DNA double-strand breaks (DSBs) are highly toxic DNA lesions that can occur spontaneously during DNA replication, but also can be introduced by exposure to ionizing radiation (IR) or to chemical mutagens. DSBs can lead to cell death, mutations and cancer, and defects in DSB repair (DSBR) underlie many human diseases, including disorders associated with cancer predisposition, radiosensitivity, immune dysfunction, neurodegeneration and premature aging. Nuclear Ubiquitous Casein and Cyclin-dependent Kinases Substrate (NUCKS) is a 27 kD, DNA-binding and vertebrate-specific protein with unknown function. NUCKS is abundant in rapidly growing cells and overexpressed in a variety of human cancers. Of particular interest, the NUCKS gene is located on human chromosome 1q32.1, a region that is commonly gained in breast cancer. Based on sequence homology to RAD51 Associated Protein 1 (RAD51AP1), a critical factor in homologous recombination repair (HRR), we have tested and determined a role for NUCKS in DSBR. Our results show that human cells with NUCKS knockdown are hypersensitive to IR and to chemical mutagens, and that NUCKS regulates not only HRR, but also cellular resistance to IR in G1-phase cells. In preliminary experiments using mice with heterozygous Trp53, we find that impaired Nucks function significantly increases the susceptibility to IR-induced tumors, alters the tumor spectrum and promotes metastasis. We now intend to further define how NUCKS regulates DSBR capacity using biochemical and cell-based assays (Aims 1 & 2). In addition, we will carry out a systematic study to further determine the phenotypic consequences of Nucks disruption in mice (Aim 2). Our findings showing a role for NUCKS in DSBR and in preventing radiation carcinogenesis are the first evidence for a biological function of NUCKS, a protein that was discovered more than 25 years ago. Given the importance of DSBR and HRR in tumor suppression and in the removal of DNA lesions induced by IR and other environmental mutagens, the results from our investigation will have direct relevance to risk predictions for health from environmental factors. In addition, our studies may also contribute to the improved diagnosis, prevention and treatment of cancer.
Homologous recombination repair (HRR) is indispensable for maintaining genomic stability and preventing cancer, and this repair mechanism is impaired in BRCA1/2-related breast cancers. NUCKS (Nuclear Ubiquitous Casein and Cyclin-dependent Kinases Substrate) is an important protein involved in the HRR pathway, and is required for the repair of DNA damage caused by ionizing radiation and several chemotherapeutic agents. The proposed studies are designed to further elucidate the role of NUCKS in HRR and cancer-relevant processes, and will make an important contribution to understanding the role of DNA repair in cancer avoidance.
| Chernikova, Sophia B; Nguyen, Rochelle B; Truong, Jessica T et al. (2018) Dynamin impacts homology-directed repair and breast cancer response to chemotherapy. J Clin Invest 128:5307-5321 |
| Pires, Elena; Sung, Patrick; Wiese, Claudia (2017) Role of RAD51AP1 in homologous recombination DNA repair and carcinogenesis. DNA Repair (Amst) 59:76-81 |
| Zhao, Weixing; Steinfeld, Justin B; Liang, Fengshan et al. (2017) BRCA1-BARD1 promotes RAD51-mediated homologous DNA pairing. Nature 550:360-365 |
| Liang, Fengshan; Longerich, Simonne; Miller, Adam S et al. (2016) Promotion of RAD51-Mediated Homologous DNA Pairing by the RAD51AP1-UAF1 Complex. Cell Rep 15:2118-2126 |
| Trego, Kelly S; Groesser, Torsten; Davalos, Albert R et al. (2016) Non-catalytic Roles for XPG with BRCA1 and BRCA2 in Homologous Recombination and Genome Stability. Mol Cell 61:535-546 |
| Yue, Yangbo; Leung, Stanley G; Liu, Yueyong et al. (2016) Nucks1 synergizes with Trp53 to promote radiation lymphomagenesis in mice. Oncotarget 7:61874-61889 |
| Zhao, Weixing; Vaithiyalingam, Sivaraja; San Filippo, Joseph et al. (2015) Promotion of BRCA2-Dependent Homologous Recombination by DSS1 via RPA Targeting and DNA Mimicry. Mol Cell 59:176-87 |
| Parplys, Ann C; Zhao, Weixing; Sharma, Neelam et al. (2015) NUCKS1 is a novel RAD51AP1 paralog important for homologous recombination and genome stability. Nucleic Acids Res 43:9817-34 |
| Parplys, Ann C; Kratz, Katja; Speed, Michael C et al. (2014) RAD51AP1-deficiency in vertebrate cells impairs DNA replication. DNA Repair (Amst) 24:87-97 |
| Dunlop, Myun Hwa; Dray, Eloïse; Zhao, Weixing et al. (2012) Mechanistic insights into RAD51-associated protein 1 (RAD51AP1) action in homologous DNA repair. J Biol Chem 287:12343-7 |
