INTRAFUSAL FIBER EXPRESSION OF CARDIAC SARCOMERIC GENES

肌梭内纤维是高度修饰的骨骼肌 控制运动和姿势所必需的细胞。这些 多核细胞表达一种纺锤体特异性肌球蛋白重亚型 链，阿尔法心脏MHC。建议项目的基本假设 运动神经元、感觉神经元和甲状腺激素相互作用 诱导和维持α-心脏MHC亚群的表达 梭内纤维肌核。首席调查员建议 研究这些因素在调节α-心脏MHC中的作用 正常、失神经、甲状腺功能亢进和甲状腺功能减退患者的基因表达 老鼠。这些实验旨在测试：1)子集是否 融合内肌核被诱导表达α-心脏MHC 神经支配或甲状腺激素升高形成纺锤；2) α-心脏MHC是否是在 持续存在于梭内的梭外纤维的分化 纤维，以及神经支配是否是导致其 在梭内纤维中的持久性。

Intrafusal fibers of muscle spindles are highly modified skeletal muscle cells essential for control of movement and posture. These multinucleated cells express a spindle-specific isoform of myosin heavy chain, alpha-cardiac MHC. The basic hypothesis for the proposed project is that motor neurons, sensory neurons, and thyroid hormone interact to induce and maintain expression of alpha-cardiac MHC in subsets of intrafusal fiber myonuclei. The principle investigator proposes to investigate the roles of these factors in regulating alpha-cardiac MHC gene expression in normal, denervated, hyperthyroid and hypothyroid rats. The experiments are designed to test: 1) whether subsets of intrafusal myonucei are induced to express alpha-cardiac MHC during spindle formation by innervation or elevated thyroid hormone; and 2) whether alpha-cardiac MHC is an isoform transiently expressed during the differentiation of extrafusal fibers which persists in intrafusal fibers, and whether innervation is the factor responsible for its persistence in intrafusal fibers.