title: Thyroid hormone suppression of β-amyloid precursor protein gene expression in the brain involves multiple epigenetic regulatory events.
abstract: Thyroid hormone (T3) suppresses cerebral gene expression of the β-amyloid precursor protein (APP), an integral membrane protein that plays a key role in the onset and progression of Alzheimer's disease. However, the mechanisms by which T3 signaling pathways inhibit APP gene transcription in the brain remain unclear. By carrying out chromatin immunoprecipitation with neuroblastoma cells and primary rat brain tissue, we show for the first time that thyroid hormone receptors (TRs) directly bind at the APP gene in vivo at a promoter region containing a negative T3-response element. We further show that T3 treatment decreases both histone H3 acetylation and histone H3 lysine 4 methylation at the APP promoter and that chemical inhibitors of histone deacetylases and histone lysine demethylase abrogate T3-dependent APP silencing. Our findings thus suggest that TRs actively facilitate T3-dependent silencing of APP gene expression via the recruitment of distinct histone modifying enzymes associated with transcriptional repression.
authors: Department of Physiology and Biophysics, Robert Wood Johnson Medical School, UMDNJ, Piscataway, NJ 08854, USA.
authors: Madesh
authors: M
authors: Belakavadi
authors: Janet
authors: J
authors: Dell
authors: Gary J
authors: GJ
authors: Grover
authors: Joseph D
authors: JD
authors: Fondell
mesh_terms: D000107:Acetylation; D000544:Alzheimer Disease; D016564:Amyloid beta-Protein Precursor / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D045744:Cell Line, Tumor; D044127:Epigenesis, Genetic; D005786:Gene Expression Regulation; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D056466:Histone Demethylases / Q000037:antagonists & inhibitors; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D008297:Male; D008745:Methylation; D011401:Promoter Regions, Genetic; D011499:Protein Processing, Post-Translational; D051381:Rats; D017207:Rats, Sprague-Dawley; D011988:Receptors, Thyroid Hormone / Q000378:metabolism; D014191:Tranylcypromine / Q000494:pharmacology; D014284:Triiodothyronine / Q000494:pharmacology / Q000502:physiology*
chemical_list: D016564:Amyloid beta-Protein Precursor; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; D011988:Receptors, Thyroid Hormone; D014284:Triiodothyronine; D014191:Tranylcypromine; C012589:trichostatin A; D056466:Histone Demethylases