Abstract 17545: Different Human Mutations in the Myosin Binding Protein C3 (MYBPC3) Produce Specific Cardiac Phenotypes in the Zebrafish
Mutations in the gene encoding myosin binding protein C3 (MYBPC3) are one of the commonest causes of Hypertrophic cardiomyopathy and can produce varying phenotypes. The exact disease mechanisms responsible remain unknown. Zebrafish model offers unique opportunities to study human cardiovascular disease mechanisms in vivo.
We have modeled different human MYBPC3 mutations in zebrafish embryos. Morpholinos targeting zebrafish mybpc3 were injected to model four disease causing missense mutations of domain C1. Mutation1 (Arg177His), Mutation 2 (Ala216Thr), Mutation 3 (Glu258Lys) that were identified in Egypt for the first time by Kassem et al  and Mutation 4 (Ser217Gly) that was recently identified in Qatar. The morpholino targets Mutation 1, 2 and 4 at exon 5 and Mutation 3 at exon 6 splice donor site in zebrafish embryos, in order to precisely recapitulate the human mutations.
Different MYBPC3 human mutations produced specific cardiac phenotypes in zebrafish embryos. These morphant embryos (3 days old) displayed aberrant cardiac phenotype and induced hypertrophic cardiomyopathy similar to the human phenotype. Defective heart phenotype was observed in 51% of Mutation 1, 2 and 4 and 68% of Mutation 3. In both groups pericardial edema was present in almost 20%; as an early manifest of heart failure. Mutation 3 resulted in severe cardiac phenotype exhibited by more zebrafish morphant embryos with enlarged cardiac chambers and reduced heart rate compared to other mutations. These results support our molecular modeling of domain C1, suggesting that Mutations 1, 2 and 4 increase intra-molecular rigidity to induce structural changes and have minimal effect on electrostatic properties at the surface. Interestingly, Mutation 3 inversely impacts the structural properties and has major effect on the surface of C1 and may lead to malfunction of the protein.
In summary: we investigated features that characterize human MYBPC3 variants in zebrafish model. The translational site blocking of zebrafish mybpc3 recapitulated the human hypertrophic cardiomyopathy, while missense Mutation 3 at exon 6 seems to cause more severe disease phenotype than Mutation 1, 2 and 4 at exon 5 in the zebrafish morphant embryos.
1. Kassem H. et al 2013 J Cardiovasc Transl Res 6: 65-80
Author Disclosures: S.I. Da’as: None. J. Yu: None. J.T. Butcher: None. N. Krishnamoorthy: None. J. Al Suwaidi: None. H. Kassem: None. K.N. Al Shafai: None. M.A. Al-Hashemi: None. L. Shuayb: None. T. Brand: None. M.H. Yacoub: None.
- © 2014 by American Heart Association, Inc.