Carbohydrate Deficient Glycoprotein Syndromes: Models and Therapy

碳水化合物缺乏糖蛋白综合征：模型和治疗

• 批准号: 8053250
• 负责人: Hudson H. Freeze
• 金额: $ 38.24万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8053250
• 关键词: Ablation; Alleles; Animal Model; Blood Coagulation Disorders; Breeding; Bypass; Carbohydrate-Deficient Glycoprotein Syndrome; Cell Line; Cells; Clinical; Congenital Disorders; Data; Defect; Development; Disease; Embryo; Engineering; Enteral; Epithelial Cells; Extravasation; Failure to Thrive; Fibrosis; Genes; Genetic; Goals; Growth; Heparitin Sulfate; Hepatic; Hereditary Disease; Human; Human Genetics; Inflammatory; Inherited; Knock-out; Lesion; Liver Dysfunction; Malignant Neoplasms; Mannose; Mannose-6-Phosphate Isomerase; Metabolic; Metabolic Diseases; Metabolic Pathway; Minor; Modeling; Mus; Mutation; N-Glycosylation Site; Pathology; Pathway interactions; Patients; Phenotype; Phosphomannomutase; Polysaccharides; Portal Hypertension; Predisposition; Protein Glycosylation; Protein-Losing Enteropathies; Proteins; Small Intestines; Stress; Surface; Symptoms; TNF gene; Therapeutic; Tissues; Variant; Vertebrates; base; dietary supplements; empowered; glycosylation; high throughput screening; human disease; in utero; man; mouse model; prevent; public health relevance; sugar

DESCRIPTION (provided by applicant): Congenital Disorders of Glycosylation (CDG) are rare inherited defects in sugar chain (glycan) synthesis and their addition to protein. All 14 types (different genes) of CDG-I patients have mutations in different genes, but share a common lesion: lack of full N-glycosylation site occupancy. Likewise, patients share many symptoms, but show broad clinical variations both within and between different types. There are no vertebrate animal models for these disorders and only one Type, CDG-Ib, has a therapy. Here we propose to analyze the first viable CDG-I mouse model, evaluate the single known therapy, and apply that therapy to currently untreatable types of CDG. CDG-Ib patients have insufficient phosphomannose isomerase (MPI, Fru-6-P_>Man-6-P) activity and develop liver dysfunction, fibrosis, failure to thrive, protein-losing enteropathy and coagulopathy. However, dietary supplements of mannose bypass the defect by increasing the flux of Mannose through a minor biosynthetic pathway (Man`Man-6-P) thus relieving nearly all symptoms. CDG-Ia patients, who are deficient in PMM2 (Man-6-P`Man-1-P), do not respond to mannose therapy because they catabolize Man-6-P via robust MPI. Note that PMM2 and MPI compete for the same critical substrate, Man-6-P, and their ratio determines its metabolic flux. We engineered a hypomorphic Mpi allele to create the first viable potential CDG-I mouse model. Analysis of these mice to date shows progressive hepatopathology and increased enteric protein loss. In Aim 1 we will determine whether these mice show pathology modeling CDG-Ib patients. Aim 2 will determine how hypomorphic lines respond to environmental stresses. Aim 3 will determine whether mannose rescues (prevents and/or reverses) the susceptibility of hypomorphic mice to pathology, specifically, protein-losing enteropathy and hepatic pathology. Since the various CDG types share many of the pathologies, successful treatment of one type may establish a paradigm to treat others. Therefore, in Aim 4 we will breed our Mpi-hypomorphic mice with Pmm2-deficient mice that currently die in utero. Based on highly encouraging preliminary data, we predict that providing mannose and genetically reducing Mpi activity in Pmm2-deficient mice will rescue the lethal phenotype by increasing the metabolic flux of Man-6-P into the depleted glycosylation pathway. If successful, this approach will show that redirecting mannose flux into the depleted glycosylation pathway has therapeutic potential and would empower high-throughput screening search for mannose flux-enhancing compounds for several types of CDG. PUBLIC HEALTH RELEVANCE: We will study the first mouse model of a rare human genetic disorder in protein glycosylation, offer a likely therapy, and apply the model/therapy to treat other human glycosylation disorders.

描述（由申请人提供）：先天性糖基化障碍（CDG）是糖链（聚糖）合成及其添加到蛋白质中的罕见遗传性缺陷。所有14种类型（不同基因）的CDG-I患者在不同的基因中具有突变，但具有共同的病变：缺乏完全的N-糖基化位点占据。同样，患者有许多共同的症状，但在不同类型内和不同类型之间显示出广泛的临床差异。目前还没有脊椎动物动物模型用于这些疾病，只有一种CDG-Ib型有治疗方法。在这里，我们建议分析第一个可行的CDG-I小鼠模型，评估单一的已知疗法，并将该疗法应用于目前无法治疗的CDG类型。CDG-Ib患者磷酸甘露糖异构酶（MPI，Fru-6-P_>Man-6-P）活性不足，并发展为肝功能障碍、纤维化、发育障碍、蛋白质丢失性肠病和凝血病。然而，甘露糖的膳食补充剂通过增加甘露糖通过次要生物合成途径（Man 'Man-6-P）的流量而绕过缺陷，从而缓解几乎所有症状。缺乏PMM 2（Man-6-P`Man-1-P）的CDG-Ia患者对甘露糖治疗没有反应，因为他们通过强MPI分解代谢Man-6-P。注意PMM 2和MPI竞争相同的关键底物Man-6-P，并且它们的比例决定其代谢通量。我们设计了一个亚型Mpi等位基因，以创建第一个可行的潜在CDG-I小鼠模型。迄今为止，对这些小鼠的分析显示肝脏病理学进展和肠道蛋白质丢失增加。在目的1中，我们将确定这些小鼠是否显示病理学建模CDG-Ib患者。目标2将确定亚纯线如何响应环境压力。目的3将确定甘露糖是否挽救（预防和/或逆转）低形态小鼠对病理学的易感性，特别是蛋白丢失性肠病和肝脏病理学。由于各种CDG类型共享许多病理，一种类型的成功治疗可以建立治疗其他类型的范例。因此，在目标4中，我们将用目前在子宫内死亡的Pmm 2缺陷小鼠繁殖我们的Mpi-亚型小鼠。基于非常令人鼓舞的初步数据，我们预测，在Pmm 2缺陷小鼠中提供甘露糖和遗传降低Mpi活性将通过增加Man-6-P进入耗尽的糖基化途径的代谢通量来挽救致死表型。如果成功的话，这种方法将表明，将甘露糖通量重新定向到耗尽的糖基化途径具有治疗潜力，并将使高通量筛选搜索甘露糖通量增强化合物用于几种类型的CDG。 公共卫生相关性：我们将研究第一个罕见的人类蛋白质糖基化遗传疾病的小鼠模型，提供一种可能的治疗方法，并将该模型/治疗方法应用于治疗其他人类糖基化疾病。