Grenz H, Carbonetto S, Goodman S L
Nephrology Research Laboratory, Medical Clinic IV, University of Erlangen-Nürnberg, Germany.
J Cell Sci. 1993 Jul;105 ( Pt 3):739-51. doi: 10.1242/jcs.105.3.739.
The movement of integrins into focal adhesive structures accompanies cell attachment to extracellular matrix. The kinetics of incorporation of integrins into focal contacts was studied during attachment to matrix of mesangial cells of the kidney glomerulus. On collagen, fibronectin, laminin and vitronectin, the number and intensity of talin-focal contacts increased with time. Talin-containing focal contacts were present in mesangial cells within 2 h of plating and in control cells (HT1080 and Rugli) within 1 h. Integrin alpha-chains colocalized with talin, dependent on the matrix substrate. The attachment, spreading and organization of integrin into focal contacts was not affected when endogenous protein synthesis was suppressed with cycloheximide. In Rugli, alpha 1 beta 1 organized into focal contacts on collagen and laminin, while in HT1080 alpha 2 beta 1 organized on collagen type I, alpha 5 beta 1 on fibronectin, alpha 6 beta 1 on laminin, and alpha 3 beta 1 and alpha 4 beta 1 were diffusely distributed on all substrates. These distributions mirrored the usage and expression patterns previously established for integrins in these cells and was as predicted from the literature. In mesangial cells, however, alpha 3 beta 1 was also organized into prominent focal contact arrays on collagen, fibronectin, EHS and human placental laminins, but not on vitronectin, while alpha 6 beta 1 was not organized. Initial attachment and spreading of mesangial cells was absolutely dependent on divalent cations. Mg2+ and Mn2+ supported attachment on all substrates, while Ca2+ stimulated attachment on laminin (E8), fibronectin and vitronectin. The data suggest that the functional integrins on mesangial cells include alpha 1 beta 1 (on collagen and laminin) alpha 2 beta 1 (on collagen), alpha 5 beta 1 (on fibronectin) and alpha V beta 3 (on vitronectin). However, mesangial cells do not use alpha 6 beta 1 on laminin, and the data support a role for alpha 3 beta 1 as putative receptor for fibronectin, collagen and laminin.
整联蛋白向粘着斑结构的移动伴随着细胞与细胞外基质的附着。在肾小球系膜细胞与基质附着过程中，研究了整联蛋白掺入粘着斑的动力学。在胶原蛋白、纤连蛋白、层粘连蛋白和玻连蛋白上，含踝蛋白的粘着斑数量和强度随时间增加。接种后2小时内，系膜细胞中出现含踝蛋白的粘着斑，而对照细胞（HT1080和Rugli）在1小时内出现。整联蛋白α链与踝蛋白共定位，这取决于基质底物。当用放线菌酮抑制内源性蛋白质合成时，整联蛋白的附着、铺展以及向粘着斑的组织化不受影响。在Rugli细胞中，α1β1在胶原蛋白和层粘连蛋白上组织形成粘着斑，而在HT1080细胞中，α2β1在I型胶原蛋白上组织形成粘着斑，α5β1在纤连蛋白上，α6β1在层粘连蛋白上，α3β1和α4β1在所有底物上呈弥散分布。这些分布反映了这些细胞中先前确定的整联蛋白的使用和表达模式，并且与文献预测一致。然而，在系膜细胞中，α3β1也在胶原蛋白、纤连蛋白、EHS和人胎盘层粘连蛋白上组织形成突出的粘着斑阵列，但在玻连蛋白上不形成，而α6β1不形成组织化。系膜细胞的初始附着和铺展绝对依赖于二价阳离子。Mg2+和Mn2+支持在所有底物上的附着，而Ca2+刺激在层粘连蛋白（E8）、纤连蛋白和玻连蛋白上的附着。数据表明，系膜细胞上的功能性整联蛋白包括α1β1（在胶原蛋白和层粘连蛋白上）、α2β1（在胶原蛋白上）、α5β1（在纤连蛋白上）和αVβ3（在玻连蛋白上）。然而，系膜细胞在层粘连蛋白上不使用α6β1，并且数据支持α3β1作为纤连蛋白、胶原蛋白和层粘连蛋白的假定受体的作用。
