Both Sp1 and Sp3 are responsible for p21(waf1) promoter activity induced by histone deacetylase inhibitor in NIH3T3 cells

Histone deacetylase inhibitor-induced expression of p21(WAF1) is p53 indepe ndent. In the present study, we provide evidence that trichostatin A (TSA), a specific inhibitor of histone deacetylase, can elevate H3 and H4 acetyla tion and p21(WAF1) expression in NIH3T3 cells at first. To identify the tra nscription factor which is responsible for histone deacetylase inhibitor-in duced expression of p21(WAF1) and understand the potential events occurred during this process, we analyze the response of the mouse p21(WAF1) promote r to TSA in detail. The region responsive to TSA treatment in the p21 promo ter is located -100 bp upstream from transcription initiation site and cont ains a GC-box. The mutation introduced into this GC-box decreases most of t he basal and TSA-induced promoter activity. The results from gel-shift assa y show that Sp1 and Sp3 bind to this GC-rich region. Cotransfection with Sp 1 and/or Sp3 expression constructs elevate both basal and induced promoter activity, and this elevation is dependent on the present of the GC-box. By contrast, cotransfection with reverse oriented Sp1 or Sp3 cDNA decreased ba sal and induced-promoter activity as well as GC-box dependency. These findi ngs provide physical and functional evidence which strongly indicated that both Sp1 and Sp3 are responsible for TSA-induced transactivation of the mur ine p21(WAF1) promoter in NIH3T3 cells. J. Cell. Biochem. 73:291-302, 1999. (C) 1999 Wiley-Liss, Inc.