JIP3 Activates Kinesin-1 Motility to Promote Axon Elongation

J Biol Chem. 2015 Jun 19;290(25):15512-15525. doi: 10.1074/jbc.M115.651885. Epub 2015 May 5.

Abstract

Kinesin-1 is a molecular motor responsible for cargo transport along microtubules and plays critical roles in polarized cells, such as neurons. Kinesin-1 can function as a dimer of two kinesin heavy chains (KHC), which harbor the motor domain, or as a tetramer in combination with two accessory light chains (KLC). To ensure proper cargo distribution, kinesin-1 activity is precisely regulated. Both KLC and KHC subunits bind cargoes or regulatory proteins to engage the motor for movement along microtubules. We previously showed that the scaffolding protein JIP3 interacts directly with KHC in addition to its interaction with KLC and positively regulates dimeric KHC motility. Here we determined the stoichiometry of JIP3-KHC complexes and observed approximately four JIP3 molecules binding per KHC dimer. We then determined whether JIP3 activates tetrameric kinesin-1 motility. Using an in vitro motility assay, we show that JIP3 binding to KLC engages kinesin-1 with microtubules and that JIP3 binding to KHC promotes kinesin-1 motility along microtubules. We tested the in vivo relevance of these findings using axon elongation as a model for kinesin-1-dependent cellular function. We demonstrate that JIP3 binding to KHC, but not KLC, is essential for axon elongation in hippocampal neurons as well as axon regeneration in sensory neurons. These findings reveal that JIP3 regulation of kinesin-1 motility is critical for axon elongation and regeneration.

Keywords: JIP3; KHC; axon; kinesin; molecular motor; motility; neurite outgrowth; regeneration.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Axons / metabolism*
  • HEK293 Cells
  • Hippocampus / cytology
  • Hippocampus / metabolism*
  • Humans
  • Kinesins / genetics
  • Kinesins / metabolism*
  • Mice
  • Microtubules / genetics
  • Microtubules / metabolism
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism*
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Protein Multimerization / physiology
  • Protein Transport / physiology
  • Sensory Receptor Cells / cytology
  • Sensory Receptor Cells / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • Mapk8ip3 protein, mouse
  • Multiprotein Complexes
  • Nerve Tissue Proteins
  • Kinesins