The Notch intracellular domain is ubiquitinated and negatively regulated by the mammalian Sel-10 homolog. |
| |
Authors: | C Oberg J Li A Pauley E Wolf M Gurney U Lendahl |
| |
Institution: | Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, SE-171 77 Stockholm, Sweden. |
| |
Abstract: | The Caenorhabditis elegans sel-10 protein is structurally similar to E3 ubiquitin ligases and is a negative regulator of Notch (lin-12) and presenilin signaling. In this report, we characterize the mammalian Sel-10 homolog (mSel-10) and analyze its effects on Notch signaling. We find that mSel-10 localizes to the cell nucleus, and that it physically interacts with the Notch 1 intracellular domain (IC) and reduces Notch 1 IC-mediated activation of the HES 1 promoter. Notch 1 IC is ubiquitinated by mSel-10, and ubiquitination requires the presence of the most carboxyl-terminal region of the Notch IC, including the PEST domain. In the presence of the proteasome inhibitor MG132, the amount of Notch 1 IC and its level of ubiquitination are increased. Interestingly, this accumulation of Notch 1 IC in the presence of MG132 is accompanied by decreased activation of the HES 1 promoter, suggesting that ubiquitinated Notch 1 IC is a less potent transactivator. Finally, we show that mSel-10 itself is ubiquitinated and degraded by the proteasome. In conclusion, these data reveal the importance of ubiquitination and proteasome-mediated degradation for the activity and turnover of Notch ICs, and demonstrate that mSel-10 plays a key role in this process. |
| |
Keywords: | |
|
|