Green tea catechin enhances cholesterol 7alpha-hydroxylase gene expression in HepG2 cells.
Green tea catechins are known to have hypocholesterolaemic effects in animals and human subjects. In the present study, we investigated the effects of green tea catechins on the mRNA level and promoter activity of hepatic cholesterol 7alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in the conversion of cholesterol to bile acids, in human hepatoma cells. Real-time PCR assays showed that different catechins, (-)-epicatechin gallate (ECG), (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC) and (-)-epicatechin (EC), up regulated the CYP7A1 mRNA level by 5.5-, 4.2-, 2.9- and 1.9-fold, respectively, compared with the control. The -1312/+358 bp of the CYP7A1 promoter was subcloned into the pGL3 basic vector that includes luciferase as a reporter gene. ECG or EGCG significantly increased CYP7A1 promoter activity by 6.0- or 4.0-fold, respectively, compared with the control. Also, EGCG stimulated CYP7A1 at both mRNA level and promoter activity in a dose-dependent manner. These results suggest that the expression of the CYP7A1 gene may be directly regulated by green tea catechins at the transcriptional level.
Lee
Mak-Soon
MS
Department of Food and Nutritional Sciences, Ewha Woman's University, Seoul 120-750, South Korea.
Park
Ju-Yeon
JY
Freake
Hedley
H
Kwun
In-Sook
IS
Kim
Yangha
Y
D000704:Analysis of Variance; D028241:Camellia sinensis; D006528:Carcinoma, Hepatocellular; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002790:Cholesterol 7-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013662:Tea
D013662:Tea; D002392:Catechin; C062669:epicatechin gallate; C045651:epigallocatechin gallate; D002790:Cholesterol 7-alpha-Hydroxylase; C057580:gallocatechol