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Differential modulation and subsequent blockade of mitogenic signaling and cell cycle progression by Pasteurella

B A Wilson1, L R Aminova, V G Ponferrada

  • 1Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. bawilson@life.uiuc.edu

Infection and Immunity
|July 19, 2000
PubMed

Insights

Pasteurella multocida toxin (PMT) activates cell signaling pathways, causing initial proliferation but ultimately cell cycle arrest. Cell type influences PMT

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Toxicology

Background:

  • Pasteurella multocida toxin (PMT) is an intracellular protein known to affect various cellular processes.
  • PMT activates the G(q/11)-alpha-protein, leading to phospholipase C (PLC) beta1 stimulation and inositol 1,4,5-trisphosphate (IP(3)) pathway activation.
  • The link between PMT's IP(3) pathway activation and its mitogenic/proliferative effects remains unclear.

Purpose of the Study:

  • To investigate the downstream effects of PMT on mitogenesis and cell cycle progression.
  • To characterize the differential cellular responses to PMT in Swiss 3T3 and Vero cells.
  • To elucidate the signaling pathways involved in PMT-induced cell cycle regulation.

Main Methods:

  • Treatment of Swiss 3T3 and Vero cells with PMT.
  • Morphological analysis and assessment of cell cycle progression using cell cycle analysis.
  • Western blot analysis to detect the expression of key cell cycle regulatory proteins (e.g., c-Myc, cyclins, PCNA, Rb proteins).

Main Results:

  • PMT induced significant morphological changes in both cell lines, with Vero cells showing multinucleation and disrupted cytokinesis.
  • A strong, but transient, mitogenic response was observed in Swiss 3T3 cells, while Vero cells showed a limited response.
  • Both cell types arrested in the G(1) phase after initial PMT exposure and became unresponsive.
  • PMT differentially regulated cell cycle proteins; Swiss 3T3 cells showed up-regulation of cyclins and proliferation markers, which was not sustained.
  • Vero cells failed to up-regulate certain key proteins like PCNA and cyclin E, correlating with their limited proliferative response.

Conclusions:

  • PMT triggers an initial mitogenic response followed by cell cycle arrest, indicating complex regulatory mechanisms.
  • The differential expression of cell cycle proteins and signaling pathways in response to PMT contributes to varying cellular outcomes.
  • Understanding these cell-type-specific responses is crucial for comprehending the overall impact of PMT toxicity.

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