Intracellular Ca2+ stimulates the binding to androgen receptors in platelets.
In this study, we demonstrated that ADP-induced platelet aggregation activates the binding of testosterone (T) to its receptor. It is well known that binding of ADP to its receptors induced the release of Ca2+ ions from dense bodies into the cytosol of platelets. In this work, we compared the binding of testosterone or dihydrotestosterone to their receptors using cytosol obtained from ADP-treated and non-treated platelets. These experiments were repeated using EGTA (a calcium chelator) or U73122 (a phospholipase C enzymatic activity inhibitor) to the ADP-treated platelets. In addition, we also developed a competition analysis for the androgen receptors (AR) using [3H]DHT, non-radioactive T, DHT or cyproterone acetate from ADP-treated platelets cytosol. The results from this study indicate that the cytosol obtained from non-ADP-treated platelets did not show any binding to [3H]T or [3H]DHT, whereas cytosol from ADP-treated platelets binds to the radio-labeled androgens. Furthermore cytosol from ADP plus U73122-treated platelets did not show binding to [3H]T or [3H]DHT. These data suggest that intracellular Ca2+ ions stimulates the binding of androgens to their receptors in platelets cytosol. The competition analysis shows that T and DHT have high affinities for the androgen receptors with similar IC50 values, whereas cyproterone acetate shows a lower affinity. The results from these data clearly indicate the presence of androgen receptors in platelets.
Cabeza
Marisa
M
Departamento de Sistemas Biológicos Universidad Autónoma Metropolitana-Xochimilco, Calzada Del Hueso No. 1100, México 04960, D.F., Mexico. marisa@correo.xoc.uam.mx
Flores
Mirthala
M
Bratoeff
Eugene
E
de la Peña
Aurora
A
Mendez
Enrique
E
Ceballos
Guillermo
G
D000244:Adenosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D001667:Binding, Competitive; D001792:Blood Platelets / Q000378:metabolism*; D015153:Blotting, Western; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D013196:Dihydrotestosterone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000378:metabolism / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D007477:Ions; D011485:Protein Binding; D011760:Pyrrolidinones / Q000494:pharmacology; D011944:Receptors, Androgen / Q000378:metabolism*; D013256:Steroids / Q000737:chemistry; D013739:Testosterone / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
D004791:Enzyme Inhibitors; D004963:Estrenes; D007477:Ions; D011760:Pyrrolidinones; D011944:Receptors, Androgen; D013256:Steroids; D013196:Dihydrotestosterone; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D013739:Testosterone; D004533:Egtazic Acid; D000244:Adenosine Diphosphate; D010738:Type C Phospholipases; D002118:Calcium