Heterogeneous Nuclear Ribonucleoprotein M Facilitates Enterovirus Infection.

Picornavirus infection involves a dynamic interplay of host and viral protein interactions that modulates cellular processes to facilitate virus infection and evade host antiviral defenses. Here, using a proteomics-based approach known as TAILS to identify protease-generated neo-N-terminal peptides, we identify a novel target of the poliovirus 3C proteinase, the heterogeneous nuclear ribonucleoproteinM(hnRNP M), a nucleocytoplasmic shuttling RNA-binding protein that is primarily known for its role in pre-mRNA splicing. hnRNPMis cleaved in vitro by poliovirus and coxsackievirus B3 (CVB3) 3C proteinases and is targeted in poliovirus- and CVB3-infected HeLa cells and in the hearts of CVB3-infected mice. hnRNPMrelocalizes from the nucleus to the cytoplasm during poliovirus infection. Finally, depletion of hnRNPMusing small interfering RNA knockdown approaches decreases poliovirus and CVB3 infections in HeLa cells and does not affect poliovirus internal ribosome entry site translation and viral RNA stability. We propose that cleavage of and subverting the function of hnRNPMis a general strategy utilized by picornaviruses to facilitate viral infection. Enteroviruses, a member of the picornavirus family, are RNA viruses that cause a range of diseases, including respiratory ailments, dilated cardiomyopathy, and paralysis. Although enteroviruses have been studied for several decades, the molecular basis of infection and the pathogenic mechanisms leading to disease are still poorly understood. Here, we identify hnRNPMas a novel target of a viral proteinase. We demonstrate that the virus subverts the function of hnRNPMand redirects it to a step in the viral life cycle. We propose that cleavage of hnRNPMis a general strategy that picornaviruses use to facilitate infection.