Altered signaling surrounding the C-lobe of cardiac troponin C in myofilaments containing an α-tropomyosin mutation linked to familial hypertrophic cardiomyopathy

Eileen M. Burkart, Grace M. Arteaga, Marius P. Sumandea, Rethinasamy Prabhakar, David F. Wieczorek, R. John Solaro

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

A region of interaction between the near N-terminal of cardiac troponin I (cTnI) and the C-lobe of troponin C (cTnC), where troponin T (cTnT) binds, appears to be critical in regulation of myofilament Ca2+-activation. We probed whether functional consequences of modulation of this interface influence the function of tropomyosin (Tm) in thin filament activation. We modified the C-lobe of cTnC directly by addition of the Ca 2+-sensitizer, EMD 57033, and indirectly by replacing native cTnI with cTnI-containing Glu residues at Ser-43 and Ser-45 (cTnI-S43E/S45E) in myofilaments from hearts of non-transgenic (NTG) and transgenic (TG) mice expressing a point mutation on α-Tm (E180G) linked to familial hypertrophic cardiomyopathy. Introduction of cTnI-S43E/S45E induced a significantly greater reduction in tension in TG myofilaments compared to NTG controls. Furthermore, the effect of EMD 57033 to restore Ca 2+-sensitivity was higher in TG compared to NTG fiber bundles containing cTnI-S43E/S45E and compared to TG or NTG fiber bundles containing native TnI. Our results indicate that alterations in regions of interaction among the N-terminal of cTnI, the C-lobe of cTnC, and the C-terminus of cTnT are important in the regulation of myofilament activity. Although levels of phosphorylation at protein kinase C-dependent sites were the same in TG and NTG myofilaments, our data indicate that the effects of phosphorylation were more depressive in TG hearts.

Original languageEnglish (US)
Pages (from-to)1285-1293
Number of pages9
JournalJournal of Molecular and Cellular Cardiology
Volume35
Issue number10
DOIs
StatePublished - Oct 1 2003

Keywords

  • Ca -sensitizers
  • Hypertrophy
  • Protein kinase C
  • Tropomyosin
  • Troponin

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

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