Histone deacetylases, HDAC1 and HSIR2, act as a negative regulator of aging in human gingival fibroblast via p53 and Sp1 transcription factors

Abstract

Recently, histone deacetylases (HDACs) such as HDAC1 and HSIR2 have been known to be involved in regulation of lifespan extension. In this study, we observed that primary human gingival fibroblasts (HGFs) from elderly donors showed features of senescence, including enlarged cell size with a considerable proportion of cells stained positive for senescence-associated beta-galactosidase (SA-beta gal), $G_0/G_1$ cell cycle arrest and gene expression pattern of senescent cell. Furthermore, it was observed that the expression levels of histone deacetylases HSIR2 and HDAC1, direct regulators of the senescence phenotype in the fibroblasts, were significantly reduced; whereas the cell cycle regulators, p53 and p21, the former in its hyperacetylated form, were significantly increased. Premature aging phenotypes were induced by either treatment of histone deacetylase inhibitors, trichostatin A (TSA) and sodium butyrate (SB), or the expression of p53 and p300 in young HGFs derived from a 9 year-old donor. Overexpression of HSIR2 and HDAC1 repressed the premature aging phenotypes induced by p53 and p300, suggesting that histone deacetylases may delay the aging process through deacetylation of p53. It was shown that Sp1 enhanced the transcriptional activation of p53 and both Sp3 and Sp1 enhanced the activation of p21 promoter; while those activations were repressed by HSIR2 and HDAC1. Moreover, coimmunoprecipitation experiments demonstrated that p53, Sp1, HDAC1, and p300 were physically associated and the DNA-binding activities of Sp1 and acetyl-p53 transcription factors were significantly enhanced in aged HGFs. Our findings suggest that histone deacetylases regulate aging in primary human gingival fibroblast, a new model for human aging, by affecting transcriptional activities of p53 and Sp1 transcription factors.