Identification of a novel immune-related long noncoding RNA in carp primary macrophages associated with bisphenol A' s immunoregulatory effects

Increasing evidence suggests that long non-coding RNAs (lncRNAs) play pivotal roles in various biological processes. However, current studies on lncRNAs mostly focus on mammalian species, with little research on the functional roles of lncRNAs in teleost fish. Here, we identified a novel intergenic lncRNA (linc-93.2) in the head kidney primary macrophages of common carp (Cyprinus carpio) after exposure to a typical environmental endocrine disrupting chemical, bisphenol A (BPA). As a result, linc-93.2 was more than 3,619 bp in length and predominantly localized to the nucleus of primary macrophages other than cytoplasm, with the highest expression level in spleen followed by head kidney among different organs. Bioinformatic analysis predicted a cis-target gene, dennd1b, and 20 trans-target genes including hsp70, gna13 and rasgap, were potentially regulated by linc-93.2; NF kappa B and estrogen receptor (ER zeta) binding sites were located in the promoter region upstream of its transcription start site, which together suggested the involvement of linc-93.2 in immune and neurological functions in fish. Based on that, the expression level of linc-93.2 was determined in macrophages following acute lipopolysaccharide (LPS) and BPA treatments, both of which significantly induced linc-93.2 and IL-1 beta expression in cells. Moreover, a NF-kappa B inhibitor PDTC significantly reduced linc-93.2 expression in macrophages, but co-exposure of macrophages to PDTC with BPA or LPS could significantly rescue linc-93.2 expression, consistent with the observation on that LPS or BPA alone significantly induced both linc-93.2 and its target gene expression. Interestingly, linc-93.2 and its target gene expression was significantly suppressed by an ER antagonist ICI 182,780, however, the co-exposure of macrophages to ICI 182,780 with BPA failed to attenuate their declined expression. Overall, the current study demonstrated that linc-93.2, a novel immune-related lncRNA, may participate in the immune processes of common carp macrophages via the NF-kappa B and ER pathway. The results presented in this study enhance our understanding of the immunotoxin mechanisms of BPA in teleost fish.