The cardiac calsequestrin gene transcription is modulated at the promoter by NFAT and MEF-2 transcription factors

Abstract

Calsequestrin-2 (CASQ2) is the main Ca2+-binding protein inside the sarcoplasmic reticulum of cardiomyocytes. Previously, we demonstrated that MEF-2 and SRF binding sites within the human CASQ2 gene (hCASQ2) promoter region are functional in neonatal cardiomyocytes. In this work, we investigated if the calcineurin/NFAT pathway regulates hCASQ2 expression in neonatal cardiomyocytes. The inhibition of NFAT dephosphorylation with CsA or INCA-6, reduced both the luciferase activity of hCASQ2 promoter constructs (-3102/+176 bp and -288/+176 bp) and the CASQ2 mRNA levels in neonatal rat cardiomyocytes. Additionally, NFATc1 and NFATc3 over-expressing neonatal cardiomyocytes showed a 2-3-fold increase in luciferase activity of both hCASQ2 promoter constructs, which was prevented by CsA treatment. Site-directed mutagenesis of the -133 bp MEF-2 binding site prevented trans-activation of hCASQ2 promoter constructs induced by NFAT overexpression. Chromatin Immunoprecipitation (ChIP) assays revealed NFAT and MEF-2 enrichment within the -288 bp to +76 bp of the hCASQ2 gene promoter. Besides, a direct interaction between NFAT and MEF-2 proteins was demonstrated by protein co-immunoprecipitation experiments. Taken together, these data demonstrate that NFAT interacts with MEF-2 bound to the -133 bp binding site at the hCASQ2 gene promoter. In conclusion, in this work, we demonstrate that the Ca2+-calcineurin/NFAT pathway modulates the transcription of the hCASQ2 gene in neonatal cardiomyocytes.

Inhibition of Jumonji demethylases reprograms severe dilated cardiomyopathy and prolongs survival

“…Further analysis of RNAseq datasets revealed that MEF2-motif containing genes were enriched in diseased hearts in both mechanical overload and CnA genetic models (Fig 3J 5). Since MEF2 is known to act in conjunction with NFAT in the regulation of cardiac gene expression during disease [40,41] [42], we bioinformatically examined if MEF2 target genes upregulated in disease and downregulated by JIB-04 included genes co-regulated by NFAT (Supplemental Fig 5A-B and Supplemental Table 6). We found that of the 54 genes that are MEF2 target genes upregulated in disease and downregulated by JIB-04 treatment in the diseased heart, about a third (17/54 or 32%) contain NFAT binding motifs (Supplemental Fig 5C ) while genes containing GATA4 motifs were not significantly represented (Supplemental Table 6).…”

Association of polymorphic variants rs6684209 and rs7521023 of the calsequestrin gene (CASQ2) with contractile myocardial function in patients with coronary artery disease

“…Одной из особенностей СР является наличие в его структуре белка, известного как кальсеквестрин 2 (CASQ2). Это основной внутриклеточный Ca 2+ -связывающий белок, нормальное функционирование которого обеспечивает удержание Ca 2+ в СР [4,5].…”