Interactions between the megakaryocyte/platelet-specific β1 tubulin and the secretory leukocyte protease inhibitor SLPI suggest a role for regulated proteolysis in platelet functions
Interactions between the megakaryocyte/platelet-specific β1 tubulin and the secretory leukocyte protease inhibitor SLPI suggest a role for regulated proteolysis in platelet functions
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DOI：
10.1182/blood-2004-03-1179
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发表时间：
2004-12-15
期刊：
影响因子：
20.3
通讯作者：
Shivdasani, RA
中科院分区：
文献类型：
--
作者：
Schulze, H;Korpal, M;Shivdasani, RA
血小板let限制性β 1微管蛋白是最佳血小板生成和盘状细胞形状所必需的。为了确定相互作用的因素，我们使用了不同的β 1-微管蛋白C-末端作为诱饵，在酵母双杂交筛选巨核细胞（MK）cDNA。我们分离出分泌性白细胞蛋白酶抑制剂（SLPI），这是一种丝氨酸蛋白酶拮抗剂，主要特征是一种分泌因子，在炎症中发挥多种作用。SLPI在MK和血小板中以2个离散的隔室表达。一个池位于点状细胞质结构中，而一个显著的部分位于沿着外周微管（MT），并在冷诱导MT破坏或β 1微管蛋白（-/-）血小板中丢失。这些发现揭示了一个突出的细胞骨架蛋白和蛋白水解抑制剂之间的意外相互作用。SLPI-/-小鼠显示完整的前血小板形成、血小板数量和形状以及边缘MT带;因此，SLPI对于血小板生成不是必需的。然而，SLPI在血小板活化时释放，这也逆转了其与静息边缘带的关联。血小板SLPI抑制中性粒细胞弹性蛋白酶，当β 1微管蛋白不存在时，这种活性降低。我们的结论是SLPI局部定位在部分沿着MK和血小板MT细胞骨架凭借与β 1微管蛋白的特定相互作用。因此，SLPI可能在MK和血小板功能中发挥意想不到的作用，包括活化后调节蛋白水解。(C)2004年，美国血液学会。
Plate let-restricted beta1 tubulin is required for optimal thrombopoiesis and discoid cell shape. To identify interacting factors, we used the divergent beta1-tubulin C-terminus as the bait in a yeast 2-hybrid screen of megakaryocyte (MK) cDNAs. We isolated secretory leukocyte protease inhibitor (SLPI), a serine protease antagonist characterized principally as a secreted factor with multiple roles in inflammation. SLPI is expressed in MKs and platelets in 2 discrete compartments. One pool resides in punctate cytoplasmic structures, whereas a significant fraction localizes along peripheral microtubules (MTs) and is lost with cold-induced MT disruption or in beta1 tubulin(-/-) platelets. These findings reveal unexpected interaction between a prominent cytoskeletal protein and an inhibitor of proteolysis. SLPI-/- mice show intact proplatelet formation, platelet numbers and shape, and marginal MT bands; thus, SLPI is not essential for thrombopoiesis. However, SLPI is released upon platelet activation, which also reverses its association with the resting marginal band. Platelet SLPI inhibits neutrophil elastase, an activity that is reduced when beta1 tubulin is absent. We conclude that SLPI localizes in part along the MK and platelet MT cytoskeleton by virtue of specific interactions with beta1 tubulin. SLPI may thus have unanticipated roles in MK and platelet functions, including regulated proteolysis after activation. (C) 2004 by The American Society of Hematology.