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

PLoS One. 2012;7(11):e49428. doi: 10.1371/journal.pone.0049428. Epub 2012 Nov 7.

Abstract

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.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • ErbB Receptors / metabolism
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • LIM Domain Proteins / metabolism*
  • Protein Interaction Domains and Motifs
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • Proto-Oncogene Proteins c-cbl / metabolism*
  • Proto-Oncogene Proteins c-cbl / physiology
  • RING Finger Domains*
  • Two-Hybrid System Techniques
  • Ubiquitination

Substances

  • Intracellular Signaling Peptides and Proteins
  • LIM Domain Proteins
  • TGFB1I1 protein, human
  • Proto-Oncogene Proteins c-cbl
  • EGFR protein, human
  • ErbB Receptors