REGULATION OF NITRIC OXIDE SYNTASE IN CARDIAC MYOCYTES

心钠素(ANF)和脑利钠肽(BNP)有 血管降压作用，而在肾脏中，它们有强大的利钠和 利尿剂活性。尽管ANF和BNP具有相似的生物学特性 除了活动，每种激素都有不同的特点。 不同之处包括组织分布，对 内肽酶，循环血浆半衰期，与生物和 清除受体，储存在分泌颗粒中的多肽的形式，以及 参与基因表达的可能的DNA调控序列。在成人中 心脏，ANF基因优先在心房表达，并且 心室的表达不到整个心脏的5%。在……里面 相反，心室BNP mRNA占整个心脏的70%以上 级别。ANF和BNP的mRNA水平在随后的脑室中增强 到一些不同的病理生理条件下的体积和 压力超负荷，包括高血压和心力衰竭。考虑到 BNP基因主要在脑室表达， BNP和ANF在心房和心室是不同的，我们假设在那里 在ANF和BNP的合成调节上有明显的差异。这个 这项提案的目标是定义转录和后转录 参与差异调控的转录机制 编码ANF和BNP的基因在病理生理条件下导致 心肌肥厚。要做到这一点，我们将利用一种新的模型 利用培养的成年猫心肌细胞刺激的心肌肥大 用异丙肾上腺素敲打。具体地说，需要检验的假设是： 1)ANF和ANF的转录速率存在差异 BNP基因，而且还存在顺式作用的调控元件 BNP基因的5‘侧翼序列(FS) 新生儿心肌细胞中ANF基因的特征；2) 在心肌肥厚过程中，ANF和BNP基因的重新表达涉及 顺式作用的调控区域有别于正常的 基因的组织特异性表达；3)有不同的反式- 作用调节蛋白对ANF和BNP基因表达的影响 静止与搏动的成年猫心肌细胞(肥大模型 生长)；4)ANF和ANF的稳定性存在差异 正常和肥厚脑室的BNP mRNAs。因此，这些研究将 详细分析ANF和ANF在监管方面的差异 BNP基因，并为理解每个基因的相关性提供了基础 疾病状态下的激素，如高血压和肥厚。

Atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) have vasodepressor effects, while in the kidney they have potent natriuretic and diuretic activities. Although ANF and BNP have similar biological activities, there are distinct features associated with each hormone. Differences include tissue distribution, susceptibility to degradation by endopeptidase, circulating plasma half-life, affinity for biological and clearance receptors, form of the peptide stored in secretory granules, and possible DNA regulatory sequences involved in gene expression. In adult hearts, the gene for ANF is preferentially expressed in the atria, and ventricular expression is less than 5% of that of the whole heart. In contrast, ventricular BNP mRNA represents greater than 70% of whole heart levels. ANF and BNP mRNA levels are augmented in the ventricle subsequent to a number of different pathophysiological conditions of volume and pressure overload, including hypertension and heart failure. Given that the BNP gene is expressed primarily in the ventricles and that the ratio of BNP to ANF is different in atria and ventricles, we hypothesize that there are clear differences in the regulation of synthesis of ANF and BNP. The objective of this proposal is to define transcriptional and post- transcriptional mechanisms involved in the differential regulation of the genes encoding ANF and BNP in pathophysiological conditions resulting in cardiac hypertrophy. To do this, we will make use of a new model of cardiac hypertrophy, utilizing cultured adult feline cardiocytes stimulated to beat with isoproterenol. Specifically, the hypotheses to be tested are: 1) that there are differences in the rates of transcription of the ANF and BNP genes, and furthermore that there are cis-acting regulatory elements in the 5' flanking sequences (FS) of the BNP gene which are distinct from those characterized for the ANF gene in neonatal cardiocytes; 2) that during cardiac hypertrophy reexpression of the ANF and BNP genes involves cis-acting regulatory regions distinct from those involved in normal tissue-specific expression of the genes; 3) that there are different trans- acting regulatory proteins affecting ANF and BNP gene expression in quiescent vs beating adult feline cardiocytes (a model of hypertrophic growth); and 4) that there are differences in the stabilities of ANF and BNP mRNAs in normal and hypertrophied ventricles. Thus, these studies will provide a detailed analysis of the differences in regulation of the ANF and BNP genes, and provide a basis for understanding the relevance of each hormone in disease states, such as hypertension and hypertrophy.