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Mechanical Stretch Inhibits MicroRNA499 via p53 to Regulate Calcineurin-A Expression in Rat Cardiomyocytes

By Su-Kiat Chua (649171), Bao-Wei Wang (505054), Li-Ming Lien (125232), Huey-Ming Lo (649172), Chiung-Zuan Chiu (649173) and Kou-Gi Shyu (505057)


<div><p>Background</p><p>MicroRNAs play an important role in cardiac remodeling. MicroRNA 499 (miR499) is highly enriched in cardiomyocytes and targets the gene for Calcineurin A (CnA), which is associated with mitochondrial fission and apoptosis. The mechanism regulating miR499 in stretched cardiomyocytes and in volume overloaded heart is unclear. We sought to investigate the mechanism regulating miR499 and CnA in stretched cardiomyocytes and in volume overload-induced heart failure.</p><p>Methods & Results</p><p>Rat cardiomyocytes grown on a flexible membrane base were stretched via vacuum to 20% of maximum elongation at 60 cycles/min. An in vivo model of volume overload with aorta-caval shunt in adult rats was used to study miR499 expression. Mechanical stretch downregulated miR499 expression, and enhanced the expression of CnA protein and mRNA after 12 hours of stretch. Expression of CnA and calcineurin activity was suppressed with miR499 overexpression; whereas, expression of dephosphorylated dynamin-related protein 1 (Drp1) was suppressed with miR499 overexpression and CnA siRNA. Adding p53 siRNA reversed the downregulation of miR499 when stretched. A gel shift assay and promoter-activity assay demonstrated that stretch increased p53 DNA binding activity but decreased miR499 promoter activity. When the miR499 promoter p53-binding site was mutated, the inhibition of miR499 promoter activity with stretch was reversed. The in vivo aorta-caval shunt also showed downregulated myocardial miR499 and overexpression of miR499 suppressed CnA and cellular apoptosis.</p><p>Conclusion</p><p>The miR499-controlled apoptotic pathway involving CnA and Drp1 in stretched cardiomyocytes may be regulated by p53 through the transcriptional regulation of miR499.</p></div

Topics: Biological Sciences, Rat Cardiomyocytes BackgroundMicroRNAs, miR 499 overexpression, gel shift assay, p 53, Mechanical Stretch Inhibits MicroRNA 499, study miR 499 expression, p 53 DNA binding activity, Mechanical stretch downregulated miR 499 expression, miR 499, cna, miR 499 promoter activity, p 53 siRNA
Year: 2016
DOI identifier: 10.1371/journal.pone.0148683
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Provided by: FigShare
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