Inhibition of HSC70 alleviates hypertrophic cardiomyopathy pathology in human induced pluripotent stem cell‐derived cardiomyocytes with a MYBPC3 mutation

Abstract

Dear Editor,We performed a comprehensive study to assess the pathogenicity of a cardiac myosin binding protein C3 (MYBPC3) variant (L460fs) and to pinpoint underlying molecular mechanisms by utilizing human-induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) model. L460fs iPSC-CMs exhibited a variety of deleterious phenotypes in response to angiotensin II (Ang II), including reduced MYBPC3 expression, hypertrophy, arrhythmia and elevated diastolic intracellular Ca 2+ [Ca 2+ ] i . Mechanistically, heat shock protein family A (HSP70) member 8 (HSC70) accelerated MYBPC3 degradation via lysosomal pathway under Ang II stress. The reduced MYBPC3binding ryanodine receptor 2 (RYR2) caused by insufficiency of MYBPC3 protein may give rise to excessive free destabilized RYR2, which in turn promoted RYR2mediated Ca 2+ leak. The resultant elevated Ca 2+ loading may trigger the development of both hypertrophy and arrhythmogenesis, particularly under stress conditions. 1 Hypertrophic cardiomyopathy (HCM), featured by asymmetric ventricular hypertrophy, arrhythmias and sudden cardiac death (SCD), is the most common form of inherited cardiac disease. 2,3 To note, HCM has been repeatedly regarded as a major cause of SCD in young people. 4 MYBPC3, which encodes cardiac myosin-binding protein C, is the most frequent HCM-associated gene, accounting for more than 50% of the HCM patients. 5 However, the exact mechanism of MYBPC3-related HCM remains to be resolved. 6,7 In this study, a MYBPC3 variant (c.1377delC; p.L460fs) was identified in four-unrelated individuals who developed HCM in middle age (Figure 1A,B). The echocardiography and cardiac magnetic resonance imaging exhibited normal ventricular function, severe interventricular septum hypertrophy but without left ventricular outflow tract obstruction (Figure 1C, Figure S1A-D and Table S1). With treatment of β blockers or Ca 2+ channel blockers,This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

A pathogenic nonsense mutation (c.1522C>T) of the MYBPC3 gene is implicated with hypertrophic cardiomyopathy

“…Moreover, the pathogenicity of MYBPC3 truncating variants has also been intensively confirmed in iPSCMs and mice. Recently, Qiu et al constructed mutant iPSCMs with a MYBPC3 truncating variant (c.1377del; p.Leu460fs; rs786204339) that was identified from a HCM family 18 . Notably, mutant iPSCMs exhibited key features of cardiac hypertrophy in the presence of angiotensin II, including increased cell volume and expression of hypertrophic‐specific markers 18 .…”

“…Recently, Qiu et al constructed mutant iPSCMs with a MYBPC3 truncating variant (c.1377del; p. Leu460fs; rs786204339) that was identified from a HCM family. 18 Notably, mutant iPSCMs exhibited key features of cardiac hypertrophy in the presence of angiotensin II, including increased cell volume and expression of hypertrophic-specific markers. 18 Consistently, a significant reduction in cardiac contractility was also observed in mice with the heterozygous MYBPC3 truncating variant.…”

“…18 Notably, mutant iPSCMs exhibited key features of cardiac hypertrophy in the presence of angiotensin II, including increased cell volume and expression of hypertrophic-specific markers. 18 Consistently, a significant reduction in cardiac contractility was also observed in mice with the heterozygous MYBPC3 truncating variant. 19 Taken together, we conclude that the MYBPC3 c.1522C>T variant is responsible for the index's HCM.…”

Myosin inhibitor reverses hypertrophic cardiomyopathy in pediatric iPSC-cardiomyocytes to mirror variant correction

“…Human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CMs) have been used to model HCM and study drug responses, either through reprogramming of patient cells to iPSCs or through CRISPR-editing of variants into healthy control iPSCs. [9][10][11][12][13][14][15][16][17][18][19][20][21] However, most studies were in adult . CC-BY-NC-ND 4.0 International license available under a was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.…”

“…It is made Patient and control iPSCs were differentiated into CMs in accordance with an established differentiation protocol using STEMdiff Cardiomyocyte Differentiation Kit 27 (STEMCELL Technologies, Vancouver, BC). The CMs were then maintained from day 8 using a combination of Stem Cell Technologies and iCell Maintenance media (FUJIFILM Cellular Dymamics, Madison, WI) where Stem Cell Technologies medium was gradually decreased by 25% and iCell medium increased by 25% every other day until CMs were maintained in 100% iCell medium (day[14][15][16]. iCell medium can effectively remove non-cardiomyocytes in differentiated cells.…”