The long noncoding RNA APR attenuates PPRV infection-induced accumulation of intracellular iron to inhibit membrane lipid peroxidation and viral replication.

Peste des petits ruminants virus (PPRV) is an important pathogen that has long been a significant threat to small ruminant productivity worldwide. Iron metabolism is vital to the host and the pathogen. However, the mechanism underlying host-PPRV interactions from the perspective of iron metabolism and iron-mediated membrane lipid peroxidation has not been reported thus far. In this study, we identified a novel host long-noncoding RNA (lncRNA), APR, that impairs PPRV infectivity by sponging miR-3955-5p, a negative microRNA (miRNA) that directly targets the gene encoding the ferritin-heavy chain 1 (FTH1) protein. Importantly, we demonstrated that PPRV infection causes aberrant cellular iron accumulation by increasing transferrin receptor (TFRC) expression and that iron accumulation induces reticulophagy and ferroptosis, which benefits PPRV replication. Moreover, PPRV infection enhanced the localization of cellular iron on the endoplasmic reticulum (ER) and caused ER membrane damage by promoting excess lipid peroxidation to induce reticulophagy. Interestingly, APR decreased PPRV infection-induced accumulation of intracellular Fe via miR-3955-5p/FTH1 axis and ultimately inhibited reticulophagy and ferroptosis. Additionally, our results indicate that interferon regulatory factor 1 promotes APR transcription by positively regulating APR promoter activity after PPRV infection. Taken together, our findings revealed a new pattern of PPRV-host interactions, involving noncoding RNA regulation, iron metabolism, and iron-related membrane lipid peroxidation, which is critical for understanding the host defense against PPRV infection and the pathogenesis of PPRV.IMPORTANCEMany viruses have been demonstrated to engage in iron metabolism to facilitate their replication and pathogenesis. However, the mechanism by which PPRV interacts with host cells from the perspective of iron metabolism, or iron-mediated membrane lipid peroxidation, has not yet been reported. Our data provide the first direct evidence that PPRV infection induces aberrant iron accumulation to promote viral replication and reveal a novel host lncRNA, APR, as a regulator of iron accumulation by promoting FTH1 protein expression. In this study, PPRV infection increased cellular iron accumulation by increasing TFRC expression, and more importantly, iron overload increased viral infectivity as well as promoted ER membrane lipid peroxidation by enhancing the localization of cellular iron on the ER and ultimately induced ferroptosis and reticulophagy. Furthermore, a host factor, the lncRNA APR, was found to decrease cellular iron accumulation by sponging miR-3955-5p, which directly targets the gene encoding the FTH1 protein, thereby attenuating PPRV infection-induced ferroptosis and reticulophagy and inhibiting PPRV infection. Taken together, the results of the present study provide new insight into our understanding of host-PPRV interaction and pathogenesis from the perspective of iron metabolism and reveal potential targets for therapeutics against PPRV infection.