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Graded titin cleavage progressively reduces tension and uncovers the source of A-band stability in contracting muscle
- Source :
- eLife, Vol 9 (2020)
- Publication Year :
- 2020
- Publisher :
- eLife Sciences Publications Ltd, 2020.
-
Abstract
- The giant muscle protein titin is a major contributor to passive force; however, its role in active force generation is unresolved. Here, we use a novel titin-cleavage (TC) mouse model that allows specific and rapid cutting of elastic titin to quantify how titin-based forces define myocyte ultrastructure and mechanics. We show that under mechanical strain, as TC doubles from heterozygous to homozygous TC muscles, Z-disks become increasingly out of register while passive and active forces are reduced. Interactions of elastic titin with sarcomeric actin filaments are revealed. Strikingly, when titin-cleaved muscles contract, myosin-containing A-bands become split and adjacent myosin filaments move in opposite directions while also shedding myosins. This establishes intact titin filaments as critical force-transmission networks, buffering the forces observed by myosin filaments during contraction. To perform this function, elastic titin must change stiffness or extensible length, unveiling its fundamental role as an activation-dependent spring in contracting muscle.
Details
- Language :
- English
- ISSN :
- 2050084X
- Volume :
- 9
- Database :
- Directory of Open Access Journals
- Journal :
- eLife
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.14e6d313415849ec9d8bc171ea89d6f9
- Document Type :
- article
- Full Text :
- https://doi.org/10.7554/eLife.64107