Combined deletion of Fxr and Shp in mice induces Cyp17a1 and results in juvenile onset cholestasis.
Bile acid homeostasis is tightly regulated via a feedback loop operated by the nuclear receptors farnesoid X receptor (FXR) and small heterodimer partner (SHP). Contrary to current models, which place FXR upstream of SHP in a linear regulatory pathway, here we show that the phenotypic consequences in mice of the combined loss of both receptors are much more severe than the relatively modest impact of the loss of either Fxr or Shp alone. Fxr-/-Shp-/- mice exhibited cholestasis and liver injury as early as 3 weeks of age, and this was linked to the dysregulation of bile acid homeostatic genes, particularly cytochrome P450, family 7, subfamily a, polypeptide 1 (Cyp7a1). In addition, double-knockout mice showed misregulation of genes in the C21 steroid biosynthesis pathway, with strong induction of cytochrome P450, family 17, subfamily a, polypeptide 1 (Cyp17a1), resulting in elevated serum levels of its enzymatic product 17-hydroxyprogesterone (17-OHP). Treatment of WT mice with 17-OHP was sufficient to induce liver injury that reproduced many of the histopathological features observed in the double-knockout mice. Therefore, our data indicate a pathologic role for increased production of 17-hydroxy steroid metabolites in liver injury and suggest that Fxr-/-Shp-/- mice could provide a model for juvenile onset cholestasis.
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA.
Sayeepriyadarshini
S
Anakk
Mitsuhiro
M
Watanabe
Scott A
SA
Ochsner
Neil J
NJ
McKenna
Milton J
MJ
Finegold
David D
DD
Moore
D019326:17-alpha-Hydroxyprogesterone / Q000097:blood; D000818:Animals; D001647:Bile Acids and Salts / Q000096:biosynthesis; D001659:Biliary Tract / Q000378:metabolism / Q000473:pathology; D002779:Cholestasis / Q000209:etiology* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002790:Cholesterol 7-alpha-Hydroxylase / Q000235:genetics; D004195:Disease Models, Animal; D004790:Enzyme Induction; D006801:Humans; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D020297:Mice, Congenic; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018160:Receptors, Cytoplasmic and Nuclear / Q000172:deficiency* / Q000235:genetics; D013253:Steroid 12-alpha-Hydroxylase / Q000235:genetics; D013254:Steroid 17-alpha-Hydroxylase / Q000096:biosynthesis*; D000099150:Receptor, Farnesoid X-Activated
D019326:17-alpha-Hydroxyprogesterone; D001647:Bile Acids and Salts; D002790:Cholesterol 7-alpha-Hydroxylase; D018160:Receptors, Cytoplasmic and Nuclear; D013253:Steroid 12-alpha-Hydroxylase; D013254:Steroid 17-alpha-Hydroxylase; D000099150:Receptor, Farnesoid X-Activated; C099713:nuclear receptor subfamily 0, group B, member 2; C502772:Cyp7a1 protein, mouse