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FHL2 expression and variants in hypertrophic cardiomyopathy.

Friedrich FW, Reischmann S, Schwalm A, Unger A, Ramanujam D, Münch J, Müller OJ, Hengstenberg C, Galve E, Charron P, Linke WA, Engelhardt S, Patten M, Richard P, van der Velden J, Eschenhagen T, Isnard R, Carrier L - Basic Res. Cardiol. (2014)

Bottom Line: 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.We assessed the structural and functional consequences of the nonsynonymous substitutions after adeno-associated viral-mediated gene transfer in cardiac myocytes and in 3D-engineered heart tissue (EHT).Finally, chronic phenylephrine stimulation depressed EHT function in all groups, but to a lower extent in T171M-transduced EHTs.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

ABSTRACT
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 cardiomyopathy (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 density 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 nonsynonymous 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 markedly down-regulated α-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 conditions. Finally, chronic phenylephrine stimulation depressed EHT function in all groups, but to a lower extent in 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 endothelin-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.

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FHL2 genetic variants detected in patients with hypertrophic cardiomyopathy. a Pedigrees of families with HCM carrying FHL2 missense variants. Roman numerals symbolize generations. Arabic numerals mark individuals within each generation. Males are symbolized as squares, females as circles. Individuals with HCM are indicated by black symbols, individuals with an intermediate phenotype by gray symbols, unaffected individuals by empty symbols, and deceased individuals by a diagonal line. Index cases are indicated by arrows. Family members with a plus sign (+) carry the respective genetic variant at the heterozygous state; non-carriers are marked with a minus sign (−); individuals without signs were not genotyped. b Variants in the FHL2 gene. Exon numbers, and translational start (ATG) and stop (TGA) codons are indicated. Light gray squares represent noncoding regions. The FHL2 variants identified in HCM patients are depicted. c Localization of FHL2 genetic variants in the LIM domains
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Fig2: FHL2 genetic variants detected in patients with hypertrophic cardiomyopathy. a Pedigrees of families with HCM carrying FHL2 missense variants. Roman numerals symbolize generations. Arabic numerals mark individuals within each generation. Males are symbolized as squares, females as circles. Individuals with HCM are indicated by black symbols, individuals with an intermediate phenotype by gray symbols, unaffected individuals by empty symbols, and deceased individuals by a diagonal line. Index cases are indicated by arrows. Family members with a plus sign (+) carry the respective genetic variant at the heterozygous state; non-carriers are marked with a minus sign (−); individuals without signs were not genotyped. b Variants in the FHL2 gene. Exon numbers, and translational start (ATG) and stop (TGA) codons are indicated. Light gray squares represent noncoding regions. The FHL2 variants identified in HCM patients are depicted. c Localization of FHL2 genetic variants in the LIM domains

Mentions: Next we evaluated whether FHL2 genetic variants could be associated with HCM. We screened a cohort of 121 HCM patients devoid of mutations in five of the major HCM disease genes (MYH7, MYBPC3, TNNT2, TNNI3, or MYL2). We identified two novel and one known FHL2 genetic variants and three other known FHL2 synonymous polymorphisms (Fig. 2; Table 1, Online Table 1).Fig. 2


FHL2 expression and variants in hypertrophic cardiomyopathy.

Friedrich FW, Reischmann S, Schwalm A, Unger A, Ramanujam D, Münch J, Müller OJ, Hengstenberg C, Galve E, Charron P, Linke WA, Engelhardt S, Patten M, Richard P, van der Velden J, Eschenhagen T, Isnard R, Carrier L - Basic Res. Cardiol. (2014)

FHL2 genetic variants detected in patients with hypertrophic cardiomyopathy. a Pedigrees of families with HCM carrying FHL2 missense variants. Roman numerals symbolize generations. Arabic numerals mark individuals within each generation. Males are symbolized as squares, females as circles. Individuals with HCM are indicated by black symbols, individuals with an intermediate phenotype by gray symbols, unaffected individuals by empty symbols, and deceased individuals by a diagonal line. Index cases are indicated by arrows. Family members with a plus sign (+) carry the respective genetic variant at the heterozygous state; non-carriers are marked with a minus sign (−); individuals without signs were not genotyped. b Variants in the FHL2 gene. Exon numbers, and translational start (ATG) and stop (TGA) codons are indicated. Light gray squares represent noncoding regions. The FHL2 variants identified in HCM patients are depicted. c Localization of FHL2 genetic variants in the LIM domains
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4215105&req=5

Fig2: FHL2 genetic variants detected in patients with hypertrophic cardiomyopathy. a Pedigrees of families with HCM carrying FHL2 missense variants. Roman numerals symbolize generations. Arabic numerals mark individuals within each generation. Males are symbolized as squares, females as circles. Individuals with HCM are indicated by black symbols, individuals with an intermediate phenotype by gray symbols, unaffected individuals by empty symbols, and deceased individuals by a diagonal line. Index cases are indicated by arrows. Family members with a plus sign (+) carry the respective genetic variant at the heterozygous state; non-carriers are marked with a minus sign (−); individuals without signs were not genotyped. b Variants in the FHL2 gene. Exon numbers, and translational start (ATG) and stop (TGA) codons are indicated. Light gray squares represent noncoding regions. The FHL2 variants identified in HCM patients are depicted. c Localization of FHL2 genetic variants in the LIM domains
Mentions: Next we evaluated whether FHL2 genetic variants could be associated with HCM. We screened a cohort of 121 HCM patients devoid of mutations in five of the major HCM disease genes (MYH7, MYBPC3, TNNT2, TNNI3, or MYL2). We identified two novel and one known FHL2 genetic variants and three other known FHL2 synonymous polymorphisms (Fig. 2; Table 1, Online Table 1).Fig. 2

Bottom Line: 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.We assessed the structural and functional consequences of the nonsynonymous substitutions after adeno-associated viral-mediated gene transfer in cardiac myocytes and in 3D-engineered heart tissue (EHT).Finally, chronic phenylephrine stimulation depressed EHT function in all groups, but to a lower extent in T171M-transduced EHTs.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

ABSTRACT
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 cardiomyopathy (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 density 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 nonsynonymous 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 markedly down-regulated α-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 conditions. Finally, chronic phenylephrine stimulation depressed EHT function in all groups, but to a lower extent in 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 endothelin-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.

Show MeSH
Related in: MedlinePlus