New Congenital Disorders of Glycosylation: Therapy and Models

新的先天性糖基化疾病：治疗和模型

• 批准号: 10183232
• 负责人: Hudson H. Freeze
• 金额: $ 56.33万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10183232
• 关键词: Affect; Aging; Alleles; Architecture; Basic Science; Biochemistry; Biological Models; Blood Coagulation Disorders; Blood Coagulation Factor; Cations; Cell model; Cells; Cellular biology; Chondroitin Sulfate Proteoglycan; Client; Clustered Regularly Interspaced Short Palindromic Repeats; Coagulants; Collagen; Complex; Congenital disorders of glycosylation; Data; Defect; Development; Diagnostic; Diet; Disease; Dwarfism; Environment; Enzymes; Epiphysial cartilage; Extracellular Matrix; Fucose; Galactose; Galactosemias; Genes; Genetic; Glucose; Glycogen; Glycogen Storage Disease; Golgi Apparatus; Guanosine Diphosphate Fucose; Hemorrhage; Intelligence; Knowledge; Link; Liver; Location; Metabolic; Modeling; Modification; Molecular; Monosaccharides; Mutation; Organ; Pathway interactions; Patients; Phenotype; Physiological; Polysaccharides; Protein Biosynthesis; Proteins; Rare Diseases; Recurrence; Route; Series; Serum; Signal Transduction; Solubility; Stable Isotope Labeling; Syndrome; Technology; Therapeutic; Work; base; blood glucose regulation; de novo mutation; expectation; glucose-6-phosphatase; glycosylation; improved; induced pluripotent stem cell; novel; persistent symptom; protein transport; small molecule; sugar; sugar nucleotide; trafficking

PROJECT SUMMARY We discover and sometimes treat rare Congenital Disorders of Glycosylation (CDG) with simple sugars (monosaccharides). But why they work so efficiently is a puzzle. One clue comes from our recent discoveries showing that one activated sugar, GDP-fucose, does not reside in a single homogenous pool, but instead occurs in multiple, distinct, non-homogenous pools determined by whether fucose comes from a de novo pathway or salvage/diet. These pools selectively feed the synthesis of different glycans. Using stable isotope-labeled sugars, we want to understand the mechanisms that underlie the import of fucose into the cell and how it is utilized for selected glycans. The same technology can be applied to the study of galactose, which is currently being used to treat other CDGs. In galactosemia patients, galactose is toxic and must be eliminated from their diet. Yet compliant patients also have glycosylation deficiencies and some persistent symptoms. Small amounts of galactose improve glycosylation, but there is no data on how different glycosylation pathways use exogenous galactose. We hypothesize that galactose also resides in highly complex, non-homogenous pools that feed different glycosylation pathways. We discovered two new CDGs, each caused by recurrent de novo mutations in genes that have well- known, but very different, autosomal recessive presentations. We want to understand the underlying basis of the new disorders and propose models to study the novel phenotypes. Saul Wilson Syndrome (SWS) patients have a progeroid dwarfism and normal intelligence due to a recurrent de novo mutation in the CDG gene, COG4. Patients with bi-allelic COG4 mutations have a very severe, often lethal phenotype with altered N-glycosylation. SWS does not alter N-glycosylation, but selectively effects chondroitin sulfate proteoglycan modification and collagen accumulation/secretion. This suggests defects in the extracellular matrix at the growth plate. We propose series of cellular models to assess the molecular details of COG4 dysregulation in SWS that can explain the phenotypes. We discovered patients with a unique coagulopathy and abnormal serum N-glycosylation. These patients have a single de novo mutation in SLC37A4. The gene encodes the ER-localized glucose-6-P transporter used for glucose homeostasis. When autosomal recessive, it causes glycogen storage disorder, GSD-Ib. In the de novo disorder, it alters only liver-derived protein N-glycosylation. Patient iPS cells show relocation of a portion of SLC37A4 from ER to the Golgi. We hypothesize that the mutation eliminates a critical ER-retention signal, mis- localizing half of the fully functional transporter. In the new location Glc-6-P accumulates in the Golgi lumen. If G6PC, its ER-localized glucose-6-phosphatase partner, comes along, Pi might also accumulate and alter glycosylation, by limiting solubility/availability of critical cations for multiple enzymes. We will create CRISPR- derived model systems to explore and validate this hypothesis. Potential small molecule therapies already exist.

项目摘要 我们发现并有时治疗罕见的先天性糖基化障碍（CDG）与单糖 （单糖）。但为什么它们的工作效率如此之高是一个谜。一条线索来自我们最近的发现 显示一种活化的糖，GDP-岩藻糖，不存在于单一的同质池中，而是发生在 在多个不同的非同质池中，确定岩藻糖是否来自从头途径或 抢救/饮食。这些池选择性地供给不同聚糖的合成。使用稳定的同位素标记的糖， 我们想了解岩藻糖进入细胞的机制，以及它是如何被利用的。 选择聚糖。同样的技术可以应用于半乳糖的研究，目前正在使用 来治疗其他的CDG在半乳糖血症患者中，半乳糖是有毒的，必须从饮食中消除。然而 顺从的患者还具有糖基化缺陷和一些持续的症状。少量的 半乳糖改善糖基化，但没有关于不同糖基化途径如何利用外源性半乳糖的数据。 半乳糖。我们假设半乳糖也存在于高度复杂的非同质池中， 不同的糖基化途径。 我们发现了两种新的CDG，每种都是由基因的复发性从头突变引起的，这些基因具有良好的- 已知但非常不同的常染色体隐性遗传。我们想了解 新的疾病，并提出模型来研究新的表型。 扫罗威尔逊综合征（SWS）患者由于发育不良而具有早老性侏儒症和正常智力。 CDG基因的复发性从头突变，COG 4。具有双等位基因COG 4突变的患者具有非常严重的， 通常具有改变的N-糖基化的致死表型。SWS不改变N-糖基化，但选择性地影响N-糖基化。 硫酸软骨素蛋白聚糖修饰和胶原积累/分泌。这表明， 生长板上的细胞外基质。我们提出了一系列的细胞模型，以评估分子的细节， SWS中的COG 4失调可以解释表型。 我们发现患者有一个独特的凝血功能障碍和异常血清N-糖基化。这些患者 在SLC 37 A4中有一个新突变。该基因编码ER定位的葡萄糖-6-P转运蛋白， 葡萄糖稳态当常染色体隐性遗传时，它会引起糖原储存障碍，GSD-Ib。在德 在新生疾病中，它仅改变肝源性蛋白质N-糖基化。患者的iPS细胞显示出部分的 SLC 37 A4从ER到高尔基体。我们假设，突变消除了一个关键的ER-保留信号，错误- 定位了半个完整的传送器在新的位置，Glc-6-P在高尔基体腔中积累。如果 G6 PC，它的ER定位的葡萄糖-6-磷酸酶伴侣，沿着，Pi也可能积累和改变 糖基化，通过限制多种酶的关键阳离子的溶解度/可用性。我们将创造CRISPR- 衍生模型系统来探索和验证这一假设。潜在的小分子疗法已经存在。