Muscular integrity--a matter of interlinking distinct structures via plectin.

Myocytes are characterized by the presence of highly specialized cytoskeletal structures that are part of regularly spaced functional units distributed over long distances. In this chapter we discuss previously published evidence as well as novel data showing that the proper positioning and architecture of Z-disks and of sarcolemma-associated costameric structures are largely dependent on the cytolinker protein plectin and its associated intermediate filament (desmin) cytoskeleton. Deficiency in either plectin or desmin lead to muscular dystrophies of similar pathology. However, while in the absence of plectin, desmin networks collapse and form aggregates, when desmin is missing, plectin retains its typical localization. This suggests that plectin recruits and anchors desmin filaments to both Z-disks and costameres and thus is a key element for maintaining and reinforcing myocyte cytoarchitecture. We hypothesize that as an essential link of the Z-disk-costamere axis, plectin is likely to play also a crucial role in myofiber signaling.