| First Author | Morita Y | Year | 2005 |
| Journal | Mol Biol Cell | Volume | 16 |
| Issue | 11 | Pages | 5433-44 |
| PubMed ID | 16162816 | Mgi Jnum | J:107109 |
| Mgi Id | MGI:3620307 | Doi | 10.1091/mbc.E05-08-0731 |
| Citation | Morita Y, et al. (2005) TRAF7 sequesters c-Myb to the cytoplasm by stimulating its sumoylation. Mol Biol Cell 16(11):5433-44 |
| abstractText | Small ubiquitin-related modifiers (SUMOs) are proteins that are posttranslationally conjugated to diverse proteins. The c-myb proto-oncogene product (c-Myb) regulates proliferation and differentiation of hematopoietic cells. PIASy is the only known SUMO E3 ligase for c-Myb. Here, we report that TRAF7 binds to c-Myb and stimulates its sumoylation. TRAF7 bound to the DNA-binding domain of c-Myb via its WD40 repeats. TRAF7 has an E3 ubiquitin ligase activity for self-ubiquitination, but TRAF7 also stimulated the sumoylation of c-Myb at Lys-523 and Lys-499, which are the same sites as those used for PIASy-induced sumoylation. TRAF7 inhibited trans-activation induced by wild-type c-Myb, but not by the sumoylation site mutant of c-Myb. The expression of both c-myb and TRAF7 was down-regulated during differentiation of M1 cells. Endogenous TRAF7 localized to both the cytoplasm and nucleus of M1 cells. Consistent with this, significant amounts of sumoylated c-Myb were found in the cytoplasm of M1 cells, whereas nonsumoylated c-Myb was found predominantly in the nucleus. Overexpressed TRAF7 was localized in the cytoplasm of CV-1 cells, and sequestered c-Myb and SUMO1 in the cytosol, whereas PIASy was localized in the nucleus. Thus, TRAF7 negatively regulates c-Myb activity by sequestering c-Myb to the cytosol via sumoylation. |
