Syntrophin isoforms at the neuromuscular junction: developmental time course and differential localization

Mol Cell Neurosci. 2000 Mar;15(3):262-74. doi: 10.1006/mcne.1999.0823.

Abstract

The syntrophins are a family of cytoplasmic adapter proteins that associate with dystrophin family proteins and have putative signaling and structural roles at the neuromuscular junction. We have localized the syntrophin family members within the rodent junction from birth to adulthood. Alpha-syntrophin is the only isoform on the postsynaptic membrane at birth. In the adult, it occurs on the crests of the junctional folds, with utrophin, and in the troughs, with dystrophin. Surprisingly, neuronal nitric oxide synthase (nNOS) does not accompany alpha-syntrophin onto the crests. Beta2-syntrophin, a junction-specific form, is not present at birth and occurs mainly in the troughs in the adult. Beta1-syntrophin is a sarcolemmal form at birth, not concentrated at the junction, and disappears entirely from most fibers by 6 weeks. In positive fibers, junctional beta1-syntrophin occurs exclusively in the troughs. These results suggest that the syntrophin isoforms have distinct functions at the junction and show that the known protein-protein associations of the syntrophins and nNOS in skeletal muscle are not sufficient to explain their localizations.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cytoskeletal Proteins / analysis
  • Denervation
  • Dystrophin-Associated Proteins*
  • Gene Expression Regulation, Developmental*
  • Membrane Proteins / analysis
  • Membrane Proteins / biosynthesis*
  • Membrane Proteins / genetics
  • Mice
  • Muscle Proteins / analysis
  • Muscle Proteins / biosynthesis*
  • Muscle Proteins / genetics
  • Nerve Tissue Proteins / analysis
  • Nerve Tissue Proteins / biosynthesis*
  • Nerve Tissue Proteins / genetics
  • Neuromuscular Junction / chemistry
  • Neuromuscular Junction / embryology
  • Neuromuscular Junction / growth & development
  • Neuromuscular Junction / metabolism*
  • Nitric Oxide Synthase / metabolism
  • Nitric Oxide Synthase Type I
  • Rabbits
  • Rats
  • Sarcolemma / chemistry
  • Utrophin

Substances

  • Cytoskeletal Proteins
  • Dystrophin-Associated Proteins
  • Membrane Proteins
  • Muscle Proteins
  • Nerve Tissue Proteins
  • Utrn protein, mouse
  • Utrophin
  • syntrophin
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type I
  • Nos1 protein, mouse
  • Nos1 protein, rat