Sphingosine-1-phosphate-activated telomerase in stroke

描述（由申请人提供）：中风是死亡和残疾的主要原因，与脑血管有关。内皮细胞（EC）的凋亡性死亡、血管生成的失败和侧支血管的生长不足会使卒中结局恶化。在脑EC中，鞘氨醇-1-磷酸（S1 P）激活Akt和端粒酶，抑制凋亡并诱导增殖。神经元和可能的神经胶质细胞是缺血中S1 P的来源，因为S1 P合成酶（鞘氨醇激酶2，SPK 2）在小鼠中的氧葡萄糖剥夺和大脑中动脉闭塞（MCAo）后在神经元中上调。我们推测，缺血后，神经元/胶质细胞衍生的S1 P通过端粒酶对EC产生抗凋亡和促血管生成作用。两（2）个具体目标将检验神经元/神经胶质源性S1 P激活EC S1 P1受体、Akt和端粒酶、保护EC免于凋亡和诱导新血管形成的假设。目的1（体外）将证实和表征EC中对S1 P的端粒酶反应（激活和上调），并测试神经元和胶质细胞SPK 2产生的S1 P诱导端粒酶激活，从而介导EC保护和增殖的假设。我们认为，S1 P1受体，Akt和热休克蛋白90（HSP 90）在这些作用中起着关键作用。目的2（体内）将显示S1 P受体激动剂前药FTY 720增加脑EC中的端粒酶表达，并扩展初步发现，该发现显示当在MCAo之前或之后施用时，该药剂降低梗塞面积。使用在EC特异性启动子控制下表达显性失活Akt的转基因小鼠，或缺乏端粒酶催化亚基或RNA模板的小鼠，我们将检验FTY 720的保护作用与EC中Akt和端粒酶活化有关的假设，这种作用不依赖于端粒酶的催化活性（FTY 720应该在RNA模板敲除中起保护作用）。本项目将研究一种新的系统，该系统可以在中风后提供持久的EC功能改善，并作为中风治疗的新靶点。

DESCRIPTION (provided by applicant): Stroke is a major cause of death and disability and brain blood vessels have been implicated. Stroke outcome is worsened by apoptotic death of endothelial cells (EC), failure of angiogenesis and insufficient growth of collateral vessels. In brain EC, sphingosine-1 -phosphate (S1P) activates Akt and telomerase, suppresses apoptosis and induces proliferation. Neurons, and possibly glial cells, are a source of S1P in ischemia because the S1P synthesizing enzyme (sphingosine kinase 2, SPK2) is upregulated in neurons following oxygen glucose deprivation and middle cerebral artery occlusion (MCAo) in mice. We hypothesize that following ischemia, neuron/glia-derived S1P exerts anti-apoptotic and pro-angiogenic effects on EC via telomerase. Two (2) specific aims will test the hypothesis that neuron/glia-derived S1P activates EC S1P1 receptors, Akt and telomerase, protecting EC from apoptosis and inducing neovascularization. Aim 1 (in vitro) will confirm and characterize the telomerase responses (activation and up-regulation) to S1P in EC, and test the hypothesis that S1P produced by neuronal and glial SPK2 induces telomerase activation, thereby mediating EC protection and proliferation. We propose that S1P1 receptors, Akt and Heat-Shock Protein 90 (HSP90) play a key role in these effects. Aim 2 (in vivo) will show that the S1P receptor agonist prodrug FTY720 increases telomerase expression in brain EC and extend preliminary findings showing that this agent decreases infarct size when administered before or after MCAo. Using transgenic mice expressing dominant negative Akt under the control of an EC-specific promoter, or mice lacking either the catalytic subunit or the RNA template of telomerase, we will test the hypothesis that the protective effect of FTY720 is related to Akt and telomerase activation in EC, and that this effect does not depend on the catalytic activity of telomerase (FTY720 should protect in RNA template knockouts).This project will study a novel system that can provide long-lasting improvement in EC function following stroke and serve as a new target for stroke therapy.