Portero, V.* ; Nicol, T.* ; Podliesna, S.* ; Marchal, G.A.* ; Baartscheer, A.* ; Casini, S.* ; Tadros, R.* ; Treur, J.L.* ; Tanck, M.W.T.* ; Cox, I.J.* ; Probert, F.* ; Hough, T.A.* ; Falcone, S.* ; Beekman, L.* ; Müller-Nurasyid, M. ; Kastenmüller, G. ; Gieger, C. ; Peters, A. ; Kääb, S.* ; Sinner, M.F.* ; Blease, A.* ; Verkerk, A.O.* ; Bezzina, C.R.* ; Potter, P.K.* ; Remme, C.A.*
     
    
        
Chronically elevated branched chain amino acid levels are pro-arrhythmic.
    
    
        
    
    
        
        Cardiovasc. Res. 118:1742–1757 (2021)
    
    
    
      
      
	
	    AIM: Cardiac arrhythmias comprise a major health and economic burden and are associated with significant morbidity and mortality, including cardiac failure, stroke and sudden cardiac death (SCD). Development of efficient preventive and therapeutic strategies is hampered by incomplete knowledge of disease mechanisms and pathways. Our aim is to identify novel mechanisms underlying cardiac arrhythmia and SCD using an unbiased approach. METHODS AND RESULTS: We employed a phenotype-driven N-ethyl-N-nitrosourea (ENU) mutagenesis screen and identified a mouse line with a high incidence of sudden death at young age (6-9 weeks) in the absence of prior symptoms. Affected mice were found to be homozygous for the nonsense mutation Bcat2p.Q300*/p.Q300* in the Bcat2 gene encoding branched chain amino acid transaminase 2. At the age of 4-5 weeks, Bcat2p.Q300*/p.Q300* mice displayed drastic increase of plasma levels of branch chain amino acids (BCAAs - leucine, isoleucine, valine) due to the incomplete catabolism of BCAAs, in addition to inducible arrhythmias ex vivo as well as cardiac conduction and repolarization disturbances. In line with these findings, plasma BCAA levels were positively correlated to ECG indices of conduction and repolarization in the German community-based KORA F4 Study. Isolated cardiomyocytes from Bcat2p.Q300*/p.Q300* mice revealed action potential (AP) prolongation, pro-arrhythmic events (early and late afterdepolarizations, triggered APs) and dysregulated calcium homeostasis. Incubation of human pluripotent stem cell-derived cardiomyocytes with elevated concentration of BCAAs induced similar calcium dysregulation and pro-arrhythmic events which were prevented by rapamycin, demonstrating the crucial involvement of mTOR pathway activation. CONCLUSIONS: Our findings identify for the first time a causative link between elevated BCAAs and arrhythmia, which has implications for arrhythmogenesis in conditions associated with BCAA metabolism dysregulation such as diabetes, metabolic syndrome and heart failure. TRANSLATIONAL PERSPECTIVES: Development of efficient anti-arrhythmic strategies is hampered by incomplete knowledge of disease mechanisms. Using an unbiased approach, we here identified for the first time a pro-arrhythmic effect of increased levels of branched chain amino acids (BCAAs). This is of particular relevance for conditions associated with BCAA dysregulation and increased arrhythmia risk, including heart failure, obesity and diabetes, as well as for athletes supplementing their diet with BCAAs. Such metabolic dysregulation is potentially modifiable through dietary interventions, paving the way for novel preventive strategies. Our findings furthermore identify mTOR inhibition as a potential anti-arrhythmic strategy in patients with metabolic syndrome.
	
	
	    
	
       
      
	
	    
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        Publication type
        Article: Journal article
    
 
    
        Document type
        Scientific Article
    
 
    
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        Keywords
        Arrhythmia ; Bcaa ; Electrophysiology ; Metabolism ; Sudden Death; Sudden Cardiac Death; Late Sodium Current; Atrial-fibrillation; Oxidative Stress; Enu Mutagenesis; Sex-differences; Calcium; Aminotransferase; Mechanisms; Obesity
    
 
    
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        Language
        english
    
 
    
        Publication Year
        2021
    
 
    
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        HGF-reported in Year
        2021
    
 
    
    
        ISSN (print) / ISBN
        0008-6363
    
 
    
        e-ISSN
        1755-3245
    
 
    
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	    Volume: 118,  
	    Issue: 7,  
	    Pages: ,  
	    Article Number: 1742–1757 
	    Supplement: ,  
	
    
 
    
        
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            Publisher
            Oxford University Press
        
 
        
            Publishing Place
            Great Clarendon St, Oxford Ox2 6dp, England
        
 
	
        
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        Reviewing status
        Peer reviewed
    
 
     
    
        POF-Topic(s)
        30202 - Environmental Health
30501 - Systemic Analysis of Genetic and Environmental Factors that Impact Health
30205 - Bioengineering and Digital Health
    
 
    
        Research field(s)
        Genetics and Epidemiology
Enabling and Novel Technologies
    
 
    
        PSP Element(s)
        G-504090-001
G-504100-001
G-503891-001
G-504091-004
G-504000-010
    
 
    
        Grants
        Brain & Behavior Research Foundation
Dutch Heart Foundation (CVON-eDETECT)
Netherlands Organization for Scientific Research
Philippa and Marvin Carsley Chair in cardiology
Fondation Leducq Transatlantic Network of Excellence
Medical Research Council, UK
Dutch Heart Foundation (CVON-PREDICT2)
    
 
    
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        Erfassungsdatum
        2021-07-16