RESUMO
Histone deacetylase 1 (HDAC1) is a major regulator of chromatin structure and gene expression. Tight control of HDAC1 expression is essential for development and normal cell cycle progression. In this report, we analyzed the regulation of the mouse HDAC1 gene by deacetylases and acetyltransferases. The murine HDAC1 promoter lacks a TATA box consensus sequence but contains several putative SP1 binding sites and a CCAAT box, which is recognized by the transcription factor NF-Y. HDAC1 promoter-reporter studies revealed that the distal SP1 site and the CCAAT box are crucial for HDAC1 promoter activity and act synergistically to constitute HDAC1 promoter activity. Furthermore, these sites are essential for activation of the HDAC1 promoter by the deacetylase inhibitor trichostatin A (TSA). Chromatin immunoprecipitation assays showed that HDAC1 is recruited to the promoter by SP1 and NF-Y, thereby regulating its own expression. Coexpression of acetyltransferases elevates HDAC1 promoter activity when the SP1 site and the CCAAT box are intact. Increased histone acetylation at the HDAC1 promoter region in response to TSA treatment is dependent on binding sites for SP1 and NF-Y. Taken together, our results demonstrate for the first time the autoregulation of a histone-modifying enzyme in mammalian cells.
Assuntos
Regulação Enzimológica da Expressão Gênica , Histona Desacetilases/fisiologia , Histonas/metabolismo , Homeostase/genética , Regiões Promotoras Genéticas/genética , Células 3T3 , Sequência de Aminoácidos , Animais , Sequência de Bases , Fator de Ligação a CCAAT/metabolismo , Cromatina/metabolismo , Ativação Enzimática , Inibidores Enzimáticos/farmacologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/enzimologia , Fibroblastos/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Inibidores de Histona Desacetilases , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Homeostase/efeitos dos fármacos , Humanos , Ácidos Hidroxâmicos/farmacologia , Camundongos , Dados de Sequência Molecular , Mutação Puntual , Fator de Transcrição Sp1/metabolismo , Fatores de Transcrição/metabolismo , Células Tumorais CultivadasRESUMO
Histone deacetylases (HDACs) modulate chromatin structure and transcription, but little is known about their function in mammalian development. HDAC1 was implicated previously in the repression of genes required for cell proliferation and differentiation. Here we show that targeted disruption of both HDAC1 alleles results in embryonic lethality before E10.5 due to severe proliferation defects and retardation in development. HDAC1-deficient embryonic stem cells show reduced proliferation rates, which correlate with decreased cyclin-associated kinase activities and elevated levels of the cyclin-dependent kinase inhibitors p21(WAF1/CIP1) and p27(KIP1). Similarly, expression of p21 and p27 is up-regulated in HDAC1-null embryos. In addition, loss of HDAC1 leads to significantly reduced overall deacetylase activity, hyperacetylation of a subset of histones H3 and H4 and concomitant changes in other histone modifications. The expression of HDAC2 and HDAC3 is induced in HDAC1-deficient cells, but cannot compensate for loss of the enzyme, suggesting a unique function for HDAC1. Our study provides the first evidence that a histone deacetylase is essential for unrestricted cell proliferation by repressing the expression of selective cell cycle inhibitors.
