Appearance of atypical 3 alpha,6 beta,7 beta,12 alpha-tetrahydroxy-5 beta-cholan-24-oic acid in spgp knockout mice.

Abstract

Bile formation and its canalicular secretion are essential functions of the mammalian liver. The sister-of-p-glycoprotein (spgp) gene was shown to encode the canalicular bile salt export protein, and mutations in spgp gene were identified as the cause of progressive familial intrahepatic cholestasis type 2. However, target inactivation of spgp gene in mice results in nonprogressive but persistent cholestasis and causes the secretion of unexpectedly large amounts of unknown tetrahydroxylated bile acid in the bile. The present study confirms the identity of this tetrahydroxylated bile acid as 3 alpha,6 beta,7 beta,12 alpha-tetrahydroxy-5 beta-cholan-24-oic acid. The data further show that in serum, liver, and urine of the spgp knockout mice, there is a significant increase in the concentration of total bile salts containing a large amount of tetrahydroxy-5 beta-cholan-24-oic acid. The increase in total bile acids was associated with up-regulation of the mRNA of cholesterol 7 alpha-hydroxylase in male mice only. It is suggested that the lower severity of the cholestasis in the spgp knockout mice may be due to the synthesis of 3 alpha,6 beta,7 beta,12 alpha-tetrahydroxy-5 beta-cholan-24-oic acid, which neutralizes in part the toxic effect of bile acids accumulated in the liver.

• Authors: Shahid Perwaiz, Dana Forrest, Diane Mignault, Beatriz Tuchweber, M James Phillip, Renxue Wang, Victor Ling, Ibrahim M Yousef
• Journal: Journal of lipid research (J Lipid Res) Vol. 44 Issue 3 Pg. 494-502 (Mar 2003) ISSN: 0022-2275 [Print] United States
• PMID: 12562825 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ATP Binding Cassette Transporter, Subfamily B, Member 11
• ATP-Binding Cassette Transporters
• Abcb11 protein, mouse
• Bile Acids and Salts
• Cholic Acids
• RNA, Messenger
• tetrahydroxy-5-cholan-24-oic acid
• Cholesterol 7-alpha-Hydroxylase

Topics

• ATP Binding Cassette Transporter, Subfamily B, Member 11
• ATP-Binding Cassette Transporters (genetics)
• Animals
• Bile (chemistry)
• Bile Acids and Salts (analysis, blood, urine)
• Cholesterol 7-alpha-Hydroxylase (genetics)
• Cholic Acids (analysis, blood, chemistry, urine)
• Female
• Gallbladder (chemistry)
• Gas Chromatography-Mass Spectrometry
• Gene Deletion
• Liver (chemistry)
• Male
• Mice
• Mice, Knockout
• RNA, Messenger (genetics, metabolism)