Arabidopsis thaliana histone deacetylase 1 (AtHD1) and epigenetic regulation

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Title: Arabidopsis thaliana histone deacetylase 1 (AtHD1) and epigenetic regulation
Author: Tian, Lu
Abstract: Epigenetic regulation is a mechanism by which heritable changes in gene expression are controlled by chromatin status rather than primary DNA sequence . Changes in chromatin structure affect accessibility of DNA elements to the transcriptional machinery and thus affect transcription activity of the gene . A key event in this process is reversible modification of core histones , which is catalyzed by histone acetyltransferases (HATs ) and histone deacetylases (HDs , HDAs , or HDACs ) . In general , histone deacetylation is related to transcriptional gene silencing , whereas acetylation is associated with gene activation .To study the role of histone deacetylase in plant gene regulation and development , we generated constitutive antisense histone deacetylase 1 (CASH ) transgenic plants . AtHD1 is a homolog of RPD3 protein , a global transcriptional regulator in yeast . Expression of the antisense AtHD1 caused dramatic reduction in endogenous AtHD1 transcription , resulting in accumulation of acetylated histones . Down -regulation of histone deacetylation caused a variety of growth and developmental abnormalities and ectopic expression of tissue -specific genes . However , changes in genomic DNA methylation were not detected in repetitive DNA sequences in the transgenic plants .We also identified a T -DNA insertion line in exon 2 of AtHD1 gene (athd1 -t1 ) , resulting in a null allele at the locus . The complete inhibition of the AtHD1 expression induced growth and developmental defects similar to those of CASH transgenic plants . The phenotypic abnormalities were heritable across the generations in the mutants . When the athd1 -t1 /athd1 -t1 plants were crossed to wild -type plants , the mutant phenotype was corrected in the F1 hybrids , which correlated with the AtHD1 expression and reduction of histone H4 Lys12 acetylation . Microarray analysis was applied to determine genome -wide changes in transcriptional profiles in the athd1 -t1 mutant . Approximately 6 .7 % (1 ,753 ) of the genes were differentially expressed in leaves between the wild -type (Ws ) and the athd1 -t1 mutant , whereas 4 .8 % (1 ,263 ) of the genes were up - or down -regulated in flower buds of the mutant . These affected genes were randomly distributed across five chromosomes of Arabidopsis and represented a wide range of biological functions . Chromatin immunoprecipitation assays indicated that the activation for a subset of genes was directly associated with changes in acetylation profiles .
URI: http : / /hdl .handle .net /1969 .1 /23
Date: 2004-09-30


Arabidopsis thaliana histone deacetylase 1 (AtHD1) and epigenetic regulation. Available electronically from http : / /hdl .handle .net /1969 .1 /23 .

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