Talin-1 variant Q244E affects cell migration in fibroblasts

Abstract

Cell migration is a plastic process that is essential for life and development. Depending on the cell type and environment, cells can migrate collectively or individually, using mesenchymal, ameboid or blebbing movement. Mesenchymal cell migration requires contractility at the cell rear as well as protrusive lamellipodia in the leading edge. Cells contractile actomyosin stress fibres are linked to surrounding extracellular matrix by focal adhesions (FA). These complexes consist of multiple proteins such as integrin and talin, and constant formation and decomposition of FAs is mandatory for adherent cell migration.

Talin is an intracellular mechanosensing protein that consists of head and rod domains. It plays a central role in focal adhesions by connecting integrins to actin filaments. Talin’s flexible chain structure enables it to stretch under mechanical forces and expose different binding sites. Recent studies have revealed that talin is associated with diseases and diverse clinical symptoms. Also, clinically relevant missense mutations have been found to disturb talin’s function as central focal adhesion adaptor protein.

In this thesis, we studied talin-1 variant Q244E, which is associated with disease lichen planus. The mutation’s effects on talin functionality were studied by conducting 2D single-cell migration assay in fibroblasts transfected with wild type and Q244E talin. In addition, we conducted pathogenicity predictions, utilizing different algorithm-based tools to compare their interpretations with migration assay results. Talin structure was also predicted to visualize the location of the mutation.

Here, we found that Q244E mutation did not have visually observable effect on cell morphology, but it reduces migration rate in fibroblasts significantly. These results indicate that Q244E variant affects talin functionality at the cellular level. Similar effects were reported in earlier studies of different talin variants with mutations in the same area.

Despite the detected reduction in cell migration rate, pathogenicity prediction tools did not indicate strong evidence for pathogenicity. This highlights the importance of experimental data, especially when studying mutations in multifunctional proteins. Even though bioinformatical predictors give valuable insight of variant effects, they have known limitations and do not always provide reliable results.