REGULATION OF RRNA SYNTHESIS DURING CARDIAC HYPERTROPHY

心肌肥厚通常发生在新生儿和成人心脏中 心脏，是由各种生理和病理条件引起的 如脑缺血、高血压和甲亢。在这个过程中 心肌细胞数量增加，但大小不变。这个 体型的增加与蛋白质速率的增加有关 综合。为了增加细胞合成蛋白质的能力， 细胞通过合成更多的核糖体来增加核糖体的数量。在……里面 这个过程提高了核糖体rna基因(RDNA)的转录速度。 是增加的。我们将同时衡量 RDNA转录系统的组成部分，以便确定如何 这些因素在肥大过程中受到调节。分子 并将开发免疫学探针来分析 转录因子在mRNA和蛋白水平的表达调控 在心肌肥厚期间的水平。克隆大鼠DNA载体的构建 两种基因中的各种突变，如缺失和替换突变 RDNA已知和推测的顺式作用调控元件 启动子，如UBF结合位点、SL-L结合位点、Cre和 AP-1位点，将用于绘制顺式作用调控元件图 参与细胞内rDNA转录的调控 肥大。这些实验将涉及到突变株的共转染 和假的野生型启动子导入培养的新生大鼠心脏 肌细胞。在最初的一系列实验中，确定了 这些顺式作用元件，转基因细胞将暴露在 肥大刺激物，如佛波醇酯和佛手可林。一旦成为 如果确定了特定元素，我们将研究其在 自发性收缩细胞所表现出的肥大反应 与Kc1相比，被捕的牢房没有收缩。他们的行为 突变和假性野生型启动子将通过寡核苷酸进行检测 利用从诱导和非诱导中分离的RNA进行定向扩增 转基因细胞。 这些实验应该：(1)证明rrna基因是如何被调控的。 在心肌肥厚期间和(2)导致实验将允许 细胞外信号转导途径(S)的阐明 启动对心肌肥大过程的刺激。

Cardiac hypertrophy occurs normally in neonatal hearts and, in adult hearts, is induced by various physiological and pathological conditions such as ischemia, hypertension, and thyrotoxicosis. During this process the cardiac muscle cells increase is size but not in number. The increase in size is associated with an increased rate of protein synthesis. To increase the cellular capacity for protein synthesis, the cells increase the number of ribosomes by synthesizing more of them. In this process the rate of transcription of the ribosomal RNA genes (rDNA) is increased. We will measure both the amounts and activities of the components of the rDNA transcription system in order to determine how these factors are regulated during the process of hYPertrophy. Molecular and immunological probes will be developed for the analysis of the regulation of expression of the factors at both the mRNA and protein levels during cardiac hypertrophy. Constructs of cloned rat DNA carrying various mutations, such as deletion and substitution mutations, in both the known and putative cis-acting regulatory elements of the rDNA promoter, such as the UBF binding site, the SL-l binding sites, CRE, and AP-1 sites, will be used to map the cis-acting regulatory elements involved in the regulation of rDNA transcription during cellular hypertrophy. These experiments will involve the cotransfection of mutant and pseudo, wild-type promoters into cultured neonatal rat cardiac myocytes. In the initial series of experiments to determine the role of these cis-acting elements, the transfected cells will be exposed to hypertrophic stimuli, such as phorbol ester and forskolin. Once a specific element is identified, we will examine its role in the hypertrophic response exhibited by spontaneously contracting cells in comparison to KC1 arrested, non-contracting cells. The behavior of the mutant and pseudo, wild-type promoters will be assayed by oligonucleotide directed primer extension using RNA isolated from induced and noninduced transfected cells. These experiments should (1) demonstrate how the rRNA genes are regulated during cardiac hypertrophy and (2) lead to experiments that will allow the elucidation of the signal transduction pathway(s) that lead from the initiating stimulus to the process of cardiac hypertrophy.