Inhibition of ubiquitin ligase Siah-1A by disabled-1.

Disabled-1 (Dab1) is a cytosolic adaptor protein that plays critical roles in cortical development. However, a detailed mechanism of action has not yet been clearly defined. Through yeast two-hybrid screening, we observed that mouse Siah-1A, an E3 ubiquitin ligase containing a RING finger motif, interacts with Dab1. Co-immunoprecipitation experiments and ...
in vitro binding experiments both indicated direct interaction between Siah and Dab1. Steady-state expression of Siah was enhanced by the presence of Dab1 or lactacystin, a representative proteasomal inhibitor. Auto-ubiquitination of Siah was inhibited by the presence of Dab1, suggesting inhibition of Siah activity and subsequent increase of Siah expression by Dab1. Both Dab1-induced increase of steady-state expression of Deleted in colorectal cancer (DCC), one of the well-known substrates of Siah, and its inhibition by Siah Delta R suggest that Dab1 increases expression of DCC through inhibiting the activity of endogenous Siah. Our results suggest that Dab1 inhibits the activity of Siah.
Mesh Terms:
Animals, Cell Adhesion Molecules, Cell Line, Gene Expression Regulation, Mice, Mice, Inbred C57BL, Nerve Tissue Proteins, Nuclear Proteins, Proteins, Receptors, Cell Surface, Recombinant Fusion Proteins, Tumor Suppressor Proteins, Two-Hybrid System Techniques, Ubiquitin, Ubiquitin-Protein Ligases
Biochem. Biophys. Res. Commun.
Date: Mar. 21, 2003
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