Thrombosis and Hemostasis Laboratory, Department of Clinical Chemistry and Hematology, University Medical Center Utrecht, Utrecht, the Netherlands.
Haematologica. 2012 Dec;97(12):1873-81. doi: 10.3324/haematol.2012.066290. Epub 2012 Jun 24.
Storing platelets for transfusion at room temperature increases the risk of microbial infection and decreases platelet functionality, leading to out-date discard rates of up to 20%. Cold storage may be a better alternative, but this treatment leads to rapid platelet clearance after transfusion, initiated by changes in glycoprotein Ibα, the receptor for von Willebrand factor.
We examined the change in glycoprotein Ibα distribution using Förster resonance energy transfer by time-gated fluorescence lifetime imaging microscopy.
Cold storage induced deglycosylation of glycoprotein Ibα ectodomain, exposing N-acetyl-D-glucosamine residues, which sequestered with GM1 gangliosides in lipid rafts. Raft-associated glycoprotein Ibα formed clusters upon binding of 14-3-3ζ adaptor proteins to its cytoplasmic tail, a process accompanied by mitochondrial injury and phosphatidyl serine exposure. Cold storage left glycoprotein Ibα surface expression unchanged and although glycoprotein V decreased, the fall did not affect glycoprotein Ibα clustering. Prevention of glycoprotein Ibα clustering by blockade of deglycosylation and 14-3-3ζ translocation increased the survival of cold-stored platelets to above the levels of platelets stored at room temperature without compromising hemostatic functions.
We conclude that glycoprotein Ibα translocates to lipid rafts upon cold-induced deglycosylation and forms clusters by associating with 14-3-3ζ. Interference with these steps provides a means to enable cold storage of platelet concentrates in the near future.
室温下储存血小板用于输血会增加微生物感染的风险，并降低血小板的功能，导致高达 20%的血小板过期报废。冷储存可能是更好的选择，但这种治疗方法会导致血小板在输注后迅速清除，这是由 von Willebrand 因子受体糖蛋白 Ibα的变化引起的。
我们使用时间门控荧光寿命成像显微镜通过Förster 共振能量转移来检查糖蛋白 Ibα分布的变化。
冷储存诱导糖蛋白 Ibα外显子去糖基化，暴露出 N-乙酰-D-葡萄糖胺残基，这些残基与 GM1 神经节苷脂一起在脂筏中隔离。与细胞质尾巴结合的 14-3-3ζ衔接蛋白结合后，脂筏相关的糖蛋白 Ibα形成簇，这一过程伴随着线粒体损伤和磷脂酰丝氨酸暴露。冷储存使糖蛋白 Ibα表面表达保持不变，尽管糖蛋白 V 减少，但下降并没有影响糖蛋白 Ibα的聚集。通过阻止去糖基化和 14-3-3ζ易位来阻止糖蛋白 Ibα聚集，增加了冷储存血小板的存活率，使其超过室温储存血小板的水平，而不影响止血功能。
我们得出结论，糖蛋白 Ibα在冷诱导去糖基化时向脂筏易位，并通过与 14-3-3ζ 结合形成簇。干扰这些步骤为将来实现血小板浓缩物的冷储存提供了一种手段。
