| Abstract | Electric cell-substrate impedance sensing (ECIS) was applied to assess the structure-function of alpha2beta1 integrin, receptor for collagen and laminin. On collagen-coated gold electrodes, expression of this integrin on human rhabdomyosarcoma (RD) cells (RDX2C2) yielded a five-fold increase in resistance when compared with mock transfected RD (RDpF) cells (34.5 +- 5.2 versus 6.5 +- 0.8 OMEGA/cell). An intermediate level of 16 +- 2 OMEGA/cell was measured upon expression of an alpha2beta1 mutant that lacked the alpha2 cytoplasmic domain (RDX2CO). On laminin, the resistance measured for RDX2C2 cells was also higher but only twice that of RDpF cells at 71 +- 4 and 37 +- 4 OMEGA/cell, respectively. In comparison, RDX2CO cells (38 +- 4 OMEGA/cell), exhibiting no enhanced adhesive function, yielded a similar result to that of RDpF cells. On fibronectin, RDX2C2 and RDpF cells, exhibiting comparable levels of adhesion, were similar in resistance measurements at 85 +- 5 and 89 +- 7 OMEGA/cell, respectively. It has been shown that deletion of alpha2 cytoplasmic domain results in dysregulated recruitment of the alpha2beta1 mutant to focal adhesion complexes that mediate binding of fibronectin. RDX2CO cells on fibronectin, exhibiting reduced adhesive function, was associated with noticeably lower resistance (60 +- 4 OMEGA/cell). Monitoring electroporation of the RD plasma membrane also indirectly validated cell attachment as reflected by the resistance measured. Results from this study demonstrated the potential of ECIS for study of the structure-function of beta1 integrin adhesion receptors. |
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