Rotavirus Infection Alters Splicing of the Stress-Related Transcription Factor XBP1

Abstract

XBP1 is a stress-regulated transcription factor also involved in mammalian host defenses and innate immune response. Our investigation of XBP1 RNA splicing during rotavirus infection revealed that an additional XBP1 RNA (XBP1es) that corresponded to exon skipping in the XBP1 pre-RNA is induced depending on the rotavirus strain used. We show that the translation product of XBP1es (XBP1es) has trans-activation properties similar to those of XBP1 on ER stress response element (ERSE) containing promoters. Using monoreassortant between ES+ (“skipping”) and ES– (“nonskipping”) strains of rotavirus, we show that gene 7 encoding the viral translation enhancer NSP3 is involved in this phenomenon and that exon skipping parallels the nuclear relocalization of cytoplasmic PABP. We further show, using recombinant rotaviruses carrying chimeric gene 7, that the ES+ phenotype is linked to the eIF4G-binding domain of NSP3. Because the XBP1 transcription factor is involved in stress and immunological responses, our results suggest an alternative way to activate XBP1 upon viral infection or nuclear localization of PABP. IMPORTANCE Rotavirus is one of the most important pathogens causing severe gastroenteritis in young children worldwide. Here we show that infection with several rotavirus strains induces an alternative splicing of the RNA encoding the stressed-induced transcription factor XBP1. The genetic determinant of XBP1 splicing is the viral RNA translation enhancer NSP3. Since XBP1 is involved in cellular stress and immune responses and since the XBP1 protein made from the alternatively spliced RNA is an active transcription factor, our observations raise the question of whether alternative splicing is a cellular response to rotavirus infection.

Construction of potential periodontitis-related miRNA-mRNA regulatory network

“…Among them, XBP1 has been reported to play a critical role in in ammatory diseases [20]. The role of XBP1 in mammalian host defenses and the innate immune response has also been uncovered by previous studies [21].…”

Treading a HOSTile path: Mapping the dynamic landscape of host cell–rotavirus interactions to explore novel host-directed curative dimensions

“…Functional dissection through rigorous reverse genetics approach only enabled to reveal a concurrency of this exon skipping with Poly(A) binding protein cytoplasmic 1 (PABPC1) nuclear re-localization by eukaryotic Initiation Factor 4 G (eIF4G)-binding domain of NSP3 ( Figure 3f ) (the latter event is described in the following sections). Although the exact functional significance of RV-induced xbp1 exon skipping on regulating host innate immune response has remained unaddressed, speculations regarding a global change in the splicing landscape within RV-infected cells have been made [ 187 ].…”

“…Moreover, host factor-independent targeting of RV has also been reported in vitro using other small molecules with viroplasm/DLP disintegrating potency [ 306 ] and viral transcription inhibitory effects [ 307 ]. With the recent advances in technological refinement such as adopting human intestinal organoids as infection model [ 86 , 123 , 140 , 141 , 213 , 257–259 , 261 , 263 , 276 , 308 , 309 ] and using rotaviral reverse genetics [ 187 , 245 , 249 , 310–313 ], future research should be propelled toward unraveling novel mechanistic aspects of host–RV interactions, and assessing therapeutic potential of reported anti-RV small molecules (host-targeted, virus-targeted, or in potential synergistic combination) in clinical settings.…”

“…Thus, even though host cells trigger UPR in response to RV infection, RV has developed evasive strategies for avoiding the potential deleterious effects of this antiviral host response. Interestingly, apart from the alternative splicing of X-box binding protein 1 (xbp1) RNA in cytosol downstream of RV-mediated IRE1 activation, a recent report also demonstrated a RV strain-specific exon skipping phenomenon (lacking exon 4) of xbp1 RNA independent of IRE1 [187]. Functional dissection through rigorous reverse genetics approach only enabled to reveal a concurrency of this exon skipping with Poly(A) binding protein cytoplasmic 1 (PABPC1) nuclear relocalization by eukaryotic Initiation Factor 4 G (eIF4G)-binding domain of NSP3 (Figure 3f) (the latter event is described in the following sections).…”

Androgen modulation of XBP1 is functionally driving part of the AR transcriptional program

“…In addition to transcriptional control of XBP1, its function is also posttranscriptionally regulated through inositol-requiring enzyme 1ɑ (IRE1ɑ), which is encoded by the ERN1 gene (hereafter both the gene and protein are referred to as ERN1, for simplicity). When ERN1 senses stress, its RNase function is activated, allowing excision of 26 nucleotides of the XBP1 mRNA which leads to a frameshift (Yoshida et al 2001, Calfon et al 2002, Hetz et al 2013, Duarte et al 2019. Consequently, XBP1 exists in two isoforms: XBP1 unspliced (XBP1u) and XBP1 spliced (XBP1s).…”