α-Dystroglycan hypoglycosylation affects cell migration by influencing β-dystroglycan membrane clustering and filopodia length: a multiscale confocal microscopy analysis

Dystroglycan (DG) serves as an adhesion complex linking the actin cytoskeleton to the extracellular matrix. DG is encoded by a single gene as a precursor, which is constitutively cleaved to form the α- and β-DG subunits. α-DG is a peripheral protein characterized by an extensive glycosylation that is essential to bind laminin and other extracellular matrix proteins, while β-DG binds the cytoskeleton proteins. The functional properties of DG depend on the correct glycosylation of α-DG and on the cross-talk between the two subunits. A reduction of α-DG glycosylation has been observed in muscular dystrophy and cancer while the inhibition of the interaction between α- and β-DG is associated to aberrant post-translational processing of the complex. Here we used confocal microscopy based techniques to get insights into the influence of α-DG glycosylation on the functional properties of the β-DG, and its effects on cell migration. We used epithelial cells transfected with wild-type and with a mutated DG harboring the mutation T190 M that has been recently associated to dystroglycanopathy. We found that α-DG hypoglycosylation, together with an increased protein instability, reduces the membrane dynamics of the β-subunit and its clustering within the actin-rich domains, influencing cell migration and spontaneous cell movement. These results contribute to give novel insights into the involvement of aberrant glycosylation of DG in the developing of muscular dystrophy and tumor metastasis.