Related Experiment Video
Updated: Feb 5, 2026
Investigating the Pathogenesis of MYH7 Mutation Gly823Glu in Familial Hypertrophic Cardiomyopathy using a Mouse Model
Published on: August 8, 2022
Variable cardiac myosin binding protein-C expression in the myofilaments due to MYBPC3 mutations in hypertrophic
R Y Parbhudayal1, A R Garra2, M J W Götte3
1Department of Physiology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Cardiovascular Sciences, the Netherlands; Department of Cardiology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Cardiovascular Sciences, the Netherlands; The Netherlands Heart Institute, Utrecht, the Netherlands.
Insights
Mutations in the MYBPC3 gene cause hypertrophic cardiomyopathy (HCM) by leading to inconsistent cardiac myosin binding protein-C (cMyBP-C) levels between heart cells. This study shows significant cell-to-cell variation in cMyBP-C expression in MYBPC3-mutant HCM patients.
Area of Science:
- Cardiovascular Biology
- Molecular Cardiology
- Genetic Diseases
Background:
- Hypertrophic cardiomyopathy (HCM) is commonly caused by mutations in the MYBPC3 gene.
- These MYBPC3 mutations lead to dysfunctional cardiac myosin binding protein-C (cMyBP-C) that is not properly incorporated into myofilaments.
- Heterozygous mutations and differing allelic expression suggest potential cell-to-cell variability in cMyBP-C levels.
Purpose of the Study:
- To investigate the hypothesis that MYBPC3 mutations in HCM lead to significant cell-to-cell variation in cardiac myosin binding protein-C (cMyBP-C) protein levels within the myocardium.
- To quantify the intercellular variability of cMyBP-C expression in cardiomyocytes from HCM patients with and without MYBPC3 mutations.
Main Methods:
- Analyzed cardiac tissue from twelve HCM patients (six with MYBPC3 mutations [MYBPC3mut] and six without [HCMsmn]).
- Utilized Western blot and RNA sequencing to measure overall cMyBP-C protein and mRNA levels.
- Employed immunofluorescence staining to assess cellular cMyBP-C and α-actin expression, quantifying the cMyBP-C:α-actin ratio for intercellular variability analysis.
Main Results:
- MYBPC3mut patients exhibited significantly reduced overall cMyBP-C protein and mRNA levels compared to HCMsmn controls.
- Immunofluorescence revealed homogenous cMyBP-C:α-actin staining in HCMsmn cardiomyocytes, contrasting with inhomogeneous staining and significant intercellular variability in MYBPC3mut patients.
- The coefficient of variance for cMyBP-C/α-actin staining was significantly higher in MYBPC3mut patients (17.30 ± 4.08%) versus HCMsmn patients (5.18 ± 0.65%).
Conclusions:
- This study provides the first evidence of intercellular variation in myofilament cMyBP-C protein expression within the myocardium of HCM patients carrying heterozygous MYBPC3 mutations.
- The findings highlight a novel aspect of MYBPC3-related HCM pathogenesis, emphasizing protein level heterogeneity at the cellular level.
Background:
Mutations in MYBPC3 are the most common cause of hypertrophic cardiomyopathy (HCM). These mutations produce dysfunctional protein that is quickly degraded and not incorporated in the myofilaments. Most patients are heterozygous and allelic expression differs between cells. We hypothesized that this would lead to cell-to-cell variation in cardiac myosin binding protein-C (cMyBP-C, encoded by MYBPC3 gene) protein levels.
Methods:
Twelve HCM patients were included (six had no sarcomere mutations (HCMsmn) and served as the control group and six harbored mutations in the MYBPC3 gene (MYBPC3mut). Western blot and RNA sequencing analysis of cardiac tissue lysates were performed to detect overall cMyBP-C protein and mRNA levels. Cellular expression of cMyBP-C and α-actin was obtained by immunofluorescence staining. Quantification of cell-to-cell variation of cMyBP-C expression between cardiomyocytes was measured by determining the ratio of cMyBP-C:α-actin stained area of each cell.
Results:
Protein and mRNA analysis revealed significantly reduced cMyBP-C levels in MYBPC3mut patients compared with HCMsmn patients (0.73 ± 0.09 vs. 1.0 ± 0.15, p < .05; 162.3 ± 16.4 vs. 326.2 ± 41.9 RPKM, p = .002), without any sign of truncated proteins. Immunofluorescence staining of individual cardiomyocytes in HCMsmn patients demonstrated homogenous and equal cMyBP-C:α-actin staining ratio. In contrast, MYBPC3mut patients demonstrated inhomogeneous staining patterns with a large intercellular variability per patient. Coefficient of variance for cMyBP-C/α-actin staining for each patient showed a significant difference between both groups (17.30 ± 4.08 vs. 5.18 ± 0.65% in MYBPC3mut vs. HCMsmn, p = .02).
Conclusion:
This is the first study to demonstrate intercellular variation of myofilament cMyBP-C protein expression within the myocardium from HCM patients with heterozygous MYBPC3 mutations.
More Related Videos
10:12A Sensitive and Specific Quantitation Method for Determination of Serum Cardiac Myosin Binding Protein-C by Electrochemiluminescence Immunoassay
Published on: August 8, 2013
08:29Assessment of Myofilament Ca2+ Sensitivity Underlying Cardiac Excitation-contraction Coupling
Published on: August 1, 2016
Related Concept Videos
01:29Cardiomyopathy III: Hypertrophic Cardiomyopathy
01:39Mutations
01:30Cardiomyopathy II: Dilated Cardiomyopathy
01:29Cardiomyopathy IV: Restrictive Cardiomyopathy
02:18The Equilibrium Binding Constant and Binding Strength
01:49Conserved Binding Sites
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally...