Apically sorted P2X7 receptors mediate purinergic-induced pore formation preferentially in apical domains of the plasma membrane.
Treatment of human epithelial cervical cells CaSki attached on filters with the P2X7-receptor (P2X7-R) agonist BzATP induced acute transient influx of calcium, most likely the result of P2X7-R channel activation, followed by slower sustained calcium influx. In cultures incubated in the presence of ethidium bromide (EB), BzATP induced slow and sustained influx of the dye with a time-course similar to the late slow calcium influx, suggesting P2X7-R pore formation. The acute and late calcium effects of BzATP were greater if the agonist was added to the luminal solution, facing the apical membrane of the cells. The EB effect of BzATP initially occurred in the apical membrane, while effects in the basolateral membrane were delayed and smaller. These results suggest that in polarized epithelial cells under steady-state conditions the P2X7-R is located in the apical membrane, and activation of the receptor induces formation of P2X7-R pores preferentially in the apical membrane.
Li
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Department of Reproductive Biology, CASE-University (Case Western Reserve), Cleveland, OH, USA.
Gorodeski
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GI
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000345:Affinity Labels / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D004996:Ethidium / Q000494:pharmacology; D005260:Female; D006801:Humans; D007364:Intercalating Agents / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D021381:Protein Transport; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D058486:Receptors, Purinergic P2X7; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy
D000345:Affinity Labels; D007364:Intercalating Agents; C546468:P2RX7 protein, human; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D004996:Ethidium; D002118:Calcium