Selective translocation of protein kinase c isozymes by PAF in rabbit platelets.
The action of platelet activating factor (PAF) on subcellular distribution and activity of protein kinase C (PKC) isoforms in rabbit platelets was analyzed. The results showed an increase of PKC alpha in membrane fraction, concomitantly with a decrease in cytosolic fraction after 5 min PAF treatment, indicating that a translocation of PKC alpha occurred. In addition, PKC zeta was redistributed in a "reverse" form, from the membrane to cytosolic fraction after PAF treatment. PAF induced an increase of PKC alpha activity, whereas a decrease rather than increase in PKC zeta was observed by using immunoprecipitation assays. In addition, some results indicated that PI3 kinase activation was not involved in PAF-induced PKC zeta translocation as occur in several cells and with other agonists. These actions were time- and concentration-dependent, and were inhibited by the treatment with a PAF antagonist. No translocation was observed when the platelets were incubated with lysoPAF, a PAF related compound. The redistribution of PKC isoforms take place through the activation of high specificity PAF binding sites. The pretreatment of the rabbit platelets with staurosporine, a putative inhibitor of PKC, completely blocked the PAF-evoked aggregation without affecting to PAF-evoked shape change and serotonin release. All together, these data could suggest that the specific translocation of PKC isoforms play an important role in the activation of rabbit platelets.
Calcerrada
M C
MC
Departamento de Bioquímica y Biología Molecular I, Facultad de Química, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Latorre
E
E
Mora-Gil
M V
MV
Catalán
R E
RE
Miguel
B G
BG
Martínez
A M
AM
D000818:Animals; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D048430:Cell Shape / Q000187:drug effects; D007527:Isoenzymes / Q000097:blood*; D010972:Platelet Activating Factor / Q000378:metabolism / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects; D011493:Protein Kinase C / Q000097:blood*; D021381:Protein Transport / Q000187:drug effects; D011817:Rabbits; D012701:Serotonin / Q000097:blood
D007527:Isoenzymes; D010972:Platelet Activating Factor; D012701:Serotonin; D011493:Protein Kinase C