Protein stability and function of p73 are modulated by a physical interaction with RanBPM in mammalian cultured cells.
Upon a certain DNA damage including cisplatin treatment, p73 is stabilized and exerts its growth-suppressive and/or proapoptotic function. However, the precise molecular basis by which the intracellular levels of p73 are regulated remains unclear. In the present study, we have identified RanBPM as a novel binding partner of p73alpha by yeast-based two-hybrid screening, and also found that RanBPM has an ability to stabilize p73alpha. GST pull-down assays and co-immunoprecipitation experiments revealed that RanBPM directly bound to the extreme COOH-terminal region of p73alpha, whereas it failed to interact with p53. Co-expression of RanBPM with p73alpha resulted in the nuclear translocation of RanBPM, and both proteins co-localized in cell nucleus as examined by indirect immunofluorescent staining. It is worth noting that the expression of RanBPM inhibited the ubiquitination of p73alpha, and thereby prolonged its half-life. Subsequent studies demonstrated that the proapoptotic activity of p73alpha was significantly enhanced in the presence of RanBPM. Taken together, our present findings implicate a novel role for RanBPM in the regulation of p73 stability and function.
Kramer
Sonja
S
Division of Biochemistry, Chiba Cancer Center Research Institute, 666-2 Nitona, Chuoh-ku, Chiba 260-8717, Japan.
Ozaki
Toshinori
T
Miyazaki
Kou
K
Kato
Chiaki
C
Hanamoto
Takayuki
T
Nakagawara
Akira
A
D048868:Adaptor Proteins, Signal Transducing; D001665:Binding Sites; D001921:Brain; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D005333:Fetus; D015723:Gene Library; D016147:Genes, Tumor Suppressor; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism / Q000502:physiology*; D013347:Subcellular Fractions / Q000378:metabolism; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D025801:Ubiquitin / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000378:metabolism / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C116005:Ran binding protein 9; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D025521:Tumor Suppressor Proteins; D025801:Ubiquitin; D020931:ran GTP-Binding Protein