A novel role for p53 in congenital disorders of glycosylation

描述(由Candiate提供)：患有罕见的先天性糖基化障碍(CDG)的儿童在N-连接蛋白糖基化所需的许多基因中的一个发生突变，在38个不同的亚型中，37个没有治疗选择。甘露糖-6-磷酸异构酶(MPI)突变可导致“胃肠型”CDG。CDG患者脂联寡糖(LLO)的合成缺陷如何导致多系统异常尚不清楚，CDG动物模型也很少。斑马鱼提供了一个强大的脊椎动物系统来研究单基因疾病，因为它们对人类具有高度的遗传保守性，而吗啡提供了快速和有效的基因敲除。我使用吗啡技术建立了残留MPI酶活力低于15%的MPI变异体。它们会在头部、眼睛、肠道、肝脏和身体形状上出现缺陷，并增加受影响组织中的细胞死亡。MPI-CDG是唯一一种已知的治疗CDG的方法：口服甘露糖通过己糖激酶和一个微小的互补代谢途径增加流量，产生甘露糖-6-磷酸，使蛋白质糖基化正常化，缓解大多数症状。同样，补充甘露糖几乎可以完全挽救MPI变异体的形态和细胞死亡表型。我在一种新的斑马鱼MPI-CDG模型中的初步数据表明，在CDG病理中，肿瘤抑制基因P53的激活。我们的目标是确定众所周知的抑癌基因P53在MPI-CDG的发病机制中是否具有新的作用。我们的中心假设是，P53是MPI-CDG疾病的罪魁祸首，并将决定P53影响糖基化或细胞凋亡的代谢变化的机制。具体目的：1：建立P53活化、甘露糖代谢与MPI缺乏症的关系。2：判断MPI-CDG是LLO还是糖蛋白形成异常所致。3：确定P53介导的细胞凋亡对MPI细胞形态表型的影响。我的长期目标是了解CDG的分子基础，重点是相关的胃肠道疾病。CDG的潜在遗传缺陷很简单，也很容易理解。然后，我将把这一知识应用于儿科患者中这些相同疾病的更常见原因，因为非酒精性脂肪性肝病、纤维化和肝硬变都与蛋白质糖基化缺陷有关。

DESCRIPTION (provided by Candidate): Children with the rare congenital disorders of glycosylation (CDG) have a mutation in one of the many genes required for N-linked protein glycosylation and of 38 distinct subtypes, 37 have no treatment options. Mutation of mannose-6-phosphate isomerase (MPI) causes the "gastrointestinal type" of CDG. It is not understood how defective synthesis of the lipid-linked oligosaccharide (LLO) in CDG patients results in multi-systemic abnormalities and few CDG animal models exist. zebrafish provide a powerful vertebrate system to study monogenic disorders with their high genetic conservation to humans, and morpholinos offer rapid and efficient gene knockdown. I used morpholino technology to establish mpi morphants with less than 15% residual Mpi enzyme activity. They develop defects in the head, eye, gut, liver, and body shape with increased cell death in affected tissues. MPI-CDG is the only CDG with a known treatment: oral mannose increases flux through hexokinase and a minor complementary metabolic pathway that produces mannose-6-phosphate and normalizes protein glycosylation, relieving most symptoms. Similarly, both the morphologic and cell death phenotype in mpi morphants are almost completely rescued by mannose supplementation. My preliminary data in a novel zebrafish model of MPI-CDG implicate activation of the tumor suppressor, p53, in CDG pathology. Our objective is to determine whether the well known tumor suppressor, p53, has a novel role in the mechanism of disease in MPI-CDG. Our central hypothesis is that p53 is responsible for disease in MPI-CDG and will determine the mechanism by which p53 affects either metabolic alterations in glycosylation or apoptosis. Specific Aims: 1: Establish the relationship between p53 activation, mannose metabolism, and Mpi deficiency. 2: Determine whether MPI-CDG is a result of abnormal LLO or glycoprotein formation. 3: Determine the contribution of p53-mediated apoptosis to the mpi morphant phenotype. My long-term goal is to understand the molecular basis of CDG with a focus on the associated gastrointestinal disorders. The underlying genetic defect in CDG is simple and well understood. I will then apply this knowledge to more common causes of these same diseases in pediatric patients, as non-alcoholic fatty liver disease, fibrosis, and cirrhosis are all associated with defects in protein glycosylation.