The Role Of Human SPATA12Gene In UV-C Induced DNA Damage Repair

Maintaining genomic integrity is a critical requirement for normal cell growth and development. UV radiation, genotoxic chemicals and ionizing radiation are potential sources for cellular DNA damage, which is key factor for genetic disease. The inability to sense and respond to genotoxins leads to various disorders in mammals, such as cell death, genomic instability or malignant transformation. Thus, it is important to understand how cells respond to and attempt to repair DNA damage. Human SPATA12is a novel spermatogenesis associated gene, which only is expressed in adult male testicular tissue and mainly locate in primary spermatocyte and sperm cells.SPATA12locates on important regions of the loss of heterozygosity of human chromosome3p14.Our previous studies implicated that SPATA12might be may play the role of an inhibitor and involved in in spermatogenesis and tumorigenesis of germ cells.In order to get a better understanding of SPATA12function, yeast two-hybride system was applied to search for proteins interacting with SPATA12in our previous study and chromodomain helicase DNA binding2(CHD2) proteins was successfully identified. As chromatin remodeling factor, CHD2is known to be involved in the later stage of DNA damage response pathway by influencing p53’s transcriptional activity. Based on these background, our hypothesis is that SPATA12might play some role in DNA damage signaling. Our research includec three parts.(1)Verify the interaction of SPATA12and CHD2in nuclei.Through bimolecular fluorescence complementation analysis(BiFC) and subcelluar co-location assay, we further confirm the interaction between CHD2and SPATA12in nuclei.(2)Establish a cell cellular DNA damage model induced by UV-CWe established a cellular DNA damage model induced by UV through MTT, FACS, Hoechst-PI staining and Comet assay.(3)The role of SPATA12in UV-C induced DNA damageRT-PCR and WB results showed SPATA12re-expression could be induced in both Hela and MCF-7cells after UV radiation. Both the colony formation assay and host cell reaction assay(HCR) were used to figure out that SATA12may accelerate cell inhibition in UV-C induced DNA damage.Through reporter gene assays and AP-1decoy ODNs system, AP-1binding site in SPATA12promoter was demonstrated to contribute to the transcriptional regulation of SPATA12in response to UV-C radiation. Further, SPATA12was transfected in both H1299(p53null),MCF7(p53wt)and Hela cells(p53functional deletion) respectively and the flow cytometry results suggested that inhibition of SPATA12on UV-C radiated cells is p53-dependent.What is more,we found that exogenous SPATA12can promote the expression of p53,which showed that SPATA12could inhibit cell proliferation by means of p53.Taken together, these findings indicate that SPATA12could be induced under UV-C stress through the AP-1binding site, and it might lead to inhibition of cellular proliferation via p53during the UV-C induced DNA damage process.