We identified a chromatin-modifying factor hMOF, the human ortholog of the Drosophila MOF gene (Males absent On the First) that interacts with and regulates the ionizing radiation (IR) response function of ATM. hMOF is a member of the MYST family of histone acetyltransferases (HATs) and acetylates histone H4 at lysine 16 (H4K16ac). Histone H4K16ac is a unique histone modification that prevents higher order chromatin packing, which can impede protein access to DNA. Mammalian MOF impacts multiple points in the cellular DNA damage response (DDR) and double-strand break (DSB) repair pathways probably as a critical regulator of chromatin structure. This competing renewal brings together and expands insights gained during the previous funding period from two separate RO1's [R01CA123232 (not being renewed), R01CA129537 (this renewal)] that focused our attention on how MOF-dependent H4K16ac levels and the phosphorylation of MOF influence DNA DSB repair and oncogenesis, as we found that acetylation of histone H4 at K16 by MOF is an epigenetic signature of cellular proliferation common to both embryogenesis and oncogenesis. In addition, our results suggest that preexisting MOF-dependent H4K16ac may influence the DDR. However the precise effect of H4K16ac chromatin status as well as most other chromatin proteins/modifications on the DDR is largely unknown. A major impediment in the mammalian DNA repair field to answering this type of question has been the non-specificity of DNA damage inducing agents (for example: ionizing radiations), making it difficult to characterize how specific differences in chromatin environment impact DNA lesion signaling/repair. We will circumvent this problem by using site-specific repair systems to determine the role of histone H4K16ac in DSB repair. We have successfully generated a high-density genome wide map identifying H4K16ac rich or poor chromosomal sites. Utilizing this data, we will directly test the hypothesis that local H4K16ac levels on chromosomes regulate DDR. To examine sites with defined H4K16ac chromatin status, we will utilize zinc finger nucleases (ZFNs) to produce DSBs within regions we have identified as having high or low H4K16ac levels and determine the subsequent recruitment of DDR components. Furthermore, we have shown that MOF itself is phosphorylated at threonine 392 (MOF-T392) post irradiation in an ATM-dependent manner that is important for the DDR and cell survival. Therefore, to determine the role of ATM dependent MOF phosphorylation in signaling/repair protein recruitment, we will generate mutant MOF-phosphorylation (mMof- T392A) site knock-in mice and examine the DSB signaling/repair mechanism and consequences for genomic integrity and cancer development. This approach uniquely allows for the determination of how MOF-dependent local H4K16ac levels and MOF phosphorylation affect the DDR, repair pathway choice and oncogenesis.

Public Health Relevance

The proposed investigation will enhance the understanding of the mechanistic basis for MOF dependent histone H4K14 acetylation function and MOF phosphorylation in DNA double strand break repair and oncogenesis. Only by gaining a thorough understanding of the DNA repair mechanism as it occurs in mammalian cells will it be possible to manipulate this process to protect healthy individuals from the side effects of cancer treatment and specifically impede DNA repair in cancer cells in order to enhance patient response to radiation therapy. We will use innovative new technologies to provide for the first time a coherent picture of the events occurring during DNA repair within the context of the cell's chromatin structure. Successful completion of proposed research will provide novel insights into the function of MOF/H4K16ac in DNA-damage responses and identify new approaches to improve cancer patient treatments.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA129537-09
Application #
8920046
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Pelroy, Richard
Project Start
2014-07-01
Project End
2019-06-30
Budget Start
2015-07-01
Budget End
2016-06-30
Support Year
9
Fiscal Year
2015
Total Cost
Indirect Cost
Name
Methodist Hospital Research Institute
Department
Type
DUNS #
185641052
City
Houston
State
TX
Country
United States
Zip Code
77030
Ahmed, Kazi Mokim; Pandita, Raj K; Singh, Dharmendra Kumar et al. (2018) ?1-Integrin Impacts Rad51 Stability and DNA Double-Strand Break Repair by Homologous Recombination. Mol Cell Biol 38:
Qin, Qian; Nan, Xinyu; Miller, Tara et al. (2018) Complete Local and Abscopal Responses from a Combination of Radiation and Nivolumab in Refractory Hodgkin's Lymphoma. Radiat Res 190:322-329
Gadhikar, Mayur A; Zhang, Jiexin; Shen, Li et al. (2018) CDKN2A/p16 Deletion in Head and Neck Cancer Cells Is Associated with CDK2 Activation, Replication Stress, and Vulnerability to CHK1 Inhibition. Cancer Res 78:781-797
Mujoo, Kalpana; Hunt, Clayton R; Pandita, Raj K et al. (2018) Harnessing and Optimizing the Interplay between Immunotherapy and Radiotherapy to Improve Survival Outcomes. Mol Cancer Res 16:1209-1214
Chakraborty, Sharmistha; Pandita, Raj K; Hambarde, Shashank et al. (2018) SMARCAD1 Phosphorylation and Ubiquitination Are Required for Resection during DNA Double-Strand Break Repair. iScience 2:123-135
Iyer, Swaminathan P; Hunt, Clayton R; Pandita, Tej K (2018) Cross Talk between Radiation and Immunotherapy: The Twain Shall Meet. Radiat Res 189:219-224
Jiang, Hanwei; Gao, Qian; Zheng, Wei et al. (2018) MOF influences meiotic expansion of H2AX phosphorylation and spermatogenesis in mice. PLoS Genet 14:e1007300
Singh, Dharmendra Kumar; Pandita, Raj K; Singh, Mayank et al. (2018) MOF Suppresses Replication Stress and Contributes to Resolution of Stalled Replication Forks. Mol Cell Biol 38:
Breed, Elise R; Hilliard, Carolyn A; Yoseph, Benyam et al. (2018) The small heat shock protein HSPB1 protects mice from sepsis. Sci Rep 8:12493
Mattoo, Abid R; Pandita, Raj K; Chakraborty, Sharmistha et al. (2017) MCL-1 Depletion Impairs DNA Double-Strand Break Repair and Reinitiation of Stalled DNA Replication Forks. Mol Cell Biol 37:

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