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Transgenic rabbits expressing mutant essential light chain do not develop hypertrophic cardiomyopathy
Jeanne James1, Yan Zhang, Kathy Wright
1Children's Hospital Research Foundation, Cincinnati, Ohio, 45229-3039, USA.
Abstract:
Mutations in multiple sarcomeric proteins can cause familial hypertrophic cardiomyopathy. Although a M149V mutation in the myosin light chain is associated with the human disease, the data from transgenic (TG) mouse models are conflicting. When a human genomic fragment containing the M149V essential myosin light chain was used to generate TG mice, the phenotype was recapitulated. However, when the mouse cDNA containing the mutation was used to generate TG animals, no phenotype could be discerned. TG rabbits can be a valuable complement and extension to mouse-based TG models and we wished to determine whether expression of this mutation in the rabbit heart would result in the disease. The rabbit essential light chain cDNA was isolated, sequenced, the M149V mutation made and the cDNA placed into the beta-myosin heavy chain promoter, which efficiently drives cardiac expression in the rabbit ventricles. Multiple TG rabbit lines showing different levels of protein replacement were obtained. No discernible pattern of disease was apparent at the structural or functional levels at either the neonatal, juvenile or adult stages. We conclude that the M149V mutation is not causative for FHC when expressed in the rabbit within the context of the endogenous protein.
Insights
The M149V mutation in myosin light chain does not cause familial hypertrophic cardiomyopathy (FHC) in rabbits. This study found no structural or functional disease patterns in transgenic rabbits expressing the mutation.
Area of Science:
- Cardiovascular Biology
- Genetics
- Molecular Medicine
Background:
- Familial hypertrophic cardiomyopathy (FHC) is linked to sarcomeric protein mutations.
- A myosin light chain M149V mutation is associated with human FHC, but mouse models show conflicting results.
- Transgenic (TG) rabbits offer a complementary model to TG mice for studying cardiac disease.
Purpose of the Study:
- To investigate if the M149V mutation in the essential myosin light chain causes FHC in a TG rabbit model.
- To assess the structural and functional impact of the M149V mutation in the rabbit heart.
Main Methods:
- Isolated and sequenced rabbit essential light chain cDNA.
- Introduced the M149V mutation into the cDNA.
- Utilized the beta-myosin heavy chain promoter for cardiac-specific expression in TG rabbits.
- Analyzed TG rabbits at neonatal, juvenile, and adult stages for disease phenotypes.
Main Results:
- Generated multiple TG rabbit lines with varying levels of M149V myosin light chain replacement.
- Observed no discernible structural or functional disease patterns in any TG rabbit cohort.
- The M149V mutation did not induce FHC-like phenotypes in rabbits.
Conclusions:
- The M149V mutation is not causative for FHC when expressed in the rabbit heart.
- TG rabbits expressing the M149V mutation do not develop hypertrophic cardiomyopathy.
- This study highlights the importance of model systems in understanding disease mechanisms.