A dual role for the class III PI3K, Vps34, in platelet production and thrombus growth.
A dual role for the class III PI3K, Vps34, in platelet production and thrombus growth.
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DOI：
10.1182/blood-2017-04-781641
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发表时间：
2017-11
期刊：
影响因子：
20.3
通讯作者：
C. Valet;M. Levade;G. Chicanne;B. Bilanges;C. Cabou;J. Viaud;M. Gratacap;F. Gaits‐Iacovoni;B. Vanhaesebroeck;B. Payrastre;S. Severin
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文献类型：
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作者：
C. Valet;M. Levade;G. Chicanne;B. Bilanges;C. Cabou;J. Viaud;M. Gratacap;F. Gaits‐Iacovoni;B. Vanhaesebroeck;B. Payrastre;S. Severin
为了揭示唯一的III类磷酸肌醇3-激酶(PI3K)Vps34在巨核细胞(MK)和血小板中的作用，我们建立了MK/血小板谱系中Vps34缺失的小鼠模型(PF4-Cre/Vps34lox/lox)。MKs中Vps34的缺失导致其调节蛋白Vps15的丢失，并与微血小板减少症和血小板颗粒异常有关。虽然VPS34缺陷不影响MK多倍化或原血小板的形成，但它抑制了MK颗粒的生物生成和向SDF1α梯度的定向迁移，导致骨髓内异位血小板释放。在MKs中，Vps34缺失显著降低了磷脂酰肌醇3-单磷酸(PI3P)的水平，导致内吞/转运缺陷。在血小板中，PI3P的基础水平仅受到Vps34丢失的轻微影响，而刺激依赖的PI3P池则显著减少。相应地，观察到急性血小板刺激后Vps34脂蛋白激酶的比活性显著增加。与Vps34缺失的血小板相似，用Vps34特异性抑制剂SAR405和Vps34-in1体外处理野生型小鼠或人血小板，可诱导异常分泌并影响动脉切变率下的血栓生长，表明Vps34激酶活性在血小板激活中发挥作用，而不是其在MKs中的作用。在体内，Vps34缺乏对尾部出血时间没有影响，但显著降低了颈动脉损伤后的血小板血栓前形成能力。这项研究揭示了Vps34的双重作用，既是MKs产生血小板的调节因子，又是血小板激活和动脉血栓形成动力学的意外调节因子。
To uncover the role of Vps34, the sole class III phosphoinositide 3-kinase (PI3K), in megakaryocytes (MKs) and platelets, we created a mouse model with Vps34 deletion in the MK/platelet lineage (Pf4-Cre/Vps34lox/lox). Deletion of Vps34 in MKs led to the loss of its regulator protein, Vps15, and was associated with microthrombocytopenia and platelet granule abnormalities. Although Vps34 deficiency did not affect MK polyploidisation or proplatelet formation, it dampened MK granule biogenesis and directional migration toward an SDF1α gradient, leading to ectopic platelet release within the bone marrow. In MKs, the level of phosphatidylinositol 3-monophosphate (PI3P) was significantly reduced by Vps34 deletion, resulting in endocytic/trafficking defects. In platelets, the basal level of PI3P was only slightly affected by Vps34 loss, whereas the stimulation-dependent pool of PI3P was significantly decreased. Accordingly, a significant increase in the specific activity of Vps34 lipid kinase was observed after acute platelet stimulation. Similar to Vps34-deficient platelets, ex vivo treatment of wild-type mouse or human platelets with the Vps34-specific inhibitors, SAR405 and VPS34-IN1, induced abnormal secretion and affected thrombus growth at arterial shear rate, indicating a role for Vps34 kinase activity in platelet activation, independent from its role in MKs. In vivo, Vps34 deficiency had no impact on tail bleeding time, but significantly reduced platelet prothrombotic capacity after carotid injury. This study uncovers a dual role for Vps34 as a regulator of platelet production by MKs and as an unexpected regulator of platelet activation and arterial thrombus formation dynamics.