The mechanism of increased biliary lipid secretion in mice with genetic inactivation of bile salt export pump

K. E. R. Gooijert, R. Havinga, Henk Wolters, R. Wang, V. Ling, S. Tazuma, H. J. Verkade*

*Bijbehorende auteur voor dit werk

OnderzoeksoutputAcademicpeer review

7 Citaten (Scopus)

Samenvatting

Human bile salt export pump (BSEP) mutations underlie progressive familial intrahepatic cholestasis type 2 (PFIC2). In the PFIC2 animal model, Bsep(-/-) mice, biliary secretion of bile salts (BS) is decreased, but that of phospholipids (PL) and cholesterol (CH) is increased. Under physiological conditions, the biliary secretion of PL and CH is positively related ("coupled") to that of BS. We aimed to elucidate the mechanism of increased biliary lipid secretion in Bsep(-/-) mice. The secretion of the BS tauro-beta-muricholic acid (T beta MCA) is relatively preserved in Bsep(-/-) mice. We infused Bsep(-/-) and Bsep(-/-) (control) mice with T beta MCA in stepwise increasing dosages (150-600 nmol/min) and determined biliary bile flow, BS, PL, and CH secretion. mRNA and protein expression of relevant canalicular transporters was analyzed in livers from noninfused Bsep(-/-) and control mice. T beta MCA infusion increased BS secretion in both Bsep(-/-) and control mice. The secreted PL or CH amount per BS, i.e., the "coupling," was continuously two- to threefold higher in Bsep(-/-) mice (P <0.05). Hepatic mRNA expression of canalicular lipid transporters Mdr2, Abcg5, and Abcg8 was 45-55% higher in Bsep(-/-) mice (Abcg5; P <0.05), as was canalicular Mdr2 and Abcg5 protein expression. Potential other explanations for the increased coupling of the biliary secretion of PL and CH to that of BS in Bsep(-/-) mice could be excluded. We conclude that the mechanism of increased biliary lipid secretion in Bsep(-/-) mice is based on increased expression of the responsible canalicular transporter proteins.

Originele taal-2English
Pagina's (van-tot)G450-G457
Aantal pagina's8
TijdschriftAmerican Journal of Physiology-Gastrointestinal and Liver Physiology
Volume308
Nummer van het tijdschrift5
DOI's
StatusPublished - 1-mrt-2015

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