SPATA12 and its possible role in DNA damage induced by ultraviolet-C

Our previous studies indicated that SPATA12, a novel spermatogenesis-associated gene, might be an inhibitor involved in spermatogenesis and tumorigenesis. To obtain a better understanding of the functions of SPATA12, a yeast two-hybrid screening system was used to search for interacting proteins, and chromodomain helicase DNA binding protein 2 (CHD2) was successfully identified. Bimolecular fluorescence complementation (BiFC) and subcellular co-localization assays further suggested a possible interaction between SPATA12 and CHD2 in the nuclei. CHD2 is known to be involved in the later stage of the DNA damage response pathway by influencing the transcriptional activity of p53. Thus, our hypothesis is that SPATA12 might play a role in DNA damage signaling. Western blotting results showed that SPATA12 expression could be induced in ultraviolet-C (UV-C) irradiated cells. Through reporter gene assays and the activator protein-1 (AP-1) decoy oligodeoxynucleotide method, we demonstrated that SPATA12 promoter activity could be up-regulated in response to UV-C radiation exposure and an AP-1 binding site in the SPATA12 promoter may have a role in transcriptional regulation of SPATA12. Using colony formation and host cell reactivation assays, it was demonstrated that SPATA12 might lead to inhibition of cellular proliferation in UV-C-irradiated DNA damage. Furthermore, SPATA12 was transfected into H1299, MCF-7 and HeLa cells, and flow cytometry (FCM) results suggested that there are some biological association between SPATA12 and p53 in UV-C-irradiated DNA damage. In addition, we investigated whether SPATA12 could up-regulate the expression of p53. Taken together, these findings indicate that SPATA12 could be induced under UV-C stress. During DNA damage process, AP-1 involves in the transcriptional up-regulation of SPATA12 in response to UV-C radiation and p53 involves in growth inhibitory effects of SPATA12 on UV-C irradiated cells.