Cbl-c ubiquitin ligase activity is increased via the interaction of its RING finger domain with a LIM domain of the paxillin homolog, Hic 5

• Published in: PloS one 2012-11, Vol.7 (11), p.e49428-e49428
• Main Authors: Ryan, Philip E, Kales, Stephen C, Yadavalli, Rajgopal, Nau, Marion M, Zhang, Han, Lipkowitz, Stanley
• Format: Article
• Language: English
• Subjects: Biology; Cancer; Cbl protein; Cbl-b protein; Cell adhesion & migration; Cell Line; Enzymes; Epidermal growth factor; Epidermal growth factor receptors; Fingers; HEK293 Cells; HeLa Cells; Homology; Humans; Hydrogen; Hydrogen peroxide; Intracellular Signaling Peptides and Proteins - metabolism; Kinases; Laboratories; Ligases; LIM Domain Proteins - metabolism; Medical research; Medical screening; Molecular biology; Mutation; Paxillin; Peroxides; Phosphorylation; Physiology; Protein Interaction Domains and Motifs; Protein Interaction Mapping; Protein Structure, Tertiary; Protein-tyrosine kinase; Proteins; Proto-Oncogene Proteins c-cbl - metabolism; Proto-Oncogene Proteins c-cbl - physiology; Receptor, Epidermal Growth Factor - metabolism; Regulators; RING Finger Domains; Rodents; Senescence; Signaling; Transfection; Two-Hybrid System Techniques; Tyrosine; Ubiquitin; Ubiquitin-protein ligase; Ubiquitination; Zinc
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0049428

Cbl proteins (Cbl, Cbl-b and Cbl-c) are ubiquitin ligases that are critical regulators of tyrosine kinase signaling. In this study we identify a new Cbl-c interacting protein, Hydrogen peroxide Induced Construct 5 (Hic-5). The two proteins interact through a novel interaction mediated by the RING finger of Cbl-c and the LIM2 domain of Hic-5. Further, this interaction is mediated and dependent on specific zinc coordinating complexes within the RING finger and LIM domain. Binding of Hic-5 to Cbl-c leads to an increase in the ubiquitin ligase activity of Cbl-c once Cbl-c has been activated by Src phosphorylation or through an activating phosphomimetic mutation. In addition, co-transfection of Hic-5 with Cbl-c leads to an increase in Cbl-c mediated ubiquitination of the EGFR. These data suggest that Hic-5 enhances Cbl-c ubiquitin ligase activity once Cbl-c has been phosphorylated and activated. Interactions between heterologous RING fingers have been shown to activate E3s. This is the first demonstration of enhancement of ubiquitin ligase activity of a RING finger ubiquitin ligase by the direct interaction of a LIM zinc coordinating domain.