A Molecular Mechanism Underlying Genotype-Specific Intrahepatic Cholestasis Resulting From MYO5B Mutations
Overeem, Arend W. (University Medical Center Groningen)
Li, Qinghong (University Medical Center Groningen)
Qiu, Yi-Ling (Children's Hospital of Fudan University, Shanghai)
Cartón-Garcia, Fernando (Hospital Universitari Vall d'Hebron)
Leng, Changsen (University Medical Center Groningen)
Klappe, Karin (University Medical Center Groningen)
Dronkers, Just (University Medical Center Groningen)
Hsiao, Nai-Hua (University Medical Center Groningen)
Wang, Jian-She (Children's Hospital of Fudan University, Shanghai)
Arango, Diego (Hospital Universitari Vall d'Hebron)
van Ijzendoorn, Sven C. D. (University Medical Center Groningen)
Universitat Autònoma de Barcelona

Date:	2020
Abstract:	Progressive familial intrahepatic cholestasis (PFIC) 6 has been associated with missense but not biallelic nonsense or frameshift mutations in MYO5B, encoding the motor protein myosin Vb (myoVb). This genotype-phenotype correlation and the mechanism through which MYO5B mutations give rise to PFIC are not understood. The aim of this study was to determine whether the loss of myoVb or expression of patient-specific myoVb mutants can be causally related to defects in canalicular protein localization and, if so, through which mechanism. We demonstrate that the cholestasis-associated substitution of the proline at amino acid position 600 in the myoVb protein to a leucine (P660L) caused the intracellular accumulation of bile canalicular proteins in vesicular compartments. Remarkably, the knockout of MYO5B in vitro and in vivo produced no canalicular localization defects. In contrast, the expression of myoVb mutants consisting of only the tail domain phenocopied the effects of the Myo5b-P660L mutation. Using additional myoVb and rab11a mutants, we demonstrate that motor domain-deficient myoVb inhibited the formation of specialized apical recycling endosomes and that its disrupting effect on the localization of canalicular proteins was dependent on its interaction with active rab11a and occurred at the trans -Golgi Network/recycling endosome interface. Our results reveal a mechanism through which MYO5B motor domain mutations can cause the mislocalization of canalicular proteins in hepatocytes which, unexpectedly, does not involve myoVb loss-of-function but, as we propose, a rab11a-mediated gain-of-toxic function. The results explain why biallelic MYO5B mutations that affect the motor domain but not those that eliminate myoVb expression are associated with PFIC6.
Note:	Altres ajuts: Supported by grants from the Nederlandse vereniging voor Gastroenterologie (to S. I. J.) and the Natural Science Foundation of China, Nos. 81873543 and 81570468 (to J. S. W.).
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Cholestasis, Progressive familial intrahepatic ; Cholestasis, Intrahepatic ; Genetics ; Humans ; Lipid metabolism ; Metabolism ; MYO5B protein, Human ; Myosin Type V ; Pediatrics
Published in:	Hepatology, Vol. 72 (april 2020) , p. 213-229, ISSN 1527-3350

DOI: 10.1002/hep.31002
PMID: 31750554

17 p, 2.5 MB

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