The ESCRT-III molecules regulate the apical targeting of bile salt export pump

Journal of Biomedical Science

Ya-Hui Chen¹  Huey-Huey Chua¹  Huey-Ling Chen²  Yen-Hsuan Ni³  Shang-Hsin Wu⁴  Chin-Sung Chien⁴  Mei-Hwei Chang⁵  Hui-Lin Wu⁶  Hui-Ling Chen⁷ 

[1] Department of Pediatrics, National Taiwan University College of Medicine and National Taiwan University Children’s Hospital, 100, Taipei, Taiwan;Department of Pediatrics, National Taiwan University College of Medicine and National Taiwan University Children’s Hospital, 100, Taipei, Taiwan;Hepatitis Research Center, National Taiwan University Hospital, 100, Taipei, Taiwan;Department and Graduate Institute of Medical Education and Bioethics, National Taiwan University College of Medicine, 100, Taipei, Taiwan;Department of Pediatrics, National Taiwan University College of Medicine and National Taiwan University Children’s Hospital, 100, Taipei, Taiwan;Hepatitis Research Center, National Taiwan University Hospital, 100, Taipei, Taiwan;Medical Microbiota Center of the First Core Laboratory, National Taiwan University College of Medicine, 100, Taipei, Taiwan;Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, 100, Taipei, Taiwan;Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, 100, Taipei, Taiwan;Department of Pediatrics, National Taiwan University College of Medicine and National Taiwan University Children’s Hospital, 100, Taipei, Taiwan;Hepatitis Research Center, National Taiwan University Hospital, 100, Taipei, Taiwan;Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, 100, Taipei, Taiwan;Hepatitis Research Center, National Taiwan University Hospital, 100, Taipei, Taiwan;Hepatitis Research Center, National Taiwan University Hospital, 100, Taipei, Taiwan;

关键词: Apical trafficking;    Bile salt export pump;    Cholestasis;    CHMP5;    ESCRT;    Liver development;    Post-Golgi trafficking;    Subapical compartment;    Rab11;   

DOI  :  10.1186/s12929-020-00706-2

来源: Springer

【 摘 要 】

BackgroundThe bile salt export pump (BSEP) is a pivotal apical/canalicular bile salt transporter in hepatocytes that drives the bile flow. Defects in BSEP function and canalicular expression could lead to a spectrum of cholestatic liver diseases. One prominent manifestation of BSEP-associated cholestasis is the defective canalicular localization and cytoplasmic retention of BSEP. However, the etiology of impaired BSEP targeting to the canalicular membrane is not fully understood. Our goal was to discover what molecule could interact with BSEP and affect its post-Golgi sorting.MethodsThe human BSEP amino acids (a.a.) 491-630 was used as bait to screen a human fetal liver cDNA library through yeast two-hybrid system. We identified a BSEP-interacting candidate and showed the interaction and colocalization in the co-immunoprecipitation in hepatoma cell lines and histological staining in human liver samples. Temperature shift assays were used to study the post-Golgi trafficking of BSEP. We further determine the functional impacts of the BSEP-interacting candidate on BSEP in vitro. A hydrodynamically injected mouse model was established for in vivo characterizing the long-term impacts on BSEP.ResultsWe identified that charged multivesicular body protein 5 (CHMP5), a molecule of the endosomal protein complex required for transport subcomplex-III (ESCRT-III), interacted and co-localized with BSEP in the subapical compartments (SACs) in developing human livers. Cholestatic BSEP mutations in the CHMP5-interaction region have defects in canalicular targeting and aberrant retention at the SACs. Post-Golgi delivery of BSEP and bile acid secretion were impaired in ESCRT-III perturbation or CHMP5-knockdown hepatic cellular and mouse models. This ESCRT-III-mediated BSEP sorting preceded Rab11A-regulated apical cycling of BSEP.ConclusionsOur results showed the first example that ESCRT-III is essential for canalicular trafficking of apical membrane proteins, and provide new targets for therapeutic approaches in BSEP associated cholestasis.

【 授权许可】

CC BY