ABSTRACT
The cytoskeleton is an intricate network of filaments and accessory proteins that allows cardiac myocytes to withstand the large mechanical stresses that are experienced during each heart beat and maintains the structural integrity of the myocyte. The cytoskeleton is comprised of three main types of filaments: microtubules, intermediate filaments, and actin filaments. The main intermediate filament type in cardiac myocytes is desmin. Desmin monomers polymerize to long rope-like filaments that are likely to provide mechanical integrity and strength to the cardiac myocyte. Desmin filaments surround myofibrils and laterally connect adjacent Z-disks and M-lines, ensuring thereby that during contraction sarcomeres of adjacent myofibrils remain in register. Actin filaments consist of actin monomers that polymerized head-to-tail to form slender filaments. In the sarcomere, F-actin filaments are associated with regulatory proteins to form thin filaments, and are crosslinked by a-actinin in the Z-disk.
