Involvement of deoxygenation-induced increase in tyrosine kinase activity in sickle cell dehydration.
Deoxygenation of sickle (SS) cells causes cationic alterations leading to cell dehydration by various mechanisms, including activation of Ca2+-sensitive K channels and possibly of K-Cl cotransport. Since an abnormal tyrosine kinase (TK) activity exists in SS cells we investigated the possible role of tyrosine phosphorylation in SS cell dehydration. In density-fractionated SS reticulocytes and discocytes, but not in normal red cells, deoxygenation increased membrane and cytosolic TK activities and tyrosine phosphorylation of band 3, independently of external Ca2+. These effects were abolished by the TK inhibitors methyl 2, 5-dihydroxycinnamate (DiOH) or tyrphostin 47 (T47). Deoxygenation-induced Ca2+ uptake was not affected by the inhibitors and Na+ gain was reduced by T47 and not by DiOH. Both inhibitors decreased the loss of K+ and cellular dehydration. The effect of the inhibitors on K+ efflux was still observed in the absence of external Ca2+. These data indicate that the TK inhibitors do not interfere with deoxygenation-induced membrane permeabilization, but affect Ca2+-independent K+ efflux. It cannot be excluded, however, that the TK inhibitors also attenuate Ca2+-sensitive K+ efflux. Based on recent evidence from the literature, it is suggested that the diminution of K+ efflux results in part from inhibition of K-Cl cotransport activity.
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Laboratoire de Biomembranes et Messagers Cellulaires, Centre National de la Recherche Scientifique ERS 571, Bat. 440, Université Paris XI, F-91405 Orsay Cedex, France.
Hardy-Dessources
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Sauvage
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Giraud
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D000755:Anemia, Sickle Cell / Q000097:blood*; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002396:Catechols / Q000494:pharmacology; D002934:Cinnamates / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology / Q000473:pathology* / Q000648:ultrastructure; D006801:Humans; D066298:In Vitro Techniques; D009570:Nitriles / Q000494:pharmacology; D010100:Oxygen / Q000097:blood*; D010766:Phosphorylation; D011188:Potassium / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D020032:Tyrphostins
D002396:Catechols; D002934:Cinnamates; D004791:Enzyme Inhibitors; D009570:Nitriles; D020032:Tyrphostins; C060152:tyrphostin 47; D014443:Tyrosine; C067472:methyl 2,5-dihydroxycinnamate; D011505:Protein-Tyrosine Kinases; D011188:Potassium; D010100:Oxygen; D002118:Calcium