Sarcomere length dependent effects on the interaction between cTnC and cTnI in skinned papillary muscle strips

King-Lun Li; Nazanin Bohlooli Ghashghaee; R. John Solaro; Wenji Dong

doi:10.1016/j.abb.2016.02.030

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Sarcomere length dependent effects on the interaction between cTnC and cTnI in skinned papillary muscle strips

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Sarcomere length dependent effects on the interaction between cTnC and cTnI in skinned papillary muscle strips

King-Lun Li, Nazanin Bohlooli Ghashghaee, R. John Solaro and Wenji Dong

Archives of biochemistry and biophysics, Vol.601, pp.69-79

07/01/2016

DOI: https://doi.org/10.1016/j.abb.2016.02.030

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https://hdl.handle.net/2376/106410

PMCID: PMC4899114

PMID: 26944554

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Abstract

Crossbridge

Thin filament regulation

Troponin

Sarcomere length dependent activation

Fluorescence resonance energy transfer (FRET)

Sarcomere length dependent activation (LDA) of myocardial force development is the cellular basis underlying the Frank-Starling law of the heart, but it is still elusive how the sarcomeres detect the length changes and convert them into altered activation of thin filament. In this study we investigated how the C-domain of cardiac troponin I (cTnI) functionally and structurally responds to the comprehensive effects of the Ca2+, crossbridge, and sarcomere length of chemically skinned myocardial preparations. Using our in situ technique which allows for simultaneous measurements of time-resolved FRET and mechanical force of the skinned myocardial preparations, we measured changes in the FRET distance between cTnI(167C) and cTnC(89C), labeled with FRET donor and acceptor, respectively, as a function of [Ca2+], crossbridge state and sarcomere length of the skinned muscle preparations. Our results show that [Ca2+], cross-bridge feedback and sarcomere length have different effects on the structural transition of the C-domain cTnI. In particular, the interplay between crossbridges and sarcomere length has significant impacts on the functional structural change of the C-domain of cTnI in the relaxed state. These novel observations suggest the importance of the C-domain of cTnI and the dynamic and complex interplay between various components of myofilament in the LDA mechanism. •The conformational change of C-domain of cTnI is Ca2+ and crossbridge states dependent.•The C-domain of cTnI is sensitive to sarcomere length and crossbridge states changes only in relaxed muscle.•The dynamic behavior of C-domain of cTnI is closely related to the binding states of crossbridges on the actin filament.•Changes in the structural dynamics of C-domain of cTnI reflect its functional importance in the thin filament regulation.

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Title: Sarcomere length dependent effects on the interaction between cTnC and cTnI in skinned papillary muscle strips
Creators: King-Lun Li - Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
Nazanin Bohlooli Ghashghaee - Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
R. John Solaro - The Department of Physiology and Biophysics, Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA
Wenji Dong - Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
Publication Details: Archives of biochemistry and biophysics, Vol.601, pp.69-79
Academic Unit: Chemical Engineering and Bioengineering, School of
Publisher: Elsevier Inc
Identifiers: 99900547495101842
Language: English
Resource Type: Journal article