Severe Cholestasis Induced by Cholic Acid Feeding in Knockout Mice of Sister of P-Glycoprotein

University of Toronto, Toronto, Ontario, Canada
Hepatology (Impact Factor: 11.06). 01/2004; 38(6):1489-99. DOI: 10.1016/j.hep.2003.09.037
Source: PubMed


Intrahepatic cholestasis is often associated with impairment of biliary bile acid secretion, a process mediated by the sister of P-glycoprotein (Spgp or Abcb11) also known as the bile salt export pump (Bsep). In humans, mutations in the Spgp gene are associated with a fatal childhood disease, type 2 progressive familial intrahepatic cholestasis (PFIC2). However in mice, the "knockout" of Spgp only results in mild cholestasis. In this study, we fed spgp(-/-) knockout mice with a cholic acid (CA)-supplemented diet to determine whether a more pronounced PFIC2-like phenotype could be induced. Such mice developed severe cholestasis characterized by jaundice, weight loss, elevated plasma bile acid, elevated transaminase, cholangiopathy (proliferation of bile ductules and cholangitis), liver necrosis, high mortality, and wide-ranging changes in the mRNA expression of major liver genes (16/36 examined). A surprising observation was that the bile acid output and bile flow in CA-fed mutant mice was significantly higher than anticipated. This suggests that the spgp(-/-) mice are able to utilize an alternative bile salt transport system. However, unlike Spgp, this system is insufficient to protect the knockout mice from cholestasis despite its high capacity. In conclusion, the spgp(-/-) mice provide a unique model to investigate molecular pathways associated with cholestasis and related diseases.

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    • "Because the human and murine ATP-binding cassette sub-family G member 5 (ABCG5) and ATP-binding cassette sub-family G member 8 (ABCG8) genes are not direct targets of miR-33 and no repression was observed after overexpressing miR-33 in mouse primary hepatocytes and human hepatocytes, the authors argue that this could be the result of off-target effects using the adenoviral approach. Indeed, mice deficient in ABCB11 showed reduced hepatic levels of ABCG5 and ABCG8 fed a lithogenic diet (Wang et al, 2003). However, the underlying mechanism involved in this reduced expression of Abcg5/8 needs to be elucidated. "
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    ABSTRACT: See related article in EMBO Molecular Medicine
    EMBO Molecular Medicine 09/2012; 4(9):863-5. DOI:10.1002/emmm.201201565 · 8.67 Impact Factor
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    • "Hence, the decreased expression of Abcg5 and Abcg8 noted in Fig 3F could be the result of off-target effects due to the supra-physiological levels of miR-33 achieved using adenovirus, thus potentially limiting the interpretation of the results. Intriguingly, mice deficient in ABCB11 show decreased hepatic levels of Abcg5 and Abcg8 when fed a lithogenic diet (Wang et al, 2003); the molecular mechanism of this cross-talk remains unknown, but authors speculate that it is independent on the levels/activity of LXR (Wang et al, 2003). Whether the drop in Abcg5/8 levels in the livers in Fig 3F are due to extreme levels of miR-33, or the result of a yet-unknown signalling pathway that links the expression of different bile transporters will require further investigation. "
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    EMBO Molecular Medicine 09/2012; 4(9):882-95. DOI:10.1002/emmm.201201228 · 8.67 Impact Factor
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    • "For example, the heme transporter Bcrp (Desuzinges-Mandon et al., 2010) is enriched in prenatal liver, suggesting a need to eliminate heme from the dead red blood cells during the transition of liver functions from a hematopoietic organ to an organ for drug metabolism and disposition. Bsep/Abcb11 is the major transporter for bile acids across the canalicular membrane into bile (Wang et al., 2003). The postnatal increase of Bsep favors the biliary excretion of bile acids in liver after birth to promote nutrient absorption (Fig. 4A). "
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