Disrupted filamin A/αIIbβ3 interaction induces macrothrombocytopenia by increasing RhoA activity
Disrupted filamin A/αIIbβ3 interaction induces macrothrombocytopenia by increasing RhoA activity
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DOI：
10.1182/blood-2018-07-861427
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发表时间：
2019-04-18
期刊：
影响因子：
20.3
通讯作者：
Raslova, Hana
中科院分区：
文献类型：
--
作者：
Donada, Alessandro;Balayn, Nathalie;Raslova, Hana
丝蛋白A （FLNa）连接细胞膜和细胞骨架，在几个细胞过程中起中心作用。x连锁FLNA基因的杂合突变与多种疾病有关，包括称为丝状蛋白病的巨血小板减少症。利用来自患者的等基因多能干细胞模型，我们发现巨核细胞（mk）中FLNa蛋白的缺失导致其不完全成熟，特别是无法产生血小板。血小板形成电位的降低与肌动球蛋白收缩性缺陷有关，这是由不适当的RhoA激活引起的。当mk被镀在纤维蛋白原上而不是其他基质（纤维连接蛋白、玻璃体连接蛋白、胶原蛋白1和血管性血友病因子）上时，观察到RhoA激活失调，这强烈表明FLNa/ α (IIb) β(3)相互作用在RhoA活性下调中的作用。通过实验证实，在α (IIb) β(3)结合域和rhoa相互作用域缺失的FLNa突变体过表达。最后，药物抑制rhoa相关激酶ROCK1/2恢复正常表型和血小板形成。总的来说，这项工作提出了一种新的大血小板减少的病因学，其中RhoA活性的增加与FLNa/ α (IIb) β(3)相互作用的破坏有关。
Filamin A (FLNa) links the cell membrane with the cytoskeleton and is central in several cellular processes. Heterozygous mutations in the X-linked FLNA gene are associated with a large spectrum of conditions, including macrothrombocytopenia, called filaminopathies. Using an isogenic pluripotent stem cell model derived from patients, we show that the absence of the FLNa protein in megakaryocytes (MKs) leads to their incomplete maturation, particularly the inability to produce proplatelets. Reduction in proplatelet formation potential is associated with a defect in actomyosin contractility, which results from inappropriate RhoA activation. This dysregulated RhoA activation was observed when MKs were plated on fibrinogen but not on other matrices (fibronectin, vitronectin, collagen 1, and von Willebrand factor), strongly suggesting a role for FLNa/alpha(IIb)beta(3) interaction in the downregulation of RhoA activity. This was confirmed by experiments based on the overexpression of FLNa mutants deleted in the alpha(IIb)beta(3)-binding domain and the RhoA-interacting domain, respectively. Finally, pharmacological inhibition of the RhoA-associated kinase ROCK1/2 restored a normal phenotype and proplatelet formation. Overall, this work suggests a new etiology for macrothrombocytopenia, in which increased RhoA activity is associated with disrupted FLNa/alpha(IIb)beta(3) interaction.