Proteolysis leads to the appearance of the long form of 脦脦₃-endonexin in human platelets

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• 作者：Sadoul ; Karin ; Vignoud ; Lucile ; Mossuz ; Pascal ; Block ; Marc R.
• 关键词：β ; ₃-endonexin ; Integrin ; Platelet ; Calpain ; Platelet storage lesion
• 刊名：Experimental Cell Research
• 出版年：2005
• 期刊代码：292_00144827
• 类别：med
• 出版时间：May 1, 2005
• 卷：305
• 期：2
• 页码：427-435
• 文件大小：484 K

摘要

After vessel injury, platelets adhere to the subendothelial matrix. Platelet adhesion leads to activation of the platelet integrin α_IIbβ₃, which then binds to fibrinogen, leading to platelet aggregation. It has been shown that a β₃-integrin binding protein, β₃-endonexin, can activate the integrin α_IIbβ₃ expressed in transfected CHO cells. Several isoforms of β₃-endonexin are known but it is not clear which isoforms are expressed in platelets and what role they may play during haemostasis. Here, we show that the long form of β₃-endonexin (EN-L) can be detected in platelet lysates several hours after thrombus formation, after long-term storage of platelets and after glucose deprivation. After subcellular fractionation, EN-L is found in the detergent insoluble fraction suggesting that it might be associated with the cytoskeleton. EN-L generation is temperature and Ca⁺⁺ dependent and requires physiological salt concentrations. Proteolysis is responsible for the appearance of EN-L since a calpain inhibitor prevents its formation and the addition of calpain to platelet lysates induces its formation. The appearance of EN-L seems to be linked to apoptotic events occurring during long-term storage of platelets and, possibly, during late steps of haemostasis after thrombus formation.