Differences in MEF2 and NFAT Transcriptional Pathways According to Human Heart Failure Aetiology

BACKGROUND:Ca(2+) handling machinery modulates the activation of cardiac transcription pathways involved in heart failure (HF). The present study investigated the effect of HF aetiology on Ca(+2) handling proteins and NFAT1, MEF2C and GATA4 (transcription factors) in the same cardiac tissue. METHODOLOGY AND PRINCIPAL FINDINGS:A total of 83 hearts from ischemic (ICM, n = 43) and dilated (DCM, n = 31) patients undergoing heart transplantation and controls (CNT, n = 9) were analyzed by western blotting. Subcellular distribution was analyzed by fluorescence and electron microscopy. When we compared Ca(+2) handling proteins according to HF aetiology, ICM showed higher levels of calmodulin (24%, p<0.01), calcineurin (26%, p<0.01) and Ca(2+)/Calmodulin-dependent kinase II (CaMKIIδ(b) nuclear isoform 62%, p<0.001) than the CNT group. However, these proteins in DCM did not significantly increase. Furthermore, ICM showed a significant elevation in MEF2C (33%, p<0.01), and GATA4 (49%, p<0.05); also NFAT1 (66%, p<0.001) was increased, producing the resultant translocation of this transcriptional factor into the nuclei. These results were supported by fluorescence and electron microscopy analysis. Whereas, DCM only had a significant increase in GATA4 (52%, p<0.05). Correlations between NFAT1 and MEF2C in both groups (ICM r = 0.38 and DCM r = 0.59, p<0.05 and p<0.01, respectively) were found; only ICM showed a correlation between GATA4 and NFAT1 (r = 0.37, p<0.05). CONCLUSIONS/SIGNIFICANCE:This study shows an increase of Ca(2+) handling machinery synthesis and their cardiac transcription pathways in HF, being more markedly increased in ICM. Furthermore, there is a significant association between MEF2, NFAT1 and GATA4. These proteins could be therapeutic targets to improve myocardial function

Secretory granule neuroendocrine protein 1 (SGNE1) genetic variation and glucose intolerance in severe childhood and adult obesity

<p>Abstract</p> <p>Background</p> <p>7B2 is a regulator/activator of the prohormone convertase 2 which is involved in the processing of numerous neuropeptides, including insulin, glucagon and pro-opiomelanocortin. We have previously described a suggestive genetic linkage peak with childhood obesity on chr15q12-q14, where the 7B2 encoding gene, <it>SGNE1 </it>is located. The aim of this study is to analyze associations of <it>SGNE1 </it>genetic variation with obesity and metabolism related quantitative traits.</p> <p>Methods</p> <p>We screened <it>SGNE1 </it>for genetic variants in obese children and genotyped 12 frequent single nucleotide polymorphisms (SNPs). Case control analyses were performed in 1,229 obese (534 children and 695 adults), 1,535 individuals with type 2 diabetes and 1,363 controls, all French Caucasians. We also studied 4,922 participants from the D.E.S.I.R prospective population-based cohort.</p> <p>Results</p> <p>We did not find any association between <it>SGNE1 </it>SNPs and childhood or adult obesity. However, the 5' region SNP -1,701A>G associated with higher area under glucose curve after oral glucose tolerance test (p = 0.0005), higher HOMA-IR (p = 0.005) and lower insulinogenic index (p = 0.0003) in obese children. Similar trends were found in obese adults. SNP -1,701A>G did not associate with risk of T2D but tends to associate with incidence of type 2 diabetes (HR = 0.75 95%CI [0.55–1.01]; p = 0.06) in the prospective cohort.</p> <p>Conclusion</p> <p><it>SGNE1 </it>genetic variation does not contribute to obesity and common forms of T2D but may worsen glucose intolerance and insulin resistance, especially in the background of severe and early onset obesity. Further molecular studies are required to understand the molecular bases involved in this process.</p

Transcriptional genomics associates FOX transcription factors with human heart failure

BACKGROUND - Specific transcription factors (TFs) modulate cardiac gene expression in murine models of heart failure, but their relevance in human subjects remains untested. We developed and applied a computational approach called transcriptional genomics to test the hypothesis that a discrete set of cardiac TFs is associated with human heart failure. METHODS AND RESULTS - RNA isolates from failing (n=196) and nonfailing (n=16) human hearts were hybridized with Affymetrix HU133A arrays, and differentially expressed heart failure genes were determined. TF binding sites overrepresented in the -5-kb promoter sequences of these heart failure genes were then determined with the use of public genome sequence databases. Binding sites for TFs identified in murine heart failure models (MEF2, NKX, NF-AT, and GATA) were significantly overrepresented in promoters of human heart failure genes (P<0.002; false discovery rate 2% to 4%). In addition, binding sites for FOX TFs showed substantial overrepresentation in both advanced human and early murine heart failure (P<0.002 and false discovery rate <4% for each). A role for FOX TFs was supported further by expression of FOXC1, C2, P1, P4, and O1A in failing human cardiac myocytes at levels similar to established hypertrophic TFs and by abundant FOXP1 protein in failing human cardiac myocyte nuclei. CONCLUSIONS - Our results provide the first evidence that specific TFs identified in murine models (MEF2, NKX, NFAT, and GATA) are associated with human heart failure. Moreover, these data implicate specific members of the FOX family of TFs (FOXC1, C2, P1, P4, and O1A) not previously suggested in heart failure pathogenesis. These findings provide a crucial link between animal models and human disease and suggest a specific role for FOX signaling in modulating the hypertrophic response of the heart to stress in humans. © 2006 American Heart Association, Inc.link_to_subscribed_fulltex