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Activation of MAPK in fibroblasts by Treponema denticola major outer sheath protein

Marie-Claude Jobin1, Inderpreet Virdee, Christopher A McCulloch

  • 1CIHR Group in Matrix Dynamics, Dental Research Institute, University of Toronto, Toronto, Ont., Canada. marieclaude.jobin@utoronto.ca

Biochemical and Biophysical Research Communications
|March 10, 2007
PubMed

Insights

Treponema denticola's major outer sheath protein (Msp) activates stress response pathways in fibroblasts. Msp triggers mitogen-activated protein (MAP) kinase pathways, influencing cell behavior.

Area of Science:

  • Microbiology
  • Cell Biology
  • Biochemistry

Background:

  • The major outer sheath protein (Msp) from Treponema denticola is known to induce calcium ion (Ca2+) entry and actin reorganization in cultured fibroblasts.
  • The precise molecular mechanisms by which Msp mediates these cellular responses remain largely undefined.

Purpose of the Study:

  • To investigate the signaling pathways activated by Msp in fibroblasts, hypothesizing a role for protein kinases in a stress response preceding actin remodeling.
  • To identify specific kinases involved in Msp-induced cellular effects and elucidate their activation patterns.

Main Methods:

  • Utilized phospho-kinase screens to identify activated kinases following Msp exposure.
  • Quantified the expression and phosphorylation of key kinases, p38 and extracellular signal-regulated kinases 1/2 (ERK 1/2), using immunoblotting and densitometry.
  • Assessed the dose- and time-dependent effects of Msp and the impact of kinase inhibitors (SB202190, U1026) and extracellular Ca2+.

Main Results:

  • Msp exposure led to the significant activation of 34 kinases, including p38 and ERK 1/2, involved in stress responses and actin assembly.
  • Both p38 and ERK 1/2 kinases demonstrated a dose- and time-dependent response to Msp.
  • Inhibition studies confirmed the involvement of p38 and ERK 1/2 pathways, with no significant effect observed from extracellular Ca2+.

Conclusions:

  • Treponema denticola Msp activates mitogen-activated protein (MAP) kinase pathways in fibroblasts as a stress response.
  • These findings suggest that Msp may induce transient cellular stress through the activation of p38 and ERK 1/2 signaling cascades.

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