SMOOTH MUSCLE CELL MEMBRANE DURING ATHEROGENESIS

在西方文化中，动脉粥样硬化仍然是导致死亡的唯一主要原因。动脉粥样硬化病变的发展被认为遵循了中膜平滑肌细胞(SMC)从收缩状态到合成状态的表型转变。许多信号似乎参与了这种调节，包括氧化应激，巨噬细胞来源的细胞因子和白介素类，以及内皮因子(内皮素类和一氧化氮)。血清高胆固醇血症作为危险因素的首要地位表明，胆固醇分子也可能在动脉粥样硬化形成中发挥作用。我们实验室的工作表明，含有胆固醇的SMC质膜的丰富会导致SMC的变化，这与动脉粥样硬化中的情况非常相似。此外，这些变化可以被雌激素逆转。我们推测，胆固醇对SMC质膜的富集性是动脉粥样硬化过程中SMC调节的一个重要因素，而雌激素逆转这一效应的能力有助于其抗动脉粥样硬化作用。我们将在两个目标中检验这一假设。目的L将确定胆固醇改变SMC膜双层结构的能力是否作为一个单一、孤立和独立的变量在动脉粥样硬化形成过程中导致SMC表型和基因表达的改变。目的2将确定雌激素的动脉粥样硬化保护作用是否直接在动脉SMC和B)水平介导，雌激素的作用机制是否部分通过对抗胆固醇对动脉SMC膜的作用而介导。在这些研究中，我们将使用两种血管细胞：1.早期传代(等于或<lt；3)的兔主动脉SMC，以及2.早期传代(等于或<lt；3)的人主动脉和冠状动脉SMC。随后将发生表型变化，包括细胞增殖和胶原合成。NFkappaB的激活和活性氧中间体的产生将被测量为潜在的信号中间体，使用适当的技术。基因表达的变化将通过测量我们已经确定的在动脉粥样硬化形成过程中在SMC中上调的两个基因(Hn-RNP-K和Prolyl-4-羟基酶)以及其他人确定的反映SMC合成表型的基因的消息和蛋白水平来评估。结合这些方法将为人类SMC在动脉粥样硬化形成过程中早期缺陷的细胞基础以及雌激素如何在这种疾病中提供细胞保护提供重要的见解

Atherosclerosis continues to be the single leading cause of mortality in Western cultures. The development of atherosclerotic lesions is thought to follow the phenotypic modulation of medial smooth muscle cells (SMC) from the contractile to the synthetic state. A variety of signals have been identified that appear to participate in this modulation including oxidative stress, cytokines and interleukins of macrophage origin and endothelial factors (endothelins and NO.). The primacy of serum hypercholesterolemia as a risk factor suggests that the molecule cholesterol may also play a role in atherogenesis. Work performed by our lab has shown that enrichment of the SMC plasma membrane with cholesterol induces alterations in SMC very similar to those seen in atherosclerosis. Moreover, these alterations are reversed by estrogen. We hypothesize that enrichment of the SMC plasma membrane with cholesterol is an important factor contributing to SMC modulation during atherogenesis, and that estrogen's ability to reverse this effect contributes to its atheroprotective actions. We will test this hypothesis in 2 aims. Aim l will determine whether cholesterol's ability to alter the SMC membrane bilayer structure, as a single, isolated and independent variable contributes to the phenotypic and gene expression alterations in SMC during atherogenesis. Aim 2 will determine whether the atheroprotective effects of estrogen are mediated A), directly at the level of the arterial SMC and B), whether the mechanism of estrogen's actions are mediated, in part, by countering cholesterol's effects on the arterial SMC membrane. For these studies,we will employ two preparations of vascular cells: 1. early passage (equal to or <3) rabbit aortic SMC, and 2, early passage (equal to or <3) human aortic and coronary artery SMC. Phenotypic alterations will be followed including cell proliferation and collagen synthesis. NFkappaB activation and the generation of reactive oxygen intermediates will be measured as potential signaling intermediates using appropriate techniques. Alterations in gene expression will be assessed by measuring message and protein levels for 2 genes we have identified to be upregulated in SMC during atherogenesis (hn-RNP-K and prolyl-4-hydroxylase) as well as genes identified by others reflecting the synthetic phenotype in SMC, collagens I and III. Combining these approaches will provide essential insights into the cellular basis for the early defects in human SMC during atherogenesis and how estrogen provides cellular protection in this disease