GPR143 directs virus-induced cell vacuolation via the MKK6–p38 pathway in teleost

Causing cytoplasmic vacuolization is a key step for many viruses to induce cell death, however, the underlying mechanisms remain unclear. Nervous necrosis virus (NNV) induces pronounced cytoplasmic vacuoles in the brain during infection. G protein-coupled receptors (GPCRs) regulate autophagosomes and cause vacuolation. Our previous genome-wide association study identified GPR143 as a key candidate gene target for anti-RGNNV approaches in groupers. Here, we used orange-spotted grouper (Epinephelus coioides) and red-spotted grouper NNV (RGNNV) as the models to investigate the role of GPR143 in mediating virus induced cellular vacuolation in the central nervous system. The results demonstrate that GPR143 promotes RGNNV-induced cell vacuolation through accelerate binding of autophagosomes and lysosomes. Further investigation revealed that RGNNV facilitates GPR143 binding to MKK6, and MKK6 regulates p38 phosphorylation in the target of rapamycin (mTOR) pathway, promoting the binding of autophagosomes and lysosomes to induce cytoplasmic vacuolization. Finally, the zebrafish with GPR143 knockout confirmed that the absence of GPR143 significantly reduces brain vacuolation and fry mortality. These results indicated that GPR143 directs virus-induced cell vacuolation via the MKK6–p38 pathway in teleost. Our study reveals a novel pathway by which viruses cause vacuolation in vertebrates.