The extracellular matrix protein βIG-H3 is expressed at myotendinous junctions and supports muscle cell adhesion
The extracellular matrix protein βIG-H3 is expressed at myotendinous junctions and supports muscle cell adhesion
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DOI：
10.1007/s00441-003-0743-z
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发表时间：
2003-07-01
影响因子：
3.6
通讯作者：
LeBaron, RG
中科院分区：
文献类型：
--
作者：
Ferguson, JW;Thoma, BS;LeBaron, RG
细胞外基质（ECM）分子在肌腱连接（MTJ）的发育和维持中起重要作用，MTJ是肌肉与骨结合的专门区域。在这份报告中，我们提供的证据表明，骨骼肌细胞合成的胶原和纤连蛋白结合ECM蛋白β IG-H3和β IG-H3是本地化的MTJs。原位杂交实验显示，在小鼠发育的E16.5-E18.5期间，β IG-H3 RNA转录物在发育中的骨骼肌纤维接触原始软骨和骨的地方表达。免疫组织化学分析证实，β IG-H3蛋白本身独特地定位于MTJs，超微结构分析表明，β IG-H3与细胞外纤维和细胞表面相关联。在体外，重组betaIG-H3作为骨骼肌细胞的粘附基质。抗整联蛋白α 7和β 1抗体显著降低了粘附，表明β IG-H3通过α 7 β 1整联蛋白与骨骼肌细胞结合。β IG-H3在骨骼肌纤维末端的定位以及β IG-H3与细胞和ECM分子的结合表明β IG-H3可能在发育MTJ中发挥组织和结构作用，将骨骼肌与ECM组分连接起来。
Molecules of the extracellular matrix (ECM) play important roles in the development and maintenance of myotendinous junctions (MTJs), specialized regions of muscle to bone union. In this report we provide evidence that skeletal muscle cells synthesize the collagen- and fibronectin-binding ECM protein betaIG-H3 and that betaIG-H3 is localized to MTJs. In situ hybridization experiments revealed that during E16.5-E18.5 of murine development, betaIG-H3 RNA transcripts were expressed where developing skeletal muscle fibers contact primordial cartilage and bone. Immunohistochemical analysis verified that the betaIG-H3 protein itself localized distinctively at MTJs, and ultrastructural analysis suggested that betaIG-H3 associates with extracellular fibers and the surface of cells. In vitro, recombinant betaIG-H3 functioned as an adhesion substratum for skeletal muscle cells. Adhesion was significantly reduced by anti-integrin alpha7 and beta1 antibodies, suggesting that betaIG-H3 binds to skeletal muscle cells via alpha7beta1 integrin. Localization of betaIG-H3 to the termini of skeletal muscle fibers and the binding of betaIG-H3 to cells and to molecules of the ECM suggests that betaIG-H3 may play an organizational and structural role in developing MTJs, linking skeletal muscle to components of the ECM.