ICAM-2 regulates vascular permeability and N-cadherin localization through ezrin-radixin-moesin (ERM) proteins and Rac-1 signalling.
ICAM-2 regulates vascular permeability and N-cadherin localization through ezrin-radixin-moesin (ERM) proteins and Rac-1 signalling.
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DOI：
10.1186/1478-811x-12-12
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发表时间：
2014-03-04
期刊：
影响因子：
--
通讯作者：
Randi AM
中科院分区：
文献类型：
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作者：
Amsellem V;Dryden NH;Martinelli R;Gavins F;Almagro LO;Birdsey GM;Haskard DO;Mason JC;Turowski P;Randi AM
内皮连接调控通透性、血管生成和接触抑制等功能。血管内皮细胞粘附素(VECad)是维持细胞间接触所必需的。在融合的内皮单层中，N-钙粘附素(NCad)主要表达在顶膜和基底膜上，但在没有VECad的情况下，它定位于交界处。这两种钙粘附素都是血管发育所必需的。细胞间黏附分子(ICAM)-2也定位于内皮细胞连接，参与白细胞募集和血管生成。在人脐静脉内皮细胞(HUVEC)中，VECad和NCad均位于融合单层的新生细胞接触处，而VECad仅定位于融合单层的成熟交界处。通过siRNA抑制ICAM-2的表达，导致连接处出现小间隙，并减少亚融合单层的NCad连接染色。来源于WT或ICAM-2缺陷小鼠(IC2neg)的内皮瘤系缺乏VECad，不能形成连接，失去接触抑制。全长ICAM-2(IC2FL)在IC2neg细胞中的重新表达通过在连接处募集NCad来恢复接触抑制。缺失ERM蛋白结合位点(IC2ERM)或细胞质尾部(IC2Tail)的突变体ICAM-2不能恢复连接。依赖ICAM-2的RAC-1活性在这些突变细胞系中也降低。IC2neg细胞在静息状态下和凝血酶刺激后，其屏障功能(通过跨内皮细胞电阻在体外测量)均降低。这依赖于ICAM-2对小GTP酶RAC-1的信号传递，因为IC2neg细胞的跨内皮电阻是由结构性活性的RAC-1恢复的。在体内，用活体荧光显微镜测量凝血酶诱导的FITC标记的白蛋白在小鼠提睾肌中的外渗显示，ICAM-2缺陷小鼠的通透性比对照组增加。这些结果表明，ICAM-2通过N-钙粘附素、ERMs和Rac-1参与调节内皮屏障功能和通透性。
Endothelial junctions control functions such as permeability, angiogenesis and contact inhibition. VE-Cadherin (VECad) is essential for the maintenance of intercellular contacts. In confluent endothelial monolayers, N-Cadherin (NCad) is mostly expressed on the apical and basal membrane, but in the absence of VECad it localizes at junctions. Both cadherins are required for vascular development. The intercellular adhesion molecule (ICAM)-2, also localized at endothelial junctions, is involved in leukocyte recruitment and angiogenesis. In human umbilical vein endothelial cells (HUVEC), both VECad and NCad were found at nascent cell contacts of sub-confluent monolayers, but only VECad localized at the mature junctions of confluent monolayers. Inhibition of ICAM-2 expression by siRNA caused the appearance of small gaps at the junctions and a decrease in NCad junctional staining in sub-confluent monolayers. Endothelioma lines derived from WT or ICAM-2-deficient mice (IC2neg) lacked VECad and failed to form junctions, with loss of contact inhibition. Re-expression of full-length ICAM-2 (IC2 FL) in IC2neg cells restored contact inhibition through recruitment of NCad at the junctions. Mutant ICAM-2 lacking the binding site for ERM proteins (IC2 ΔERM) or the cytoplasmic tail (IC2 ΔTAIL) failed to restore junctions. ICAM-2-dependent Rac-1 activation was also decreased in these mutant cell lines. Barrier function, measured in vitro via transendothelial electrical resistance, was decreased in IC2neg cells, both in resting conditions and after thrombin stimulation. This was dependent on ICAM-2 signalling to the small GTPase Rac-1, since transendothelial electrical resistance of IC2neg cells was restored by constitutively active Rac-1. In vivo, thrombin-induced extravasation of FITC-labeled albumin measured by intravital fluorescence microscopy in the mouse cremaster muscle showed that permeability was increased in ICAM-2-deficient mice compared to controls. These results indicate that ICAM-2 regulates endothelial barrier function and permeability through a pathway involving N-Cadherin, ERMs and Rac-1.