Tumour metastasis suppressor KAI1/CD82 inhibits tumour cell movement. As a transmembrane protein, tetraspanin CD82 bridges the interactions between membrane microdomains of lipid rafts and tetraspanin-enriched microdomains (TEMs). In this study, we found that CD82 and other tetraspanins contain cholesterol recognition/interaction amino-acid consensus (CRAC) sequences in their transmembrane domains and revealed that cholesterol binding of CD82 determines its interaction with lipid rafts but not with TEMs. Functionally, CD82 needs cholesterol binding to inhibit solitary migration, collective migration, invasion and infiltrative outgrowth of tumour cells. Importantly, CD82-cholesterol/-lipid raft interaction not only promotes extracellular release of lipid raft components such as cholesterol and gangliosides but also facilitates extracellular vesicle (EV)-mediated release of ezrin-radixin-moesin (ERM) protein Ezrin. Since ERM proteins link actin cytoskeleton to the plasma membrane, we show for the first time that cell movement can be regulated by EV-mediated releases, which disengage the plasma membrane from cytoskeleton and then impair cell movement. Our findings also conceptualize that interactions between membrane domains, in this case converge of lipid rafts and TEMs by CD82, can change cell movement. Moreover, CD82 coalescences with both lipid rafts and TEMs are essential for its inhibition of tumour cell movement and for its enhancement of EV release. Finally, our study underpins that tetraspanins as a superfamily of functionally versatile molecules are cholesterol-binding proteins. Abbreviations: Ab: antibody; CBM: cholesterol-binding motif; CCM: cholesterol consensus motif; CRAC/CARC: cholesterol recognition or interaction amino-acid consensus; CTxB: cholera toxin B subunit; ECM: extracellular matrix; ERM: ezrin, radixin and moesin; EV: extracellular vesicles; FBS: foetal bovine serum; mAb: monoclonal antibody; MST: microscale thermophoresis; pAb: polyclonal antibody; and TEM: tetraspanin-enriched microdomain.

中文翻译：

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四跨膜蛋白CD82与胆固醇的相互作用促进细胞外囊泡介导的ezrin释放，从而抑制肿瘤细胞的运动。

肿瘤转移抑制因子KAI1 / CD82抑制肿瘤细胞运动。作为跨膜蛋白，四跨膜蛋白CD82桥接脂质筏的膜微结构域与富四跨膜蛋白的微结构域（TEM）之间的相互作用。在这项研究中，我们发现CD82和其他四跨膜蛋白在其跨膜结构域中包含胆固醇识别/相互作用氨基酸共有（CRAC）序列，并揭示了CD82与胆固醇的结合决定了其与脂质筏的相互作用，但与TEM的相互作用却没有。在功能上，CD82需要结合胆固醇以抑制肿瘤细胞的单独迁移，集体迁移，侵袭和浸润性生长。重要的，CD82-胆固醇/脂质筏相互作用不仅促进脂质筏成分（例如胆固醇和神经节苷脂）的细胞外释放，而且还促进细胞外囊泡（EV）介导的ezrin-radixin-moesin（ERM）蛋白Ezrin的释放。由于ERM蛋白将肌动蛋白的细胞骨架链接到质膜，我们首次展示了可以通过EV介导的释放来调节细胞的运动，这种释放使质膜脱离细胞骨架，从而损害细胞的运动。我们的发现还概念化了膜结构域之间的相互作用，在这种情况下通过CD82融合了脂筏和TEM，可以改变细胞的运动。而且，具有脂筏和TEM的CD82结合对于其抑制肿瘤细胞运动和增强EV释放是必不可少的。最后，我们的研究表明，四跨膜蛋白作为功能多样的分子的超家族是胆固醇结合蛋白。缩写：Ab：抗体；CBM：胆固醇结合基序；CCM：胆固醇共有基序；CRAC / CARC：胆固醇识别或相互作用氨基酸共识；CTxB：霍乱毒素B亚基；ECM：细胞外基质；企业风险管理：ezrin，radixin和moesin；EV：细胞外囊泡；FBS：胎牛血清；mAb：单克隆抗体；MST：微型热泳；pAb：多克隆抗体；多克隆抗体；多克隆抗体。TEM：富含四跨膜蛋白的微区。细胞外基质 企业风险管理：ezrin，radixin和moesin；EV：细胞外囊泡；FBS：胎牛血清；mAb：单克隆抗体；MST：微型热泳；pAb：多克隆抗体；多克隆抗体；多克隆抗体；多克隆抗体。TEM：富含四跨膜蛋白的微区。细胞外基质 企业风险管理：ezrin，radixin和moesin；EV：细胞外囊泡；FBS：胎牛血清；mAb：单克隆抗体；MST：微型热泳；pAb：多克隆抗体；多克隆抗体；多克隆抗体；多克隆抗体。TEM：富含四跨膜蛋白的微区。