SNTA1 gene rescues ion channel function and is antiarrhythmic in cardiomyocytes derived from induced pluripotent stem cells from muscular dystrophy patients

Abstract

Background:Patients with cardiomyopathy of Duchenne Muscular Dystrophy (DMD) are at risk of developing life-threatening arrhythmias, but the mechanisms are unknown. We aimed to determine the role of ion channels controlling cardiac excitability in the mechanisms of arrhythmias in DMD patients.Methods:To test whether dystrophin mutations lead to defective cardiac NaV1.5–Kir2.1 channelosomes and arrhythmias, we generated iPSC-CMs from two hemizygous DMD males, a heterozygous female, and two unrelated control males. We conducted studies including confocal microscopy, protein expression analysis, patch-clamping, non-viral piggy-bac gene expression, optical mapping and contractility assays.Results:Two patients had abnormal ECGs with frequent runs of ventricular tachycardia. iPSC-CMs from all DMD patients showed abnormal action potential profiles, slowed conduction velocities, and reduced sodium (INa) and inward rectifier potassium (IK1) currents. Membrane NaV1.5 and Kir2.1 protein levels were reduced in hemizygous DMD iPSC-CMs but not in heterozygous iPSC-CMs. Remarkably, transfecting just one component of the dystrophin protein complex (α1-syntrophin) in hemizygous iPSC-CMs from one patient restored channelosome function, INa and IK1 densities, and action potential profile in single cells. In addition, α1-syntrophin expression restored impulse conduction and contractility and prevented reentrant arrhythmias in hiPSC-CM monolayers.Conclusions:We provide the first demonstration that iPSC-CMs reprogrammed from skin fibroblasts of DMD patients with cardiomyopathy have a dysfunction of the NaV1.5–Kir2.1 channelosome, with consequent reduction of cardiac excitability and conduction. Altogether, iPSC-CMs from patients with DMD cardiomyopathy have a NaV1.5–Kir2.1 channelosome dysfunction, which can be rescued by the scaffolding protein α1-syntrophin to restore excitability and prevent arrhythmias.Funding:Supported by National Institutes of Health R01 HL122352 grant; ‘la Caixa’ Banking Foundation (HR18-00304); Fundación La Marató TV3: Ayudas a la investigación en enfermedades raras 2020 (LA MARATO-2020); Instituto de Salud Carlos III/FEDER/FSE; Horizon 2020 - Research and Innovation Framework Programme GA-965286 to JJ; the CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovación (MCIN) and the Pro CNIC Foundation), and is a Severo Ochoa Center of Excellence (grant CEX2020-001041-S funded by MICIN/AEI/10.13039/501100011033). American Heart Association postdoctoral fellowship 19POST34380706s to JVEN. Israel Science Foundation to OB and MA [824/19]. Rappaport grant [01012020RI]; and Niedersachsen Foundation [ZN3452] to OB; US-Israel Binational Science Foundation (BSF) to OB and TH [2019039]; Dr. Bernard Lublin Donation to OB; and The Duchenne Parent Project Netherlands (DPPNL 2029771) to OB. National Institutes of Health R01 AR068428 to DM and US-Israel Binational Science Foundation Grant [2013032] to DM and OB.

Ion channels as biomarkers of altered myogenesis in myofiber precursors of Duchenne muscular dystrophy

“…In addition, whereas the barium‐sensitive component seemed to contribute only in part to the outward current in WT cells, DYS myocyte outward currents were almost barium‐insensitive. In cardiomyocytes, a similar reduction of this Kir‐mediated attribute has been observed in mdx ventricular cardiomyocytes 19 and in iPSC‐cardiomyocytes from DMD patients 62 …”

“…In cardiomyocytes, a similar reduction of this Kir-mediated attribute has been observed in mdx ventricular cardiomyocytes 19 and in iPSC-cardiomyocytes from DMD patients. 62 The lower expression of Kcnj2 is also in agreement with reduced Myog mRNA level in DYS myocytes; this again corroborates that terminal differentiation may be altered in DYS cells. Of note, Kcnj2…”

Plasticity occurs in a specific phenotype of neurons in the nucleus tractus solitarius of dystrophin gene‐mutated rats

“…We are considering the possibility of alterations in other ion channel properties because of dystrophin deficiency. In fact, downregulation of voltage‐sensitive sodium channels was reported in cardiomyocytes derived from induced pluripotent stem cells from muscular dystrophy patients (Jienez‐Vazquez et al, 2022). If the similar changes happened to DS‐type neurons in D m rats, it might be reasonable that no significant change was observed in action potential waveforms between WT and D m rats (Table 1).…”

Brugada syndrome: from genetics, diagnosis to clinical therapy

“…The aforementioned variants may impair membrane trafficking, modify channel gating properties or kinetics, or cause haploinsufficiency due to premature transcriptional stop signals. Specifically, previous research has revealed a decrease in I Na and I K1 density and conduction www.cardiologyplus.org Huang K and Ren J: Cardiology Plus velocities or a loss of regulation by intracellular factors in signal transduction, including protein kinase A (PKA), ankyrin G, or a1-syntrophin [20][21] .…”