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

Journal of Biomedical Science

Huey-Ling Chen¹  Huey-Huey Chua¹  Yen-Hsuan Ni¹  Ya-Hui Chen¹  Hui-Lin Wu²  Shang-Hsin Wu²  Chin-Sung Chien²  Mei-Hwei Chang²  Hui-Ling Chen³ 

[1] Department of Pediatrics, National Taiwan University College of Medicine and National Taiwan University Children’s Hospital;Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine;Hepatitis Research Center, National Taiwan University Hospital;

关键词: Apical trafficking;    Bile salt export pump;    Cholestasis;    CHMP5;    ESCRT;    Liver development;   

DOI  :  10.1186/s12929-020-00706-2

来源: DOAJ

【 摘 要 】

Abstract Background The 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. Methods The 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. Results We 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. Conclusions Our 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】

Unknown