Calcium sensitivity and myofilament lattice structure in titin N2B KO mice

Eun Jeong Lee, Joshua Nedrud, Peter Schemmel, Michael Gotthardt, Thomas C. Irving, Hendrikus "Henk" Granzier

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The cellular basis of the Frank-Starling "Law of the Heart" is the length-dependence of activation, but the mechanisms by which the sarcomere detects length changes and converts this information to altered calcium sensitivity has remained elusive. Here the effect of titin-based passive tension on the length-dependence of activation (LDA) was studied by measuring the tension-pCa relation in skinned mouse LV muscle at two sarcomere lengths (SLs). N2B KO myocardium, where the N2B spring element in titin is deleted and passive tension is elevated, was compared to WT myocardium. Myofilament lattice structure was studied with low-angle X-ray diffraction; the myofilament lattice spacing (d1,0) was measured as well as the ratio of the intensities of the 1,1 and 1,0 diffraction peaks (I1,1/I1,0) as an estimate of the degree of association of myosin heads with the thin filaments. Experiments were carried out in skinned muscle in which the lattice spacing was reduced with Dextran-T500. Experiments with and without lattice compression were also carried out following PKA phosphorylation of the skinned muscle. Under all conditions that were tested, LDA was significantly larger in N2B KO myocardium compared to WT myocardium, with the largest differences following PKA phosphorylation. A positive correlation between passive tension and LDA was found that persisted when the myofilament lattice was compressed with Dextran and that was enhanced following PKA phosphorylation. Low-angle X-ray diffraction revealed a shift in mass from thin filaments to thick filaments as sarcomere length was increased. Furthermore, a positive correlation was obtained between myofilament lattice spacing and passive tension and the change in I 1,1/I1,0 and passive tension and these provide possible explanations for how titin-based passive tension might regulate calcium sensitivity.

Original languageEnglish (US)
Pages (from-to)76-83
Number of pages8
JournalArchives of Biochemistry and Biophysics
Volume535
Issue number1
DOIs
StatePublished - Jul 1 2013

Fingerprint

Connectin
Myofibrils
Sarcomeres
Phosphorylation
Myocardium
Chemical activation
Calcium
Muscle
Dextrans
X-Ray Diffraction
Muscles
Starlings
X ray diffraction
Myosins
Diffraction
Experiments
Association reactions

Keywords

  • Calcium sensitivity
  • Cardiac contraction
  • Lattice structure
  • Passive tension
  • Titin

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Cite this

Calcium sensitivity and myofilament lattice structure in titin N2B KO mice. / Lee, Eun Jeong; Nedrud, Joshua; Schemmel, Peter; Gotthardt, Michael; Irving, Thomas C.; Granzier, Hendrikus "Henk".

In: Archives of Biochemistry and Biophysics, Vol. 535, No. 1, 01.07.2013, p. 76-83.

Research output: Contribution to journalArticle

Lee, Eun Jeong ; Nedrud, Joshua ; Schemmel, Peter ; Gotthardt, Michael ; Irving, Thomas C. ; Granzier, Hendrikus "Henk". / Calcium sensitivity and myofilament lattice structure in titin N2B KO mice. In: Archives of Biochemistry and Biophysics. 2013 ; Vol. 535, No. 1. pp. 76-83.
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