Mutant Muscle LIM Protein C58G causes cardiomyopathy through protein depletion
Research output: Contribution to journal › Article
Colleges, School and Institutes
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, OX3 9DU, UK.
- From the Division of Cardiovascular Medicine, British Heart Foundation Centre for Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, United Kingdom (E.M., D.J., J.P., P.C., K.M.C.); Wellcome Trust Centre for Human Genetics, Headington, Oxford, United Kingdom (E.M., J.P., P.C., K.M.C.); and Sir William Dunn School of Pathology, University of Oxford, United Kingdom (A.J.I., L.T., D.R.G.). firstname.lastname@example.org.
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, UK; Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK; Experimental Therapeutics, Radcliffe Department of Medicine, University of Oxford, UK.
- King's College London
- Department of Medicine, Howard Hughes Medical Institute, University of California at San Diego School of Medicine, 9500 Gilman Drive, La Jolla, CA 92093-0651, USA.
- Transgenic Core, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
Cysteine and glycine rich protein 3 (CSRP3) encodes Muscle LIM Protein (MLP), a well-established disease gene for Hypertrophic Cardiomyopathy (HCM). MLP, in contrast to the proteins encoded by the other recognised HCM disease genes, is non-sarcomeric, and has important signalling functions in cardiomyocytes. To gain insight into the disease mechanisms involved, we generated a knock-in mouse (KI) model, carrying the well documented HCM-causing CSRP3 mutation C58G. In vivo phenotyping of homozygous KI/KI mice revealed a robust cardiomyopathy phenotype with diastolic and systolic left ventricular dysfunction, which was supported by increased heart weight measurements. Transcriptome analysis by RNA-seq identified activation of pro-fibrotic signalling, induction of the fetal gene programme and activation of markers of hypertrophic signalling in these hearts. Further ex vivo analyses validated the activation of these pathways at transcript and protein level. Intriguingly, the abundance of MLP decreased in KI/KI mice by 80% and in KI/+ mice by 50%. Protein depletion was also observed in cellular studies for two further HCM-causing CSRP3 mutations (L44P and S54R/E55G). We show that MLP depletion is caused by proteasome action. Moreover, MLP C58G interacts with Bag3 and results in a proteotoxic response in the homozygous knock-in mice, as shown by induction of Bag3 and associated heat shock proteins. In conclusion, the newly generated mouse model provides insights into the underlying disease mechanisms of cardiomyopathy caused by mutations in the non-sarcomeric protein MLP. Furthermore, our cellular experiments suggest that protein depletion and proteasomal overload also play a role in other HCM-causing CSPR3 mutations that we investigated, indicating that reduced levels of functional MLP may be a common mechanism for HCM-causing CSPR3 mutations.
|Number of pages||10|
|Journal||Journal of Molecular and Cellular Cardiology|
|Publication status||Published - Aug 2018|
- hypertrophic cardiomyopathy, Sarcomere, Proteasome, Protein depletion, RNAseq transcriptome analysis, MLP C58G mutation, Mouse knock-in model, In vivo phenotyping