Treatment of CBS deficiency with proteostasis modulators

用蛋白质稳态调节剂治疗 CBS 缺乏症

• 批准号: 9769008
• 负责人: WARREN D KRUGER
• 金额: $ 46.75万
• 依托单位: RESEARCH INST OF FOX CHASE CAN CTR
• 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 2021-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9769008
• 关键词: Adult; Affect; Alleles; Amino Acids; Back; Behavior; Binding; Bortezomib; Complex; Cystathionine beta-Synthase; Data; Disease; Dose; Drug usage; Effectiveness; Environment; Enzymes; FDA approved; Genetic Diseases; Goals; Homocysteine; Human; Immunoprecipitation; Inborn Errors of Metabolism; Incidence; Individual; Kidney; Lead; Liver; Longitudinal Studies; Mediating; Mental Retardation; Metabolism; Methionine; Missense Mutation; Modeling; Molecular Chaperones; Mus; Mutation; Osteoporosis; Other Genetics; Pathway interactions; Patients; Pharmaceutical Preparations; Pharmacotherapy; Phenotype; Plasma; Proteasome Inhibition; Proteasome Inhibitor; Proteins; Public Health; Serine; Serum; Supplementation; System; Techniques; Testing; Thrombosis; Toxic effect; Ubiquitin; Vitamin B6; Work; arimoclomol; cancer therapy; cancer type; dietary restriction; enzyme activity; experimental study; functional restoration; humanized mouse; lens; mouse model; multicatalytic endopeptidase complex; mutant; novel; novel strategies; polypeptide; promoter; protein aggregation; proteostasis; small molecule; treatment strategy; vitamin therapy

PROJECT SUMMARY/ABSTRACT Inborn errors of metabolism comprise a large class of genetic diseases involving disorders of cellular metabolism. Homocysteine is an intermediary metabolite derived from methionine that can either be recycled back to methionine, or shunted down the transsulfuration pathway by the action of cystathionine beta-synthase (CBS), an enzyme primarily expressed in the liver and kidney. Individuals with mutations in CBS have CBS deficiency, characterized by extreme elevations in plasma total homocysteine (tHcy) and phenotypes including increased incidence of thrombosis, osteoporosis, dislocated lenses, and mental retardation. In healthy adults, tHcy concentration in plasma ranges from 5 to 15 M, but untreated patients with CBS deficiency often have tHcy in excess of 200 M. Current treatment strategies involve dietary restriction and vitamin therapy, but these are only partially effective and do not work in all patients. Over 85% of the described mutations in CBS deficient patients are missense mutations in which a single incorrect amino acid is substituted into the CBS polypeptide. Over the past decade, our lab has developed six different humanized mouse models that each express a different patient-derived mutant human CBS protein using an inducible promoter expressed at high levels in the liver. In all of these models, liver CBS activity is greatly diminished (<5% of wild-type), and serum tHcy is elevated by at least 20-fold. However, the behavior of each mutant CBS protein is not identical, with mutations affecting protein stability, protein aggregation, enzymatic function, or a combination of all three. The decreased protein stability effects of the mutations are mediated via the ubiquitin/proteasome system. Amazingly, treatment of mutant-expressing mice with proteasome inhibitors (PIs) can functionally reverse the effects of a majority of the missense mutations, resulting in large increases in CBS activity in the liver, and in some cases lowering of tHcy to near wild-type levels. PIs are FDA approved drugs for the treatments of certain types of cancer, but have never been studied in the context of inborn errors of metabolism. Our data suggests that low-dose PI treatment may be able to restore sufficient CBS enzyme activity to be phenotypically beneficial, but not have the toxicities associated with the high levels used in cancer therapy. In addition, we have preliminary data that suggests the combination of PIs with other drugs that modulate the cellular proteostasis network, may be useful in increasing the effectiveness of PIs. Thus, the overall goal of the current proposal is to extend these studies and determine if PIs and proteostasis modulators are effective in restoring function to patient-derived CBS alleles. If successful, the experiments described here could lead to novel treatments of CBS deficiency and potentially other genetic diseases associated with missense mutations.

项目摘要/摘要 新陈代谢的天生错误包括大量涉及细胞疾病的遗传疾病 代谢。同型半胱氨酸是一种衍生自蛋氨酸的中间代谢物，可以回收 返回甲硫氨酸，或通过胱淀粉β-合酶的作用将过渡途径分流 （CBS），一种主要在肝脏和肾脏中表达的酶。 CBS中突变的个体患有CBS 缺乏症，特征是血浆总型半胱氨酸（THCY）和表型的极高升高 血栓形成，骨质疏松症，脱位透镜和智力低下的出现增加。在健康的成年人中 血浆的THCY浓度范围为5至15毫米，但未经治疗的CBS缺乏症患者通常具有 超过200米。当前的治疗策略涉及饮食限制和维生素治疗，但 这些只是部分有效的，并且在所有患者中不起作用。 在CBS特异性患者中，超过85％的描述突变是错义突变。 将不正确的氨基酸取代为CBS多肽。在过去的十年中，我们的实验室已经开发了六个 每个人都表达不同患者衍生的突变体人CBS蛋白的不同人性化小鼠模型 使用在肝脏中高水平表达的诱导启动子。在所有这些模型中，肝CBS活性是 大大减少（<野生型的5％），血清THCY至少升高20倍。但是，行为 每个突变的CBS蛋白的蛋白质都不相同，突变影响蛋白质稳定性，蛋白质聚集， 酶促功能，或所有三个组合。突变的蛋白质稳定性降低是 通过泛素/蛋白酶体系统介导。令人惊讶的是，用 蛋白酶体抑制剂（PI）可以在功能上扭转大多数错义突变的影响，即 导致肝脏中CBS活性大大增加，在某些情况下将THCY降低至近乎野生型 水平。 PI是FDA批准的某些类型癌症治疗的药物，但从未研究过 在天生的新陈代谢错误的背景下。我们的数据表明，低剂量PI治疗可能能够 恢复足够的CBS酶活性在表型上是有益的，但没有毒性 癌症治疗中使用的高水平。此外，我们还有初步数据表明 PI的组合与调节细胞蛋白抑制网络的其他药物可能在 提高PI的有效性。这是当前建议的总体目标是扩展这些研究 并确定PIS和蛋白杀菌调节剂是否有效地恢复了患者来源的CBS 等位基因。如果成功，此处描述的实验可能会导致CBS缺乏症的新型治疗方法 可能与错义突变有关的其他遗传疾病。