title: PIG3 functions in DNA damage response through regulating DNA-PKcs homeostasis.
abstract: The p53-inducible gene 3 (PIG3) recently has been reported to be a new player in DNA damage signaling and response, but the crucial mechanism remains unclear. In the present study, the potential mechanism of PIG3 participation in the DNA damage response induced by ionizing radiation (IR) was investigated in multiple cell lines with depleted expression of PIG3 transiently or stably by the small interference RNA and lentivirus-mediated shRNA expression strategies. PIG3 knockdown led to an abnormal DNA damage response, including decreased IR-induced phosphorylation of H2AX, Chk1, Chk2 and Kap-1 as well as a prolonged G2-M arrest and aberrant mitotic progression. Notably, PIG3 knockdown resulted in a striking depression of cellular DNA-PKcs protein level, and was accompanied by a downregulation of ATM. Re-expression of PIG3 effectively rescued the depression of DNA-PKcs in PIG3-depleted cells. This negative regulation of DNA-PKcs by depleting PIG3 seemed to take place at the translational level but not at the levels of transcription or protein degradation. However, a compensatory feedback of increased mRNA expression of DNA-PKcs was formed in PIG3-depleted cells after a few passages or cell cycles of subculture, which led the recovery of the DNA-PKcs protein level and the consequent recovered efficiency of the DNA damage response. These results provide a new insight into the mechanism of PIG3's functioning in DNA damage signaling and the regulation network of cellular DNA-PKcs expression homeostasis.
authors.affiliation: Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 27 Taiping Road, Haidian District, Beijing 100850, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.forename: Zeng-Fu
authors.initials: ZF
authors.lastname: Shang
authors.forename: Jiao-Jiao
authors.initials: JJ
authors.lastname: Yin
authors.forename: Qin-Zhi
authors.initials: QZ
authors.lastname: Xu
authors.forename: Xiao-Dan
authors.initials: XD
authors.lastname: Liu
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Shi-Meng
authors.initials: SM
authors.lastname: Zhang
authors.forename: Hua
authors.initials: H
authors.lastname: Guan
authors.forename: Ping-Kun
authors.initials: PK
authors.lastname: Zhou
mesh_terms: D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D004249:DNA Damage / Q000235:genetics* / Q000528:radiation effects; D051747:DNA-Activated Protein Kinase / Q000378:metabolism*; D005434:Flow Cytometry; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D011839:Radiation, Ionizing
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D011518:Proto-Oncogene Proteins; C411296:TP53I3 protein, human; D051747:DNA-Activated Protein Kinase
keywords: ATM.; DNA damage response; DNA-PKcs; PIG3; cell cycle progression; checkpoint