Regulation of Vascular Wall Extracellular Matrix

血管壁细胞外基质的调节

基本信息

批准号：
6582674
负责人：
WILLIAM C PARKS
金额：
$ 34.43万
依托单位：
WASHINGTON UNIVERSITY
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）：大血管的结构组织和弹性是由富含弹性蛋白的细胞外基质提供的。弹性蛋白是原弹性蛋白（分泌性前体蛋白）的共价交联聚合物，在微原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时期，从胎儿生长期间开始，在新生儿早期达到顶峰。此后，原纤维形成迅速下降。成熟后，弹性纤维的组装完成，原弹性蛋白的活性合成急剧下降。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，原弹性蛋白的产生重新开始，导致弹性纤维的异常积累和血流动力学特性的改变。相比之下，腹主动脉瘤（AAA）中弹性片层的选择性降解严重损害了血管壁的完整性。然而，AAA 中弹性蛋白原的表达并未重新启动，尽管动脉中的弹性纤维存在大量损失，因此需要修复。我们假设，控制弹性纤维生成所需蛋白质生成的机制，以及其他血管疾病中准确重新启动纤维形成的机制，在 AAA 中不起作用。我们的研究表明，弹性蛋白原产生的停止受到介导原弹性蛋白 mRNA 加速衰减的转录后机制的严格控制。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原弹性蛋白前体 mRNA，但完全加工的转录物的明显不稳定性阻止了成人组织中原弹性蛋白蛋白的合成。我们已经证明，发育调节的胞质蛋白与弹性蛋白原 mRNA 开放阅读框元件内的 18 核苷酸序列特异性相互作用，并且这种相互作用与转录物的加速衰减有关。我们的数据表明，原弹性蛋白表达的重新启动与该胞质因子的抑制有关。对于该应用，我们预测原弹性蛋白 mRNA 结合蛋白保持活性，从而阻止 AAA 组织中弹性蛋白分解位点产生弹性蛋白。我们的目标是分离该因子，证明其在 mRNA 周转中的作用，确定其介导转录降解的机制，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的产生的基本信息。