BACKGROUND: The human class I alcohol dehydrogenase (ADH) genes (ADH1A, ADH1B, and ADH1C) differ in expression during development and in various tissues. They are repressed in the HepG2 human hepatoma cell line. We hypothesized that epigenetic modifications play a role in this repression and that class I ADH gene expression would be enhanced upon global inhibition of DNA methylation and histone deacetylation. METHODS: Southern blotting was used to assess the methylation status of each class I ADH gene. HepG2 and HeLa cells were treated with either the DNA methylation inhibitor 5-aza-2'-deoxycytidine (5-aza-dC), the histone deacetylase inhibitor Trichostatin A (TSA), or both in combination, and class I ADH gene expression was analyzed. Chromatin immunoprecipitation assays were performed to analyze histone H3 acetylation. Transient transfections and gel mobility shift assays were used to analyze the role that methylation plays in inhibiting transcription factor binding and promoter function. RESULTS: We show that the upstream regions of ADH1A, ADH1B, and ADH1C are methylated in HepG2 cells. 5-Aza-2'-deoxycytidine treatment enhanced expression of both ADH1B and ADH1C. Trichostatin A treatment elevated expression of ADH1C. ADH1A expression was not stimulated by either 5-aza-dC or TSA. H3 histones associated with a methylated upstream region of ADH1B were hyperacetylated in TSA-treated, but not in 5-aza-dC-treated, HepG2 cells. A methylated upstream region of ADH1C achieved histone H3 hyperacetylation upon either 5-aza-dC or TSA treatment. Methylation of the ADH1B proximal promoter in vitro decreased its activity to 54% and inhibited the binding of the upstream stimulatory factor. CONCLUSIONS: These findings suggest that the class I ADH genes are regulated by epigenetic mechanisms in human hepatoma cells. The temporal and tissue-specific expression of these genes may in part result from differences in epigenetic modifications and the availability of key transcription factors.
BACKGROUND: The human class I alcohol dehydrogenase (ADH) genes (ADH1A, ADH1B, and ADH1C) differ in expression during development and in various tissues. They are repressed in the HepG2 humanhepatoma cell line. We hypothesized that epigenetic modifications play a role in this repression and that class I ADH gene expression would be enhanced upon global inhibition of DNA methylation and histone deacetylation. METHODS: Southern blotting was used to assess the methylation status of each class I ADH gene. HepG2 and HeLa cells were treated with either the DNA methylation inhibitor 5-aza-2'-deoxycytidine (5-aza-dC), the histone deacetylase inhibitor Trichostatin A (TSA), or both in combination, and class I ADH gene expression was analyzed. Chromatin immunoprecipitation assays were performed to analyze histone H3 acetylation. Transient transfections and gel mobility shift assays were used to analyze the role that methylation plays in inhibiting transcription factor binding and promoter function. RESULTS: We show that the upstream regions of ADH1A, ADH1B, and ADH1C are methylated in HepG2 cells. 5-Aza-2'-deoxycytidine treatment enhanced expression of both ADH1B and ADH1C. Trichostatin A treatment elevated expression of ADH1C. ADH1A expression was not stimulated by either 5-aza-dC or TSA. H3 histones associated with a methylated upstream region of ADH1B were hyperacetylated in TSA-treated, but not in 5-aza-dC-treated, HepG2 cells. A methylated upstream region of ADH1C achieved histone H3 hyperacetylation upon either 5-aza-dC or TSA treatment. Methylation of the ADH1B proximal promoter in vitro decreased its activity to 54% and inhibited the binding of the upstream stimulatory factor. CONCLUSIONS: These findings suggest that the class I ADH genes are regulated by epigenetic mechanisms in humanhepatoma cells. The temporal and tissue-specific expression of these genes may in part result from differences in epigenetic modifications and the availability of key transcription factors.
Authors: Chris Downing; Thomas E Johnson; Colin Larson; Tatiana I Leakey; Rachel N Siegfried; Tonya M Rafferty; Craig A Cooney Journal: Alcohol Date: 2010-08-12 Impact factor: 2.405
Authors: Patricio Godoy; Nicola J Hewitt; Ute Albrecht; Melvin E Andersen; Nariman Ansari; Sudin Bhattacharya; Johannes Georg Bode; Jennifer Bolleyn; Christoph Borner; Jan Böttger; Albert Braeuning; Robert A Budinsky; Britta Burkhardt; Neil R Cameron; Giovanni Camussi; Chong-Su Cho; Yun-Jaie Choi; J Craig Rowlands; Uta Dahmen; Georg Damm; Olaf Dirsch; María Teresa Donato; Jian Dong; Steven Dooley; Dirk Drasdo; Rowena Eakins; Karine Sá Ferreira; Valentina Fonsato; Joanna Fraczek; Rolf Gebhardt; Andrew Gibson; Matthias Glanemann; Chris E P Goldring; María José Gómez-Lechón; Geny M M Groothuis; Lena Gustavsson; Christelle Guyot; David Hallifax; Seddik Hammad; Adam Hayward; Dieter Häussinger; Claus Hellerbrand; Philip Hewitt; Stefan Hoehme; Hermann-Georg Holzhütter; J Brian Houston; Jens Hrach; Kiyomi Ito; Hartmut Jaeschke; Verena Keitel; Jens M Kelm; B Kevin Park; Claus Kordes; Gerd A Kullak-Ublick; Edward L LeCluyse; Peng Lu; Jennifer Luebke-Wheeler; Anna Lutz; Daniel J Maltman; Madlen Matz-Soja; Patrick McMullen; Irmgard Merfort; Simon Messner; Christoph Meyer; Jessica Mwinyi; Dean J Naisbitt; Andreas K Nussler; Peter Olinga; Francesco Pampaloni; Jingbo Pi; Linda Pluta; Stefan A Przyborski; Anup Ramachandran; Vera Rogiers; Cliff Rowe; Celine Schelcher; Kathrin Schmich; Michael Schwarz; Bijay Singh; Ernst H K Stelzer; Bruno Stieger; Regina Stöber; Yuichi Sugiyama; Ciro Tetta; Wolfgang E Thasler; Tamara Vanhaecke; Mathieu Vinken; Thomas S Weiss; Agata Widera; Courtney G Woods; Jinghai James Xu; Kathy M Yarborough; Jan G Hengstler Journal: Arch Toxicol Date: 2013-08-23 Impact factor: 5.153
Authors: Hui Li; Sheng Gu; Xiaoyun Cai; William C Speed; Andrew J Pakstis; Efim I Golub; Judith R Kidd; Kenneth K Kidd Journal: PLoS One Date: 2008-04-02 Impact factor: 3.240