Construction of ceRNA and m6A related-lncRNA networks associated with anti-inflammation of AdipoAI

Adiponectin (APN) is an endogenous adipokine secreted from adipocytes that exerts an anti-inflammation property. AdipoAI is an orally active adiponectin receptor agonist identified by our group, which can emulate APN's anti-inflammatory properties through mechanisms not fully understood. To explore AdipoAI function, we used lncRNA microarray and got differential lncRNA/mRNA expression medicated by AdipoAI. Identified as one kind of non-coding RNA with more than 200bp length, lncRNA has been demonstrated to have abundance biological functions, including anti-inflammatory response. In the current study, we performed an lncRNA microarray in LPS-induced Raw264.7 cells which pre-stimulated with AdipoAI, and screened 110 DElncRNAs and 190 DEmRNAs. Enrichment analyses were conducted to total mRNAs and DEmRNAs, including GSVA, ssGSEA, GO/KEGG, GSEA and PPI analysis. Among all these processes, endocytosis was significantly enriched. A co-expression analysis was built based on DElncRNAs and DEmRNAs. Then, using Targetscan and miRwalk to predict related microRNAs of DElncRNAs and DEmRNAs respectively, we established competing endogenous RNA (ceRNA) networks including 54 mRNAs from 8 GO items. Furthermore, 33 m6A methylation related marker genes were obtained from previous study and used for the construction of m6A related-lncRNA network using the co-expression analysis. We identified FTO as the hub gene of the network, and 14 lncRNAs that interacted with it. The expression levels of 10 lncRNAs selected from ceRNA and FTO- related lncRNAs networks were validated with qRT-PCR. Finally, Macrophage phenotype scores showed that AdipoAI could attenuate the M2b and M2c polarization of macrophage and correlate with the above lncRNAs. Our work reveals that lncRNA might involve in the anti-inflammation process of AdipoAI in LPS-induced macrophages through ceRNA network and epigenetic regulation of m6A. Mechanistically, these lncRNAs associated with AdipoAI might be related to endocytosis and polarization in macrophage, and provide new candidates for the anti-inflammatory application of APN and its receptor agonist. Raw264.7 cells were stimulated with AdipoAI for 24 h followed by incubation with 100 ng/ml of LPS (E. coli 0111: B4, Sigma-Aldrich, St. Louis, MO, USA) for an additional 6 h. Total RNA of cells was extracted, and 5-μg total RNA from each cell sample was sent to Arraystar Inc. (Rockville, MD, USA) for microarray analysis. Image processing and data extraction and analysis also were performed by Arraystar Inc. using their established protocols.