Influence of nebulin on the assembly mechanics of desmin

Abstract

Desmin intermediate filaments (DIFs) bind to nebulin, forming a direct link between the intermediate filament (IF) cytoskeletal network and the Z-discs of myofibrils in muscle cells. As the main IF in muscles, desmin is important for the sarcomeres functional and structural organization. This structural alignment of myofibrils is responsible for maintaining the contractile apparatus, providing cellular stability and force transmission throughout the muscle system. The DIF mutant, E245D, is a missense mutation resulting in the substitution of aspartic acid for glutamic acid in the coil 1B region of desmin, a major binding site for nebulin. This DIF mutation is linked to desminopathy in humans, which is a debilitating familial disease associated with restrictive cardiomyopathies and progressive skeletal muscle weakness of the upper and lower extremities. This study aims to gain insight on the molecular mechanisms involved in desmin IF assembly when influenced by its association with nebulin. The E245D mutation was chosen as it maps in the high-affinity nebulin-binding 1B region of desmin. We will employ atomic force microscopy (AFM) to analyze the lengths and elasticity of DIFs using recombinantly generated human desmin and nebulin proteins.