p90RSK: A flow responsive mediator of inflammation

描述(申请人提供)：炎症在心血管疾病和糖尿病(DM)中的作用已变得越来越明显。特别是，高血压、肥胖、糖尿病、吸烟、高脂血症和遗传易感性等危险因素的组合造成了促炎环境，导致内皮(EC)功能障碍。这种功能障碍因对抗EC的血流紊乱(d-flow)而加剧。在生理状态下，由于层流/稳定血流和高切应力(S流)刺激的抗动脉粥样硬化信号的释放，维持了正常的内皮细胞功能。我们的数据显示，p90RSK的激活抑制了丝点蛋白/相扑特异的蛋白水解酶2(SENP2)的去SUMO化活性，增加了P53和ERK5-SUMO化，从而增加了P53的核输出，增强了P53的凋亡功能，抑制了ERK5的转录活性及其抗炎反应。主要的假设是，内皮细胞中动脉粥样硬化蛋白区域的p90RSK激活抑制ERK5依赖的转录活性，并刺激P53-SUMO化，从而促进内皮细胞的炎症和凋亡，特别是在DM中。实验方法将是确定p90RSK调控AIMS 1和2中ERK5、P53、EC炎症和凋亡的机制。在AIMS 3中，我们将在明确的流动环境中使用AIMS 1和2中产生的突变和抑制片段来证明我们可以通过抑制p90RSK和SENP2介导的炎症和凋亡来减轻d-flow的有害影响。在目标4中，我们将使用遗传小鼠模型来评估p90RSK和SENP2活性在动脉粥样硬化中的相对作用。我们预计，特定的d-Flow和依赖于DM的p90RSK激活以及随后的ERK5和P53-SUMO化使EC atheroprone。这些研究将为D-FLOW和DM相关的EC功能障碍中的两个重要问题提供重要的新信息：1.p90RSK激活在SENP2去甲基化活性和随后的EC凋亡和炎症中的作用；2.p90RSK介导的ERK5磷酸化在EC炎症中的作用。P90RSK-SENP2和p90RSK-ERK5在动脉粥样硬化中的区域化(细胞核与胞浆)的概念是新的，并强调了翻译后机制在疾病发病机制中的重要性。这些途径中的蛋白质应该是有吸引力的药物靶点，因为它们具有区别于其他MAPK和信号事件的独特功能。我们相信，我们的新的小分子，特异性的p90RSK抑制剂，应该为减少DM的动脉粥样硬化提供新的治疗策略。 与公共卫生相关：炎症在心血管疾病和糖尿病中的作用日益明显。在基础科学水平上，了解这些机制中涉及的特定信号事件是一个关键问题，这里将通过生物化学、细胞生物学和体内转基因小鼠来解决。这些研究应该有助于深入了解血流紊乱促进血管炎症的机制，并促进限制动脉粥样硬化的新治疗方法的开发，特别是在糖尿病患者。

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.