p53-independent induction of Gadd45 by histone deacetylase inhibitor: coordinate regulation by transcription factors Oct-1 and NF-Y

Abstract

Histone deacetylase (HDAC) inhibitors cause growth arrest at the G1 and/or G2/M phases, and induce differentiation and/or apoptosis in a wide variety of tumour cells. The growth arrest at G1 phase by HDAC inhibitors is thought to be highly dependent on the upregulation of p21/WAF1, but the precise mechanism by which HDAC inhibitors cause G2/M arrest or apoptosis in tumour cells is unknown. Gadd45 causes cell cycle arrest at the G2/M phase transition and participates in genotoxic stress-induced apoptosis. We show here that it is also induced by a typical HDAC inhibitor, trichostatin A (TSA), through its promoter, in a p53-independent manner. To identify the mechanism of activation of the gadd45 promoter, we performed luciferase reporter analyses and electrophoretic mobility shift assays. These revealed that both the Oct-1 and CCAAT sites are needed for the full activation by TSA. We also found that the transcription factors Oct-1 and NF-Y specifically bind to each site. Thus, HDAC inhibitors can induce Gadd45 through its promoter without the need for functional p53, and both the Oct-1 and NF-Y concertedly participate in TSA-induced activation of the gadd45 promoter.

The histone deacetylase inhibitor trichostatin A induces GADD45γ expression via Oct and NF-Y binding sites

“…However, EMSAs showed that TSA treatment did not change the affinity of nuclear factors for the NF-Y or Oct sites in the murine GADD45g promoter (unpublished observations). This agrees with the lack of effect of TSA on the affinity of NF-Y or Oct-1 for their sites in the human GADD45a promoter (Hirose et al, 2003). Alternatively, TSA treatment may affect the interaction of Oct-1 with SMRT-HDAC1, and/or the interactions of NF-Y with HDAC1 or PCAF.…”

“…The murine GADD45g promoter shares some structural features with the murine GADD45a promoter, namely Oct and NF-Y putative binding sites. Mutation of these sites in the human GADD45a promoter decreases its basal activity (Hirose et al, 2003). Similarly, we have shown that mutation of either the Oct or NF-Y sites decreases the murine GADD45g promoter basal activity and that expression of Oct-1 and NF-YA increases its activity.…”

“…Because we have not directly investigated whether GADD45a or GADD45b expression is induced by TSA in NIH3T3 cells, we cannot rule out that this inhibitor might also induce the expression of these genes in NIH3T3 or Jurkat cells. In the human GADD45a promoter, two sets of Oct and NF-Y sites contribute to its activation by TSA (Hirose et al, 2003). However, the human GADD45b proximal promoter contains NF-Y sites but no Oct site, as predicted by MatInspector analysis (Cartharius et al, 2005).…”

“…Mutation of individual Oct or NF-Y sites in the murine GADD45g promoter did not hamper its activation by TSA, suggesting that either site is sufficient to mediate activation by TSA. This inhibitor has been previously shown to upregulate GADD45a mRNA levels in human colon carcinoma and osteosarcoma cells (Della-Ragione et al, 2001;Chen et al, 2002;Hirose et al, 2003) and GADD45b mRNA levels in human colon carcinoma cells (Chen et al, 2002). Because we have not directly investigated whether GADD45a or GADD45b expression is induced by TSA in NIH3T3 cells, we cannot rule out that this inhibitor might also induce the expression of these genes in NIH3T3 or Jurkat cells.…”

“…HDAC inhibitors, such as trichostatin A (TSA; Sigma, Tres Cantos, Madrid, Spain), induce many genes coding for proteins involved in cell cycle control, including GADD45a and GADD45b (Della-Ragione et al, 2001;Chen et al, 2002;Hirose et al, 2003), and stop tumor growth by eliciting either cell cycle arrest or apoptosis in tumor cells (Johnstone, 2002).…”