EphA7 promotes contact-dependent myogenesis

EphA7促进接触依赖性肌生成

基本信息

批准号：
10219157
负责人：
Dawn D Cornelison
金额：
$ 31.68万
依托单位：
UNIVERSITY OF MISSOURI-COLUMBIA
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-07-17 至 2025-05-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10219157
关键词：
Address Adhesions Adult Animals Binding Biology Birth Cell Culture Techniques Cell Differentiation process Cell membrane Cell physiology Cell surface Cells Cephalic Communities Cultured Cells Data Development Developmental Process Differentiation Antigens Embryo Eph Family Receptors Ephrin-A5 Ephrins Epigenetic Process Exhibits Exposure to Extracellular Domain Fiber Genetic Transcription Giant Cells Hindlimb Human Hypertrophy In Vitro Individual Injury Lead Life Ligands Link Mediating Mediator of activation protein Membrane Modeling Molecular Mus Muscle Muscle Cells Muscle Development Muscle Fibers Muscle satellite cell Myoblasts Myogenin Natural regeneration Neural Tube Closure Phenotype Population Process Proliferating Proteins Receptor Protein-Tyrosine Kinases Regenerative Medicine Resistance Role Serum Signal Transduction Signal Transduction Pathway Signaling Molecule Skeletal Muscle Surface Testing Tissue Differentiation Tissue Engineering Tissues Vertebrates Work adverse outcome base density experimental study fetal in vivo in vivo regeneration innovation insight member muscle form muscle regeneration muscle strength myogenesis postnatal precursor cell prevent protein protein interaction receptor repaired retinal axon satellite cell stem cell expansion transcription factor

项目摘要

SUMMARY The conversion of proliferating skeletal muscle precursors (myoblasts) to terminally-differentiated myocytes is a critical step in skeletal muscle development and repair; control of this process is therefore of fundamental importance in both muscle development and muscle regeneration after injury. The tendency for myogenic cells cultured densely to differentiate and, conversely, the resistance to differentiation of cells at low density has been called the 'Community Effect'; understanding this phenomenon represents a basic question in muscle biology. Based on our initial observation that EphA7, a juxtacrine signaling molecule, is expressed on myocytes during embryonic and fetal myogenesis and on nascent myofibers during muscle regeneration in vivo we examined the muscle phenotype of EphA7-/- mice. We found that their hindlimb muscles possess fewer myofibers at birth, and those myofibers are reduced in size and have fewer myonuclei and reduced overall numbers of precursor cells throughout postnatal life. Adult EphA7-/- mice have reduced numbers of satellite cells and exhibit delayed and protracted muscle regeneration, and satellite cell-derived myogenic cells from EphA7-/- mice are delayed in their expression of differentiation markers in vitro. Exposure to exogenous EphA7 extracellular domain will rescue the null phenotype, and will also accelerate commitment to differentiation in WT cells, which led us to propose a model in which EphA7 expression on differentiated myocytes promotes commitment of adjacent myoblasts to terminal differentiation via reverse signaling. The experiments we propose in Aims 1 and 2 will address the role of EphA7 in myogenic commitment in both the myocyte ("How does commitment to differentiation lead to expression of EphA7?") and the myoblast ("How does receiving an EphA7 signal lead to commitment to differentiation?"). Once they have differentiated, myocytes must fuse with each other or with a growing myotube in order to generate a functional muscle cell (the contractile myocyte fiber), thus this also represents a critical process in both development and regeneration. However, the molecular requirements for fusion in mammalian muscle cells have been elusive. Our data suggest EphA7 also promotes myogenic fusion, possibly via different molecular mechanisms/interactions from its role in promoting myogenic differentiation. The experiments we propose in Aim 3 will test the ability of EphA7 to promote fusion in myogenic and nonmyogenic cells, determine whether it associates with the cell-surface fusogen myomaker, and identify other protein-protein interactions it is participating in at the interface of myocytes and growing myotubes in cis (on the same cell membrane) or in trans (on opposing cell membranes). Collectively, these studies will address the molecular mechanisms regulating two fundamental cellular processes during myogenic differentiation; they also have the potential to provide insight into potential innovations in muscle stem cell expansion in vitro and thus applications in tissue engineering and regenerative medicine.

概括增殖的骨骼肌前体（成肌细胞）转化为终止分化的心肌细胞是骨骼肌发育和修复的关键一步；因此，控制这个过程是受伤后的肌肉发育和肌肉再生的基本意义。趋势肌原性细胞密集地培养以区分，相反，对细胞分化的抗性低密度被称为“社区效应”；了解这种现象代表了基本肌肉生物学的问题。基于我们最初的观察，以Epha7（一种近距离信号分子）为在胚胎和胎儿肌发生期间在肌细胞和肌肉新生肌纤维上表达在体内再生，我们检查了epha7 - / - 小鼠的肌肉表型。我们发现他们的后肢肌肉出生时的肌纤维较少，这些肌纤维的大小降低，较少整个产后生活中，肌核和减少了前体细胞的总数。成人以Epha7 - / - 小鼠减少了卫星细胞的数量，表现出延迟和持久的肌肉再生，并且来自epha7 - / - 小鼠的卫星细胞衍生的肌源性细胞在分化的表达上被延迟体外标记。暴露于外源Epha7细胞外域将挽救无效的表型，并将还加快了对WT细胞分化的承诺，这使我们提出了一个模型，其中epha7 在分化的肌细胞上的表达促进了相邻成肌细胞对终末的承诺通过反向信号传导分化。我们在目标1和2中提出的实验将解决在肌细胞中肌原性承诺中的Epha7（“对差异化的承诺如何导致 epha7的表达？”）和肌细胞（“接收epha7信号如何导致承诺差异化吗？ Myotube为了产生功能性肌肉细胞（收缩肌细胞纤维），因此也代表发展和再生的关键过程。但是，分子要求对于哺乳动物细胞的融合，难以捉摸。我们的数据表明epha7还促进了肌源融合，可能是通过不同的分子机制/相互作用来促进肌源的作用分化。我们在AIM 3中提出的实验将测试EPHA7促进融合的能力肌原性和非基因性细胞，确定它是否与细胞表面富菌素肌动蛋白制造物相关联，并确定其他蛋白质 - 蛋白质相互作用，它正在参加肌细胞的界面并增长顺式（在同一细胞膜上）或反式（在相对的细胞膜上）中的肌管。总的来说，这些研究将解决调节两个基本细胞过程的分子机制肌原性分化；他们还有可能洞悉肌肉潜在的创新干细胞在体外扩张，因此在组织工程和再生医学中应用。