{alpha}-Syntrophin regulates ARMS localization at the neuromuscular junction and enhances EphA4 signaling in an ARMS-dependent manner

J Cell Biol. 2005 Jun 6;169(5):813-24. doi: 10.1083/jcb.200412008.

Abstract

EphA4 signaling has recently been implicated in the regulation of synapse formation and plasticity. In this study, we show that ankyrin repeat-rich membrane spanning (ARMS; also known as a kinase D-interacting substrate of 220 kD), a substrate for ephrin and neurotrophin receptors, was expressed in developing muscle and was concentrated at the neuromuscular junction (NMJ). Using yeast two-hybrid screening, we identified a PDZ (PSD-95, Dlg, ZO-1) domain protein, alpha-syntrophin, as an ARMS-interacting protein in muscle. Overexpression of alpha-syntrophin induced ARMS clustering in a PDZ domain-dependent manner. Coexpression of ARMS enhanced EphA4 signaling, which was further augmented by the presence of alpha-syntrophin. Moreover, the ephrin-A1-induced tyrosine phosphorylation of EphA4 was reduced in C2C12 myotubes after the blockade of ARMS and alpha-syntrophin expression by RNA interference. Finally, alpha-syntrophin-null mice exhibited a disrupted localization of ARMS and EphA4 at the NMJ and a reduced expression of ARMS in muscle. Altogether, our findings suggest that ARMS may play an important role in regulating postsynaptic signal transduction through the syntrophin-mediated localization of receptor tyrosine kinases such as EphA4.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells
  • Calcium-Binding Proteins
  • Chlorocebus aethiops
  • Ephrins / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Knockout
  • Muscle Fibers, Skeletal / metabolism
  • Muscle Proteins / genetics
  • Muscle Proteins / metabolism*
  • Muscle, Skeletal / growth & development*
  • Muscle, Skeletal / innervation
  • Neuromuscular Junction / cytology
  • Neuromuscular Junction / growth & development*
  • Neuromuscular Junction / metabolism
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Protein Structure, Tertiary / physiology
  • RNA Interference / physiology
  • Rats
  • Receptor, EphA4 / metabolism*
  • Signal Transduction / physiology
  • Synaptic Membranes / metabolism*
  • Up-Regulation / physiology

Substances

  • Calcium-Binding Proteins
  • Ephrins
  • Kidins220 protein, rat
  • Membrane Proteins
  • Muscle Proteins
  • Phosphoproteins
  • syntrophin alpha1
  • Receptor, EphA4