Lysine 63-linked ubiquitination modulates mixed lineage kinase-3 interaction with JIP1 scaffold protein in cytokine-induced pancreatic β cell death

J Biol Chem. 2013 Jan 25;288(4):2428-40. doi: 10.1074/jbc.M112.425884. Epub 2012 Nov 21.


The mixed lineage kinase MLK3 plays a crucial role in compromising mitochondrial integrity and functions as a proapoptotic competence factor in the early stages of cytokine-induced pancreatic β cell death. In an effort to identify mechanisms that regulate MLK3 activity in β cells, we discovered that IL-1β stimulates Lys-63-linked ubiquitination of MLK3 via a conserved, TRAF6-binding peptapeptide motif in the catalytic domain of the kinase. TRAF6-mediated ubiquitination was required for dissociation of inactive monomeric MLK3 from the scaffold protein IB1/JIP1, facilitating the subsequent dimerization, autophosphorylation, and catalytic activation of MLK3. Inability to ubiquitinate MLK3, or the presence of A20, an upstream Lys-63-linked deubiquitinase, strongly curtailed the ability of MLK3 to affect the proapoptotic translocation of BAX in cytokine-stimulated pancreatic β cells, an early step in the progression toward β cell death. These studies suggest a novel mechanism for MLK3 activation and provide new clues for therapeutic intervention in promoting β cell survival.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Apoptosis
  • Cell Death
  • Cell Line
  • Coculture Techniques
  • Cytokines / metabolism
  • Diabetes Mellitus / metabolism
  • Dimerization
  • Hep G2 Cells
  • Humans
  • Insulin-Secreting Cells / cytology*
  • Islets of Langerhans / cytology*
  • Lysine / chemistry*
  • MAP Kinase Kinase Kinases / metabolism*
  • Mice
  • TNF Receptor-Associated Factor 6 / metabolism
  • Toll-Like Receptors / metabolism
  • Ubiquitin / chemistry*
  • bcl-2-Associated X Protein / metabolism


  • Adaptor Proteins, Signal Transducing
  • Cytokines
  • MAPK8IP1 protein, human
  • Mapk8ip protein, mouse
  • TNF Receptor-Associated Factor 6
  • Toll-Like Receptors
  • Ubiquitin
  • bcl-2-Associated X Protein
  • MAP Kinase Kinase Kinases
  • mitogen-activated protein kinase kinase kinase 11
  • Lysine