Stress activated signalling impaired protein quality control pathways in human hypertrophic cardiomyopathy

Roua Hassoun,Melina Tangos,Samuel Sossalla,Heidi Budde,Muhammad Jarkas,Melissa Herwig,Hans Georg Mannherz,Marina Skrygan,Andreas Mügge,Nusratul Mostafi,Cris Dos Remedios,Nazha Hamdani,Kamilla Gömöri,Mária Lódi,Saltanat Zhazykbayeva,Simin Delalat,Thilo Gambichler,Steffen Pabel,Marcel Sieme,Vasco Sequeira,Stefanie Bruckmüller,Kornélia Jaquet ,Árṕad Kov́acs

doi:10.1016/j.ijcard.2021.09.009

Abstract

Hypertrophic cardiomyopathy (HCM) is a complex myocardial disorder with no well-established disease-modifying therapy so far. Our study aimed to investigate how autophagy, oxidative stress, inflammation, stress signalling pathways, and apoptosis are hallmark of HCM and their contribution to the cardiac dysfunction. Demembranated cardiomyocytes from patients with HCM display increased titin-based stiffness (Fpassive), which was corrected upon antioxidant treatment. Titin as a main determinant of Fpassive was S-glutathionylated and highly ubiquitinated in HCM patients. This was associated with a shift in the balance of reduced and oxidized forms of glutathione (GSH and GSSG, respectively). Both heat shock proteins (HSP27 and α-ß crystalline) were upregulated and S-glutathionylated in HCM. Administration of HSPs in vitro significantly reduced HCM cardiomyocyte stiffness. High levels of the phosphorylated monomeric superoxide anion-generating endothelial nitric oxide synthase (eNOS), decreased nitric oxide (NO) bioavailability, decreased soluble guanylyl cyclase (sGC) activity, and high levels of 3-nitrotyrosine were observed in HCM. Many regulators of signal transduction pathways that are involved in autophagy, apoptosis, cardiac contractility, and growth including the mitogen-activated protein kinase (MAPK), protein kinase B (AKT), glycogen synthase kinase 3ß (GSK-3ß), mammalian target of rapamycin (mTOR), forkhead box O transcription factor (FOXO), c-Jun N-terminal protein kinase (JNK), and extracellular-signal-regulated kinase (ERK1/2) were modified in HCM. The apoptotic factors cathepsin, procaspase 3, procaspase 9 and caspase 12, but not caspase 9, were elevated in HCM hearts and associated with increased proinflammatory cytokines (Interleukin 6 (IL-6), interleukin 18 (IL-18), intercellular cell adhesion molecule-1 (ICAM1), vascular cell adhesion molecule-1 (VCAM1), the Toll-like receptors 2 (TLR2) and the Toll-like receptors 4 (TLR4)) and oxidative stress (3-nitrotyrosine and hydrogen peroxide (H2O2)). Here we reveal stress signalling and impaired PQS as potential mechanisms underlying the HCM phenotype. Our data suggest that reducing oxidative stress can be a viable therapeutic approach to attenuating the severity of cardiac dysfunction in heart failure and potentially in HCM and prevent its progression.

Highlights

In demembranated cardiomyocytes Ca2+-independent passive force (Fpas sive) Fig. 1A was significantly elevated at sarcomere length (SL) 2.0 to 2.3 μm compared to controls, this increase was restored at SL 2.2 μm or higher upon treat ment with GSH, while Fpassive of control cardiomyocytes remained un altered, indicating the contribution of oxidative stress and potentially titin oxidation to the diastolic dysfunction observed in Hypertrophic cardiomyopathy (HCM)
We found a significant increase in total titin glutathionylation and a high level of titin ubiquitination in HCM samples compared to humannon failing hearts (Fig. 1C)
In the present study we provide evidence of 1) increased myocardial stiffness which can be partially attributed to increased oxidative stress, 2) dysregulated protein quality control system (PQS) as shown by the upregulation of heat shock proteins (HSPs), ubiquitinproteasome and autophagy markers, 3) increased levels of apoptotic factors, 4) alterations of signalling pathways involved in post trans lational modifications of sarcomeric proteins, metabolic stress, and hy pertrophy induction

Summary

Introduction

Hypertrophic cardiomyopathy (HCM) is a complex myocardial dis order characterized by asymmetrical ventricular hypertrophy, hyper contractile systolic function, and impaired relaxation. HCM is the most common cardiomyopathy with a prevalence of 1:500–1:1000 [1]. It can be acquired or of genetic disorder, whereby more than 70% of the cases are familial [1]. The enhanced Ca2+-sensitivity of contraction is known to be the main characteristic feature of HCM and considered as the primary pathological mechanism [2,3]. Functional studies on the effects of HCM mutations on Ca2+-sensitivity provided evidence on the linkage between the altered myofilament Ca2+-response and hypercontractility, impaired relaxation, and ventricular arrythmia observed in HCM patients

Results

Discussion

Conclusion