Sphingolipid Signaling in Endothelial Function

描述（申请人提供）：1-磷酸鞘氨醇（S1P）是一种生物活性鞘脂，调节多种细胞功能，如增殖、存活、趋化性等。最近，研究表明S1P是G蛋白偶联受体EDG-1（内皮分化基因1）的高亲和力配体。重要的是，最近提出了 S1P/EDG-1 在血管发育和成熟中的新功能。例如，S1P 在体外促进内皮细胞的形态发生，并在体内增强 VEGF 和 FGF 诱导的血管生成。此外，EDG-1的缺失会因形成不成熟的脉管系统而导致胚胎死亡。然而，S1P/EDG-1 调节血管生成的分子机制仍然难以捉摸。因此，我们的长期目标是了解这种鞘脂在内皮功能中的信号传导和作用。在本提案中，我们将描述 EDG-1 受体调节的信号通路。最初，通过利用亲和纯化程序，发现一组细胞多肽与 EDG-1 受体的第三个细胞内环（i3 结构域）特异性结合。其中，鉴定出两种表观分子量为 120 kDa 和 56 kDa 的蛋白激酶以及一种 21 kDa 的磷蛋白。我们假设这些 EDG-1 相关激酶/多肽对于 S1 P/EDG-1 信号转导至关重要，特别是在调节内皮细胞功能方面。初步数据表明 pp120 激酶可能在 EDG-1 信号传导中发挥重要功能。因此，我们建议优先考虑并重点确定血管生物学背景下 EDG-1 信号传导中 pp120 激酶的身份和功能。研究目的是I)纯化和克隆pp120EDG-1相关激酶，II)表征pp120激酶在S1 P/EDG-1信号传导中的相关性，III)研究pp120激酶在内皮细胞激活中的功能，以及IV)确定EDG-I-i3的结构-功能关系。这些研究的完成预计将加深我们对血管生成分子机制的了解，最终可能导致未来治疗的发展。

DESCRIPTION (provided by applicant): Sphingosine-1-phosphate (S1P), a bioactive sphingolipid, regulates a variety of cellular functions such as proliferation, survival, chemotaxis etc. Recently, it has been shown that S1P is the high affinity ligand for the G-protein coupled receptor, EDG-1 (Endothelial Differentiation Gene-1). Importantly, a novel function of S1P/EDG-1 in blood vessel development and maturation has been proposed recently. For example, S1P promotes morphogenesis of endothelial cells in vitro and potentiates VEGF and FGF-induced angiogenesis in vivo. Furthermore, deletion of EDG-1 resulted in embryonic lethality due to the formation of immature vasculature. However, the molecular mechanisms underlying S1P/EDG-1 regulated angiogenesis remain elusive. Thus, our long-term goal is to understand the signaling and roles of this sphingolipid in endothelial functions. In this proposal, we will characterize signaling pathways regulated by the EDG-1 receptor. Initially, by utilizing the affinity purification procedure, a panel of cellular polypeptides was found to specifically associate with the third intracellular loop (i3 domain) of EDG-1 receptor. Among them, two protein kinases with apparent molecular masses of 120- and 56-kDa and a 21-kDa phosphoprotein were identified. We hypothesize that these EDG-1 associated kinases/polypeptides are critical for the S1 P/EDG-1 signaling, in particular in regulating the function of endothelial cells. Preliminary data suggest that pp120 kinase may be functionally important in EDG-1 signaling. Thus, we propose to prioritize and focus on determining the identity and functions of pp120 kinase in EDG-1 signaling in the context of vascular biology. The research aims are I) purify and clone the pp120EDG-1 associated kinase, II) characterize the relevance of pp120 kinase in S1 P/EDG-1 signaling, III) study the functions of pp120 kinase in endothelial cells activation, and IV) determine the structure-function relationship of EDG-I-i3. The completion of these studies is anticipated to better our knowledge of molecular mechanisms underlying angiogenesis, which ultimately may lead to future therapeutic development.