Role for S1P2 in the Arterial Injury Response

描述（由申请人提供）：内膜增生是由内膜平滑肌细胞（SMCs）的增殖和迁移引起的，并有助于动脉重建后再狭窄（血管再闭塞）。本研究探讨了内膜生长发生的可能性，因为通常抑制损伤后SMCs过度增殖的途径被抑制。我们发现，缺乏鞘氨醇-1-磷酸（S1P2） 2型受体的小鼠颈动脉损伤导致大的新生内膜形成，而野生型小鼠则没有。由于S1P2缺陷小鼠发育正常，不表现出任何血管表型，因此S1P2显然在脉管系统的发育中不起关键作用。我们的总体假设是，S1P在损伤后产生，并与S1P2结合，导致心肌素样蛋白家族的血清反应因子及其辅助因子激活。已知这种转录因子复合物调节SMC特异性基因的表达，我们假设这些基因抑制SMC增殖。这种抑制途径在S1P2敲除小鼠中不存在，这可能是这些动物在动脉损伤反应中产生大内膜病变的原因。本提案的目标是验证这一假设，并提出了四个具体目标。在目的1中，我们将测量SMC特异性基因在野生型和s1p缺陷小鼠损伤动脉中的表达。在目标2中，我们将定义SMCs中表达的所有三种S1P受体在SRF依赖性基因调控中的作用。在目标3中，我们将描述由S1P2激活并调节smc特异性基因表达的转录复合体。在目标4中，我们将使用微阵列技术识别血管壁上由S1P2直接控制的新基因，这些基因对损伤做出反应。公共卫生相关性：动脉再狭窄是动脉修复的一种严重且昂贵的并发症，约30%的患者发生这种并发症。S1P2表达水平和信号的变化可能决定内膜病变是否发生。因此，S1P2通路中的蛋白质可能构成有希望的内膜生长药理控制的新靶点。

DESCRIPTION (provided by applicant): Intimal hyperplasia is caused by proliferation and migration of intimal smooth muscle cells (SMCs) and contributes to restenosis (the re-occlusion of vessels) after arterial reconstruction. This proposal investigates the possibility that intimal growth occurs because a pathway that normally inhibits excessive proliferation of SMCs after injury is suppressed. We have found that carotid injury in a mouse lacking the type-2 receptor for sphingosine-1-phosphate (S1P2), but not in their wild-type counterpart, results in the formation of a large neointima. Because S1P2-deficient mice develop normally and do not exhibit any vascular phenotype, S1P2 does apparently not play a critical role in the development of the vasculature. Our overall hypothesis is that S1P is generated after injury and binds to S1P2, which causes activation of serum-response factor and its cofactor of the myocardin-like protein family. This transcription factor complex is known to regulate expression of SMC-specific genes, and we hypothesize that these genes inhibit SMC proliferation. This inhibitory pathway is absent in the S1P2 knock-out mouse, and this might be the reason that these animals develop large intimal lesions in response to arterial injury. The goal of this proposal is to test this hypothesis, and four specific aims are proposed. In aim 1, we will measure expression of SMC- specific genes in injured arteries of wild-type and S1P-deficient mice. In aim 2, we will define a role for all three S1P receptors expressed in SMCs in the regulation of SRF- dependent genes. In aim 3, we will characterize the transcriptional complex that is activated by S1P2 and regulates the expression of SMC-specific genes. In aim 4, we will use micro array technology to identify novel genes in the vessel wall that are directly controlled by S1P2 in response to injury. PUBLIC HEALTH RELEVANCE: Restenosis is a serious and costly complication of arterial repair which occurs in ca. 30% of patients. Variations in S1P2 expression levels and signaling might determine if intimal lesions develop. Thus, proteins in the S1P2 pathway may constitute promising novel targets to pharmacological control of intimal growth.