Increased regulatory activity of the calcineurin/NFAT pathway in human heart failure

Background: Cardiac hypertrophy may initiate progression to a compromised cardiac function. While the clinical consequences of hypertrophy are well understood, only little is known about the underlying molecular pathways. As reported from animal experiments, the Ca2+‐calmodulin activated phosphatase...

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Bibliographic Details
Published in:European journal of heart failure 2004-01, Vol.6 (1), p.3-9
Main Authors: Diedrichs, Holger, Chi, Mei, Boelck, Birgit, Mehlhorm, Uwe, Schwinger, Robert H.G.
Format: Article
Language:English
Subjects:
Adult
Calcineurin
Calcineurin - genetics
Calcineurin - metabolism
Cardiomyopathy
Cardiomyopathy, Dilated - metabolism
Cell Nucleus - metabolism
DNA-Binding Proteins - genetics
DNA-Binding Proteins - metabolism
Female
GATA-4
GATA4 Transcription Factor
Heart failure
Humans
Hypertrophy
Male
Middle Aged
Myocardium - metabolism
NFAT-3
NFATC Transcription Factors
Nuclear Proteins
RNA, Messenger - genetics
Signal Transduction - physiology
Transcription Factors - genetics
Transcription Factors - metabolism
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Summary:Background: Cardiac hypertrophy may initiate progression to a compromised cardiac function. While the clinical consequences of hypertrophy are well understood, only little is known about the underlying molecular pathways. As reported from animal experiments, the Ca2+‐calmodulin activated phosphatase calcineurin and its downstream transcriptional effector NFAT have been implicated as transducers of the hypertrophic response. Methods and results: To study whether the calcineurin pathway is activated in human heart failure, we investigated samples of human left ventricular myocardium from patients with dilated (idiopathic) cardiomyopathy (DCM, NYHA IV, n=8) in comparison with non‐failing controls (NF, n=8). We not only analyzed the pathway by measuring the calcineurin activity, but also by determination of the protein expression of the calcineurin B subunit and additional key markers of the calcineurin signaling cascade (NFAT‐3, GATA‐4). Calcineurin enzymatic activity was increased by 80% in human dilated cardiomyopathy compared with non‐failing human hearts (135.424±11.69 and 83.484±1.81 nmol Pi/min per μl). This was in line with increased protein expression of calcineurin B in DCM (71.18+9.11 vs. 46.41±11.23 densitometric units (DU)/μg protein). In order to verify the activated calcineurin pathway as described in animal models, we compared the protein expression of NFAT‐3 in homogenates within nuclear extracts. In nuclear extracts the protein level of NFAT‐3 was increased in dilated cardiomyopathy compared with non‐failing myocardium (104.01±8.85 vs. 71.47±8.79 DU/μg protein). In contrast, in homogenates the expression of NFAT‐3 was higher in the non‐failing tissue indicating subcellular redistribution (19.56±3.36 vs. 25.84±3.16 DU/μg protein). The protein expression of GATA‐4 was increased in DCM (43.14±2.89 vs. 29.87±2.17 DU/μg protein). Conclusions: In human heart failure (DCM) the calcineurin signaling pathway is activated not only by an increased activity of calcineurin and expression of GATA‐4, but also by the shift from dephosphorylated NFAT‐3 to the nucleus indicating subcellular redistribution and regulatory activation.
ISSN:1388-9842
1879-0844
DOI:10.1016/j.ejheart.2003.07.007