The distinctive mechanical and structural signatures of residual force enhancement in myofibers.

Autor:	Hessel AL; Institute of Physiology II, University of Muenster; Muenster, Germany., Kuehn M; Institute of Physiology II, University of Muenster; Muenster, Germany., Palmer BM; Department of Molecular Physiology and Biophysics, University of Vermont; Burlington, VT, 05405-1705, USA., Nissen D; BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA., Mishra D; Department of Biological Sciences, University of Northern Arizona; Flagstaff AZ, USA., Joumaa V; Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB T2N1N4, Canada., Freundt J; Institute of Physiology II, University of Muenster; Muenster, Germany., Ma W; BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA., Nishikawa KC; Department of Biological Sciences, University of Northern Arizona; Flagstaff AZ, USA., Irving T; BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA., Linke WA; Institute of Physiology II, University of Muenster; Muenster, Germany.
Jazyk:	angličtina
Zdroj:	BioRxiv : the preprint server for biology [bioRxiv] 2023 Feb 21. Date of Electronic Publication: 2023 Feb 21.
DOI:	10.1101/2023.02.19.529125
Abstrakt:	In muscle, titin proteins connect myofilaments together and are thought to be critical for contraction, especially during residual force enhancement (RFE) when force is elevated after an active stretch. We investigated titin's function during contraction using small-angle X-ray diffraction to track structural changes before and after 50% titin cleavage and in the RFE-deficient, mdm titin mutant. We report that the RFE state is structurally distinct from pure isometric contractions, with increased thick filament strain and decreased lattice spacing, most likely caused by elevated titin-based forces. Furthermore, no RFE structural state was detected in mdm muscle. We posit that decreased lattice spacing, increased thick filament stiffness, and increased non-crossbridge forces are the major contributors to RFE. We conclude that titin directly contributes to RFE. Competing Interests: Competing interests: Authors declare that they have no competing interests.
Databáze:	MEDLINE
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