JNK-mediated phosphorylation of DLK suppresses its ubiquitination to promote neuronal apoptosis

J Cell Biol. 2013 Sep 2;202(5):747-63. doi: 10.1083/jcb.201303066. Epub 2013 Aug 26.

Abstract

Neurons are highly polarized cells that often project axons a considerable distance. To respond to axonal damage, neurons must transmit a retrograde signal to the nucleus to enable a transcriptional stress response. Here we describe a mechanism by which this signal is propagated through injury-induced stabilization of dual leucine zipper-bearing kinase (DLK/MAP3K12). After neuronal insult, specific sites throughout the length of DLK underwent phosphorylation by c-Jun N-terminal kinases (JNKs), which have been shown to be downstream targets of DLK pathway activity. These phosphorylation events resulted in increased DLK abundance via reduction of DLK ubiquitination, which was mediated by the E3 ubiquitin ligase PHR1 and the de-ubiquitinating enzyme USP9X. Abundance of DLK in turn controlled the levels of downstream JNK signaling and apoptosis. Through this feedback mechanism, the ubiquitin-proteasome system is able to provide an additional layer of regulation of retrograde stress signaling to generate a global cellular response to localized external insults.

MeSH terms

  • Animals
  • Apoptosis* / drug effects
  • Axons / drug effects
  • Axons / pathology
  • Embryo, Mammalian / cytology
  • Enzyme Activation / drug effects
  • Enzyme Stability / drug effects
  • HEK293 Cells
  • Humans
  • JNK Mitogen-Activated Protein Kinases / metabolism*
  • MAP Kinase Kinase Kinases / metabolism*
  • Mice
  • Models, Biological
  • Molecular Weight
  • Nerve Crush
  • Nerve Growth Factor / pharmacology
  • Optic Nerve / drug effects
  • Optic Nerve / pathology
  • Phosphorylation / drug effects
  • Proteasome Endopeptidase Complex / metabolism
  • Sensory Receptor Cells / drug effects
  • Sensory Receptor Cells / enzymology*
  • Sensory Receptor Cells / pathology*
  • Signal Transduction / drug effects
  • Stress, Physiological / drug effects
  • Ubiquitin / metabolism
  • Ubiquitination* / drug effects

Substances

  • Ubiquitin
  • Nerve Growth Factor
  • JNK Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase Kinases
  • mitogen-activated protein kinase kinase kinase 12
  • Proteasome Endopeptidase Complex