Levitt L K, O'Mahoney J V, Brennan K J, Joya J E, Zhu L, Wade R P, Hardeman E C
Muscle Development Unit, Children's Medical Research Institute, Wentworthville, NSW Australia.
DNA Cell Biol. 1995 Jul;14(7):599-607. doi: 10.1089/dna.1995.14.599.
Troponin I (TnI) is a muscle-specific protein involved in the calcium-mediated contraction of striated muscle. Three TnI isoforms have been identified, each encoded by a separate gene and expressed in specific striated muscles in the adult. The slow isoform gene (TnIs) is transcriptionally regulated during skeletal muscle development such that its expression in the adult is restricted to muscle fibers innervated by a slow nerve. To delineate regions of this gene that are responsive to information imparted by the slow nerve, we generated transgenic mice carrying -4,200 to +12 bp of the human TnIs gene linked to the bacterial chloramphenicol acetyltransferase (CAT) coding region. By Northern blot analysis, we detected transgene transcripts only in muscles containing slow-twitch fibers. CAT histochemical analysis revealed that expression of the transgene is restricted solely to slow-twitch fibers as characterized by type I myosin heavy-chain (MyHC) expression. Using regeneration as a model for neural influenced expression, we show that this gene construct also contains sequences necessary to respond to cues from the central nervous system.
肌钙蛋白I（TnI）是一种肌肉特异性蛋白，参与钙介导的横纹肌收缩。已鉴定出三种TnI亚型，每种亚型由一个单独的基因编码，并在成体的特定横纹肌中表达。慢肌亚型基因（TnIs）在骨骼肌发育过程中受到转录调控，因此其在成体中的表达仅限于由慢神经支配的肌纤维。为了确定该基因中对慢神经传递的信息有反应的区域，我们构建了转基因小鼠，其携带与人TnIs基因-4200至+12 bp相连的细菌氯霉素乙酰转移酶（CAT）编码区。通过Northern印迹分析，我们仅在含有慢肌纤维的肌肉中检测到转基因转录本。CAT组织化学分析表明，转基因的表达仅局限于以I型肌球蛋白重链（MyHC）表达为特征的慢肌纤维。以再生作为神经影响表达的模型，我们表明该基因构建体还包含对来自中枢神经系统的信号作出反应所必需的序列。
