Reversal of methylation-mediated repression with short-chain fatty acids: evidence for an additional mechanism to histone deacetylation.
We have constructed a stable cell line, human embryonal kidney 293M+, containing a lacZ reporter gene controlled by an in vitro methylated hormone-responsive enhancer. Methylation of the enhancer-promoter abolishes lacZ expression controlled by ponasterone A (an analogue of ecdysone). Ponasterone A-induced expression is restored by the short-chain fatty acids valeric > butyric > propionic > acetic acid, but not by the histone deacetylase inhibitors trichostatin A and suberoylanilide hydroxamic acid (SAHA). lacZ expression is restored to levels approaching that from an unmethylated counterpart. Incubation with short-chain fatty acids alone does not promote demethylation of the lacZ promoter, however, some demethylation (30%) is observed when transcription is triggered by addition of ponasterone A. Similar levels of hyperacetylated histones H3 and H4 were observed in cells treated with short-chain fatty acids, trichostatin A or SAHA. In vivo DNase I footprinting indicates a more open chromatin structure at the promoter region for butyric acid-treated cells. A synergistic effect in reversing the methylation-mediated repression of the lacZ gene is obtained by combined treatments with the normally ineffective compounds trichostatin A and the short-chain fatty acid caproic acid. Our results suggest the existence of an alternative silencing mechanism to histone deacetylation in executing methylation-directed gene silencing.
Benjamin
D
D
Friedrich Miescher Institute, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.
Jost
J P
JP
D000818:Animals; D020148:Butyric Acid / Q000494:pharmacology; D002208:Caproates / Q000494:pharmacology; D002460:Cell Line; D002843:Chromatin / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D018983:DNA Footprinting; D019175:DNA Methylation; D004357:Drug Synergism; D004441:Ecdysterone / Q000031:analogs & derivatives* / Q000494:pharmacology; D005232:Fatty Acids, Volatile / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D020868:Gene Silencing; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D007700:Kinetics; D007763:Lac Operon / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D013997:Time Factors; D001616:beta-Galactosidase / Q000187:drug effects / Q000378:metabolism
D002208:Caproates; D002843:Chromatin; D005232:Fatty Acids, Volatile; D006657:Histones; D006877:Hydroxamic Acids; D020148:Butyric Acid; C012589:trichostatin A; D004441:Ecdysterone; C008999:ponasterone A; D004247:DNA; D001616:beta-Galactosidase; D006655:Histone Deacetylases