This work was supported by grants from the Spanish Ministry of Economy and Competitiveness (SAF2015-65722-R to Dr. Lara-Pezzi and SAF2014-59594-R to Dr. Serratosa), Autonomous Community of Madrid (2010-BMD2321, FIBROTEAM Consortium), European Union's FP7 (CardioNeT-ITN-289600, CardioNext-ITN-608027), the Spanish Carlos III Institute of Health (CPII14/00027 to Dr. Lara-Pezzi, PI13/00865 to Dr. Sanchez and RD12/0042/066 to Drs. Garcia-Pavia and Lara-Pezzi), and the National Institute of Neurological Disorders And Stroke of the National Institutes of Health (P01NS097197 to Dr. Sanchez). This work was also supported by the Plan Estatal de I+D+I 2013-2016-European Regional Development Fund (FEDER) "A way of making Europe," Spain. The Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC) is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and the Pro-CNIC Foundation, and is a Severo Ochoa Center of Excellence (MINECO award SEV-2015-0505). ; Sí
BACKGROUND In response to pressure overload, the heart develops ventricular hypertrophy that progressively decompensates and leads to heart failure. This pathological hypertrophy is mediated, among others, by the phosphatase calcineurin and is characterized by metabolic changes that impair energy production by mitochondria. OBJECTIVES The authors aimed to determine the role of the calcineurin splicing variant CnA beta 1 in the context of cardiac hypertrophy and its mechanism of action. METHODS Transgenic mice overexpressing CnAb1 specifically in cardiomyocytes and mice lacking the unique C-terminal domain in CnA beta 1 (CnA beta 1(Delta i12) mice) were used. Pressure overload hypertrophy was induced by transaortic constriction. Cardiac function was measured by echocardiography. Mice were characterized using various molecular analyses. RESULTS In contrast to other calcineurin isoforms, the authors show here that cardiac-specific overexpression of CnA beta 1 in transgenic mice reduces cardiac hypertrophy and improves cardiac function. This effect is mediated by activation of serine and one-carbon metabolism, and the production of antioxidant mediators that prevent mitochondrial protein oxidation and preserve ATP production. The induction of enzymes involved in this metabolic pathway by CnAb1 is dependent on mTOR activity. Inhibition of serine and one-carbon metabolism blocks the beneficial effects of CnA beta 1. CnA beta 1(Delta i12) mice show increased cardiac hypertrophy and declined contractility. CONCLUSIONS The metabolic reprogramming induced by CnAb1 redefines the role of calcineurin in the heart and shows for the first time that activation of the serine and one-carbon pathway has beneficial effects on cardiac hypertrophy and function, paving the way for new therapeutic approaches. (J Am Coll Cardiol 2018; 71: 654-67) (C) 2018 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/). ; This work was supported by grants from the European Union (CardioNeT-ITN-289600 and CardioNext-608027 to Dr. Lara-Pezzi; Meet-ITN-317433 to Dr. Enriquez; UE0/MCA1108 to Dr. Acin-Perez), from the Spanish Ministry of Economy and Competitiveness (SAF2015-65722-R and SAF2012-31451 to Dr. Lara-Pezzi; SAF2015-71521-REDC, BFU2013-50448, and SAF2012-32776 to Dr. Enriquez; RyC-2011-07826 to Dr. Acin-Perez; BIO2012-37926 and BIO2015-67580-P to Dr. Vazquez), from the Spanish Carlos III Institute of Health (CPII14/00027 to Dr. Lara-Pezzi; RD12/0042/066 to Drs. Garcia-Pavia and Lara-Pezzi), from the Regional Government of Madrid (2010-BMD-2321 ``Fibroteam´´ to Dr. Lara-Pezzi; 2011-BMD-2402 ``Mitolab´´ to Dr. Enriquez) and the FIS-ISCIII (PRB2-IPT13/0001 and RD12/0042/0056-RIC-RETICS to Dr. Vazquez). This work was also supported by the Plan Estatal de IthornDthornI 2013-2016-European Regional Development Fund (FEDER) ``A way of making Europe,´´ Spain. The CNIC is supported by the Spanish Ministry of Economy and Competitiveness and by the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (MINECO award SEV-2015-0505). Drs. Vazquez and Garcia-Pavia have served as consultants for VL39. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Drs. Padron-Barthe, Villalba-Orero, and Gomez-Salinero contributed equally to this work and are joint first authors. Robyn Shaw, MD, PhD, served as Guest Editor for this paper. ; Sí
Arrhythmogenic cardiomyopathy/arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiac disease characterized by fibrofatty replacement of the myocardium, resulting in heart failure and sudden cardiac death. The most aggressive arrhythmogenic cardiomyopathy/ARVC subtype is ARVC type 5 (ARVC5), caused by a p.S358L mutation in TMEM43 (transmembrane protein 43). The function and localization of TMEM43 are unknown, as is the mechanism by which the p.S358L mutation causes the disease. Here, we report the characterization of the first transgenic mouse model of ARVC5. Methods: We generated transgenic mice overexpressing TMEM43 in either its wild-type or p.S358L mutant (TMEM43-S358L) form in postnatal cardiomyocytes under the control of the α-myosin heavy chain promoter. Results: We found that mice expressing TMEM43-S358L recapitulate the human disease and die at a young age. Mutant TMEM43 causes cardiomyocyte death and severe fibrofatty replacement. We also demonstrate that TMEM43 localizes at the nuclear membrane and interacts with emerin and β-actin. TMEM43-S358L shows partial delocalization to the cytoplasm, reduced interaction with emerin and β-actin, and activation of glycogen synthase kinase-3β (GSK3β). Furthermore, we show that targeting cardiac fibrosis has no beneficial effect, whereas overexpression of the calcineurin splice variant calcineurin Aβ1 results in GSK3β inhibition and improved cardiac function and survival. Similarly, treatment of TMEM43 mutant mice with a GSK3β inhibitor improves cardiac function. Finally, human induced pluripotent stem cells bearing the p.S358L mutation also showed contractile dysfunction that was partially restored after GSK3β inhibition. Conclusions: Our data provide evidence that TMEM43-S358L leads to sustained cardiomyocyte death and fibrofatty replacement. Overexpression of calcineurin Aβ1 in TMEM43 mutant mice or chemical GSK3β inhibition improves cardiac function and increases mice life span. Our results pave the way toward new therapeutic approaches for ARVC5 ; his work was supported by grants from the European Union (CardioNeT-ITN-289600 and CardioNext-608027 to Dr Lara-Pezzi), the Spanish Ministry of Economy and Competitiveness (RTI2018-096961-B-I00, SAF2015-65722-R, and SAF2012-31451 to Dr Lara-Pezzi; SAF2015-71863-REDT to Dr Garcia-Pavia), the Spanish Carlos III Institute of Health (PI14/0967 to Dr Garcia-Pavia, CPII14/00027 to Dr Lara-Pezzi; RD012/0042/0066 to Drs Garcia-Pavia and Lara-Pezzi), the Regional Government of Madrid (2010-BMD-2321 "Fibroteam" to Dr Lara-Pezzi), the Isabel Gemio Foundation (Todos somos Raros grant to Dr Garcia-Pavia), and the Spanish Society of Cardiology (2014 Basic Research Grant to Dr Garcia-Pavia). This work was also supported by the Plan Estatal de I+D+I 2013-2016–European Regional Development Fund (FEDER) "A way of making Europe," Spain
BACKGROUND: Arrhythmogenic cardiomyopathy/arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiac disease characterized by fibrofatty replacement of the myocardium, resulting in heart failure and sudden cardiac death. The most aggressive arrhythmogenic cardiomyopathy/ARVC subtype is ARVC type 5 (ARVC5), caused by a p.S358L mutation in TMEM43 (transmembrane protein 43). The function and localization of TMEM43 are unknown, as is the mechanism by which the p.S358L mutation causes the disease. Here, we report the characterization of the first transgenic mouse model of ARVC5. METHODS: We generated transgenic mice overexpressing TMEM43 in either its wild-type or p.S358L mutant (TMEM43-S358L) form in postnatal cardiomyocytes under the control of the α-myosin heavy chain promoter. RESULTS: We found that mice expressing TMEM43-S358L recapitulate the human disease and die at a young age. Mutant TMEM43 causes cardiomyocyte death and severe fibrofatty replacement. We also demonstrate that TMEM43 localizes at the nuclear membrane and interacts with emerin and β-actin. TMEM43-S358L shows partial delocalization to the cytoplasm, reduced interaction with emerin and β-actin, and activation of glycogen synthase kinase-3β (GSK3β). Furthermore, we show that targeting cardiac fibrosis has no beneficial effect, whereas overexpression of the calcineurin splice variant calcineurin Aβ1 results in GSK3β inhibition and improved cardiac function and survival. Similarly, treatment of TMEM43 mutant mice with a GSK3β inhibitor improves cardiac function. Finally, human induced pluripotent stem cells bearing the p.S358L mutation also showed contractile dysfunction that was partially restored after GSK3β inhibition. CONCLUSIONS: Our data provide evidence that TMEM43-S358L leads to sustained cardiomyocyte death and fibrofatty replacement. Overexpression of calcineurin Aβ1 in TMEM43 mutant mice or chemical GSK3β inhibition improves cardiac function and increases mice life span. Our results pave the way toward new therapeutic approaches for ARVC5. ; This work was supported by grants from the European Union (CardioNeTITN-289600 and CardioNext-608027 to Dr Lara-Pezzi), the Spanish Ministry of Economy and Competitiveness (RTI2018-096961-B-I00, SAF2015-65722-R, and SAF2012-31451 to Dr Lara-Pezzi; SAF2015-71863-REDT to Dr Garcia-Pavia), the Spanish Carlos III Institute of Health (PI14/0967 to Dr Garcia-Pavia, CPII14/00027 to Dr Lara-Pezzi; RD012/0042/0066 to Drs Garcia-Pavia and Lara-Pezzi), the Regional Government of Madrid (2010-BMD-2321 "Fibroteam" to Dr Lara-Pezzi), the Isabel Gemio Foundation (Todos somos Raros grant to Dr Garcia-Pavia), and the Spanish Society of Cardiology (2014 Basic Research Grant to Dr Garcia-Pavia). This work was also supported by the Plan Estatal de I+D+I 2013-2016–European Regional Development Fund (FEDER) "A way of making Europe," Spain. The Centro Nacional de Investigaciones Cardiovasculares Carlos III is supported by the Ministerio de Ciencia, Innovación y Universidades (MCNU), and Pro Centro Nacional de Investigaciones Cardiovasculares Carlos III Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505). ; Sí
