Dynamic regulation of sarcomeric actin filaments in striated muscle.
Bottom Line: Actin and myosin filaments are organized in sarcomeres and specialized for producing contractile forces.Regular arrangement of actin filaments with uniform length and polarity is critical for the contractile function.Recent studies have suggested that both enhancers of actin dynamics and stabilizers of actin filaments are important for sarcomeric actin organization.
Affiliation: Department of Pathology and Department of Cell Biology, Emory University, Atlanta, Georgia 30322, USA. email@example.comShow MeSH
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Mentions: Studies in live muscle cells have demonstrated that actin in sarcomeres is dynamic during assembly and even in mature myofibrils. A number of regulators of sarcomeric actin dynamics have been identified, and functional studies have revealed their important roles in myofibril assembly, sarcomere organization, and maintenance of myofibrils (Fig. 2). Regulators of sarcomeric actin dynamics can be classified into two types: enhancers of actin dynamics and stabilizers of actin filaments (Fig. 2). Actin-dynamics enhancers (e.g., ADF/cofilin) and actin-filament stabilizers (e.g., tropomyosin) often antagonistically regulate actin turnover. Therefore, a simple model would be that these two types of actin regulators maintain a balance for proper assembly and maintenance of sarcomeric actin organizations. However, the actual process in muscle cells is expected to be much more complex, involving multiple mechanisms at different parts of sarcomeres under different cellular conditions. Importantly, we still do not understand why actin filaments even in mature sarcomeres must be dynamic. Further investigations on the functions of actin-dynamics regulators and physiological significance of actin dynamics in muscle should provide insights into the pathogenesis of muscle diseases as well as the normal mechanism of myofibril assembly and maintenance.
Affiliation: Department of Pathology and Department of Cell Biology, Emory University, Atlanta, Georgia 30322, USA. firstname.lastname@example.org