Mechanisms and role of β1 integrin dynamics in muscle cell adhesion

Integrin of the β1 family play crucial roles in cell adhesion, migration and in the assembly and organization of the extracellular scaffold. While the ligand specificity of the β1 integrins is controlled by its associated α chain, the β1 chain mediates the interaction with the cytoplasmic adaptor proteins talin and kindlin. During development, β1 integrins are mainly expressed as A splice variants. However, during myotube formation and muscle maturation, the D splice variant replaces the A. In order to understand the physiological changes associated with alternative splicing of the β1 integrin, we developed GFP-tagged β1 integrins and investigated their dynamic incorporations into focal or fibrillar adhesions by time-lapse microscopy and FRAP. Our results demonstrate that with identical extracellular ligand binding capacities, the selectivity of adapter protein recruitment can switch integrins from matrix synthesizing, to force-bearing or to migration stimulating receptors, allowing a cell to respond optimally to its environment