Key result
Titin-based passive tension in striated and smooth muscle cells is regulated by alternative splicing and posttranslational modifications during normal function and disease.
Provides an overview of the structure-function relationship of titin in muscle cells and its role in determining myocardial passive tension.
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Should not yet change management of myocardial stiffness; leaves open titin splicing and modifications as targets for future mechanistic studies.
The striated muscle sarcomere contains, in addition to thin and thick filaments, a third myofilament comprised of titin. The extensible region of titin spans the I-band region of the sarcomere and develops passive force in stretched sarcomeres. This force positions the A-bands in the middle of the sarcomere, maintains sarcomere length homogeneity and, importantly, is responsible for myocardial passive tension that determines diastolic filling. Recent work suggests that smooth muscle expresses a truncated titin isoform with a short extensible region that is predicted to develop high passive force levels. Several mechanisms for tuning the titin-based passive tension have been discovered that involve alternative splicing as well as posttranslational modification, mechanisms that are at play both during normal muscle function as well as during disease.
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Granzier et al. (2007) reported a review. Titin-based passive tension in striated and smooth muscle cells is regulated by alternative splicing and posttranslational modifications during normal function and disease.
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