- 作者：Gerald Ulrich Denk ; Carl Philipp Kleiss ; Ralf Wimmer ; Timo Vennegeerts ; Florian Paul Reiter ; Sabine Schulz ; Hans Zischka ; Christian Rust
- 关键词：GCDCA ; glycochenodeoxycholic acid ; MCA ; muricholic acid ; T¦ÂMCA ; tauro-¦Â-muricholic acid ; TUDCA ; tauroursodeoxycholic acid
- 刊名：Biochemical and Biophysical Research Communications
- 出版年：2012
- 出版时间：10 August, 2012
- 年：2012
- 卷：424
- 期：4
- 页码：758-764
- 全文大小：705 K
Purpose
¦Â-Muricholic acid (¦ÂMCA) is a trihydroxylated bile acid that constitutes the major bile acid in rat and mouse. ¦ÂMCA is more hydrophilic than ursodeoxycholic acid and has been evaluated for dissolution of cholesterol gallstones. Since it is unknown if ¦ÂMCA has beneficial effects on hepatocyte cell death we determined the effect of tauro-¦ÂMCA (T¦ÂMCA) on apoptosis in vitro.Methods
Human Ntcp-transfected HepG2 cells and primary hepatocytes from rat and mouse were incubated with the proapoptotic glycochenodeoxycholic acid (GCDCA) as well as the free fatty acid palmitate in the absence and presence of T¦ÂMCA. Apoptosis was quantified using caspase 3/7-assays and after Hoechst 33342 staining. The mitochondrial membrane potential (MMP) was measured fluorometrically using JC-1 (5,5¡ä,6,6¡ä-tetrachloro-1,1¡ä,3,3¡ä-tetraethyl-benzimidazol-carbocyaniniodide). Immunoblotting was performed against the proapoptotic Bcl-2-protein Bax.
Results
In Ntcp-HepG2 cells, GCDCA markedly increased apoptosis after 4 h. Co-incubation with T¦ÂMCA reduced apoptosis to 49 % (p < 0.01 vs. GCDCA, each; n = 6). While GCDCA (100 ¦Ìmol/L) reduced the MMP to 34 % after 6 h, combination treatment with T¦ÂMCA restored the MMP to control levels at all time points (n = 4). T¦ÂMCA also restored breakdown of the MMP induced by palmitate. GCDCA induced a translocation of Bax from the cytosol to mitochondria that was inhibited by simultaneous treatment with T¦ÂMCA in eqimolar concentrations.
Conclusions
T¦ÂMCA restricts hepatocellular apoptosis induced by low micromolar concentrations of GCDCA or palmitate via inhibition of Bax translocation to mitochondria and preservation of the MMP. Thus, further studies are warranted to evaluate a potential use of T¦ÂMCA in ameliorating liver injury in cholestasis.