FHL2 expression and variants in hypertrophic cardiomyopathy

Felix W. Friedrich (1, 2) , Silke Reischmann (1, 2) , Aileen Schwalm (1, 2) , Andrea Unger (3) , Deepak Ramanujam (2, 4) , Julia Münch (5) , Oliver J Müller (2, 6) , Christian Hengstenberg (7) , Enrique Galve (8) , Philippe Charron (9, 10) , Wolfgang A Linke (3) , Stefan Engelhardt (2, 4) , Monica Patten (5) , Pascale Richard (10, 9, 11, 11) , Jolanda van Der Velden (12) , Thomas Eschenhagen (1, 2) , Richard Isnard (9, 11, 10) , Lucie Carrier (1, 2)

1 Department of Experimental Pharmacology and Toxicology
2 DZHK - German Centre for cardiovasculat research
3 Department of cardiovascular physiology
4 Institute of pharmacology and toxicology
5 University Heart Center Hamburg
6 Department of cardiology
7 Klinik und poliklinik für Innere Medizin II
8 Unitat d'insuficiencia cardiaca
9 U956
10 ICAN - Unité de Recherche sur les Maladies Cardiovasculaires, du Métabolisme et de la Nutrition = Research Unit on Cardiovascular and Metabolic Diseases
11 CHU Pitié-Salpêtrière [AP-HP]
12 Laboratory for physiology

Based on evidence that FHL2 (four and a half LIM domains protein 2) negatively regulates cardiac hypertrophy we tested whether FHL2 altered expression or variants could be associated with hypertrophic cardiomy-opathy (HCM). HCM is a myocardial disease characterized by left ventricular hypertrophy, diastolic dysfunction and increased interstitial fibrosis and is mainly caused by mutations in genes coding for sarcomeric proteins. FHL2 mRNA level, FHL2 protein level and I-band-binding den-sity were lower in HCM patients than control individuals. Screening of 121 HCM patients without mutations in established disease genes identified 2 novel (T171M, V187L) and 4 known (R177Q, N226N, D268D, P273P) FHL2 variants in unrelated HCM families. We assessed the structural and functional consequences of the nonsynony-mous substitutions after adeno-associated viral-mediated gene transfer in cardiac myocytes and in 3D-engineered heart tissue (EHT). Overexpression of FHL2 wild type or nonsynonymous substitutions in cardiac myocytes mark-edly down-regulated a-skeletal actin and partially blunted hypertrophy induced by phenylephrine or endothelin-1. After gene transfer in EHTs, force and velocity of both contraction and relaxation were higher with T171M and V187L FHL2 variants than wild type under basal condi-tions. Finally, chronic phenylephrine stimulation depressed EHT function in all groups, but to a lower extent in Electronic supplementary material The online version of this article (T171M-transduced EHTs. These data suggest that (1) FHL2 is down-regulated in HCM, (2) both FHL2 wild type and variants partially protected phenylephrine-or endo-thelin-1-induced hypertrophy in cardiac myocytes, and (3) FHL2 T171M and V187L nonsynonymous variants induced altered EHT contractility. These findings provide evidence that the 2 novel FHL2 variants could increase cardiac function in HCM.

Domaines: Cardiologie et système cardiovasculaire

Felix W. Friedrich, Silke Reischmann, Aileen Schwalm, Andrea Unger, Deepak Ramanujam, et al.. FHL2 expression and variants in hypertrophic cardiomyopathy. Basic Research in Cardiology, 2014, 109, pp.451. ⟨10.1007/s00395-014-0451-8⟩. ⟨hal-01110561⟩