Sialic acid inhibits agrin signaling in C2 myotubes

Wade A. Grow, Herman Gordon

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Acetylcholine receptor (AChR) clustering is an early event in neuromuscular synapse formation that is commonly studied using muscle cell culture. Motor neuron-derived agrin induces the postsynaptic tyrosine phosphorylation of both a muscle-specific kinase (MuSK) and the AChR β-subunit. These phosphorylation events are required for AChR clustering, suggesting an agrin-driven signaling pathway. Both the phosphorylation events and AChR clustering can also be induced by neuraminidase, an enzyme that cleaves sialic acid from glycoconjugates, suggesting that neuraminidase is able to activate the agrin signaling pathway. A postulated signal for postsynaptic differentiation at sites of nerve-muscle contact during vertebrate development is the enzymatic removal of basal lamina components. We show here that bath-applied sialic acid has an effect directly opposite that of agrin or neuraminidase. Sialic acid not only decreases AChR clustering but also diminishes the tyrosine phosphorylation of MuSK and the AChR β-subunit signal-transduction events normally driven by agrin. However, sialic acid does not prevent agrin-binding molecules from colocalizing with the decreased number of AChR clusters that do form, suggesting that sialic acid is acting to inhibit the agrin signaling pathway downstream of agrin binding to the muscle cell membrane. We propose a regulatory role for sialic acid in the signal transduction events of neuromuscular synapse formation, in which agrin or neuraminidase can overcome this sialic acid repression, resulting in the clustering of AChRs and other postsynaptic molecules.

Original languageEnglish (US)
Pages (from-to)273-279
Number of pages7
JournalCell & Tissue Research
Volume299
Issue number2
DOIs
StatePublished - 2000

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Agrin
Skeletal Muscle Fibers
N-Acetylneuraminic Acid
Cholinergic Receptors
Phosphorylation
Cluster Analysis
Muscle
Neuraminidase
Signal transduction
Muscles
Synapses
Muscle Cells
Tyrosine
Signal Transduction
Molecules
Glycoconjugates
Motor Neurons
Cell membranes
Baths
Cell culture

Keywords

  • Acetylcholine receptor
  • Cell culture
  • Glycoconjugates
  • MuSK
  • Neuraminidase
  • Neuromuscular synapse
  • Tyrosine phosphorylation

ASJC Scopus subject areas

  • Anatomy
  • Clinical Biochemistry
  • Cell Biology

Cite this

Sialic acid inhibits agrin signaling in C2 myotubes. / Grow, Wade A.; Gordon, Herman.

In: Cell & Tissue Research, Vol. 299, No. 2, 2000, p. 273-279.

Research output: Contribution to journalArticle

Grow, Wade A. ; Gordon, Herman. / Sialic acid inhibits agrin signaling in C2 myotubes. In: Cell & Tissue Research. 2000 ; Vol. 299, No. 2. pp. 273-279.
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