2016
Robert, Carine; Nagaria, Pratik K; Pawar, Nisha; Adewuyi, Adeoluwa; Gojo, Ivana; Meyers, David J; Cole, Philip A; Rassool, Feyruz V
In: Leuk Res, vol. 45, pp. 14-23, 2016, ISSN: 1873-5835.
Abstract | Links | BibTeX | Tags: Acetylation, Acute, Benzamides, Chromatin, Cultured, DNA Breaks, DNA End-Joining Repair, Double-Stranded, Histone Deacetylase Inhibitors, Humans, Ku Autoantigen, Leukemia, Myeloid, Poly (ADP-Ribose) Polymerase-1, Pyridines, Tumor Cells
@article{1299967,
title = {Histone deacetylase inhibitors decrease NHEJ both by acetylation of repair factors and trapping of PARP1 at DNA double-strand breaks in chromatin},
author = {Carine Robert and Pratik K Nagaria and Nisha Pawar and Adeoluwa Adewuyi and Ivana Gojo and David J Meyers and Philip A Cole and Feyruz V Rassool},
doi = {10.1016/j.leukres.2016.03.007},
issn = {1873-5835},
year = {2016},
date = {2016-06-01},
journal = {Leuk Res},
volume = {45},
pages = {14-23},
abstract = {Histone deacetylase inhibitors (HDACi) induce acetylation of histone and non-histone proteins, and modulate the acetylation of proteins involved in DNA double-strand break (DSB) repair. Non-homologous end-joining (NHEJ) is one of the main pathways for repairing DSBs. Decreased NHEJ activity has been reported with HDACi treatment. However, mechanisms through which these effects are regulated in the context of chromatin are unclear. We show that pan-HDACi, trichostatin A (TSA), causes differential acetylation of DNA repair factors Ku70/Ku80 and poly ADP-ribose polymerase-1 (PARP1), and impairs NHEJ. Repair effects are reversed by treatments with p300/CBP inhibitor C646, with significantly decreased acetylation of PARP1. In keeping with these findings, TSA treatment significantly increases PARP1 binding to DSBs in chromatin. Notably, AML patients treated with HDACi entinostat (MS275) in vivo also show increased formation of poly ADP-ribose (PAR) that co-localizes with DSBs. Further, we demonstrate that PARP1 bound to chromatin increases with duration of TSA exposure, resembling PARP "trapping". Knockdown of PARP1 inhibits trapping and mitigates HDACi effects on NHEJ. Finally, combination of HDACi with potent PARP inhibitor talazoparib (BMN673) shows a dose-dependent increase in PARP "trapping", which correlates with increased apoptosis. These results provide a mechanism through which HDACi inhibits deacetylation and increases binding of PARP1 to DSBs, leading to decreased NHEJ and cytotoxicity of leukemia cells.},
keywords = {Acetylation, Acute, Benzamides, Chromatin, Cultured, DNA Breaks, DNA End-Joining Repair, Double-Stranded, Histone Deacetylase Inhibitors, Humans, Ku Autoantigen, Leukemia, Myeloid, Poly (ADP-Ribose) Polymerase-1, Pyridines, Tumor Cells},
pubstate = {published},
tppubtype = {article}
}
Histone deacetylase inhibitors (HDACi) induce acetylation of histone and non-histone proteins, and modulate the acetylation of proteins involved in DNA double-strand break (DSB) repair. Non-homologous end-joining (NHEJ) is one of the main pathways for repairing DSBs. Decreased NHEJ activity has been reported with HDACi treatment. However, mechanisms through which these effects are regulated in the context of chromatin are unclear. We show that pan-HDACi, trichostatin A (TSA), causes differential acetylation of DNA repair factors Ku70/Ku80 and poly ADP-ribose polymerase-1 (PARP1), and impairs NHEJ. Repair effects are reversed by treatments with p300/CBP inhibitor C646, with significantly decreased acetylation of PARP1. In keeping with these findings, TSA treatment significantly increases PARP1 binding to DSBs in chromatin. Notably, AML patients treated with HDACi entinostat (MS275) in vivo also show increased formation of poly ADP-ribose (PAR) that co-localizes with DSBs. Further, we demonstrate that PARP1 bound to chromatin increases with duration of TSA exposure, resembling PARP "trapping". Knockdown of PARP1 inhibits trapping and mitigates HDACi effects on NHEJ. Finally, combination of HDACi with potent PARP inhibitor talazoparib (BMN673) shows a dose-dependent increase in PARP "trapping", which correlates with increased apoptosis. These results provide a mechanism through which HDACi inhibits deacetylation and increases binding of PARP1 to DSBs, leading to decreased NHEJ and cytotoxicity of leukemia cells.
Zucconi, B. E.; Luef, B.; Xu, W.; Henry, R. A.; Nodelman, I. M.; Bowman, G. D.; Andrews, A. J; Cole, P. A.
Modulation of p300/CBP Acetylation of Nucleosomes by Bromodomain Ligand I-CBP112 Journal Article
In: Biochemistry, vol. 55, no. 27, pp. 3727-34, 2016, ISSN: 1520-4995.
Abstract | Links | BibTeX | Tags: Acetylation, Bromine Compounds, Cell Proliferation, Crystallography, Cultured, E1A-Associated p300 Protein, Histones, Humans, Leukemia, Male, Models, Molecular, Mutagenesis, Nucleosomes, p300-CBP Transcription Factors, Prostatic Neoplasms, Protein Binding, Protein Conformation, Site-Directed, Tumor Cells, X-Ray
@article{1299963,
title = {Modulation of p300/CBP Acetylation of Nucleosomes by Bromodomain Ligand I-CBP112},
author = {B. E. Zucconi and B. Luef and W. Xu and R. A. Henry and I. M. Nodelman and G. D. Bowman and A. J Andrews and P. A. Cole},
doi = {10.1021/acs.biochem.6b00480},
issn = {1520-4995},
year = {2016},
date = {2016-00-00},
journal = {Biochemistry},
volume = {55},
number = {27},
pages = {3727-34},
abstract = {The histone acetyltransferase (HAT) enzymes p300 and CBP are closely related paralogs that serve as transcriptional coactivators and have been found to be dysregulated in cancer and other diseases. p300/CBP is a multidomain protein and possesses a highly conserved bromodomain that has been shown to bind acetylated Lys residues in both proteins and various small molecules, including I-CBP112 and CBP30. Here we show that the ligand I-CBP112 can stimulate nucleosome acetylation up to 3-fold while CBP30 does not. Activation of p300/CBP by I-CBP112 is not observed with the isolated histone H3 substrate but requires a nucleosome substrate. I-CBP112 does not impact nucleosome acetylation by the isolated p300 HAT domain, and the effects of I-CBP112 on p300/CBP can be neutralized by CBP30, suggesting that I-CBP112 likely allosterically activates p300/CBP through bromodomain interactions. Using mass spectrometry and Western blots, we have found that I-CBP112 particularly stimulates acetylation of Lys18 of histone H3 (H3K18) in nucleosomes, an established in vivo site of p300/CBP. In addition, we show that I-CBP112 enhances H3K18 acetylation in acute leukemia and prostate cancer cells in a concentration range commensurate with its antiproliferative effects. Our findings extend the known pharmacology of bromodomain ligands in the regulation of p300/CBP and suggest a novel approach to modulating histone acetylation in cancer.},
keywords = {Acetylation, Bromine Compounds, Cell Proliferation, Crystallography, Cultured, E1A-Associated p300 Protein, Histones, Humans, Leukemia, Male, Models, Molecular, Mutagenesis, Nucleosomes, p300-CBP Transcription Factors, Prostatic Neoplasms, Protein Binding, Protein Conformation, Site-Directed, Tumor Cells, X-Ray},
pubstate = {published},
tppubtype = {article}
}
The histone acetyltransferase (HAT) enzymes p300 and CBP are closely related paralogs that serve as transcriptional coactivators and have been found to be dysregulated in cancer and other diseases. p300/CBP is a multidomain protein and possesses a highly conserved bromodomain that has been shown to bind acetylated Lys residues in both proteins and various small molecules, including I-CBP112 and CBP30. Here we show that the ligand I-CBP112 can stimulate nucleosome acetylation up to 3-fold while CBP30 does not. Activation of p300/CBP by I-CBP112 is not observed with the isolated histone H3 substrate but requires a nucleosome substrate. I-CBP112 does not impact nucleosome acetylation by the isolated p300 HAT domain, and the effects of I-CBP112 on p300/CBP can be neutralized by CBP30, suggesting that I-CBP112 likely allosterically activates p300/CBP through bromodomain interactions. Using mass spectrometry and Western blots, we have found that I-CBP112 particularly stimulates acetylation of Lys18 of histone H3 (H3K18) in nucleosomes, an established in vivo site of p300/CBP. In addition, we show that I-CBP112 enhances H3K18 acetylation in acute leukemia and prostate cancer cells in a concentration range commensurate with its antiproliferative effects. Our findings extend the known pharmacology of bromodomain ligands in the regulation of p300/CBP and suggest a novel approach to modulating histone acetylation in cancer.