Ubc9 interacts with SOX4 and represses its transcriptional activity.
SOX4 is a member of SOX transcriptional factor family that is crucial for many cellular processes. In this study, a yeast two-hybrid screening of human mammary cDNA library identified human ubiquitin-conjugating enzyme 9 (hUbc9) that interacted with SOX4. This interaction was confirmed by GST pull-down in vitro and co-immunoprecipitation assays in vivo. Deletion mapping demonstrated that HMG-box domain of SOX4 is required to mediate the interaction with Ubc9 in yeast. Furthermore, confocal microscopy showed that Ubc9 co-localized with SOX4 in the nucleus. Luciferase assays found that Ubc9 specifically repressed SOX4 transcriptional activity in 293T cells. We further demonstrated that Ubc9 could functionally repress the transcriptional activity of endogenous SOX4 induced by progesterone in T47D cells. The C93S mutant of Ubc9, which abrogates SUMO-1 conjugation activity, did not abolish the ability to repress SOX4 activity. It shows that Ubc9 interacts with SOX4 and represses its transcriptional activity independent of its SUMO-1-conjugating activity.
Pan
Xin
X
National Center of Biomedical Analysis, Beijing 100850, PR China.
Li
Huiyan
H
Zhang
Peijing
P
Jin
Baofeng
B
Man
Jianghong
J
Tian
Lifeng
L
Su
Guiying
G
Zhao
Jie
J
Li
Weihua
W
Liu
Hui
H
Gong
Weili
W
Zhou
Tao
T
Zhang
Xuemin
X
D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D055751:SOXC Transcription Factors; D013489:Suppression, Genetic / Q000502:physiology*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism*; D000098843:Ubiquitin-Conjugating Enzyme UBC9
D006609:High Mobility Group Proteins; C083431:SOX4 protein, human; D055751:SOXC Transcription Factors; D015534:Trans-Activators; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9