Pertussis toxin directly activates endothelial cell p42/p44 MAP kinases via a novel signaling pathway

Joe G. N. Garcia, Peiyi Wang, Feng Liu, Marc B. Hershenson, Talaibek Borbiev, Alexander D. Verin


Bordetella pertussisgenerates a bacterial toxin utilized in signal transduction investigation because of its ability to ADP ribosylate specific G proteins. We previously noted that pertussis toxin (PTX) directly activates endothelial cells, resulting in disruption of monolayer integrity and intercellular gap formation via a signaling pathway that involves protein kinase C (PKC). We studied the effect of PTX on the activity of the 42- and 44-kDa extracellular signal-regulated kinases (ERK), members of a kinase family known to be activated by PKC. PTX caused a rapid time-dependent increase in bovine pulmonary artery endothelial cell ERK activity that was significantly attenuated by1) pharmacological inhibition of MEK, the upstream ERK activating kinase, 2) an MEK dominant-negative construct, and 3) PKC inhibition with bisindolylmaleimide. There was little evidence for the involvement of either Gβγ-subunits, Ras GTPases, Raf-1, p60src, or phosphatidylinositol 3′-kinases in PTX-mediated ERK activation. Both the purified β-oligomer binding subunit of the PTX holotoxin and a PTX holotoxin mutant genetically engineered to eliminate intrinsic ADP ribosyltransferase activity completely reproduced PTX effects on ERK activation, suggesting that PTX-induced ERK activation involves a novel PKC-dependent signaling mechanism that is independent of either Ras or Raf-1 activities and does not require G protein ADP ribosylation.

  • signal transduction
  • endothelium
  • bacterial toxin
  • adenosine 5′-diphosphate ribosylation
  • extracellular signal-regulated kinases
  • β-oligomer
  • Raf-1 activation
  • p21 Ras activity


  • This work was supported by National Heart, Lung, and Blood Institute Grants HL-50533 and HL-58064 and by the Dr. David Marine Endowment (J. G. N. Garcia).

  • Address for reprint requests and other correspondence: J. G. N. Garcia, Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, 4B.77, Baltimore, MD 21224-6801 (E-mail:drgarcia{at}

  • The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

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