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EphA7 promotes contact-dependent myogenesis

EphA7促进接触依赖性肌生成

基本信息

批准号：
10672896
负责人：
Dawn D Cornelison
金额：
$ 32.63万
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/10672896
关键词：
Acceleration Adhesions Adult Animals Binding Biology Birth Cell Culture Techniques Cell Differentiation process Cell membrane Cell physiology Cell surface Cells Cephalic Communities 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 Maps Mediating Mediator 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 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 translational applications

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.

摘要增殖性骨骼肌前体细胞(成肌细胞)向终末分化肌细胞的转化是骨骼肌发育和修复的关键步骤；因此，控制这一过程是对于肌肉的发育和受伤后的肌肉再生都是至关重要的。对…的倾向密集培养的肌源性细胞分化，反之，对分化的抵抗细胞低密度一直被称为“社区效应”；理解这一现象代表了一种基本的肌肉生物学中的问题。根据我们的初步观察，EphA7，一种旁分泌信号分子，是在胚胎和胎儿肌肉发生过程中表达在肌细胞上，在肌肉发生过程中表达在新生肌纤维上体内再生我们检测了EphA7-/-小鼠的肌肉表型。我们发现它们的后肢肌肉在出生时拥有较少的肌纤维，这些肌纤维尺寸变小，具有更少的在出生后的整个生命过程中，肌核和前体细胞的总数减少。成年EphA7-/-小鼠减少卫星细胞的数量，并表现出延迟和延长的肌肉再生，以及 EphA7-/-小鼠卫星细胞来源的肌源性细胞分化延迟表达体外标记物。暴露于外源EphA7胞外区将挽救无效表型，并将也加速了WT细胞的分化，这导致我们提出了一个模型，在该模型中，EphA7 分化后的肌细胞表达促进相邻成肌细胞对末端的承诺通过反向信号进行分化。我们在目标1和2中提出的实验将解决 EphA7在两个肌细胞中的成肌承诺(“承诺分化如何导致 EphA7的表达？)和成肌细胞(接收EphA7信号如何导致承诺分化？“)。一旦分化，心肌细胞必须相互融合或与生长中的肌管以产生有功能的肌肉细胞(收缩肌细胞纤维)，因此这也代表着发展和再生的关键过程。然而，分子要求对于哺乳动物肌肉细胞的融合一直是难以捉摸的。我们的数据表明，EphA7也促进了生肌融合，可能通过不同的分子机制/相互作用促进生肌差异化。我们在目标3中提出的实验将测试EphA7促进融合的能力肌源性和非肌源性细胞，确定它是否与细胞表面FusoGen肌瘤分子有关，并确定它在肌细胞和生长的界面上参与的其他蛋白质-蛋白质相互作用顺式(在同一细胞膜上)或反式(在相对细胞膜上)中的肌管。总而言之，这些研究将涉及调控两个基本细胞过程的分子机制肌源性分化；它们也有可能提供对肌肉潜在创新的洞察干细胞体外扩增及其在组织工程和再生医学中的应用。