Degradation of ABC transporters in genetic liver disease

描述（由申请人提供）： 该候选人有两年博士后和三年研究科学家的经验，目前正在被提名为耶鲁大学医学院助理教授。本申请的指导K 01奖提交的目标是为候选人提供进一步的培训经验，作为一个独立的研究者在肝细胞生物学领域工作。该项目的长期目标是了解包括胆汁淤积在内的一些遗传性疾病中肝转运蛋白降解的机制。这是开发新策略以克服遗传性胆汁淤积症中的胆汁分泌缺陷的先决条件，并且这种策略也可以应用于其他遗传性疾病，如囊性纤维化。 我们和其他人已经证明，在遗传性胆汁淤积症和Dubin-Johnson综合征中，基因突变导致胆盐输出泵（BSEP）和多药耐药蛋白2（MRP 2）的细胞内滞留和随后的降解。这导致了这样的假设，即内质网相关蛋白降解（ERAD）和泛素化酶负责这些疾病中BSEP和MRP 2的降解。初步数据表明，一种新的泛素连接酶的目标BSEP的一个突变体降解。候选人建议I）表征遗传性胆汁淤积症中BSEP突变体降解的不同细胞途径。II）确定靶向BSEP突变体降解的泛素连接酶。III）检查BSEP突变体降解中的ERAD特异性泛素缀合酶。IV）确定负责BSEP的ERAD的主要泛素连接酶是否也靶向其他ABC转运蛋白的突变体，例如Dubin-Johnson综合征和囊性纤维化中的MRP 2和CFTR蛋白。 耶鲁大学消化疾病科和分子生物物理学和生物化学系是开展此类研究的理想选择，因为他们的教师素质，他们作为导师的经验以及耶鲁肝脏中心的核心设施。医学院已承诺在此进一步培训期间为候选人提供保护时间，然后再担任独立调查员。

DESCRIPTION (provided by applicant): The candidate has two years post-doctoral and three years research-scientist experience, and is currently being proposed for an Assistant Professor appointment at School of Medicine of Yale University. This application for a mentored K01 award is submitted with the goal of providing the candidate with the further training experience to function as an independent investigator working in the field of liver cell biology. The project's long-term objectives are to understand the mechanisms that underlie the degradation of hepatic transporters in a number of hereditary diseases including cholestasis. This is a prerequisite for developing novel stratagies to overcome the bile secretion defect in hereditary cholestasis and such stratagies may also apply to other genetic diseases such as cystic fibrosis. We and others have demonstrated that in hereditary cholestasis and Dubin-Johnson syndrome genetic mutations lead to the intracellular retention and subsequent degradation of the bile salt export pump (BSEP) and the multidrug resistance protein 2 (MRP2) by proteasomes. This leads to the hypothesis that endoplasmic reticulum-associated protein degradation (ERAD) and ubiquitination enzymes are responsible for the degradation of the BSEP and MRP2 in these disorders. The preliminary data demonstrates that a novel ubiquitin ligase targets one mutant of BSEP to degradation. The candidate proposes to I) Characterize the different cellular pathways in the degradation of the BSEP mutants in hereditary cholestasis. II) Determine the ubiqutin ligase(s) that target BSEP mutants to degradation. III) Examine the ERAD-specific ubiquitin conjugating enzymes in the degradation of the BSEP mutants. IV) Establish whether the primary ubiquitin ligase responsible for the ERAD of BSEP also targets the mutants of other ABC transporters such as MRP2 and CFTR protein in Dubin-Johnson syndrome and cystic firbosis. The Section of Digestive Diseases and Department of Molecular Biophysics and Biochemistry at Yale University are ideal for carrying out such studies because of the quality of their faculty, their experience as mentors and the core facility at the Yale Liver Center. The School of Medicine has pledged protected time for the candidate during this further training period prior to functioning as an independent investigator.