NgBR as a regulator of endothelial function

项目摘要 我们实验室发现了Nogo-B受体(NGBR)和一种与RTN-4B相互作用的结合蛋白(称为 Nogo-B)、Niemann Pick C2蛋白和顺式异戊二烯转移酶(HCIT)。NGBR与NPC2的相互作用 通过稳定Niemann Pick C2蛋白(NPC2)提高细胞内胆固醇代谢 NGBR在胆固醇动态平衡的基本方面发挥基础作用的可能性。最近，我们 发现ngbr与hcit的异构体相互作用是顺式戊烯基转移酶活性所必需的。 (顺式PTase)和酵母菌、小鼠和人的苯二醇合成。多糖醇是糖链的必备载体。 (糖)用于蛋白质糖基化反应。此外，我们还发现了一种功能缺失突变 通过外显子组测序保守的NGBR(R290H)C末端，导致先天性疾病 糖基化。 从受影响患者分离的成纤维细胞显示游离胆固醇和 与缺乏NGBR的小鼠成纤维细胞相同，降低了二醇组分。人类NGBR-R290H基因突变 酵母中的同源基因强调了这种进化上保守的残基对顺式PTase的重要性 活动和功能。因此，这些数据为ngbr在体内的重要作用提供了坚实的遗传学基础。 胆固醇代谢、多醇合成和蛋白质糖基化。有趣的是，NGBR对 胆固醇动态平衡和糖基化独立于Nogo-B发生，因为Nogo-B的丢失不 影响游离胆固醇水平或cisPTase活性。因此，考虑到这些新数据，我们推测 NGBR与NPC2和HCIT的相互作用调节内质网(ER)功能，如胆固醇 并提出了通过分离的结构域和实验来全面表征这些化合物的合成。 体外和体内途径。我们将：(1)研究ngbr/hcit蛋白复合体与疾病的关系 突变体；(2)剖析NGBR如何调节胆固醇代谢和蛋白质糖基化， (3)利用转基因小鼠破译NGBR在体内的作用。总体而言，这些目标将在 我们的发现，并推动该领域向前发展。

Project Summary Our lab discovered Nogo-B receptor (NgBR) and a binding protein that interacts with RTN-4B (called Nogo-B), Niemann Pick C2 protein and cis-isoprenyltransferase (hCIT). The interaction of NgBR with NPC2 regulates intracellular cholesterol metabolism by stabilizing the Niemann Pick C2 protein (NPC2) raising the possibility that NgBR exerts a fundamental role in basic aspects of cholesterol homeostasis. Recently, we have discovered the heteromeric interaction of NgBR with hCIT is required for cis-prenyltransferase activity (cis-PTase) and dolichol synthesis in yeast, mice and man. Dolichol is an obligate carrier of glycans (sugars) for protein glycosylation reactions. In addition, we identified a loss of function mutation in the conserved C terminus of NgBR (R290H) via exome sequencing that causes a congenital disorder of glycosylation. Fibroblasts isolated from affected patients exhibit enhanced accumulation of free cholesterol and reduced dolichol profiles identically to fibroblasts from mice lacking NgBR. Mutation of NgBR-R290H in man and orthologs in yeast underscores the importance of this evolutionarily conserved residue for cis-PTase activity and function. Thus, these data provide a firm genetic basis for the essential role of NgBR in cholesterol metabolism, dolichol synthesis and protein glycosylation. Interestingly, NgBR regulation of cholesterol homeostasis and glycosylation occur independent of Nogo-B, since the loss of Nogo-B does not influence free cholesterol levels or cisPTase activity. Thus, with these new data in mind, we surmise that NgBR interaction with NPC2 and hCIT regulates endoplasmic reticulum (ER) functions such as cholesterol and dolichol synthesis via separate domains and experiments are proposed to fully characterize these pathways in vitro and in vivo. We will: (1) Characterize the NgBR/hCIT protein complex and disease causing mutants; (2) Dissect how NgBR regulates both cholesterol metabolism and protein glycosylation and, (3) Decipher the role of NgBR in vivo using genetically modified mice. Collectively, these aims will build upon our discoveries and move the field forward.