title: Transcript profiling in Arabidopsis reveals complex responses to global inhibition of DNA methylation and histone deacetylation.
abstract: Blocking histone deacetylation with trichostatin A (TSA) or blocking cytosine methylation using 5-aza-2'-deoxycytosine (aza-dC) can derepress silenced genes in multicellular eukaryotes, including animals and plants. We questioned whether DNA methylation and histone deacetylation overlap in the regulation of endogenous plant genes by monitoring changes in expression of approximately 7800 Arabidopsis thaliana genes following treatment with azadC, TSA, or both chemicals together. RNA levels for approximately 4% of the genes were reproducibly changed 3-fold or more by at least one treatment. Distinct subsets of genes are up-regulated or down-regulated in response to aza-dC, TSA, or simultaneous treatment with both chemicals, with little overlap among subsets. Surprisingly, the microarray data indicate that TSA and aza-dC are often antagonistic rather than synergistic in their effects. Analysis of green fluorescent protein transgenic plants confirmed this finding, showing that TSA can block the up-regulation of silenced green fluorescent protein transgenes in response to aza-dC or a ddm1 (decrease in DNA methylation 1) mutation. Our results indicate that global inhibition of DNA methylation or histone deacetylation has complex, nonredundant effects for the majority of responsive genes and suggest that activation of some genes requires one or more TSA-sensitive deacetylation events in addition to cytosine demethylation.
authors.affiliation: Department of Biology, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: Shuang
authors.initials: S
authors.lastname: Chang
authors.forename: Craig S
authors.initials: CS
authors.lastname: Pikaard
mesh_terms: D000107:Acetylation; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D056572:Histone Deacetylase Inhibitors; D006657:Histones / Q000378:metabolism*; D006877:Hydroxamic Acids / Q000494:pharmacology; D030821:Plants, Genetically Modified; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; C118957:DDM1 protein, Arabidopsis; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; D014157:Transcription Factors; C012589:trichostatin A