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，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结合，会产生促炎环境，导致内皮（EC）功能障碍。这种功能障碍会因对抗EC的血流紊乱而加剧。在生理状态下，通过层流/稳定血流和高剪切应力（s-flow）刺激的抗动脉粥样硬化信号的释放，维持正常的EC功能。我们的数据显示，p90RSK激活抑制Sentrin/SUMO-特异性蛋白酶2 （SENP2）去SUMO化活性，增加p53和erk5 -SUMO化，从而增加p53核输出，增强p53的凋亡功能，抑制erk5转录活性及其抗炎反应。主要的假设是，在动脉粥样硬化区，p90RSK在EC中的激活抑制ERK5依赖的转录活性，刺激p53- sumoylation，从而促进EC炎症和凋亡，特别是在糖尿病中。实验方法将是确定p90RSK在Aims 1和Aims 2中调节ERK5、p53、EC炎症和凋亡的机制。在aims 3中，我们将使用aims 1和2中在明确的流动环境中产生的突变体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Aim 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。我们预计特异性d-flow和dm依赖的p90RSK激活以及随后的ERK5和p53-SUMOylation会使EC动脉粥样硬化。拟议的研究应该提供关于d-flow和dm相关的EC功能障碍的两个重要问题的重要新信息：2. p90RSK激活对SENP2去sumo化活性和随后的EC凋亡和炎症的作用；p90rsk介导的ERK5磷酸化在EC炎症中的作用。动脉粥样硬化中p90RSK-SENP2和p90RSK-ERK5区隔化（细胞核vs细胞质）的概念是新颖的，强调了疾病发病机制中翻译后机制的重要性。这些通路中的蛋白质应该是有吸引力的药物靶标，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，我们的新型小分子特异性p90RSK抑制剂应该为减少糖尿病的动脉粥样硬化提供新的治疗策略。

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.