Bacterial induced miR-144-5p modulates intestinal inflammatory response of Japanese flounder by targeting Hsp90α-dependent NLR signaling pathway

Abstract

Pathogens infection could induce intestinal inflammatory processes, appropriate intestinal inflammation response had beneficial effects in fish, while excessive inflammation alters enteroendocrine signaling, leading to deregulated immune response. Recently, many researches revealed that microRNAs in teleost serve as vital regulators in innate immunity responses against pathogen infection. However, there are few studies on miRNAs mediated regulatory networks of intestinal inflammatory response in teleost. In our study, miR-144-5p was identified as negative regulators in teleost against bacterial infection. First, we found that the expression of miR-144-5p in flounder both in vivo and in vitro was significantly up-regulated, while the expression of Hsp90α, NLRP3, Caspase1 and IL-1β were significantly down-regulated upon the stimulation of Edwardsiella tarda and lipopolysaccharide (LPS). Furthermore, we confirmed that miR-144-5p modulates intestinal inflammatory responses of flounder by targeting Hsp90α-dependent NLR signaling pathway, in which the miR-144-5p-Hsp90α-NLRP3 signaling pathway was constructed. Besides, the miR-144-5p-Hsp90α-NLRP3 signaling pathway could inhibit antibacterial immune response of flounder and promote the survival of E. tarda. Moreover, the study demonstrated that the miR-144-5p-Hsp90α regulatory network was widely existed in other teleost and human. In conclusion, the expression of miR-144-5p was significantly up-regulated after challenged by E. tarda and LPS, which then down-regulated the expression of inflammation-related cytokines of NLRP3, Caspase1 and IL-1β by targeting Hsp90α, and ultimately promoted bacterial infection. Our findings constructed a novel miR-144-5p-Hsp90α-NLRP3 signaling pathway, which enriched the regulatory network of miRNA on fish intestinal mucosal immunity and would benefit the development of fish disease therapeutic strategies to prevent potentially lethal bacterial infection.