hnRNPs Relocalize to the Cytoplasm following Infection with Vesicular Stomatitis Virus

Abstract

Vesicular stomatitis virus (VSV) matrix protein inhibits nuclear-cytoplasmic mRNA transport. The goal of this work is to determine whether VSV inhibits the nuclear-cytoplasmic transport of heterogeneous ribonucleoproteins (hnRNPs), which are thought to serve as mRNA export factors. Confocal microscopy experiments showed that hnRNPA1, hnRNPK, and hnRNPC1/C2, but not hnRNPB1 or lamin A/C, are relocalized to the cytoplasm during VSV infection. We determined whether protein import is inhibited by VSV by transfecting cells with a plasmid encoding enhanced green fluorescent protein (EGFP) tagged with either the M9 nuclear localization sequence (NLS) or the classical NLS. These experiments revealed that both the M9 NLS and the classical NLS are functional during VSV infection. These data suggest that the inhibition of protein import is not responsible for hnRNP relocalization during VSV infection but that hnRNP export is enhanced. We found that hnRNPA1 relocalization was significantly reduced following the silencing of the mRNA export factor Rae1, indicating that Rae1 is necessary for hnRNP export. In order to determine the role of hnRNPA1 in VSV infection, we silenced hnRNPA1 in HeLa cells and assayed three aspects of the viral life cycle: host protein synthesis shutoff concurrent with the onset of viral protein synthesis, replication by plaque assay, and cell killing. We observed that host shutoff and replication are unaffected by the reduction in hnRNPA1 but that the rate of VSV-induced apoptosis is slower in cells that have reduced hnRNPA1. These data suggest that VSV promotes hnRNPA1 relocalization in a Rae1-dependent manner for apoptotic signaling.

Human Immunodeficiency Virus Type 1 (HIV-1) Induces the Cytoplasmic Retention of Heterogeneous Nuclear Ribonucleoprotein A1 by Disrupting Nuclear Import

“…Refs. [45][46][47]. This phenomenon has been attributed to a disruption in its nucleocytoplasmic shuttling activity.…”

Differential effect of acute and persistent Junín virus infections on the nucleo-cytoplasmic trafficking and expression of heterogeneous nuclear ribonucleoproteins type A and B

“…Subcellular localization of hnRNP A1 is an important determinant of apoptotic signalling, and it has been proven that cytoplasmic hnRNP A1 negatively regulates the translation of inhibitors of apoptosis such as XIAP and apaf-1 ( Lewis et al, 2007;Zhao et al, 2009). We propose that, during acute infection, relocalization of hnRNP A1 to the cytoplasm may be involved in the induction of apoptotic cell death and the development of cytopathic action, as has been described for VSV infection (Pettit Kneller et al, 2009). In contrast, non-cytopathic persistent JUNV infection may be related to low levels of hnRNPs A/B and modulation of nucleo-cytoplasmic trafficking, which results in the nuclear retention of overexpressed hnRNP A1.…”

“…In contrast, during poliovirus (PV) infection, hnRNP E is essential for the internal initiation of translation at internal ribosome entry sites (IRES) (Walter et al, 1999), and the cytoplasmic relocalization of hnRNP C1 enables its association with viral proteins to promote replication (Brunner et al, 2005). Furthermore, it has been demonstrated that alterations in the nucleo-cytoplasmic trafficking of several hnRNPs during vesicular stomatitis virus (VSV) infection might play a role in virus-induced apoptosis (Pettit Kneller et al, 2009).…”

“…In contrast, during poliovirus (PV) infection, hnRNP E is essential for the internal initiation of translation at internal ribosome entry sites (IRES) (Walter et al, 1999), and the cytoplasmic relocalization of hnRNP C1 enables its association with viral proteins to promote replication (Brunner et al, 2005). Furthermore, it has been demonstrated that alterations in the nucleo-cytoplasmic trafficking of several hnRNPs during vesicular stomatitis virus (VSV) infection might play a role in virus-induced apoptosis (Pettit Kneller et al, 2009).In an attempt to identify cellular factors involved in JUNV replication and to gain insight into virus-cell interactions that lead to the death or survival of the infected cell, in the present study we characterized the effect of expression of hnRNPs A/B during acute and persistent JUNV infections in Vero cells. …”

Proteomic Characterization of Plasma Cells from Patients with Multiple Myeloma

“…The fifth protein, isoform 1 of heterogeneous nuclear ribonucleoprotein A3 (hnRNP A3), is a relatively less known protein compared to the best known members of the hnRNP family (i.e., A1, A2/B1). The hnRNP proteins have a major nucleoplasmic localization with several of them (A, D, E, I, K, L) capable of nucleo-cytoplasmic shuttling, while others (C and U) do not exit the nucleus except under certain cellular conditions [46,47]. In addition to the major nuclear role of hnRNPs in mRNA processing (splicing, polyadenylation) and transport, they are known to participate in several other events, including transcription, DNA repair and telomere DNA formation [48,49].…”