ABSTRACT
Human ZAP inhibits many viruses, including HIV and coronaviruses, by binding to viral RNAs to promote their degradation and/or translation suppression. However, the regulatory role of ZAP in host mRNAs is largely unknown. Two major alternatively spliced ZAP isoforms, the constitutively expressed ZAPL and the infection-inducible ZAPS, play overlapping yet different antiviral and other roles that need further characterization. We found that the splicing factors hnRNPA1/A2, PTBP1/2, and U1-snRNP inhibit ZAPS production and demonstrated the feasibility to modulate the ZAPL/S balance by splice-switching antisense oligonucleotides in human cells. Transcriptomic analysis of ZAP-isoform-specific knockout cells revealed uncharacterized host mRNAs targeted by ZAPL/S with broad cellular functions such as unfolded protein response (UPR), epithelial-mesenchymal transition (EMT), and innate immunity. We established that endogenous ZAPL and ZAPS localize to membrane compartments and cytosol, respectively, and that the differential localization correlates with their target-RNA specificity. We showed that the ZAP isoforms regulated different UPR branches under resting and stress conditions and affected cell viability during ER stress. We also provided evidence for a different function of the ZAP isoforms in EMT-related cell migration, with effects that are cell-type dependent. Overall, this study demonstrates that the competition between splicing and IPA is a potential target for the modulation of the ZAPL/S balance, and reports new cellular transcripts and processes regulated by the ZAP isoforms.
Subject(s)
Epithelial-Mesenchymal Transition , RNA, Messenger , RNA, Viral , RNA-Binding Proteins , Unfolded Protein Response , Epithelial-Mesenchymal Transition/genetics , Heterogeneous Nuclear Ribonucleoprotein A1/metabolism , Heterogeneous-Nuclear Ribonucleoproteins/genetics , Heterogeneous-Nuclear Ribonucleoproteins/metabolism , Humans , Polypyrimidine Tract-Binding Protein/genetics , Polypyrimidine Tract-Binding Protein/metabolism , Protein Isoforms/genetics , Protein Isoforms/metabolism , RNA, Messenger/metabolism , RNA, Viral/metabolism , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Ribonucleoproteins, Small Nuclear/metabolismABSTRACT
SARS-CoV-2 neurotropism has been increasingly recognized by its imaging and syndromic manifestations in the literature. The purpose of this report is to explore the limited yet salient current evidence that SARS-CoV-2's host genomic targets PTBP1 and the 14-3-3 protein isoform encoding genes YWHAE and YWHAZ may be hold the key to understanding how neurotropism triggers neurodegeneration and how it may contribute to the onset of neurodegenerative disease. Considering that PTBP1 silencing in particular has recently been shown to reverse clinical parkinsonism and induce neurogenesis, as well as the known interactions of PTBP1 and YWHAE/Z with coronaviruses - most notably 14-3-3 and SARS-CoV, recent studies reinvigorate the infectious etiology hypotheses on major neurodegenerative disease such as AD and iPD. Considering that human coronaviruses with definite neurotropism have been shown to achieve long-term latency within the mammalian CNS as a result of specific accommodating mutations, the corroboration of genomic-level evidence with neuroimaging has vast potential implications for neurodegenerative disease.