Mandarin Fish (Siniperca chuatsi) p53 Regulates Glutaminolysis Induced by Virus via the p53/miR145-5p/c-Myc Pathway in Chinese Perch Brain Cells

p53, as an important tumor suppressor protein, has recently been implicated in host antiviral defense. The present study found that the expression of mandarin fish (Siniperca chuatsi) p53 (Sc-p53) was negatively associated with infectious spleen and kidney necrosis virus (ISKNV) and Siniperca chuatsi rhabdovirus (SCRV) proliferation as well as the expression of glutaminase 1 (GLS1) and glutaminolysis pathway-related enzymes glutamate dehydrogenase (GDH) and isocitrate dehydrogenase 2 (IDH2). This indicated that Sc-p53 inhibited the replication and proliferation of ISKNV and SCRV by negatively regulating the glutaminolysis pathway. Moreover, it was confirmed that miR145-5p could inhibit c-Myc expression by targeting the 3' untranslated region (UTR). Sc-p53 could bind to the miR145-5p promoter region to promote its expression and to further inhibit the expression of c-Myc. The expression of c-Myc was proved to be positively correlated with the expression of GLS1 as well. All these suggested a negative relationship between the Sc-p53/miR145-5p/c-Myc pathway and GLS1 expression and glutaminolysis. However, it was found that after ISKNV and SCRV infection, the expressions of Sc-p53, miR145-5p, c-Myc, and GLS1 were all significantly upregulated, which did not match the pattern in normal cells. Based on the results, it was suggested that ISKNV and SCRV infection altered the Sc-p53/miR145-5p/c-Myc pathway. All of above results will provide potential targets for the development of new therapeutic strategies against ISKNV and SCRV. IMPORTANCE Infectious spleen and kidney necrosis virus (ISKNV) and Siniperca chuatsi rhabdovirus (SCRV) as major causative agents have caused a serious threat to the mandarin fish farming industry (J.-J. Tao, J.-F. Gui, and Q.-Y. Zhang, Aquaculture 262:1-9, 2007, https://doi.org/10.1016/j.aquaculture.2006.09.030). Viruses have evolved the strategy to shape host-cell metabolism for their replication (S. K. Thaker, J. Ch'ng, and H. R. Christofk, BMC Biol 17:59, 2019, https://doi.org/10.1186/s12915-019-0678-9). Our previous studies showed that ISKNV replication induced glutamine metabolism reprogramming and that glutaminolysis was required for efficient replication of ISKNV and SCRV. In the present study, the mechanistic link between the p53/miR145-5p/c-Myc pathway and glutaminolysis in the Chinese perch brain (CPB) cells was provided, which will provide novel insights into ISKNV and SCRV pathogenesis and antiviral treatment strategies.