The DNA dependent protein kinase catalytic subunit (DNA-PKcs) and its DNA-binding partner the Ku70/80 heterodimer are the key components of the non-homologous end-joining (NHEJ) pathway. In response to DNA double-strand breaks (DSBs), DNA-PKcs is rapidly phosphorylated at the T2609 cluster, an event critical for DSB repair. DNA-PKcs """"""""3A"""""""" knockin mice, in which phosphorylation at three residues in the mouse T2605 cluster (human T2609 cluster) are ablated via alanine substitution, die prematurely due to congenital bone marrow failure. Loss of hematopoietic stem cells (HSCs) in DNA-PKcs3A/3A mice is caused by elevated genotoxic stress as evidenced by increased intestinal crypt apoptosis and skin hyperpigmentation. Although these mice die prematurely, they can be rescued with bone marrow transplantation. BMT-rescued DNA- PKcs3A/3A mice are prone to develop both hematologic and non-hematologic cancers. HSC loss and hyperpigmented skin are the main features found in human dyskeratosis congenita (DC) syndrome and in mice double knockout of protection of telomeres 1b (POT1b) and telomerase RNA (mTR) genes. In addition, DC patients are also prone to cancer development. DC patients and POT1b/mTR DKO mice are unable to properly maintain the telomeres. Based on these findings, we hypothesize that the expression of the DNA-PKcs3A protein will lead to telomere dysregulation, genome instability, and carcinogenesis. We propose in this project to further elucidate the mechanism by which DNA-PKcs T2609 cluster phosphorylation impacts HSC homeostasis and telomere maintenance.
Our specific aims are: 1. To investigate how DNA-PKcs T2609 cluster phosphorylation and the DNA-PKcs interaction with the Ku70/80 heterodimer impacts hematopoietic stem cell homeostasis. 2. To investigate the effect of DNA-PKcs T2609 cluster phosphorylation on telomere maintenance. 3. To determine the effect of DNA-PKcs T2609 cluster phosphorylation on the production and protection of telomeric 3'overhangs.

Public Health Relevance

Telomere length preservation is essential to sustain the life of eukaryotes. Dysregulation of telomere often leads to cell death, genome instability, and carcinogenesis. Investigation how DNA-PKcs and its phosphorylation impacts telomere length maintenance will facilitate our understanding on the mechanism of telomere metabolism and the pathophysiology of bone marrow failure diseases.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA166677-03
Application #
8633438
Study Section
Special Emphasis Panel (ZRG1-CE-M (09))
Program Officer
Pelroy, Richard
Project Start
2012-04-01
Project End
2017-03-31
Budget Start
2014-05-28
Budget End
2015-03-31
Support Year
3
Fiscal Year
2014
Total Cost
$320,027
Indirect Cost
$118,752
Name
University of Texas Sw Medical Center Dallas
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
800771545
City
Dallas
State
TX
Country
United States
Zip Code
75390
Kuo, Ching-Te; Wang, Jong-Yueh; Lin, Yu-Fen et al. (2017) Three-dimensional spheroid culture targeting versatile tissue bioassays using a PDMS-based hanging drop array. Sci Rep 7:4363
Nagasawa, Hatsumi; Lin, Yu-Fen; Kato, Takamitsu A et al. (2017) Coordination of the Ser2056 and Thr2609 Clusters of DNA-PKcs in Regulating Gamma Rays and Extremely Low Fluencies of Alpha-Particle Irradiation to G0/G1 Phase Cells. Radiat Res 187:259-267
Zhang, Tianpeng; Zhang, Zepeng; Li, Feng et al. (2017) Looping-out mechanism for resolution of replicative stress at telomeres. EMBO Rep 18:1412-1428
Yin, Yi; Li, Rui; Xu, Kangling et al. (2017) Androgen Receptor Variants Mediate DNA Repair after Prostate Cancer Irradiation. Cancer Res 77:4745-4754
Yu, Lan; Shang, Zeng-Fu; Abdisalaam, Salim et al. (2016) Tumor suppressor protein DAB2IP participates in chromosomal stability maintenance through activating spindle assembly checkpoint and stabilizing kinetochore-microtubule attachments. Nucleic Acids Res 44:8842-8854
Zhang, S; Matsunaga, S; Lin, Y-F et al. (2016) Spontaneous tumor development in bone marrow-rescued DNA-PKcs(3A/3A) mice due to dysfunction of telomere leading strand deprotection. Oncogene 35:3909-18
Bunch, Heeyoun; Lawney, Brian P; Lin, Yu-Fen et al. (2015) Transcriptional elongation requires DNA break-induced signalling. Nat Commun 6:10191
Yu, Lan; Shang, Zeng-Fu; Hsu, Feng-Ming et al. (2015) NSCLC cells demonstrate differential mode of cell death in response to the combined treatment of radiation and a DNA-PKcs inhibitor. Oncotarget 6:3848-60
Sui, Jiangdong; Lin, Yu-Fen; Xu, Kangling et al. (2015) DNA-PKcs phosphorylates hnRNP-A1 to facilitate the RPA-to-POT1 switch and telomere capping after replication. Nucleic Acids Res 43:5971-83
Lee, Kyung-Jong; Shang, Zeng-Fu; Lin, Yu-Fen et al. (2015) The Catalytic Subunit of DNA-Dependent Protein Kinase Coordinates with Polo-Like Kinase 1 to Facilitate Mitotic Entry. Neoplasia 17:329-38

Showing the most recent 10 out of 20 publications