Paths to stability - actin regulation of adherens junction mechanics

The ability of cells to stick to each other and form tissues is mediated by protein complexes at the plasma membrane, such as adherens junctions (AJs). Key aspects of AJ stability are the biomechanical properties of the constituent proteins and the forces generated by the associated actin cytoskeleton. This Review concisely overviews our current understanding of how these factors play out at different length scales. When actomyosin pulls on the cadherin-catenin complex, the molecular interactions within the complex lead to an increase in AJ stability. Transcellular E-cadherin clusters are dynamically maintained by constant turnover and recruitment of actin-binding proteins organises the internal actin cytoskeleton. Among these are actin polymerisers that sustain the actin network and provide the mechanical forces important for AJ integrity. Finally, the distribution of AJs around the cell periphery and the long-range organisation of the associated actin bundles could contribute to maintaining AJ stability across tissues. We conclude with a summary of recently developed biophysical tools useful for the study of AJ mechanics and a few open questions that we expect to see answered in the not-too-distant future.