Stat3 in Post-Ischemic Myocardial Inflammation

心肌再灌注通过激活氧化还原敏感基因诱导促炎基因的表达 核转录因子。我们已经发现信号转导和转录激活因子-3 (STAT3)在心肌缺血-再灌流后被激活，其激活方式依赖于小GTP酶rac1， 并与细胞间黏附分子-1(ICAM-1)基因中的GAS启动子元件结合，该基因 一种重要的内皮细胞黏附分子的密码，它与白细胞相互作用。磷酸化后 在其727个丝氨酸残基中，STATS与转录激活因子Sp1结合。我们假设这代表着一个 促进缺血再灌注后内皮细胞ICAM-1转录的新机制。在……里面 支持这一观点的是，抑制培养内皮细胞中STAT3/Sp1的活性显著减少了ICAM-1的转录 1缺氧-复氧后。在本提案中，我们将确定STATS在ICAM-1调节中的作用 和其他促炎基因在心肌缺血再灌注后的血管内皮细胞中的表达。在目标1中，我们 我将研究STATS与Sp1相互作用的分子机制，包括机制 参与了两个分子之间的结合和STATS S727残基的磷酸化作用。我们 将决定抑制STAT3-Sp1相互作用是否影响内皮细胞ICAM-1基因调控，以及是否 STAT3/Sp1改善缺血后微血管炎症(通过视频显微镜评估)或心肌 缺血再灌注损伤，采用在体小鼠模型。在目标2中，我们将研究负责的机制 对于缺氧-复氧后的rac1依赖的STATS激活，包括这两个分子如何结合在一起， 这种结合是如何促进STATS的Y705和S727残基的磷酸化的，以及哪些激酶是 牵涉其中。在目标3中，我们将确定低氧-复氧内皮细胞中STATS的激活是否受一种 负反馈环参与T细胞淋巴瘤侵袭转移的STATS转录调控2 鸟嘌呤交换因子(TIAM2)和GTP酶激活蛋白racGAPI，两者依次 下调rac1的激活状态，从而下调STATS本身的激活状态。

Myocardial reperfusion results in the induction of pro-inflammatory genes through the activation of redoxsensitive nuclear transcription factors. We have found that signal transducer and activator of transcription-3 (Stat3) is activated after myocardial ischemia-reperfusion, in a manner dependent on the small GTPase Rac1, and binds to a GAS promoter element in the intercellular adhesion molecule-1 (ICAM-1) gene, a gene which codes for an important endothelial cell adhesion molecule which interacts with leukocytes. After phosphorylation of its serine 727 residue, StatS binds to the transcriptional activator Sp1. We hypothesize that this represents a novel mechanism for enhancing ICAM-1 transcription in endothelial cells (ECs) after ischemia-reperfusion. In support of this idea, inhibition of Stat3/Sp1 activity in cultured ECs significantly reduces the transcription of ICAM- 1 after hypoxia-reoxygenation. In this proposal, we will determine the role of StatS in the regulation of ICAM-1 and other pro-inflammatory genes in vascular endothelium after myocardial ischemia-reperfusion. In Aim 1 we will investigate the molecular mechanisms responsible for StatS interaction with Sp1, including the mechanisms involved in binding between the two molecules and the role of phosphorylation of the StatS S727 residue. We will determine whether inhibition of the Stat3-Sp1 interaction affects ICAM-1 gene regulation in ECs, and whether Stat3/Sp1 modifies post-ischemic microvascular inflammation (assessed by videomicroscopy) or myocardial ischemia-reperfusion injury, using in vivo murine models. In Aim 2 we will examine the mechanisms responsible for Rac1-dependent StatS activation after hypoxia-reoxygenation, including how the two molecules bind together, how this binding promotes the phosphorylation of the Y705 and S727 residues of StatS, and which kinases are involved. In Aim 3 we will determine whether activation of StatS in hypoxic-reoxygenated ECs is self-limited by a negative feedback loop involving StatS transcriptional regulation of T-cell lymphoma invasion and metastasis 2 (TIAM2), a guanine exchange factor, and RacGAPI, a GTPase-activating protein, both of which in turn downregulate the activation state of Rac1, and thereby of StatS itself.