TROPONIN I IN CARDIAC DEVELOPMENT

肌钙蛋白I是肌钙蛋白的抑制性亚单位，是一种重要的肌钙蛋白。 横纹肌中的调节蛋白。 不同的基因编码三种 这种蛋白质的组织特异性同种型。 在成熟快-和 这些同种型特异性地 然而，在胎儿和新生大鼠以及人类心脏中， 和慢骨骼肌钙蛋白I mRNA和同种型共表达。 收缩器官对酸中毒反应的改变， β-肾上腺素能刺激可能是由于存在缓慢的骨骼肌 肌钙蛋白I的含量 这项工作的长期目标 是为了了解肌钙蛋白I亚型的功能后果， 在心脏的变化，并了解顺式和反式作用 使骨骼肌和心肌肌钙蛋白表达缓慢的因子 I mRNA在未成熟心脏中的表达，以及那些指导I mRNA特异性表达的基因。 心肌肌钙蛋白I 具体目标是 建议如下：1.为了表征大鼠的调节区域， 心肌肌钙蛋白I基因的瞬时表达试验， 报告基因构建体转染原代新生大鼠 心肌细胞 要描述的区域包括以下要素， 在心脏成熟过程中调节表达， 心脏特异性表达。2.获得大鼠慢病毒基因组克隆 通过筛选λ载体中的大鼠基因组文库来检测骨骼肌钙蛋白I。 为了通过使用瞬时荧光标记来表征该基因的调控区， 报告基因构建体在骨骼肌细胞中的表达测定 线，并在原代心肌细胞。 要定性的要素 包括赋予肌肉特异性那些，抑制 在心脏成熟过程中的表达，以及对甲状腺激素敏感的元件 激素. 3.为了确定快速骨骼肌钙蛋白I或“胚胎” 心肌肌钙蛋白I同种型在胚胎或胎鼠心脏中表达， 以及其表达的时间过程。 如果发现胚胎基因， 确定其mRNA是否在压力模型中重新表达， 结扎成年大鼠主动脉造成的超负荷肥大。4.到 纯化重组表达的野生型和突变型大鼠心肌肌钙蛋白 为了评估心肌肌钙蛋白I分子中 导致收缩器官对 当心脏同种型存在于肌钙蛋白复合物中时的酸中毒。

Troponin I, the inhibitory subunit of troponin, is an important regulatory protein in striated muscle. Separate genes encode three tissue-specific isoforms of this protein. In mature fast- and slow-twitch skeletal and cardiac muscle these isoforms are specifically expressed, however, in fetal and neonatal rat and human heart the cardiac and slow skeletal troponin I mRNAs and isoforms are co-expressed. Alterations in the response of the contractile apparatus to acidosis and beta-adrenergic stimulation may result from the presence of slow skeletal troponin I in the immature heart. The long term objectives of-this work are to understand the functional consequences of troponin I isoform variation in the heart, and to understand the cis- and trans-acting factors which allow expression of the slow skeletal and cardiac troponin I mRNAs in immature heart, and those which direct specific expression of cardiac troponin I in the mature heart. The specific aims of this proposal are: 1. To characterize the regulatory regions of the rat cardiac troponin I gene by the use of transient expression assays of reporter gene constructs transfected into primary neonatal rat cardiocytes. The regions to be characterized include elements which regulate expression during cardiac maturation and elements which direct cardiac-specific expression. 2. To obtain genomic clones of rat slow skeletal troponin I by screening rat genomic libraries in lambda vectors. To characterize regulatory regions of this gene by the use of transient expression assays of reporter gene constructs in skeletal muscle cell lines, and in primary cardiocytes. The elements to be characterized include those which confer muscle-specificity, those which inhibit expression during cardiac maturation, and elements responsive to thyroid hormone. 3. To determine if fast skeletal troponin I or an "embryonic" cardiac troponin I isoform is expressed in embryonic or fetal rat heart, and the time course of its expression. If an embryonic gene is found, to determine whether its mRNA is re-expressed in a model for pressure overload hypertrophy created by banding the aorta of adult rats. 4. To purify recombinantly expressed wild type and mutant rat cardiac troponin I in order to assess regions of the cardiac troponin I molecule which result in the greater sensitivity of the contractile apparatus to acidosis when the cardiac isoform in present in the troponin complex.