title: Plk3 inhibits pro-apoptotic activity of p73 through physical interaction and phosphorylation.
abstract: Plk3, one of Polo-like kinase family members, is involved in the regulation of cell cycle progression and DNA damage response. In this study, we found that Plk3 inhibits pro-apoptotic activity of p73 through physical interaction and phosphorylation. During cisplatin (CDDP)-mediated apoptosis, Plk3 was transcriptionally induced, whereas its protein level was kept at basal level, suggesting that Plk3 might rapidly degrade in response to CDDP. Immunoprecipitation and in vitro pull-down experiments demonstrated that Plk3 interacts with p73. Luciferase reporter assays and RT-PCR experiments revealed that Plk3 inhibits p73-mediated transcriptional activity. Consistent with these results, pro-apoptotic activity of p73 was blocked by Plk3. Additionally, Plk3 decreased the stability of p73. Intriguingly, kinase-deficient Plk3 failed to inhibit p73 function, indicating that kinase activity of Plk3 is required for Plk3-mediated inhibition of p73. Indeed, in vitro kinase reaction showed that NH(2)-terminal portion of p73 is phosphorylated by Plk3. In accordance with these observations, knocking down of Plk3 increased the stability of p73 and promoted CDDP-mediated apoptosis in association with up-regulation of p73. Collectively, our present findings suggest that Plk3 plays an important role in the regulation of cell fate determination in response to DNA damage through the inhibition of p73.
authors.affiliation: Division of Biochemistry, Chiba Cancer Center Research Institute, Chiba, Japan.
authors.forename: Meixiang
authors.initials: M
authors.lastname: Sang
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Ando
authors.forename: Rintaro
authors.initials: R
authors.lastname: Okoshi
authors.forename: Nami
authors.initials: N
authors.lastname: Koida
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Li
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Zhu
authors.forename: Osamu
authors.initials: O
authors.lastname: Shimozato
authors.forename: Cuizhi
authors.initials: C
authors.lastname: Geng
authors.forename: Baoen
authors.initials: B
authors.lastname: Shan
authors.forename: Akira
authors.initials: A
authors.lastname: Nakagawara
authors.forename: Toshinori
authors.initials: T
authors.lastname: Ozaki
mesh_terms: D000818:Animals; D017209:Apoptosis; D019556:COS Cells; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D018613:Microscopy, Confocal; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D014158:Transcription, Genetic; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D000097868:Polo-like Kinases
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; D034741:RNA, Small Interfering; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; C000606460:TP73 protein, human; C486256:PLK3 protein, human; D000097868:Polo-like Kinases