Phosphorylation of neurofilament subunit NF-M is regulated by activation of NMDA receptors and modulates cytoskeleton stability and neuronal shape

H. Fiumelli, I. M. Riederer, J. L. Martin*, B. M. Riederer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The cytoskeleton is essential for the structural organization of neurons and is influenced during development by excitatory stimuli such as activation of glutamate receptors. In particular, NMDA receptors are known to modulate the function of several cytoskeletal proteins and to influence cell morphology, but the underlying molecular and cellular mechanisms remain unclear. Here, we characterized the neurofilament subunit NF-M in cultures of developing mouse cortical neurons chronically exposed to NMDA receptor antagonists. Western blots analysis showed that treatment of cortical neurons with MK801 or AP5 shifted the size of NF-M towards higher molecular weights. Dephosphorylation assay revealed that this increased size of NF-M observed after chronic exposure to NMDA receptor antagonists was due to phosphorylation. Neurons treated with cyclosporin, an inhibitor of the Ca2+-dependent phosphatase calcineurin, also showed increased levels of phosphorylated NF-M. Moreover, analysis of neurofilament stability revealed that the phosphorylation of NF-M, resulting from NMDA receptor inhibition, enhanced the solubility of NF-M. Finally, cortical neurons cultured in the presence of the NMDA receptor antagonists MK801 and AP5 grew longer neurites. Together, these data indicate that a blockade of NMDA receptors during development of cortical neurons increases the phosphorylation state and the solubility of NF-M, thereby favoring neurite outgrowth. This also underlines that dynamics of the neurofilament and microtubule cytoskeleton is fundamental for growth processes.

Original languageEnglish (US)
Pages (from-to)495-504
Number of pages10
JournalCell Motility and the Cytoskeleton
Volume65
Issue number6
DOIs
StatePublished - Jun 2008
Externally publishedYes

Keywords

  • AP5
  • Cortical neurons
  • Cytoskeleton
  • Glutamate
  • Immunocytochemistry
  • Mice
  • MK801
  • Neurofilament
  • NMDA receptor antagonist
  • Western blot

ASJC Scopus subject areas

  • Structural Biology
  • Cell Biology

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