Endothelial Sphingolipid Synthesis and Tissue Inflammatory Response

内皮损伤促进血流紊乱部位动脉粥样硬化的发展。 鞘氨醇-1-磷酸(S1P)是由鞘磷脂代谢产生的一种分泌型脂质介质，可 与G蛋白偶联受体相互作用，称为S1P1-5。本地生产和流通的S1P 激活S1P受体，特别是内皮细胞中含量最丰富的S1P1受体，以维持血管 动态平衡。鞘脂代谢和S1P信号的改变与血管病变有关 疾病，包括冠状动脉疾病(CAD)。目前的拨款带来了几项进展。首先，我们 发现了一种调节内皮鞘脂脂生物合成的新机制。NOGO-B，a 内质网的膜蛋白在血管中高表达，结合并抑制丝氨酸 棕榈酰基转移酶(SPT)，神经鞘糖脂产生的限速酶。第二, 我们发现Nogo-B/SPT相互作用下调局部S1P信号转导 炎症、高血压和心力衰竭。第三，我们发现炎症刺激和氧化低密度脂蛋白 诱导Nogo-B磷酸化，进一步抑制导致内皮损伤的SPT活性。 第四，在肿瘤坏死因子-α之后，NOGO-B的N-末端被切割并移位到细胞核以影响 内皮转录组。我们的长期目标是了解Nogo-B是如何调节局部鞘脂的 信号转导及其在冠心病发病机制中对冠脉功能的影响。我们的假设是 Nogo-B控制血管内皮细胞衍生的S1P信号，这是血管内稳态的关键调节因素 和疾病--从而影响冠状动脉斑块的进展。从机制上讲，我们假设 Nogo-B通过两个主要机制促进血管炎症和疾病；SPT抑制，从而 扰乱局部衍生的S1P信号，并激活基因图谱。理性的是， 调节内皮炎症的新机制的发现将提供潜在的治疗方法 CAD的目标。对于更新，我们建议：1)研究内皮细胞Nogo-B在血管内皮细胞中的作用 小鼠对冠状动脉粥样硬化的易感性；2)确定内皮细胞S1P的重要性 Nogo-B信号转导及其作为下游效应因子在冠状动脉粥样硬化发病中的作用 剖析Nogo-B信号在心肌内皮损伤中的作用机制。 这一贡献意义重大，因为它将确定治疗冠心病的新靶点，特别是在 现有的治疗方法只取得了部分成功，除了他汀类药物外，目前还没有 有效解决血管炎症的有效药理策略。建议数 这项研究具有创新性，因为我们研究了神经鞘脂动态平衡和S1P变化的影响 通过使用一种新的冠心病和冠状动脉粥样硬化小鼠模型，在冠状动脉粥样硬化进展中发出信号 心肌梗死更好地概括了人类的疾病，这是一个迄今未被研究的过程。

Endothelial injury promotes the development of atherosclerosis at the site of disturbed flow. Sphingosine-1-phosphate (S1P), produced by sphingolipid metabolism, is a secreted lipid mediator that interacts with G protein-coupled receptors, named S1P1-5. Locally produced and circulating S1P activate S1P receptors, particularly S1P1 the most abundant in the endothelium, to maintain vascular homeostasis. Altered sphingolipid metabolism and S1P signaling has been implicated in vascular disease, including coronary artery diseases (CAD). The current grant led to several advances. First, we discovered a novel mechanism by which endothelial sphingolipid biosynthesis is regulated. Nogo-B, a membrane protein of the ER, highly expressed in blood vessels, binds to and inhibits serine palmitoyltransferase (SPT), the rate-limiting enzyme of the de novo sphingolipid production. Second, we revealed that Nogo-B/SPT interaction downregulates local S1P signaling contributing to inflammation, hypertension and heart failure. Third, we found that inflammatory stimuli and ox-LDL induce Nogo-B phosphorylation, which further inhibits SPT activity contributing to endothelial injury. Fourth, following TNF-α, the N-terminus of Nogo-B is cleaved and translocates to the nucleus to impact endothelial transcriptome. Our long-term goal is to understand how Nogo-B regulates local sphingolipid signaling and its impact on coronary functions in the pathogenesis of CAD. Our hypothesis is that Nogo-B controls endothelial-derived S1P signaling, which is a key regulator of vascular homeostasis and disease- thereby influencing coronary plaque progression. Mechanistically, we hypothesize that Nogo-B promotes vascular inflammation and diseases via two major mechanisms; SPT inhibition, thus disrupting locally-derived S1P signaling, and the activation of gene profile. The rational is that the discovery of new mechanisms regulating endothelial inflammation will provide potential therapeutic targets for CAD. For the renewal, we propose to: 1) Investigate the role of endothelial Nogo-B in the susceptibility of mice to coronary atherosclerosis; 2) Determine the importance of endothelial S1P signaling and its role as downstream effector of Nogo-B in the onset of coronary atherosclerosis; 3) Dissecting the mechanism of Nogo-B signaling in myocardial endothelial injury. This contribution is significant since will identify novel targets for the treatment of CAD, especially since available therapies have been only partially successful, and beyond the statins, there are currently no effective pharmacological strategies that effectively address vascular inflammation. The proposed research is innovative because we investigate the effects of altered sphingolipid homeostasis and S1P signaling on the progression of coronary atherosclerosis, by using a novel mouse model of CAD and myocardial infarction that better recapitulates the human disease, a heretofore-unexamined process.