title: The expression of endothelial nitric-oxide synthase is controlled by a cell-specific histone code.
abstract: Expression of endothelial nitric-oxide synthase (eNOS) mRNA is highly restricted to the endothelial cell layer of medium to large sized arterial blood vessels. Here we assessed the chromatin environment of the eNOS gene in expressing and nonexpressing cell types. Within endothelial cells, but not a variety of nonendothelial cells, the nucleosomes that encompassed the eNOS core promoter and proximal downstream coding regions were highly enriched in acetylated histones H3 and H4 and methylated lysine 4 of histone H3. This differentially modified chromatin domain was selectively associated with functionally competent RNA polymerase II complexes. Endothelial cells were particularly enriched in acetylated histone H3 lysine 9, histone H4 lysine 12, and di- and tri-methylated lysine 4 of histone H3 at the core promoter. Histone modifications at this region, which we have previously demonstrated to exhibit cell-specific DNA methylation, were functionally relevant to eNOS expression. Inhibition of histone deacetylase activity by trichostatin A increased acetylation of histones H3 and H4 at the eNOS proximal promoter in nonexpressing cell types and led to increased steady-state eNOS mRNA transcript levels. H3 lysine 4 methylation was also essential for eNOS expression, since treatment of endothelial cells with methylthioadenosine, a known lysine 4 methylation inhibitor, decreased eNOS RNA levels, H3 lysine 4 methylation, and RNA polymerase II loading at the eNOS proximal promoter. Importantly, methylthioadenosine also prevented the trichostatin A-mediated increase in eNOS mRNA transcript levels in nonendothelial cells. Taken together, these findings provide strong evidence that the endothelial cell-specific expression of eNOS is controlled by cell-specific histone modifications.
authors.affiliation: Department of Medical Biophysics, St. Michael's Hospital and University of Toronto, Toronto, Ontario M5S 1A8, Canada.
authors.forename: Jason E
authors.initials: JE
authors.lastname: Fish
authors.forename: Charles C
authors.initials: CC
authors.lastname: Matouk
authors.forename: Alisa
authors.initials: A
authors.lastname: Rachlis
authors.forename: Steven
authors.initials: S
authors.lastname: Lin
authors.forename: Sharon C
authors.initials: SC
authors.lastname: Tai
authors.forename: Cheryl
authors.initials: C
authors.lastname: D'Abreo
authors.forename: Philip A
authors.initials: PA
authors.lastname: Marsden
mesh_terms: D000107:Acetylation; D000818:Animals; D001374:Azacitidine / Q000737:chemistry; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002843:Chromatin / Q000737:chemistry; D047369:Chromatin Immunoprecipitation; D018899:CpG Islands; D019175:DNA Methylation; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D006367:HeLa Cells; D006657:Histones / Q000737:chemistry*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008239:Lysine / Q000737:chemistry; D008745:Methylation; D051379:Mice; D008822:Mice, Transgenic; D008957:Models, Genetic; D009130:Muscle, Smooth / Q000166:cytology; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000737:chemistry; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D009707:Nucleosomes / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012694:Serine / Q000737:chemistry; D013997:Time Factors; D019076:Transgenes; D014471:Umbilical Veins / Q000166:cytology; D001616:beta-Galactosidase / Q000737:chemistry / Q000378:metabolism
chemical_list: D002843:Chromatin; D006657:Histones; D006877:Hydroxamic Acids; D009707:Nucleosomes; C012589:trichostatin A; D012694:Serine; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D012319:RNA Polymerase II; D001616:beta-Galactosidase; D008239:Lysine; D001374:Azacitidine