Sci. STKE, 20 November 2007
Cell Adhesion Remembering the Last Engagement
Elizabeth M. Adler
Science's STKE, AAAS, Washington, DC 20005, USA
The experimental analysis of single-molecule biomechanical interactions frequently involves sequentially repeated measurements that are used to obtain a sufficiently large amount of data. The validity of this approach depends on the assumption that such sequential measurements are identical and independent of each other, an assumption Zarnitsyna et al. tested using a micropipette adhesion frequency assay. Cells expressing a particular ligand were held in a micropipette, and their adhesion (or lack thereof) to a second cell expressing the cognate receptor was repeatedly determined after an identical period of contact. Analyses of different receptor-ligand pairs revealed three distinct behaviors. The interaction between lymphocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) was consistent with the assumption of independent and identical measurements. In contrast, interactions between the T cell receptor (TCR) and an antigen peptide bound to a major histocompatibility complex (pMHC) or between C-cadherins appeared to show molecular "memory." Thus, adhesion between a TCR-pMHC pair in one test increased the probability of adhesion in the next test, whereas adhesion between C-cadherins in one test decreased the likelihood that they would adhere in the next. Thus, the authors propose that receptor-ligand interactions involved in mediating cell adhesion show molecular memory, likely mediated through responses triggered by receptor engagement.
Citation: E. M. Adler, Remembering the Last Engagement. Sci. STKE 2007, tw426 (2007).
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