Muscle Muscle Contraction Muscle Fibers Mutate Mutation Myocardial dysfunction Myocardium Myopathy Myosin ATPase Myosin Heavy Chains Myosin Light Chain Kinase Myosin Regulatory Light Chains N-terminal Nonmuscle Myosin Type IIA Nonsense Codon Papillary Pathologic Pathway interactions Patients Pattern Phenotype Phosphorylation Point Mutation Preparation Proteomics RNA Splicing Recombinant Proteins Regulation Reporting Risk Sarcomeres Severities Signal Pathway Site Skeletal Muscle Skeletal Muscle Myosins Skin Soleus Muscle Splice-Site Mutation Symptoms Time Transgenic Mice Transgenic Organisms Troponin Valine Variant X ray diffraction analysis X-Ray Diffraction base design disease phenotype experience experimental study in vivo infancy insight mouse model mutant novel papillary muscle premature public health relevance reconstitution retinal rods skeletal sudden cardiac death tandem mass spectrometry tool

项目摘要

DESCRIPTION (provided by applicant): Infantile fiber-type I hypotrophy with simultaneously occurring severe onset of cardiomyopathy were previously reported in Dutch and Italian families and genetically linked to the MYL2 gene encoding for the human myosin regulatory light chain MLC2ventr/slow expressed in the ventricles and in slow-twitch skeletal muscles. Shortly after birth the patients experienced progressive slow-twitch skeletal myopathy and ultimately died of heart failure between 4 and 6 months of age. Dominant mutations in MYL2 have been known to cause familial hypertrophic cardiomyopathy (FHC) of extensive diversity in the course of the disease, age of onset and severity of symptoms. The mutation-specific dysregulation of the molecular events that trigger pathological remodeling of the heart, will be assessed using our transgenic (Tg) mice expressing the malignant: R58Q and D166V and benign: K104E mutations in MLC2ventr/slow. In addition to cardiac phenotypes, this application for the first time will include the slow-twitch skeletal muscle and the study of the splice site IVS6-1 mutation in MYL2 shown to cause severe myopathy in humans and premature death of IVS6-1-homozygous patients. AIM 1: Identify molecular mechanisms responsible for cardioskeletal dysfunction caused by MLC2ventr/slow mutations. We hypothesize that the mutation-induced structural changes trigger pathological remodeling of the heart and slow skeletal muscle leading to altered contractility and cardioskeletal myopathy. Proteomics study will be employed to identify the signaling pathways involved in cardioskeletal dysfunction associated FHC mutations. Structural phenotypes specific to MLC2ventr/slow mutations in the heart will be correlated with the respective phenotypes in the slow-twitch skeletal muscles using small angle X-ray diffraction patterns. Histopathology and electron microscopy (EM) will complement the effect of mutations on structural reorganization of the sarcomere in the heart and soleus muscle. Measurements of contractile force, force-pCa relationship and the myosin cross-bridge kinetics in skinned papillary/soleus muscle fibers from all proposed Tg mouse models of FHC will complete the phenotypic characterization of MLC2ventr/slow-specific cardioskeletal myopathy. Importantly, we will also study the IVS6-1 mutation associated with premature infantile cardiac death. AIM 2: Determine FHC induced cardiac phenotypes in vivo and explore novel rescue mechanisms in transgenic mice expressing constitutively phosphorylated P-MLC2. We hypothesize that by altering the Ca2+-dependent regulation of muscle contraction, D166V and R58Q mutations increase the propensity of affected patients toward malignant disease phenotypes. We also hypothesize that the underlying mechanisms relate to the steric inhibition of myosin light chain kinase dependent phosphorylation of MLC2. These hypotheses will be addressed using our recently developed double mutant Tg-S15D-D166V rescue mice, designed to mitigate the effects of the malignant D166V mutation with a constitutively phosphorylated Ser-15 (S15D).

描述（由适用提供）：先前在荷兰和意大利家族中报道了婴儿型纤维型I低疗法，并且仅发生严重的心肌病发作，并且通常与针对人肌球蛋白调节光链MLC2Ventr/Slow Slow seplect in Cblectricles和Slow Sell-Twitch-Twitch Skletal Skletal Mussccss s s serge the Myl2基因相关。出生后不久，患者经历了进行性缓慢的骨骼肌病，最终死于4至6个月大的心力衰竭。众所周知，MYL2中的主要突变会导致疾病，发病年龄和症状严重程度的农场肥厚性心肌病（FHC）。将使用表达恶性肿瘤的转基因（TG）小鼠评估触发心脏病理重塑的分子事件的突变特异性失调：R58Q和D166V和良性：MLC2VENTR/慢速中的K104E突变。除心脏表型外，该应用首次申请包括慢速骨骼肌以及对MYL2的剪接部位IVS6-1突变的研究。 AIM 1：确定负责由MLC2VENTR/缓慢突变引起的心骨骼功能障碍的分子机制。我们假设突变引起的结构变化会触发心脏的病理重塑和慢慢的骨骼肌，从而导致收缩力和心骨肌病改变。蛋白质组学研究将用于确定与心脏骨骼功能障碍相关的FHC突变所涉及的信号传导途径。使用小角度X射线衍射模式，对心脏中MLC2VENTR/慢速突变特异性的结构表型将与慢速骨骼骨骼肌肉中的相应表型相关。组织病理学和电子显微镜（EM）将完成突变对心脏和比目鱼肌肉结构重组的影响。来自所有提出的FHC的TG小鼠模型的皮肤乳头状/比目鱼肌纤维中收缩力，力PCA关系和肌球蛋白跨桥动力学的测量将完成MLC2VENTR/慢慢特异性心脏骨骼骨骼肌病的表型表征。重要的是，我们还将研究与早产基础设施心脏死亡相关的IVS6-1突变。目标2：在体内确定FHC诱导的心脏表型，并探索表达组成磷酸化的P-MLC2的转基因小鼠的新型救援机制。我们假设通过改变Ca2+依赖性肌肉收缩的调节，D166V和R58Q突变增加了受影响患者对恶性疾病表型的承诺。我们还假设，与MLC2的肌球蛋白轻链激酶依赖性磷酸化相关的潜在机制。这些假设将使用我们最近开发的双突变体TG-S15D-D166V救援小鼠来解决，该救援小鼠旨在减轻具有组成性磷酸化的Ser-15（S15D）的恶性D166V突变的影响。