The Role of Human Osteopontin Isoforms in Collateral Formation

描述（由申请人提供）：为缺血组织提供血流的新侧支血管的形成是一个极其复杂的过程，它的发生有几种不同的机制，包括从现有血管结构中产生新血管、骨髓来源的内皮前体细胞向缺血部位迁移、炎症细胞的募集以及内皮通道（既有和新形成的）与血管平滑肌细胞的动脉化。虽然关于生长因子在这些过程中的参与已经了解了很多，但由其他因素（如炎症蛋白）介导的适应性血管生长的精确分子机制非常复杂，需要进一步研究。通过了解驱动侧支血管形成的潜在机制，我们可以开发新的治疗方法来增加阻塞性动脉疾病患者的功能性侧支生长，而手术基本上是唯一可用的治疗方法。我们已经证明骨桥蛋白（OPN），一种炎症细胞因子和基质细胞蛋白，是侧支血管生长形成的组成部分，其表达在缺血反应中显着上调。然而，最近有证据表明，人类表达三种OPN亚型（a、b和c），它们在不同的疾病环境中被不同地上调，可能具有不同的功能。目前尚不清楚这三种OPN亚型是如何影响心血管疾病中的细胞迁移和侧支血管形成的。因此，本职业发展建议旨在通过使用一种新颖的翻译方法将这些OPN异构体传递到缺血组织，来定义人类OPN异构体在侧枝形成过程中的功能差异。我们的初步数据有力地支持了人类骨桥蛋白异构体对侧支血管形成、平滑肌细胞迁移和细胞信号传导的差异调节。因此，我们假设人类OPN亚型通过对炎症细胞和血管平滑肌细胞迁移的不同影响，对侧支形成表现出不同的影响，而炎症细胞和血管平滑肌细胞是动脉化所必需的。本应用中描述的实验将剖析这三种人类OPN同工异构体如何调节这些反应。我们建议利用骨桥蛋白缺陷小鼠来确定每个人骨桥蛋白异构体在新血管形成中的具体作用，并将通过研究以下具体目标来验证我们的总体假设：1)明确人OPN异构体在体内侧支血管形成中的作用；2)研究人OPN异构体对血管平滑肌细胞迁移的差异影响；3)确定人OPN异构体介导细胞差异迁移的机制。

DESCRIPTION (provided by applicant): The development of new collateral blood vessels to provide blood flow to ischemic tissues is an extremely complex process that occurs as a result of several distinct mechanisms including sprouting of new blood vessels from existing vascular structures, migration of bone marrow-derived endothelial precursor cells to sites of ischemia, recruitment of inflammatory cells, and the arterialization of endothelial channels (both existing and newly formed) with vascular smooth muscle cells. While much has been learned about the involvement of growth factors in these processes, the precise molecular mechanisms underlying adaptive vascular growth mediated by other factors, such as inflammatory proteins, are extremely complex and require further investigation. By understanding the underlying mechanisms that drive collateral vessel formation, we can develop new therapeutic approaches to increase functional collateral growth in patients with obstructive arterial disease for which surgery is essentially the only available treatment. We have demonstrated that osteopontin (OPN), an inflammatory cytokine and matricellular protein, is integral to the formation of collateral vessel growth and its expression is significantly upregulated in response to ischemia. However, it has recently become evident that humans express three OPN isoforms (a, b, and c), which are differentially upregulated in various disease settings and may have different functions. There is currently nothing known about how these three OPN isoforms function to influence cell migration and collateral vessel formation in cardiovascular disease. Therefore, this career development proposal was designed to define the functional differences of the human OPN isoforms in the collateral formation process by using a novel and translational approach to deliver these OPN isoforms to ischemic tissues. Our preliminary data strongly support that human osteopontin isoforms differentially regulate collateral vessel formation, smooth muscle cell migration, and cell signaling. We therefore hypothesize that human OPN isoforms exhibit differential effects on collateral formation through divergent effects on the migration of inflammatory cells and vascular smooth muscle cells, necessary for arterialization. The experiments described in this application will dissect how these three human OPN isoforms function to modulate these responses. We propose to make use of osteopontin deficient mice to define the specific role of each human osteopontin isoform in new vessel formation and will test our overall hypothesis by investigating the following specific aims: 1) Define the role of human OPN isoforms on collateral vessel formation in vivo, 2) Investigate the differential effects of human OPN isoforms on vascular smooth muscle cell migration, and 3) Determine the mechanism by which human OPN isoforms mediate differential cell migration.