Nrf2-dependent regulation of miRNA and mRNA expressions alters basal myocardial redox state

Background NFE2L2 (nuclear factor, erythroid 2 like 2; Nrf2), is a stress-responsive transcription factor that regulates cellular redox homeostasis. 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 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. Methods Cardiac specific Nrf2 transgenic (Nrf2-TG) and non-transgenic (NTG) litter mates in the C57/BL6 background at the age of 6-8 months were used to examine transcriptional (mRNA) and post-transcriptional (miRNA) signatures in the heart. Next generation sequencing (NGS) for RNA (RNAseq) and miRNA (miRNAseq) expressions (n=3-6/group) were performed. qPCR validation of the NGS data for selected miRNAs or mRNAs and in-silico analysis were also performed to determine the miRNA–mRNA interactome networks, and the pathways that are potentially regulated by these networks. Results NGS 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 55 miRNAs were significantly altered in Nrf2-TG versus NTG hearts. Among these miRNAs, 39 were upregulated and 16 were downregulated significantly. Validation of key targets for mRNA and miRNA by qPCR confirmed the NGS results. In-silico analysis revealed that the majority of the miRNAs and mRNAs that are significantly altered in response to transgene expression are potentially involved in regulating the Nrf2 signaling, glutathione metabolism, cardiac development, chaperone activity, oxidoreductase capacity, and mitochondrial bioenergetics. Conclusion Our comprehensive analysis indicates that Nrf2 may directly or indirectly regulates these sub-sets of cardiac miRNA–mRNA interactome networks under basal physiological setting.