Beyond the sarcomere: CSRP3 mutations cause hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a frequent genetic cardiac disease and the most common cause of sudden cardiac death in young individuals. Most of the currently known HCM disease genes encode sarcomeric proteins. Previous studies have shown an association between CSRP3 missense mutations and either dilated cardiomyopathy (DCM) or HCM, but all these studies were unable to provide comprehensive genetic evidence for a causative role of CSRP3 mutations. We used linkage analysis and identified a CSRP3 missense mutation in a large German family affected by HCM. We confirmed CSRP3 as an HCM disease gene. Furthermore, CSRP3 missense mutations segregating with HCM were identified in four other families. We used a newly designed monoclonal antibody to show that muscle LIM protein (MLP), the protein encoded by CSRP3, is mainly a cytosolic component of cardiomyocytes and not tightly anchored to sarcomeric structures. Our functional data from both in vitro and in vivo analyses suggest that at least one of MLP's mutated forms seems to be destabilized in the heart of HCM patients harbouring a CSRP3 missense mutation. We also present evidence for mild skeletal muscle disease in affected persons. Our results support the view that HCM is not exclusively a sarcomeric disease and also suggest that impaired mechano-sensory stress signalling might be involved in the pathogenesis of HCM.

Asymmetric dimethylarginine is an independent risk factor for coronary heart disease: results from the multicenter Coronary Artery Risk Determination investigating the Influence of ADMA Concentration (CARDIAC) study.

BACKGROUND: Asymmetric dimethylarginine (ADMA) plasma levels have been shown to be elevated in diseases related to endothelial dysfunction such as hypertension, hyperlipidemia, diabetes mellitus, and others. It has been shown that ADMA predicts cardiovascular mortality in patients who have coronary heart disease (CHD). However, the question whether ADMA is an independent risk factor for CHD still remains unresolved. METHODS: The CARDIAC study is a multicenter case-control study, designed to detect differences in ADMA plasma levels between patients with CHD and controls from the general population. We included in our analysis 131 cases and 131 controls, matched for age, sex, and body mass index. RESULTS: We found that cases had higher ADMA plasma levels than controls (0.70 micromol/L [0.59-0.87 micromol/L] vs 0.60 micromol/L [0.54-0.69 micromol/L], P < .001). To evaluate the predictive power of ADMA regarding CHD, we calculated 2 multivariate logistic regression models including laboratory parameters and traditional risk factors. The odds ratio for ADMA in the multivariate model including the laboratory characteristics was 2.59 (1.61-4.17; P < .001); the odds ratio for the multivariate model including other risk factors was 6.04 (2.56-14.25; P < .001) for the third tertile (>0.72 micromol/L) versus the first (<0.58 micromol/L). CONCLUSIONS: We conclude from the results of our study that ADMA is an independent risk factor for CHD.

Calcineurin in human heart hypertrophy.

BACKGROUND: In animal models, increased signaling through the calcineurin pathway has been shown to be sufficient for the development of cardiac hypertrophy. Calcineurin activity has been reported to be elevated in the myocardium of patients with congestive heart failure. In contrast, few data are available about calcineurin activity in patients with pressure overload or cardiomyopathic hypertrophy who are not in cardiac failure. METHODS AND RESULTS: We investigated calcineurin activity and protein expression in 2 different forms of cardiac hypertrophy: hypertrophic obstructive cardiomyopathy (HOCM) and aortic stenosis (AS). We found that the C-terminus of calcineurin A protein containing the autoinhibitory domain was less abundant in myocardial hypertrophy than in normal heart, which suggests the possibility of proteolysis. No new splice variants could be detected by reverse-transcription polymerase chain reaction. This resulted in a significant elevation of calcineurin enzymatic activity in HOCM and AS compared with 6 normal hearts. Increased calcineurin phosphatase activity caused increased migration of NF-AT2 (nuclear factor of activated T cells 2) in SDS-PAGE compatible with pronounced NF-AT dephosphorylation in hypertrophied myocardial tissue. CONCLUSIONS: Hypertrophy in HOCM and AS without heart failure is characterized by a significant increase in calcineurin activity. This might occur by (partial) proteolysis of the calcineurin A C-terminus containing the autoinhibitory domain. Increased calcineurin activity has functional relevance, as shown by altered NF-AT phosphorylation state. Although hypertrophy in AS and HOCM may be initiated by different upstream triggers (internal versus external fiber overload), in both cases, there is activation of calcineurin, which suggests an involvement of this pathway in the pathogenesis of human cardiac hypertrophy.

Expression profiling of human idiopathic dilated cardiomyopathy.

OBJECTIVE: To investigate the global changes accompanying human dilated cardiomyopathy (DCM) we performed a large-scale expression screen using myocardial biopsies from a group of DCM patients with moderate heart failure. By hierarchical clustering and functional annotation of the deregulated genes we examined extensive changes in the cellular and molecular processes associated to DCM. METHODS: The expression profiles were obtained using a whole genome covering library (UniGene RZPD1) comprising 30336 cDNA clones and amplified RNA from myocardiac biopsies from 10 DCM patients in comparison to tissue samples from four non-failing, healthy donors. RESULTS: By setting stringent selection criteria 364 differentially expressed, sequence-verified non-redundant transcripts were identified with a false discovery rate of <0.001. Numerous genes and ESTs were identified representing previously recognised, as well as novel DCM-associated transcripts. Many of them were found to be upregulated and involved in cardiomyocyte energetics, muscle contraction or signalling. Two hundred and twenty-two deregulated transcripts were functionally annotated and hierarchically clustered providing an insight into the pathophysiology of DCM. Data was validated using the MLP-deficient mouse, in which several differentially expressed transcripts identified in the human DCM biopsies could be confirmed. CONCLUSIONS: We report the first genome-wide expression profile analysis using cardiac biopsies from DCM patients at various stages of the disease. Although there is a diversity of links between the cytoskeleton and the initiation of DCM, we speculate that genes implicated in intracellular signalling and in muscle contraction are associated with early stages of the disease. Altogether this study represents the most comprehensive and inclusive molecular portrait of human cardiomyopathy to date.

Effects of ACE gene insertion/deletion polymorphism on response to spironolactone in patients with chronic heart failure.

BACKGROUND: Angiotensin-converting enzyme (ACE) is involved in the pathophysiology of chronic heart failure, and its activity is determined in part by a polymorphism of the ACE gene. We hypothesized that the benefits of spironolactone, which inhibits downstream elements of ACE-mediated abnormalities, may depend on ACE genotype. METHODS: We randomly assigned 93 chronic heart failure patients to treatment with spironolactone (n = 47) or to a control group (n = 46) and followed them for 12 months. Genotype for the insertion/deletion polymorphism of the ACE gene was determined by polymerase chain reaction. An echocardiographic examination was performed at baseline and at the end of the 12 months. RESULTS: The mean (+/- SD) age of the 93 patients was 62 +/- 9 years, and the mean New York Heart Association class was 2 +/- 1. The genotype was DD in 26 patients (28%). Forty-seven patients were assigned to spironolactone treatment (mean dose, 32 +/- 16 mg). In the treated group, only patients with a non-DD genotype showed significant improvement in left ventricular ejection fraction (3.0%; 95% confidence interval [CI]: 1.2% to 4.8%; P = 0.002), end-systolic volume (-23 mL; 95% CI: -36 to -11; P = 0.0005), and end-diastolic volume (-27 mL; 95% CI: -43 to -12; P = 0.001). In the multivariate analysis, the estimated net effect of treatment was 29 mL better (95% CI: -20 to 78 mL) for end-diastolic volume, 20 mL better (95% CI: -18 to 58 mL) for end-systolic volume, but 1.4% worse (95% CI: -3.4% to 6.2%) for left ventricular ejection fraction in patients with non-DD versus DD genotypes. CONCLUSION: The effects of spironolactone treatment on left ventricular systolic function and remodeling may in part depend on ACE genotype.

Multidimensional reference regions for IGF-I, IGFBP-2 and IGFBP-3 concentrations in serum of healthy adults.

CONTEXT: The insulin-like growth factor (IGF) system exerts many effects on the growth and differentiation of both normal and malignant cells. The serum concentrations of insulin-like growth factor I (S-IGF-I), insulin-like growth factor-binding protein 2 (S-IGFBP-2) and insulin-like growth factor-binding protein 3 (S-IGFBP-3) and their inter-relations may differ in certain disease states from those seen in healthy individuals. OBJECTIVE: To estimate age-, gender- and body mass index (BMI)-specific univariate, bivariate and trivariate 95% reference regions for these components in healthy adults and present indices that will facilitate interpretation of patient observations in relation to these reference regions. DESIGN: Blood samples were taken in the morning from 427 healthy, non-fasting German blood donors of both genders (age range, 18-79 years; BMI range, 16-44 kg/m(2)). Reference regions were developed with multivariate regression methods. RESULTS: Regression analyses showed that S-IGF-I and S-IGFBP-3 levels decrease with increasing age, whereas S-IGFBP-2 concentrations increase with age (P<0.0001). Females had significantly higher S-IGFBP-3 levels than males (P<0.0001) and similar S-IGF-I and S-IGFBP-2 concentrations. Increasing BMI was associated with decreasing S-IGFBP-2 (P<0.0001), but was not significantly associated with the concentrations of the other two analytes. Controlling for age, gender and BMI, S-IGF-I and S-IGFBP-3 were positively correlated (r=0.58), whereas S-IGF-I and S-IGFBP-2, and S-IGFBP-2 and S-IGFBP-3 were negatively correlated (r=-0.11 and r=-0.18, respectively). Based on the regression models, which were controlled for age, gender and BMI, two- and three-dimensional 95% reference regions with associated patient indices were described for each pair of analytes and for the trio of analytes, respectively. CONCLUSIONS: The multivariate reference regions developed in this study should be useful in identifying patients with an abnormal IGF-IGFBP axis. It is suggested that introducing multidimensional reference regions and the described patient indices into clinical practice may aid monitoring of the safety of GH therapy. These patient indices may also be useful in the assessment of cancer risk.

Expression of the protein phosphatase 1 inhibitor KEPI is downregulated in breast cancer cell lines and tissues and involved in the regulation of the tumor suppressor EGR1 via the MEK-ERK pathway.

KEPI is a protein kinase C-potentiated inhibitory protein for type 1 Ser/Thr protein phosphatases. We found no or reduced expression of KEPI in breast cancer cell lines, breast tumors and metastases in comparison to normal breast cell lines and tissues, respectively. KEPI protein expression and ubiquitous localization was detected with a newly generated antibody. Ectopic KEPI expression in MCF7 breast cancer cells induced differential expression of 95 genes, including the up-regulation of the tumor suppressors EGR1 (early growth response 1) and PTEN (phosphatase and tensin homolog), which is regulated by EGR1. We further show that the up-regulation of EGR1 in MCF7/KEPI cells is mediated by MEK-ERK signaling. The inhibition of this pathway by the MEK inhibitor UO126 led to a strong decrease in EGR1 expression in MCF7/KEPI cells. These results reveal a novel role for KEPI in the regulation of the tumor suppressor gene EGR1 via activation of the MEK-ERK MAPK pathway.

The heart in Anderson Fabry disease.

Anderson Fabry disease is a life threatening, X-linked inborn metabolic defect of the lysosomal enzyme áalpha-galactosidase A. The deficiency of alpha-galactosidase A leads to a progressive accumulation of globotriaosylceramide (Gb(3)), the major glycosphingolipid substrate of the enzyme, within vulnerable cells, tissues, and organs, including the cardiovascular system. Cardiac involvement is frequent and patients with cardiac affection develop progressive hypertrophic infiltrative cardiomyopathy, valvular abnormalities, arrhythmias, and conduction abnormalities and may develop coronary heart disease. Hemizygous male patients have no detectable alpha-galactosidase A activity, while affected heterozygous females may have normal level of alpha-galactosidase A activity. Death occurs in male patients at 45 to 50 years, about 15 to 20 years earlier than in female patients due to a vicious circle from chronic renal insufficiency, arterial hypertension, atherosclerotic lesions and cerebrovascular hemorrhage or insults, and cardiomyopathy. Cardiac involvement in hetero- and hemizygotes will be discussed as well as the influence of enzyme replacement of alpha-galactosidase A.