| 20139366 |
Rosado JA, Pariente JA, Salido GM, Redondo PC: SERCA2b activity is regulated by cyclophilins in human platelets. . Arterioscler Thromb Vasc Biol. 2010 Mar;30(3):419-25. Epub 2010 Feb 5.
OBJECTIVE: The role of cyclophilins (chaperones that are widely expressed in different cell types, including human platelets) was explored in sarcoendoplasmic calcium (Ca (2+)) adenosine triphosphatase (SERCA) activity. METHODS AND RESULTS: Cyclophilin inhibition by cyclosporin A (CsA) evoked a time- and concentration-dependent reduction of Ca (2+) uptake by SERCA2b. However, other Ca (2+)-adenosine triphosphatases expressed in platelets, such as SERCA3 and plasma membrane Ca (2+) adenosine triphophatase, remained unaltered after CsA treatment. Cypermethrin, a non-CsA-related calcineurin inhibitor, did not alter SERCA2b activity. Furthermore, SERCA2b was affected by other CsA analogues, which do not interfere with calcineurin, such as PKF-211-811-NX5 (NIM811) and sanglifehrin A. Inhibition of the immunophilin family members using FK506 (tacrolimus) did not alter SERCA2b ability to sequester Ca (2+) into the dense tubular system. Coimmunoprecipitation experiments confirmed that cyclophilin A associates with SERCA2b and stromal interaction molecule-1 in resting platelets. This interaction is attenuated by the physiological agonist thrombin but enhanced by treatment with CsA or sanglifehrin A. CONCLUSIONS: Cyclophilin A is a regulator of SERCA2b in human platelets. |
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