Abstract

BackgroundNFE2L2 (nuclear factor, erythroid 2 like 2; Nrf2), is a stress-responsive transcription factor that regulates cellular redox homeostasis. The action mechanism of Nrf2 occurs through sensing oxidative stress in the cellular environment in responses to various stresses including altered metabolism, toxic insult and xenobiotic stresses. However, under the basal condition, the role of excess Nrf2 on global miRNA-mRNA interactions in the myocardium is unknown. Here, we tested a hypothesis that excess Nrf2 (transgene) will promote the transcription of antioxidants, which then might escalate the basal defense mechanisms in the heart. Furthermore, we investigated whether changes in the miRNA profile might have a strong role on the transcriptome in TG hearts.\n\nMethodsNon-transgenic (NTG), and Cardiac specific Nrf2 transgenic (Nrf2-TG) mice in the C57/BL6 background at the age of 6-8 months were used to examine transcriptional and post-transcriptional signatures (mRNA and miRNA expressions) by performing next generation sequencing (NGS) for RNA (RNAseq) and small RNA (sRNAseq) for miRNA expressions in the heart (n=3-6/group). Validation of the NGS data was performed by quantitative real time PCR (qRT-PCR) using specific primers targeting selected miRNAs or mRNAs. Finally, in-silico analyses were performed to determine the miRNA-mRNA interactome networks and the pathways that are potentially regulated by these networks.\n\nResultsNGS analysis for mRNA indicated that there were 5727 differently expressed genes (DEGs) in the Nrf2-TG vs. NTG myocardium. Of which, 3552 were upregulated and 2175 were downregulated significantly. Small RNAseq analysis revealed that 112 miRNAs were significantly altered in Nrf2-TG versus NTG hearts. Among these miRNAs, 68 were upregulated and 44 were downregulated significantly. Validation of key targets for mRNA and miRNA by qPCR confirmed the NGS results. In-silico analysis (IPA) revealed that the majority of the miRNAs and mRNAs that are significantly altered in response to transgene expression are potentially involved in Nrf2 mediated oxidative stress response, ILK Signaling, hypoxia signaling in the cardiovascular system and glutathione-mediated detoxification etc.\n\nConclusionThese high-throughput sequencing data sets from cardiac specific Nrf2-TG mice revealed the transcriptome-wide effects of Nrf2 in the myocardium. Furthermore, our comprehensive analysis indicates that Nrf2 may directly or indirectly regulates these sub-sets of cardiac miRNA-mRNA interactome networks under basal physiological setting.