Figure 1.
Bacteria-mediated BA metabolism.
(a) Deconjugation, dehydroxylation, oxidation, and epimerization of cholic acid (CA) in the intestine of mice. Black dotted arrows represent for deconjugation, black solid arrows represent for 7-dehydroxylation, grey dotted arrows represent for oxidation, grey solid arrows represent for epimerization; (b) Deconjugation, dehydroxylation, oxidation, and epimerization of chenodeoxycholic acid (CDCA) and muricholic acid (MCA) in the intestine of mice. Black dotted arrows represent for deconjugation, black solid arrows represent for 7-dehydroxylation, grey dotted arrows represent for oxidation, grey solid arrows represent for epimerization; (c) Structures and abbreviations of various BAs. TCA and GCA stand for taurocholic acid and glycocholic acid, respectively.
Figure 2.
Concentrations of primary and secondary BAs in the feces of WT and Oatp1a1-null mice.
Feces were collected from WT and Oatp1a1-null mice for 24 hr and dried under vacuum. The concentrations of primary BAs (a, b, and c) and secondary BAs (d, e, and f) in the feces of male WT and Oatp1a1-null mice (n = 5/group) were analyzed using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and normalized by fecal dry weight. All data are expressed as mean ± S.E. of five mice in each group. *, statistically significant difference between WT and Oatp1a1-null mice (p<0.05).
Figure 3.
BA concentrations in livers (a and b) and bile (c and d) of mice.
BA concentrations in livers and bile of male WT and Oatp1a1-null mice (n = 5/group) were analyzed using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). All data are expressed as mean ± S.E. for five mice in each group. *, statistically significant difference between WT and Oatp1a1-null mice (p<0.05).
Figure 4.
BA composition in the small (a and b) and large (c and d) intestinal contents of mice.
BA concentrations in the intestinal contents of male WT and Oatp1a1-null mice (n = 5/group) were analyzed using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). All data are expressed as mean ± S.E. for five mice in each group. *, statistically significant difference between WT and Oatp1a1-null mice (p<0.05).
Figure 5.
Small and large intestinal bacteria in WT and Oatp1a1-null mice.
Clostridia (a), Bacteroides (b), Lactobacilli (c), and other bacteria (d) in the small and large intestinal contents of WT and Oatp1a1-null mice were quantified using a branched DNA assay (Panomics/Affymetrix, Fremont, CA). All data are expressed as mean ± S.E. of five mice in each group. *, statistically significant difference between WT and Oatp1a1-null mice (p<0.05).
Figure 6.
mRNA of Fxr, Shp, and Fgf15 in ilea as well as Fgfr4 in livers of mice.
Total RNA from ilea and livers of male WT and Oatp1a1-null mice (n = 5/group) was analyzed using multiplex suspension array. The mRNA of each gene was normalized to GAPDH. All data are expressed as mean ± S.E. of five mice in each group. *, statistically significant difference between WT and Oatp1a1-null mice (p<0.05).
Figure 7.
Oatp1a1-null mice had higher hippuric acid, but lower indole-3-carboxylic acid-glucuronide in urine than WT mice.
Structural elucidations were performed based on accurate mass measurement and MS/MS fragmentations of hippuric acid (a) and indole-3-carboxylic acid-glucuronide (b) in urine of WT and Oatp1a1-null mice. By comparison of the retention time in the same MS/MS chromatograph window between authentic standards and urine samples, hippuric acid (c) and indole-3-carboxylic acid-G (d) were confirmed. The authentic standard indole-3-carboxylic acid-glucuronide (indole-3-carboxylic acid-G) was enzymatically synthesized from indole-3-carboxylic acid.
Table 1.
Gene accession numbers of the 16 s rRNA gene assessed in this study.