Selective translocation of the Bordetella pertussis adenylate cyclase toxin across the basolateral membranes of polarized epithelial cells.
The catalytic domain of Bordetella pertussis adenylate cyclase toxin (ACT) translocates directly across the plasma membrane of mammalian cells to induce toxicity by the production of cAMP. Here, we use electrophysiology to examine the translocation of toxin into polarized epithelial cells that model the mucosal surfaces of the host. We find that both polarized T84 cell monolayers and human airway epithelial cultures respond to nanomolar concentrations of ACT when applied to basolateral membranes, with little or no response to toxin applied apically. The induction of toxicity is rapid and fully explained by increases in intracellular cAMP, consistent with toxin translocation directly across the basolateral membrane. Intoxication of T84 cells occurs in the absence of CD11b/CD18 or evidence of another specific membrane receptor, and it is not dependent on post-translational acylation of the toxin or on host cell membrane potential, both previously reported to be required for toxin action. Thus, elements of the basolateral membrane render epithelial cells highly sensitive to the entry of ACT in the absence of a specific receptor for toxin binding.
Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
Joshua C
JC
Eby
William P
WP
Ciesla
Wendy
W
Hamman
Gina M
GM
Donato
Raymond J
RJ
Pickles
Erik L
EL
Hewlett
Wayne I
WI
Lencer
D000215:Acylation; D037361:Adenylate Cyclase Toxin / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D001980:Bronchi / Q000166:cytology / Q000378:metabolism*; D039481:CD11b Antigen / Q000378:metabolism; D018821:CD18 Antigens / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D016764:Cell Polarity; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D004594:Electrophysiology; D004847:Epithelial Cells / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D008564:Membrane Potentials; D021381:Protein Transport; D014132:Trachea / Q000166:cytology / Q000378:metabolism*
D037361:Adenylate Cyclase Toxin; D039481:CD11b Antigen; D018821:CD18 Antigens; D002712:Chlorides; D000242:Cyclic AMP