S100A1 Genetically Targeted Therapy Reverses Dysfunction of Human Failing Cardiomyocytes

Abstract

Objectives This study investigated the hypothesis whether S100A1 gene therapy can improve pathological key features in human failing ventricular cardiomyocytes (HFCMs). Background Depletion of the Ca2+-sensor protein S100A1 drives deterioration of cardiac performance toward heart failure (HF) in experimental animal models. Targeted repair of this molecular defect by cardiac-specific S100A1 gene therapy rescued cardiac performance, raising the immanent question of its effects in human failing myocardium. Methods Enzymatically isolated HFCMs from hearts with severe systolic HF were subjected to S100A1 and control adenoviral gene transfer and contractile performance, calcium handling, signaling, and energy homeostasis were analyzed by video-edge-detection, FURA2-based epifluorescent microscopy, phosphorylation site-specific antibodies, and mitochondrial assays, respectively. Results Genetically targeted therapy employing the human S100A1 cDNA normalized decreased S100A1 protein levels in HFCMs, reversed both contractile dysfunction and negative force-frequency relationship, and improved contractile reserve under beta-adrenergic receptor (β-AR) stimulation independent of cAMP-dependent (PKA) and calmodulin-dependent (CaMKII) kinase activity. S100A1 reversed underlying Ca2+ handling abnormalities basally and under β-AR stimulation shown by improved SR Ca2+ handling, intracellular Ca2+ transients, diastolic Ca2+ overload, and diminished susceptibility to arrhythmogenic SR Ca2+ leak, respectively. Moreover, S100A1 ameliorated compromised mitochondrial function and restored the phosphocreatine/adenosine-triphosphate ratio. Conclusions Our results demonstrate for the first time the therapeutic efficacy of genetically reconstituted S100A1 protein levels in HFCMs by reversing pathophysiological features that characterize human failing myocardium. Our findings close a gap in our understanding of S100A1’s effects in human cardiomyocytes and strengthen the rationale for future molecular-guided therapy of human HF.

Targeting S100A1 in heart failure

“…Mechanistically, these effects were independent of PKA-and CaM-dependent protein kinase II pathway activation, supporting the hypothesis for a direct interaction of S100A1 with its various target proteins. 57 Taken together, these data foster previous results from various animal models and present an exciting step towards first human clinical studies. However, attention should be paid against premature exploration of these in vitro findings of isolated failing CM into the intact organ and the human clinical stetting, as S100A1 is not only expressed in CM but also in the vasculature and is furthermore released from damaged CM, eventually fostering paracrine effects.…”

“…56,57 These initial findings promoted further elaborate analysis and started the extensive research on the impact of S100A1 on cardiovascular pathology.…”

“…57 Adenoviral-mediated S100A1 gene transfer resulted in re-expression of S100A1 protein levels in failing CM and was able to improve contractile performance and reverse negative force-frequency relationship, a hallmark of human failing hearts. Furthermore, S100A1 gene therapy was able to improve cellular Ca 2+ handling and SR Ca 2+ load, inhibit pro-arrhythmogenic diastolic SR Ca 2+ leak and restore mitochondrial function and energy homeostasis.…”

S100A1 Protein Does Not Compete with Calmodulin for Ryanodine Receptor Binding but Structurally Alters the Ryanodine Receptor·Calmodulin Complex

“…However, given that S100A1 has other targets found in native SR preparations, there is a strong need to determine whether competition is specifically for RyR1. Furthermore, it is important to determine whether this mechanism also applies to CaM and S100A1 binding to RyR2, particularly given the strong therapeutic potential of S100A1 for heart failure (10,23,(25)(26)(27). There are few data indicative of S100A1 interacting at the CaM binding site on RyR2.…”

Research Advances in Heart Failure

“…As pointed out in the review by Pleger et al 46 in this Compendium, SERCA2a and phospholamban are important targets of gene transfer. Other agents that may improve myocardial contractility by acting on myocyte Ca 2+ cycling include S100A1, a protein that interacts with both SERCA2a and RyR2, 47 which also requires gene transfer, as well as small molecules, such as mecamtiv mecarbil, that increase the sensitivity of cardiac myofilaments to Ca 2+ and increase stroke volume by increasing the duration, but not the rate, of cardiac contraction and therefore do not require much additional oxygen. 48 Also, RyR2 stabilizers 49 are being actively investigated.…”