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Histone deacetylases specifically down-regulate p53-dependent gene activation
1National Health Research Institutes, 128 Yen-Chiu-Yuan Road, Sec 2, Taipei 115, Taiwan.
Abstract:
p53, the most commonly mutated gene in cancer cells, directs cell cycle arrest or induces programmed cell death (apoptosis) in response to stress. It has been demonstrated that p53 activity is up-regulated in part by posttranslational acetylation. In agreement with these observations, here we show that mammalian histone deacetylase (HDAC)-1, -2, and -3 are all capable of down-regulating p53 function. Down-regulation of p53 activity by HDACs is HDAC dosage-dependent, requires the deacetylase activity of HDACs, and depends on the region of p53 that is acetylated by p300/CREB-binding protein (CBP). These results suggest that interactions of p53 and HDACs likely result in p53 deacetylation, thereby reducing its transcriptional activity. In support of this idea, GST pull-down and immunoprecipitation assays show that p53 interacts with HDAC1 both in vitro and in vivo. Furthermore, a pre-acetylated p53 peptide was significantly deacetylated by immunoprecipitated wild type HDAC1 but not deacetylase mutant. Also, co-expression of HDAC1 greatly reduced the in vivo acetylation level of p53. Finally, we report that the activation potential of p53 on the BAX promoter, a natural p53-responsive system, is reduced in the presence of HDACs. Taken together, our findings indicate that deacetylation of p53 by histone deacetylases is likely to be part of the mechanisms that control the physiological activity of p53.
Insights
Histone deacetylases (HDACs) regulate the tumor suppressor p53 by removing acetyl groups, which reduces p53
Area of Science:
- Molecular Biology
- Cancer Biology
- Epigenetics
Background:
- p53 is a critical tumor suppressor gene frequently mutated in cancer.
- p53 activity is regulated by posttranslational modifications, including acetylation.
- Acetylation generally enhances p53 activity, promoting cell cycle arrest or apoptosis.
Purpose of the Study:
- To investigate the role of mammalian histone deacetylases (HDACs) in regulating p53 function.
- To determine if HDACs can down-regulate p53 activity through deacetylation.
- To elucidate the interaction between p53 and HDACs.
Main Methods:
- Co-expression of HDACs (1, 2, and 3) with p53.
- Assays to measure p53 acetylation levels and transcriptional activity.
- GST pull-down and immunoprecipitation assays to assess protein interactions.
- In vitro deacetylation assays using p53 peptides and HDAC1.
Main Results:
- HDAC1, HDAC2, and HDAC3 were found to down-regulate p53 function in a dosage-dependent manner.
- HDAC-mediated down-regulation of p53 requires deacetylase activity and targets specific acetylation sites.
- p53 directly interacts with HDAC1 both in vitro and in vivo.
- HDAC1 deacetylated p53 in vitro and reduced p53 acetylation and transcriptional activity in vivo.
- HDACs reduced p53's activation of the BAX promoter.
Conclusions:
- Mammalian HDACs, particularly HDAC1, can deacetylate and inhibit p53 activity.
- p53 deacetylation by HDACs is a mechanism controlling p53's physiological function.
- These findings highlight a novel regulatory pathway for the tumor suppressor p53.