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Cytoskeleton‐dependent inhibition of the ADP‐ribosyl cyclase activity of CD38 in thrombin‐stimulated platelets
Author(s) -
Torti Mauro,
Tolnai Festetics Enrico,
Bertoni Alessandra,
Sinigaglia Fabiola,
Balduini Cesare
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00712-1
Subject(s) - platelet , cd38 , thrombin , cytoskeleton , cyclase , chemistry , adenosine diphosphate , biochemistry , microbiology and biotechnology , biophysics , enzyme , platelet aggregation , biology , medicine , cell , stem cell , cd34
Stimulation of human platelets with thrombin caused a 42% inhibition of the ADP‐ribosyl cyclase activity of membrane CD38. This effect was mediated by the activation of the platelet thrombin receptor rather than by proteolysis of CD38, and was not due to a different distribution of the synthesised nucleotide or to a reduced accessibility of CD38 to the substrate. The inhibitory effect of thrombin required actin polymerisation and was not observed when interaction of CD38 with the cytoskeleton was prevented by cytochalasin D. Finally, we analysed whether cADPR could play a role as a Ca 2+ ‐mobilising agent in human platelets. Using saponin‐permeabilised cells, we found that unlike IP 3 , cADPR did not induce any release of Ca 2+ from intracellular stores. These results indicate that the enzymatic activity of membrane CD38 can be modulated by platelet activation, and that the function of this glycoprotein is probably not related to Ca 2+ mobilisation.