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Pasteurella multocida toxin stimulates mitogenesis and cytoskeleton reorganization in Swiss 3T3 fibroblasts
Author(s) -
Dudet Laure I.,
Chailler Pierre,
Dubreuil J. Daniel,
MartineauDoize Beatrice
Publication year - 1996
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199607)168:1<173::aid-jcp21>3.0.co;2-7
Subject(s) - internalization , okadaic acid , 3t3 cells , microbiology and biotechnology , membrane ruffling , cytoskeleton , bombesin , biology , motility , actin , cell growth , cell culture , cell , phosphatase , biochemistry , transfection , receptor , phosphorylation , genetics , neuropeptide
Pasteurella multocida toxin (PMT) causes cytoplasmic retraction in epithelial cells, activates osteoclast neoformation, and is a potent mitogen for Swiss 3T3 fibroblasts. In the present study designed to further investigate the effects of PMT on cell shape and proliferation, we report that the mitogenic effect of affinity‐purified PMT on quiescent 3T3 cells was even superior at 5 ng/ml to that of fetal bovine serum or bombesin. This positive effect was inhibited by heat denaturation and methylamine treatment (this agent blocks internalization). Preincubation of PMT with gangliosides GM 1 , GM 2 , or GM 3 counteracted its effect on DNA synthesis, suggesting that the toxin binds to GM‐type ceramides on target cells. The distribution of F‐actin was analyzed in control/treated cells using FITC‐conjugated phalloidin. In comparison with FBS and bombesin, PMT triggered a more rapid and profound reorganization of cortical actin into prominent stress fibers after only 5–10 min. This event lead to the retraction of cells after only 30 min and ultimately to the induction of mitotic figures. Interestingly, methylamine blocked the effects of PMT on stress fiber formation and cell retraction but not the ruffling response, suggesting that some early events may not require toxin internalization. In summary, these findings indicate that PMT concomitantly exerts a strong mitogenic activity and a rapid stimulation of cytoskeletal rearrangements, possibly after binding to membrane gangliosides and subsequent internalization. We propose that this toxin could be used in the future as a defined inducer of transduction signals involved in cellular proliferation and control of cell shape. © 1996 Wiley‐Liss, Inc.