Elodie Mareux1, Martine Lapalus1, Rachida Amzal1, Marion Almes1,2, Tounsia Aït-Slimane3, Jean-Louis Delaunay3, Pauline Adnot1, Mauricette Collado-Hilly1, Anne Davit-Spraul1,4, Thomas Falguières1, Isabelle Callebaut5, Emmanuel Gonzales1,2, Emmanuel Jacquemin1,2. 1. Inserm, Physiopathogénèse et traitement des maladies du foie, UMR_S 1193, Hepatinov, Université Paris-Saclay, Orsay, France. 2. Paediatric Hepatology & Paediatric Liver Transplant Department, Reference Center for Rare Paediatric Liver Diseases, FILFOIE, ERN RARE LIVER, Assistance Publique-Hôpitaux de Paris, Faculty of Medicine Paris-Saclay, CHU Bicêtre, Le Kremlin-Bicêtre, France. 3. Inserm, Centre de Recherche Saint-Antoine (CRSA), UMR_S 938, Institute of Cardiometabolism and Nutrition (ICAN), Sorbonne Université, Paris, France. 4. CHU Bicêtre, Biochemistry Unit, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France. 5. Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie de Physique des Matériaux et de Cosmochimie, IMPMC, Sorbonne Université, Paris, France.
Abstract
BACKGROUND & AIM: The canalicular bile salt export pump (BSEP/ABCB11) of hepatocytes is the main adenosine triphosphate (ATP)-binding cassette (ABC) transporter responsible for bile acid secretion. Mutations in ABCB11 cause several cholestatic diseases, including progressive familial intrahepatic cholestasis type 2 (PFIC2) often lethal in absence of liver transplantation. We investigated in vitro the effect and potential rescue of a BSEP mutation by ivacaftor, a clinically approved cystic fibrosis transmembrane conductance regulator (CFTR/ABCC7) potentiator. METHODS: The p.T463I mutation, identified in a PFIC2 patient and located in a highly conserved ABC transporter motif, was studied by 3D structure modelling. The mutation was reproduced in a plasmid encoding a rat Bsep-green fluorescent protein. After transfection, mutant expression was studied in Can 10 cells. Taurocholate transport activity and ivacaftor effect were studied in Madin-Darby canine kidney (MDCK) clones co-expressing the rat sodium-taurocholate co-transporting polypeptide (Ntcp/Slc10A1). RESULTS: As the wild-type protein, BsepT463I was normally targeted to the canalicular membrane of Can 10 cells. As predicted by 3D structure modelling, taurocholate transport activity was dramatically low in MDCK clones expressing BsepT463I . Ivacaftor treatment increased by 1.7-fold taurocholate transport activity of BsepT463I (P < .0001), reaching 95% of Bsepwt activity. These data suggest that the p.T463I mutation impairs ATP-binding, resulting in Bsep dysfunction that can be rescued by ivacaftor. CONCLUSION: These results provide experimental evidence of ivacaftor therapeutic potential for selected patients with PFIC2 caused by ABCB11 missense mutations affecting BSEP function. This could represent a significant step forward for the care of patients with BSEP deficiency.
BACKGROUND & AIM: The canalicular bile salt export pump (BSEP/ABCB11) of hepatocytes is the main adenosine triphosphate (ATP)-binding cassette (ABC) transporter responsible for bile acid secretion. Mutations in ABCB11 cause several cholestatic diseases, including progressive familial intrahepatic cholestasis type 2 (PFIC2) often lethal in absence of liver transplantation. We investigated in vitro the effect and potential rescue of a BSEP mutation by ivacaftor, a clinically approved cystic fibrosis transmembrane conductance regulator (CFTR/ABCC7) potentiator. METHODS: The p.T463I mutation, identified in a PFIC2patient and located in a highly conserved ABC transporter motif, was studied by 3D structure modelling. The mutation was reproduced in a plasmid encoding a ratBsep-green fluorescent protein. After transfection, mutant expression was studied in Can 10 cells. Taurocholate transport activity and ivacaftor effect were studied in Madin-Darby canine kidney (MDCK) clones co-expressing the ratsodium-taurocholate co-transporting polypeptide (Ntcp/Slc10A1). RESULTS: As the wild-type protein, BsepT463I was normally targeted to the canalicular membrane of Can 10 cells. As predicted by 3D structure modelling, taurocholate transport activity was dramatically low in MDCK clones expressing BsepT463I . Ivacaftor treatment increased by 1.7-fold taurocholate transport activity of BsepT463I (P < .0001), reaching 95% of Bsepwt activity. These data suggest that the p.T463I mutation impairs ATP-binding, resulting in Bsep dysfunction that can be rescued by ivacaftor. CONCLUSION: These results provide experimental evidence of ivacaftor therapeutic potential for selected patients with PFIC2 caused by ABCB11 missense mutations affecting BSEP function. This could represent a significant step forward for the care of patients with BSEP deficiency.
Authors: Victor Emanuel Miranda Soares; Thiago Inácio Teixeira do Carmo; Fernanda Dos Anjos; Jonatha Wruck; Sarah Franco Vieira de Oliveira Maciel; Margarete Dulce Bagatini; Débora Tavares de Resende E Silva Journal: Mol Cell Biochem Date: 2021-09-16 Impact factor: 3.396
Authors: David F Woods; Stephanie Flynn; Jose A Caparrós-Martín; Stephen M Stick; F Jerry Reen; Fergal O'Gara Journal: Antibiotics (Basel) Date: 2021-06-24