p90RSK: A flow responsive mediator of inflammation

描述（由申请人提供）：炎症在心血管疾病和糖尿病（DM）中的作用越来越明显。特别是，风险因素如高血压、肥胖、DM、吸烟、高脂血症和遗传易感性的组合产生导致内皮（EC）功能障碍的促炎环境。这种功能障碍会因对EC的血流（d-流）受到干扰而加剧。在生理状态下，正常EC功能通过释放由层流/稳定血流和高剪切应力（s-flow）刺激的抗动脉粥样硬化信号来维持。我们的数据显示，p90 RSK激活抑制Sentrin/SUMO特异性蛋白酶2（SENP 2）去SUMO化活性，并增加p53和ERK 5-SUMO化，这增加了p53核输出，增强了p53的凋亡功能，并抑制ERK 5-转录活性及其抗炎反应。主要的假设是，EC中atheroprone区域的p90 RSK激活抑制ERK 5依赖性转录活性并刺激p53-SUMO化，从而促进EC炎症和凋亡，特别是在DM中。实验方法将是确定p90 RSK调节ERK 5、p53、EC炎症和凋亡的机制，目的1和2。在目标3中，我们将在明确定义的流动环境中使用目标1和2中产生的突变体和抑制片段，以证明我们可以通过抑制p90 RSK和SENP 2介导的炎症和凋亡来减轻d-流动的有害影响。在目的4中，我们将使用遗传小鼠模型来评估p90 RSK和SENP 2活性在动脉粥样硬化中的相对作用。我们预计，特定的d-流动和DM依赖性p90 RSK激活和随后的ERK 5和p53-SUMO化使EC atheroprone。拟议的研究应提供有关d-flow和DM相关EC功能障碍的两个重要问题的重要新信息：1。p90 RSK激活对SENP 2去类小泛素化活性和随后的EC凋亡和炎症的作用，以及2. p90 RSK介导的ERK 5磷酸化在EC炎症中的作用动脉粥样硬化中p90 RSK-SENP 2和p90 RSK-ERK 5区室化（细胞核vs细胞质）的概念是新颖的，并突出了翻译后机制在疾病发病机制中的重要性。这些通路中的蛋白质应该是有吸引力的药物靶点，因为它们具有独特的特征，将它们与其他MAPK和信号事件区分开来。我们相信，我们的新的小分子，特异性p90 RSK抑制剂，应该提供一个新的治疗策略，减少糖尿病动脉粥样硬化。 公共卫生相关性：炎症在心血管疾病和糖尿病中的作用越来越明显。在基础科学水平上，理解这些机制中涉及的特定信号事件是一个关键问题，将在这里通过生物化学，细胞生物学和体内转基因小鼠来解决。这些研究将提供对血流紊乱促进血管炎症的机制的深入了解，并促进新的治疗方法的发展，以限制动脉粥样硬化，特别是在糖尿病。

DESCRIPTION (provided by applicant): The role of inflammation in cardiovascular disease and diabetes (DM) has become increasingly evident. Especially, a combination of risk factors such as hypertension, obesity, DM, smoking, hyperlipidemia, and genetic predisposition create a proinflammatory environment that leads to endothelial (EC) dysfunction. This dysfunction is exacerbated by disturbed blood flow (d-flow) against the EC. In the physiological state, normal EC function is maintained with the release of anti-atherosclerotic signals stimulated by laminar/steady blood flow and high shear stress (s-flow). Our data show that p90RSK activation inhibits Sentrin/SUMO- specific proteases 2 (SENP2) de-SUMOylation activity and increases both p53 and ERK5-SUMOylation, which increases p53 nuclear export and enhances the apoptotic function of p53 and inhibits ERK5-transcriptional activity and its anti-inflammatory responses. The major hypothesis is that p90RSK activation in EC at atheroprone areas inhibits ERK5-dependent transcriptional activity and stimulates p53-SUMOylation thereby promoting EC inflammation and apoptosis, especially in DM. The experimental approach will be to define the mechanisms by which p90RSK regulates ERK5, p53, EC inflammation and apoptosis in Aims 1 and 2. In Aim 3 we will use mutants and inhibitory fragments generated in aims 1 and 2 in well-defined flow environments to prove that we can mitigate the harmful effects of d-flow by inhibiting p90RSK- and SENP2-mediated inflammation and apoptosis. In Aim 4 we will use genetic mouse models to evaluate the relative roles of p90RSK and SENP2 activity in atherosclerosis. We anticipate that specific d-flow and DM-dependent p90RSK activation and subsequent ERK5 and p53-SUMOylation make EC atheroprone. The proposed studies should provide significant new information regarding two important questions in d-flow and DM-related EC dysfunction: 1. The role of p90RSK activation on SENP2 de-sumoylation activity and subsequent EC apoptosis and inflammation, and 2. The role of p90RSK-mediated ERK5 phosphorylation on EC inflammation. The concept of p90RSK-SENP2 and p90RSK-ERK5 compartmentalization (nucleus vs cytosol) in atherosclerosis is novel and highlights the importance of post-translational mechanisms in disease pathogenesis. The proteins in these pathways should be attractive drug targets since they have unique features that distinguish them from other MAPK and signal events. We believe that our novel small molecule, specific p90RSK inhibitor, should provide a new therapeutic strategy for reducing atherosclerosis in DM. PUBLIC HEALTH RELEVANCE: The role of inflammation in cardiovascular disease and diabetes has become increasingly evident. At the basic science level understanding the specific signaling events involved in these mechanisms is a key issue that will be addressed here by biochemistry, cell biology, and in vivo transgenic mice. These studies should provide insight into mechanisms by which disturbed flow promotes vascular inflammation and facilitate development of new therapeutic approaches to limit atherosclerosis, especially in DM.