title: Inhibition of ubiquitin ligase Siah-1A by disabled-1.
abstract: 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.
authors.affiliation: Lab for Neurodegeneration Signal, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Tae-Ju
authors.initials: TJ
authors.lastname: Park
authors.forename: Hiroki
authors.initials: H
authors.lastname: Hamanaka
authors.forename: Toshio
authors.initials: T
authors.lastname: Ohshima
authors.forename: Noriko
authors.initials: N
authors.lastname: Watanabe
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Mikoshiba
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Nukina
mesh_terms: D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D000075389:DCC Receptor; D005786:Gene Expression Regulation; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011506:Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D000098563:Seven in Absentia Proteins
chemical_list: D015815:Cell Adhesion Molecules; D000075389:DCC Receptor; C103773:Dab1 protein, mouse; C501910:Dcc protein, mouse; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D011506:Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D025521:Tumor Suppressor Proteins; D025801:Ubiquitin; C484442:Siah1a protein, mouse; D044767:Ubiquitin-Protein Ligases; D000098563:Seven in Absentia Proteins