Knockdown of both hnRNP A1 and A2 decreased Enterovirus 71 virus titer by 4 logs, and knockdown of hnRNP A1 alone reduced Sindbis virus RNA synthesis by over 95% and virus titer by over 3 logs.
The study provides the first direct evidence that cytoplasmic relocalization of hnRNP A1 controls both IRES-dependent and non-IRES-dependent translation initiations of RNA viruses.
Heterogeneous nuclear ribonucleoprotein (hnRNP) A1 is involved in pre-mRNA splicing in the nucleus and translational regulation in the cytoplasm. The cytoplasmic redistribution of hnRNP A1 is a regulated process during viral infection and cellular stress. Here we demonstrate that hnRNP A1 not only is an internal ribosome entry site (IRES) trans-acting factor that binds specifically to the 5' untranslated region (UTR) of enterovirus 71 (EV71) and regulates IRES-dependent translation but also binds to the 5' UTR of Sindbis virus (SV) and facilitates its translation. The cytoplasmic relocalization of hnRNP A1 in EV71-infected cells leads to the enhancement of EV71 IRES-mediated translation, and its function can be substituted by hnRNP A2, whereas the cytoplasmic relocalization of hnRNP A1 following SV infection enhances the SV translation, but this function cannot be replaced by hnRNP A2. Our study provides the first direct evidence that the cytoplasmic relocalization of hnRNP A1 controls not only the IRES-dependent but also non-IRES-dependent translation initiations of RNA viruses.
Lin et al. (Thu,) conducted a other in Enterovirus 71 and Sindbis Virus infection (in vitro). hnRNP A1 and A2 knockdown via siRNA vs. No siRNA / mock transfection was evaluated on Viral replication (RNA synthesis and virus yield). Knockdown of both hnRNP A1 and A2 decreased Enterovirus 71 virus titer by 4 logs, and knockdown of hnRNP A1 alone reduced Sindbis virus RNA synthesis by over 95% and virus titer by over 3 logs.