Regulation of Vascular Wall Extracellular Matrix

血管壁细胞外基质的调节

基本信息

批准号：
6937022
负责人：
WILLIAM C PARKS
金额：
$ 24.48万
依托单位：
UNIVERSITY OF WASHINGTON
依托单位国家：
美国
项目类别：
财政年份：
2003
资助国家：
美国
起止时间：
2003-04-01 至 2007-03-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): The structural organization and resiliency of large blood vessels is provided by the elastin-rich extracellular matrix of the media. Elastin is a covalently crosslinked polymer of tropoelastin, the secreted precursor protein, which are assembled into fibers on a microfibrillar scaffold. Unlike most proteins, elastic fiber production is limited to a brief period of development, beginning during fetal growth and peaking during early neonatal periods. Thereafter, fibrillogenesis declines rapidly. By maturity, assembly of elastic fibers is complete, and active synthesis of tropoelastin plummets. Several important vascular diseases, however, are characterized by overt changes in elastin production and integrity. For example, in hypertension and atherosclerosis, tropoelastin production is re-initiated leading to an abnormal accumulation of elastic fibers and altered hemodynamic properties. In contrast, selective degradation of elastic lamellae in abdominal aortic aneurysms (AAA) severely compromises the integrity of vessel wall. Tropoelastin expression, however, is not re-initiated in AAA, even though there is massive loss and, hence, need for repair of elastic fibers in these arteries. We hypothesize that the mechanisms that control the production of proteins needed for elastic fiber production, mechanisms that accurately re-initiate fibrillogenesis in other vascular diseases, are inoperative in AAA. Our studies have demonstrated that the cessation of tropoelastin production is controlled strictly by a post-transcriptional mechanism that mediates an accelerated decay of tropoelastin mRNA. Although the gene continues to transcribe tropoelastin pre-mRNA at the same rate in neonatal and adult tissue, marked instability of the fully-processed transcript prevents synthesis of tropoelastin protein in adult tissue. We have demonstrated that a developmentally-regulated cytosolic protein interacts specifically with a 18-nucleotide sequence within an open-reading frame element of tropoelastin mRNA and that this interaction is associated with accelerated decay of the transcript. Our data demonstrates that re-initiation of tropoelastin expression is associated with repression of this cytosolic factor. For this application, we predict that the tropoelastin mRNA-binding protein remains active, thus barring elastin production at sites of elastin breakdown in AAA tissue. Our aims are to isolate this factor, demonstrate its role in mRNA turnover, determine the mechanism of how it mediates transcript degradation, and assess its activity in AAA and atherosclerotic tissues. This work will provide fundamental information on how production of a key vascular protein is regulated.

描述（由申请人提供）：大型血管的结构组织和弹性由富含弹性的细胞外基质提供。弹性蛋白是Tropoelastin的共价交联聚合物，Tropoelastin是分泌的前体蛋白，在微纤维支架上组装成纤维。与大多数蛋白质不同，弹性纤维的产生仅限于短暂的发育，从胎儿生长和新生儿早期峰值开始。此后，原纤维发生迅速下降。通过成熟度，弹性纤维的组装是完整的，并且热弹性蛋白粉的活跃合成。然而，几种重要的血管疾病的特征是弹性蛋白产生和完整性的明显变化。例如，在高血压和动脉粥样硬化中，肌动蛋白的产生是重新发射的，导致弹性纤维的异常积累和血液动力学特性改变。相反，腹主动脉瘤（AAA）中弹性薄片的选择性降解严重损害了血管壁的完整性。然而，尽管在AAA中没有重新启动Tropoelastin的表达，即使存在巨大的损失，因此需要修复这些动脉中的弹性纤维。我们假设控制弹性纤维生产所需的蛋白质的机制，这些机制在其他血管疾病中准确地重新启动原纤维生成的机制在AAA中是不起作用的。我们的研究表明，暂停Tropoelastin产生的停止受到转录后机制的控制，该机制介导了Tropoelastin mRNA的加速衰变。尽管该基因在新生儿和成人组织中继续以相同的速率转录Tropoelastin Prepoelastin Pre-MRNA，但明显的全面处理转录本的不稳定性阻止了成人组织中tropoelastin蛋白的合成。我们已经证明，在tropoelastin mRNA的开放式读取框架元素中，发育调节的胞质蛋白与18-核苷酸序列特别相互作用，并且这种相互作用与转录本的加速衰变有关。我们的数据表明，对tropoelastin表达的重新生成与该胞质因子的抑制有关。对于此应用，我们预测，Tropoelastin mRNA结合蛋白保持活跃，因此禁止在AAA组织中弹性蛋白分解部位产生弹性蛋白。我们的目的是隔离这一因素，证明其在mRNA周转中的作用，确定其如何介导转录物降解的机制，并评估其在AAA和动脉粥样硬化组织中的活性。这项工作将提供有关如何调节关键血管蛋白产生的基本信息。