Andrographolide-induced pi class of glutathione S-transferase gene expression via PI3K/Akt pathway in rat primary hepatocytes.
Andrographis paniculata is an herb widely used in China, Korea, and India for its anti-hepatotoxic, anti-viral, and anti-inflammatory effects. Andrographolide is the major bioactive diterpene lactone in A. paniculata. The pi class of glutathione S-transferase (GSTP) is one of the phase II biotransformation enzymes. Our previous study indicated that andrographolide upregulates the expression of GSTP. The aim of this study was to investigate the mechanism by which andrographolide induces GSTP gene expression in rat primary hepatocytes. In hepatocytes treated with 40 μM andrographolide, immunoblots showed maximal Akt phosphorylation at 0.5 h and maximal c-jun phosphorylation at 3 h. However, pretreatment with PI3K inhibitors, wortmannin and LY294002, or siPI3K inhibited the andrographolide-induced phosphorylation of c-jun and GSTP protein expression. EMSA showed that pretreatment with wortmannin, LY294002, or siPI3K attenuated the AP-1-DNA-binding activity caused by andrographolide. Results of immunoprecipitation indicated that nuclear c-fos/c-jun heterodimer increases with andrographolide treatment. Addition of antibodies against c-jun and c-fos decreased nuclear protein bound to the AP-1 consensus DNA sequence. In summary, andrographolide induces GSTP gene expression in rat primary hepatocytes through activation of the PI3K/Akt, phosphorylation of c-jun, nuclear accumulation of AP-1, and subsequent binding to the response element in the gene promoter region.
Department of Nutrition, Chung Shan Medical University, Taichung, Taiwan.
Chia-Yang
CY
Lu
Chien-Chun
CC
Li
Chong-Kuei
CK
Lii
Hsien-Tsung
HT
Yao
Kai-Li
KL
Liu
Chia-Wen
CW
Tsai
Haw-Wen
HW
Chen
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D004224:Diterpenes / Q000494:pharmacology*; D024202:Electrophoretic Mobility Shift Assay; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005982:Glutathione Transferase / Q000235:genetics*; D022781:Hepatocytes / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction
D017931:DNA Primers; D004224:Diterpenes; D005982:Glutathione Transferase; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; C030419:andrographolide