Kindlins, integrin activation and the regulation of talin recruitment to αIIbβ3.
Kindlins, integrin activation and the regulation of talin recruitment to αIIbβ3.
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DOI：
10.1371/journal.pone.0034056
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Ye F
中科院分区：
文献类型：
--
作者：
Kahner BN;Kato H;Banno A;Ginsberg MH;Shattil SJ;Ye F
Talins和kindlins结合到整合素β3细胞质尾部，它们都是有效激活整合素αIIbβ3并在血小板中产生高亲和力配体结合所必需的。然而，仅talin头部结构域与β3结合就足以在体外激活纯化的整合素αIIbβ3。由于talin定位于未受刺激的血小板的细胞质，因此激活需要它重新定位于质膜和整合素。在这里，我们探讨了kindlins作为整合素共激活剂的作用机制。为了验证kindlins是否调节talin向质膜和αIIbβ3的募集，我们使用重建的CHO细胞模型系统研究全长talin和kindlin向β3的募集，该模型系统再现了激动剂诱导的αIIbβ3激活。内源性kindlin-2在CHO细胞中的过度表达，促进par1介导的和talin依赖的配体结合。相反，shRNA敲低kindlin-2抑制配体结合。然而，通过亚细胞分离评估，shRNA耗尽kindlin-2并不影响talin向质膜募集，并且通过双分子荧光互补监测，kindlin-2的过表达和耗尽都不会影响活细胞中talin与αIIbβ3的相互作用。此外，talin在CHO细胞中未能促进kindlin-2与α iib - β3的关联。此外，纯化的talin和在血小板中表达的kindlin-3异构体在体外不能促进彼此与β3细胞质尾部的结合。因此，kindlins不促进αIIbβ3的初始talin募集，表明它们通过一种独立于募集的机制共同激活整合素。
Talins and kindlins bind to the integrin β3 cytoplasmic tail and both are required for effective activation of integrin αIIbβ3 and resulting high-affinity ligand binding in platelets. However, binding of the talin head domain alone to β3 is sufficient to activate purified integrin αIIbβ3 in vitro. Since talin is localized to the cytoplasm of unstimulated platelets, its re-localization to the plasma membrane and to the integrin is required for activation. Here we explored the mechanism whereby kindlins function as integrin co-activators. To test whether kindlins regulate talin recruitment to plasma membranes and to αIIbβ3, full-length talin and kindlin recruitment to β3 was studied using a reconstructed CHO cell model system that recapitulates agonist-induced αIIbβ3 activation. Over-expression of kindlin-2, the endogenous kindlin isoform in CHO cells, promoted PAR1-mediated and talin-dependent ligand binding. In contrast, shRNA knockdown of kindlin-2 inhibited ligand binding. However, depletion of kindlin-2 by shRNA did not affect talin recruitment to the plasma membrane, as assessed by sub-cellular fractionation, and neither over-expression of kindlins nor depletion of kindlin-2 affected talin interaction with αIIbβ3 in living cells, as monitored by bimolecular fluorescence complementation. Furthermore, talin failed to promote kindlin-2 association with αIIbβ3 in CHO cells. In addition, purified talin and kindlin-3, the kindlin isoform expressed in platelets, failed to promote each other's binding to the β3 cytoplasmic tail in vitro. Thus, kindlins do not promote initial talin recruitment to αIIbβ3, suggesting that they co-activate integrin through a mechanism independent of recruitment.
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影响因子：
2.7
作者：
Kodama, Yutaka;Hu, Chang-Deng
通讯作者：
Hu, Chang-Deng
影响因子：
5.3
作者：
DUBRIDGE, RB;TANG, P;CALOS, MP
通讯作者：
CALOS, MP
DOI：
10.1074/jbc.m109.085746
发表时间：
2010-06-11
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Bialkowska K;Ma YQ;Bledzka K;Sossey-Alaoui K;Izem L;Zhang X;Malinin N;Qin J;Byzova T;Plow EF
通讯作者：
Plow EF
影响因子：
7.5
作者：
Boettcher, Ralph T.;Lange, Anika;Faessler, Reinhard
通讯作者：
Faessler, Reinhard
影响因子：
12.3
作者：
Choy MK;Movassagh M;Siggens L;Vujic A;Goddard M;Sánchez A;Perkins N;Figg N;Bennett M;Carroll J;Foo R
通讯作者：
Foo R