Functional analysis of the FLNC W2164c missense variant associated with hypertrophic cardiomyopathy

Azad, Amar Joseph Singh (2023). Functional analysis of the FLNC W2164c missense variant associated with hypertrophic cardiomyopathy. University of Birmingham. Ph.D.

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Abstract

Hypertrophic cardiomyopathy (HCM) is an inherited cardiac condition associated with diastolic dysfunction and sudden cardiac death. Disease genes for HCM are traditionally coding for proteins involved in force generation. More recently, it has emerged that variants in genes coding for proteins involved in biomechanical stress-signalling can also cause HCM.
One such protein is filamin C, with proposed mechano-sensing functions in the heart. Within the protein, the immunogloblulin-like domain 20 (Ig20) may play a crucial role in mediating biomechanical stress responses. While the mechano-sensing functions of filamin C have been investigated well in skeletal muscle, the underlying cardiac disease mechanisms are not completely understood. A multi-generational family affected by cardiomyopathy were found to carry a FLNC variant located in the mechano-sensing Ig20 – FLNC W2164C.

Aim: This work attempts to provide insights into the role of filamin C in cardiac mechano-sensing and dissect disease pathways leading to HCM in the presence of the FLNC W2164C variant.

Methods: Using mass spectrometry, a detailed analysis of the proteome of mice carrying the filamin C variant, using ventricular tissue samples from 14wk old homozygous mice. An induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) model which harbored the FLNC W2164C variant was also investigated. Molecular biology techniques were utilized to determine the molecular phenotype of the FLNC W2164C variant in both mice and iPSC-CMs. iPSC-CMs were developed for improved characterization by fabricating culturing surfaces of physiological stiffness.

Results: Mice carrying this variant recapitulate molecular features of HCM and restrictive cardiomyopathy in the homozygous setting and showed evidence of protein redistribution to the intercalated disc. An HCM molecular phenotype was also described in the iPSC-CM model.

Conclusion: This work supports the pathogenic role of the FLNC W2164C variant in cardiomyopathy. This thesis highlights the importance of using both mice and iPSC-CMs for modelling cardiovascular disease in order to overcome individual model deficiencies.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):