α5β1 integrin mediates strong tissue cohesion
α5β1 integrin mediates strong tissue cohesion
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DOI：
10.1242/jcs.00231
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发表时间：
2003-01-15
影响因子：
4
通讯作者：
Foty, RA
中科院分区：
文献类型：
--
作者：
Robinson, EE;Zazzali, KM;Foty, RA
整合素和钙粘蛋白被认为具有不同的和相反的功能。整合素在传统上被认为在细胞-基质相互作用中起作用，而钙粘蛋白被认为介导强的细胞间粘附。总之，这些粘附系统在各种各样的细胞和发育过程中起着至关重要的作用，包括细胞迁移、形态、分化和增殖。在这份手稿中，我们提出的证据表明，整合素具有强大的细胞间的凝聚力，当细胞生长为3D aggregate.Much的数据阐明整合素作为细胞-细胞外基质（ECM）相互作用的介质的作用已经产生使用传统的细胞培养技术，其中细胞接种到ECM包被的2D表面的能力。在体内，细胞嵌入ECM蛋白的3D网络中。我们假设，在这个网络中，整合素-ECM相互作用可能通过将相邻细胞连接在一起而赋予细胞聚集体凝聚力。为了验证这一假设，我们转染中国仓鼠卵巢（CHO-B2）细胞表达α 5 β 1整联蛋白，发现这些细胞形成紧凑的球形聚集体。我们使用组织表面张力测定法测量聚集体的凝聚力，这是一种在生理条件下量化球状体的细胞-细胞凝聚力的新技术。我们确定α 5 β 1整联蛋白能够赋予α 5-整联蛋白转染的细胞聚集体强的凝聚性（σ =8.22+/-0.68达因/cm）。发现这种粘附性不依赖于钙粘蛋白的表达，并且显著大于用N-钙粘蛋白转染的CHO-B2细胞所赋予的粘附性（σ =3.14+/-0.20达因/厘米，P小于或等于0.0001），一个更传统的细胞间的凝聚系统。纤维连接蛋白-表达α 5 β 1整联蛋白但不分泌内源性纤连蛋白的无效CHO细胞在纤连蛋白耗尽的培养基中不形成聚集体。向这些细胞中添加增加量的外源性二聚体纤连蛋白导致剂量依赖性压实。然而，压实未能发生在纤连蛋白单体的存在下。这些数据表明，纤连蛋白是必需的α 5 β 1介导的压实和纤连蛋白的二聚体结构是必不可少的这一过程。此外，α 5整联蛋白转染子的聚集体形成被RGD肽抑制，从而证实了α 5 β 1整联蛋白特异性。总的来说，这些数据证实了我们的假设，即α 5 β 1整联蛋白通过纤连蛋白将相邻细胞连接在一起，从而促进三维细胞聚集体中的细胞间粘附。
Integrins and cadherins are considered to have distinct and opposing functions. Integrins are traditionally cited for their role in cell-substratum interactions, whereas cadherins are thought to mediate strong intercellular cohesion. Together, these adhesion systems play crucial roles in a wide variety of cellular and developmental processes including cell migration, morphology, differentiation and proliferation. In this manuscript we present evidence that integrins possess the ability to mediate strong intercellular cohesion when cells are grown as 3D aggregates.Much of the data elucidating the role of integrins as mediators of cell-extracellular matrix (ECM) interactions have been generated using conventional cell culture techniques in which cells are plated onto ECM-coated 2D surfaces. In vivo, cells are embedded in a 3D meshwork of ECM proteins. We hypothesized that, within this meshwork, integrin-ECM interactions may impart cohesivity to an aggregate of cells by linking adjacent cells together. To test this hypothesis, we transfected Chinese hamster ovary (CHO-B2) cells to express alpha5beta1 integrin and found that these cells formed compact, spherical aggregates. We measured aggregate cohesivity using tissue surface tensiometry, a novel technique that quantifies cell-cell cohesivity of spheroids under physiological conditions. We determined that alpha5beta1 integrin is capable of conferring strong cohesivity (sigma=8.22+/-0.68 dynes/cm) to aggregates of alpha5-integrin-transfected cells. This cohesion was found to be independent of cadherin expression and was significantly greater than the cohesivity conferred onto CHO-B2 cells transfected with N-cadherin (sigma=3.14+/-0.20 dynes/cm, Pless than or equal to0.0001), a more traditional cell-cell cohesion system.Fibronectin-null CHO cells that express alpha5beta1 integrin but do not secrete endogenous fibronectin do not form aggregates in fibronectin-depleted medium. Addition of increasing amounts of exogenous dimeric fibronectin to these cells resulted in a dose-dependent compaction. However, compaction failed to occur in the presence of fibronectin monomers. These data indicate that fibronectin is required for alpha5beta1-mediated compaction and that the dimeric structure of fibronectin is essential for this process. Additionally, aggregate formation of the alpha5 integrin transfectants was inhibited by an RGD peptide thus confirming alpha5beta1 integrin specificity. Collectively, these data confirm our hypothesis that alpha5beta1 integrin acts through fibronectin to link adjacent cells together, thus promoting strong intercellular cohesion in 3D cellular aggregates.