NUCLEAR EFFECTS OF ANGIOTENSIN ON VASCULAR SMOOTH MUSCLE

血管紧张素II(Ang II)有多个作用部位，并诱导不同的 组织反应的类型。尽管Ang II的行动被认为是 由跨膜信号转导机制介导，蓄积 有证据表明，血管紧张素II也可能具有直接的核效应。这 核行动可能至少在一定程度上解释了一些拖延的、漫长的 Ang II的长期影响。这项建议的总体目标是研究 核效应在分子水平上的机制。 我们已经鉴定了大鼠肝脏中的核Ang II结合部位。在……里面 在没有洗涤剂的情况下，Ang II结合部位似乎是一种可溶的 可以通过冷冻和解冻从细胞核中释放出来的蛋白质 在物理化学性质上与膜结合受体截然不同。 将cAMP激活的核提取物与血管紧张素Ⅱ预先孵育可导致 在与调节器相互作用后产生特定的延迟带 凝胶滞留实验显示肾素基因的区域。核电 血管紧张素Ⅱ的作用可能是激素-受体复合体结合的结果 结合到特定的DNA序列，导致靶基因表达的变化 基因，比如甲状腺和类固醇激素。 我们将研究这种核受体的表达调控。 已知的调节血浆Ang II受体的扰动将是 用来确定血浆和核受体是否在 平行的。赋予血管紧张素反应性所需的序列 基因将使用分子生物学技术来确定。我们会 同时研究与细胞核结合的细胞内血管紧张素II的来源 受体。这些研究的结果应该会大大增加我们的 对这一重要多肽作用机制的认识。

Angiotensin II (Ang II) has multiple sites of action and induces diverse types of tissue responses. Although the action of Ang II is believed to be mediated by transmembrane signal transduction mechanisms, accumulating evidence suggests that Ang II may also have a direct nuclear effect. This nuclear action may account, at least in part, for some of the delayed, long term effects of Ang II. The overall goal of this proposal is to study the mechanism of the nuclear effects at the molecular level. We have characterized nuclear Ang II binding sites in the rat liver. In the absence of detergent, Ang II binding sites appear to be a soluble protein that can be released from nuclei by freezing and thawing and which is distinct in physicochemical properties to the membrane bound receptor. Preincubating cAMP activated nuclear extract with Ang II resulted in generation of specific retarded bands after interacting with the regulatory region of renin gene, as revealed by gel retardation assay. The nuclear Ang II effects may be the result of binding of the hormone-receptor complex to a specific DNA sequence, leading to changes in expression of target genes, like that of thyroid and steroid hormones. We will study the regulation of expression of this nuclear receptor. Perturbations which are known to regulate plasma Ang II receptors will be employed to determine if plasma and nuclear receptors are regulated in parallel. The sequence necessary to confer angiotensin responsiveness to a gene will be determined using molecular biological techniques. We will also study the origin of intracellular Ang II which binds to the nuclear receptor. The results of these studies should greatly increase our understanding on the mechanism of action of this important peptide.