1
|
Gehmlich K, Jiang A, Wadmore K, Hooper C, Douglas G, Ehler E, Broadway-Stringer S, Kalisch-Smith J, Sparrow D, Gautel M, Davies B, Watkins H. Crucial functions of alpha-actinin 2 in the embryonic heart. Cardiovasc Res 2022. [DOI: 10.1093/cvr/cvac066.137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: Foundation. Main funding source(s): Wellcome Trust; British Heart Foundation
Background/Introduction
Alpha-actinin is an integral protein of the Z-discs in heart and skeletal muscle cells, with important structural and signalling functions. Missense variants in alpha-actinin can cause inherited conditions, e.g. myopathies and cardiomyopathies. The underlying disease mechanisms are still unknown.
Purpose
In order to study the disease mechanisms of an alpha-actinin missense variant, which is known to cause Hypertrophic Cardiomyopathy in human patients, a mouse model was generated.
Methods
Mice carrying the alpha-actinin missense variant were generated by CRISPR-Cas9 genome editing. The heterozygous adult mice carrying the alpha-actinin variant were characterised by echocardiography and quantitative PCR. Hearts of homozygous embryos were analysed at E15.5 by high-resolution episcopic microscopy (HREM).
Results
Mice carrying a single copy of the missense variant were viable and had normal appearance. Adult heterozygous mice showed no signs of cardiomyopathy on echocardiography. However, mature male mice displayed molecular signs of cardiomyopathy, such as induction of the fetal gene programme at transcript level.
The attempt to generate adult mice homozygous for the variant failed: 9 breeding pairs produced 18 litters with 83 weaned pups, but no homozygous offspring. Embryonic lethality was confirmed and E15.5 was the latest stage homozygous pups were reliably found to be viable. At this timepoint, genotype distribution was within the expected Mendelian ratios.
HREM of the hearts at this stage revealed increased right ventricular chamber size and decreased left atrial size, when compared to wildtype littermates. Membranous ventricular septal defects were observed in 3 out of 8 homozygous hearts. Further these embryos displayed aortic stenosis and dysplasic leaflets of the pulmonary valve.
Conclusions
Heterozygous adult mice only displayed sub-clinical signs of disease. In contrast, the missense variant is embryonic lethal in the homozygous setting and leads to a range of morphological abnormalities in E15.5 hearts. Future work will identify how altered functions of alpha-actinin cause these changes.
Collapse
Affiliation(s)
- K Gehmlich
- Institute of Cardiovascular Sciences , Birmingham , United Kingdom of Great Britain & Northern Ireland
| | - A Jiang
- University of Oxford, Cardiovascular Medicine , Oxford , United Kingdom of Great Britain & Northern Ireland
| | - K Wadmore
- Institute of Cardiovascular Sciences , Birmingham , United Kingdom of Great Britain & Northern Ireland
| | - C Hooper
- University of Oxford, Cardiovascular Medicine , Oxford , United Kingdom of Great Britain & Northern Ireland
| | - G Douglas
- University of Oxford, Cardiovascular Medicine , Oxford , United Kingdom of Great Britain & Northern Ireland
| | - E Ehler
- King's College London , London , United Kingdom of Great Britain & Northern Ireland
| | - S Broadway-Stringer
- Institute of Cardiovascular Sciences , Birmingham , United Kingdom of Great Britain & Northern Ireland
| | - J Kalisch-Smith
- University of Oxford, Department of Physiology, Anatomy and Genetics , Oxford , United Kingdom of Great Britain & Northern Ireland
| | - D Sparrow
- University of Oxford, Department of Physiology, Anatomy and Genetics , Oxford , United Kingdom of Great Britain & Northern Ireland
| | - M Gautel
- King's College London , London , United Kingdom of Great Britain & Northern Ireland
| | - B Davies
- University of Oxford, Wellcome Centre for Human Genetics , Oxford , United Kingdom of Great Britain & Northern Ireland
| | - H Watkins
- University of Oxford, Cardiovascular Medicine , Oxford , United Kingdom of Great Britain & Northern Ireland
| |
Collapse
|