Metformin hydrochloride regulates glycolysis and inhibits PEDV replication by inhibition of PI3K-AKT signaling pathway

Viruses rely on energy and biosynthetic materials of host cell from glucose metabolism to support their replication, and glucose plays a crucial role in viral infection. In this study, we found that porcine epidemic diarrhea virus (PEDV) infection significantly increased cellular glucose uptake and stimulated the production of the glycometabolite lactate. Exogenous supplementation of glucose or L-lactate confirmed that it significantly promoted PEDV proliferation, indicating that replication of PEDV was enhanced by regulating host glucose metabolism, particularly reprogramming glycolysis. Based on these findings, we explored the potential antiviral approach targeting the virus through regulating glycolytic processes. Metformin hydrochloride (MH) is a well-known hypoglycemic agent, which has shown notable anti-PEDV activity. After MH treatment, the transcriptome analysis showed the differential genes were mainly enriched in PI3K-AKT signaling pathway, and the expression levels of its downstream molecule GSK3B and MYC were significantly upregulated and downregulated, respectively. The gene expression related to glycolysis was also significantly inhibited. Further experiments showed that MH significantly inhibited the phosphorylation of AKT and its translocation to plasma membrane, while reducing the phosphorylation level of GSK3B. MH maintained GSK3B in a non-phosphorylated state by blocking the activation of the EGFR/PI3K/AKT/GSK3B pathway, mediated the degradation of c-MYC through phosphorylation, inhibited the glycolysis process, reduced the production of lactic acid, and finally exerted its antiviral effect. This study demonstrated that PEDV infection could induce glycolysis through metabolic reprogramming, thereby promoting viral replication; whereas, MH was able to effectively reverse this process, significantly inhibiting the virus-induced glycolysis pathway and exhibiting antiviral activity.IMPORTANCEThis study aims to elucidate the antiviral effects and molecular mechanisms of MH against PEDV. The results show that MH can inhibit the activation of the PI3K-AKT signaling pathway induced by PEDV infection, thereby suppressing the production of the glycolytic product L-lactic acid and ultimately resisting PEDV infection. This research provides new insights into the prevention and control of PEDV and offers scientific evidence for the application of MH in veterinary medicine.