LncRNA NRON Alleviates Atrial Fibrosis Through Suppression Of M1 Macrophages Activated By Atrial Myocytes

Objective: long non-coding RNA(lnc RNA)is a subset of RNA transcripts,which is greater than 200 nucleotides in length,mostly derived from transcription,and has almost no function of protein-coding translation,but It plays multiple roles in protein translation and has extremely important regulatory functions.The Lnc RNA NRON is the inhibitor of NFAT(nuclear factor of activated T cells).NFAT is a very sensitive transcription factor and was first discovered in activated T cells and extracts.Recent studies have shown that NFAT plays a key role in the development and differentiation of the heart,muscle tissue,and neural tissue.Studies have shown that Lnc RNA NRON can reduce the nuclear factor input by promoting the phosphorylation of activated T cells 3(NFATc3)nuclear factor,thereby reducing Progress of atrial fibrosis.More and more studies have also shown that during the development of myocardial fibrosis,a large number of pro-inflammatory cells,such as macrophages,are present in cardiac tissue.Macrophages are important natural immune cells,and their functional phenotype can be polarized into two forms in the inflammatory response,namely M1 macrophages and M2 macrophages.The purpose of this study is to explore the role of lncrna nron in atrial fibrosis and whether its potential mechanism is related to macrophage polarization.Methods: Primary atrial myocytes of mice were subcultured,transfected with related plasmids,and co-cultured.NRON overexpression vectors(NRON)and controls(Vector)were constructed,and NRON si RNAs(si-NRON)and control si RNA(si-Ctrl)were specifically inhibited.Enzyme-linked immunosorbent assay(ELISA)was used to detect the levels of IL-1?,TNF-? and IL-12 in cell culture to discover that Lnc RNA NRON responds to Ang II-induced cardiomyocyte inflammation.The role of Western blot to detect the expression of NFATc3,p-NFATc3,the ingress and egress of nuclear and the expression of Collagen I,Collagen III.Quantitative real-time PCR(QRT-PCR)to detect the expression of interleukin-12(IL-12)and i NOS,IFN-?,Arg in macrophages-1,IL-10 expression level.The luciferase activity assay and The chromatin immunoprecipitation(Ch IP)were used to analyze the binding of NFATc3 to the IL-12 gene promoter.The proportion of M1 and M2 macrophages was detected by flow cytometry.Results: ELISA analysis of pro-inflammatory cytokines revealed that NRON overexpression suppressed,whereas NRON silencing facilitated the angiotensin II(Ang II)-induced inflammatory response in primary cultured atrial myocytes.The Ch IP results showed that nuclear factor of activated T cell 3(NFATc3)was recruited to the promoter region of IL-12 in atrial myocytes.Further data showed that NRON overexpression suppressed,whereas NRON silencing further promoted the Ang II-induced NFATc3 nuclear transport and IL-12 expression in atrial myocytes.Moreover,RAW264.7 macrophages were incubated with the conditioned medium from the Ang II-treated atrial myocytes transfected with NRON and IL-12 overexpression vectors.IL-12 overexpression abrogated the NRON overexpression-mediated inhibition of RAW264.7 macrophage polarization to the M1-like phenotype.Conclusion: Collectively,our data indicate that lncRNA NRON alleviates atrial fibrosis through suppression of M1 macrophages activated by atrial myocytes.