Contractile dysfunction in a mouse model expressing a heterozygous MYBPC3 mutation associated with hypertrophic cardiomyopathy Journal Article


Authors: Barefield, D.; Kumar, M; de Tombe, P. P.; Sadayappan, S
Article Title: Contractile dysfunction in a mouse model expressing a heterozygous MYBPC3 mutation associated with hypertrophic cardiomyopathy
Abstract: The etiology of hypertrophic cardiomyopathy (HCM) has been ascribed to mutations in genes encoding sarcomere proteins. In particular, mutations in MYBPC3, a gene which encodes cardiac myosin binding protein-C (cMyBP-C), have been implicated in over one third of HCM cases. Of these mutations, 70% are predicted to result in C'-truncated protein products, which are undetectable in tissue samples. Heterozygous carriers of these truncation mutations exhibit varying penetrance of HCM, with symptoms often occurring later in life. We hypothesize that heterozygous carriers of MYBPC3 mutations, while seemingly asymptomatic, have subtle functional impairments that precede the development of overt HCM. This study compared heterozygous (+/t) knock-in MYBPC3 truncation mutation mice with wild-type (+/+) littermates to determine whether functional alterations occur at the whole-heart or single-cell level before the onset of hypertrophy. The +/t mice show approximately 40% reduction in MYBPC3 transcription, but no changes in cMyBP-C level, phosphorylation status, or cardiac morphology. Nonetheless, +/t mice show significantly decreased maximal force development at sarcomere lengths of 1.9 mum (+/t 68.5 +/- 4.1 mN/mm(2) vs. +/+ 82.2 +/- 3.2) and 2.3 mum (+/t 79.2 +/- 3.1 mN/mm(2) vs. +/+ 95.5 +/- 2.4). In addition, heterozygous mice show significant reductions in vivo in the early/after (E/A) (+/t 1.74 +/- 0.12 vs. +/+ 2.58 +/- 0.43) and E'/A' (+/t 1.18 +/- 0.05 vs. +/+ 1.52 +/- 0.15) ratios, indicating diastolic dysfunction. These results suggest that seemingly asymptomatic heterozygous MYBPC3 carriers do suffer impairments that may presage the onset of HCM.
Journal Title: American Journal of Physiology - Heart Circulatory Physiology
Volume: 306
Issue: 6
ISSN: 0363-6135
Publisher: Unknown  
Journal Place: United States
Date Published: 2014
Start Page: H807
End Page: 15
Language: eng
DOI/URL:
Notes: GR: HL-101297/HL/NHLBI NIH HHS/United States; GR: HL-62426/HL/NHLBI NIH HHS/United States; GR: HL-75494/HL/NHLBI NIH HHS/United States; GR: K02HL-114749/HL/NHLBI NIH HHS/United States; GR: R01HL-105826/HL/NHLBI NIH HHS/United States; JID: 100901228; 0 (Carrier Proteins); 0 (myosin-binding protein C); OID: NLM: PMC3949045 [Available on 03/15/15]; OTO: NOTNLM; PMCR: 2015/03/15 00:00; 2014/01/24 [aheadofprint]; ppublish