A novel role for p53 in congenital disorders of glycosylation

描述（由候选人提供）：患有罕见的先天性糖基化疾病（CDG）的儿童在n -连锁蛋白糖基化所需的许多基因之一发生突变，并且在38种不同亚型中，37种没有治疗选择。甘露糖-6-磷酸异构酶（MPI）突变引起“胃肠道型”CDG。目前尚不清楚CDG患者脂联寡糖（LLO）合成缺陷是如何导致多系统异常的，也很少有CDG动物模型存在。斑马鱼具有高度的遗传保守性，为研究人类的单基因疾病提供了强大的脊椎动物系统，而morpholinos提供了快速有效的基因敲除。我使用morpholino技术建立了mpi变体，其mpi酶残留活性低于15%。他们在头部、眼睛、肠道、肝脏和体型上产生缺陷，受影响组织中细胞死亡增加。MPI-CDG是唯一已知治疗方法的CDG：口服甘露糖通过己糖激酶增加流量，并通过少量补充代谢途径产生甘露糖-6-磷酸并使蛋白质糖基化正常化，缓解大多数症状。同样，在mpi突变体中，形态和细胞死亡表型几乎完全被补充甘露糖所拯救。我在一种新型MPI-CDG斑马鱼模型中的初步数据暗示了CDG病理中肿瘤抑制因子p53的激活。我们的目的是确定众所周知的肿瘤抑制因子p53是否在MPI-CDG的疾病机制中具有新的作用。我们的中心假设是p53在MPI-CDG中负责疾病，并将确定p53影响糖基化代谢改变或细胞凋亡的机制。具体目的：1：建立p53激活、甘露糖代谢与Mpi缺乏之间的关系。2：确定MPI-CDG是否是LLO异常或糖蛋白形成的结果。3：确定p53介导的细胞凋亡对mpi形态表型的贡献。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，我将把这些知识应用于儿科患者中这些疾病的更常见原因，因为非酒精性脂肪性肝病、纤维化和肝硬化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.