ABSTRACT
Objective To investigate the effect of SARS-CoV-2 membrane protein on the processing of the 3' untranslated region (UTR) of the mRNA precursor (pre-mRNA) in host cells. Methods Based on the cell model of human lung epithelial cells A549, over-expression of the SARS-CoV-2 membrane protein was performed. The RNA-Seq high-throughput sequencing technique and bioinformatics methods was employed to analyze the systematic characterization of alternative polyadenylation (APA) events in host cells. Genes with significant APA events were uploaded to the Metascape database for functional enrichment analysis. In addition, alternative 3'UTR length of genes with APA events was verified by RT-qPCR. Then the target protein expression level was detected by Western blot. Results A total of 813 genes that were significant dynamic APA events in host cells that over-expressed SARS-CoV-2 membrane protein. These genes were enriched in cell biologicial processes such as the mitotic cell cycle and regulation of cellular response to stress. We further screened AKT1, which encodes a critical regulator involved in the above biological process, showing a 3'UTR lengthening in IGV software. RT-qPCR verified the trend of 3'UTR length changes of AKT1. Western blot showed the increased level of phosphorylated AKT1 protein in over-expressed group of M protein. Conclusion SARS-CoV-2 membrane protein potentially affects the 3' processing of host pre-mRNAs. AKT1, which is involved in a variety of viral biological processes, with 3'UTR lengthening, and its protein function was activated intracellularly. © 2022 Institute of Biophysics,Chinese Academy of Sciences. All rights reserved.
ABSTRACT
Objective To investigate the effect of SARS-CoV-2 membrane protein on the processing of the 3' untranslated region (UTR) of the mRNA precursor (pre-mRNA) in host cells. Methods Based on the cell model of human lung epithelial cells A549, over-expression of the SARS-CoV-2 membrane protein was performed. The RNA-Seq high-throughput sequencing technique and bioinformatics methods was employed to analyze the systematic characterization of alternative polyadenylation (APA) events in host cells. Genes with significant APA events were uploaded to the Metascape database for functional enrichment analysis. In addition, alternative 3'UTR length of genes with APA events was verified by RT-qPCR. Then the target protein expression level was detected by Western blot. Results A total of 813 genes that were significant dynamic APA events in host cells that overexpressed SARS-CoV-2 membrane protein. These genes were enriched in cell biologicial processes such as the mitotic cell cycle and regulation of cellular response to stress. We further screened AKT1, which encodes a critical regulator involved in the above biological process, showing a 3'UTR lengthening in IGV software. RT-qPCR verified the trend of 3'UTR length changes of AKT1. Western blot showed the increased level of phosphorylated AKT1 protein in over-expressed group of M protein. Conclusion SARS-CoV-2 membrane protein potentially affects the 3' processing of host pre-mRNAs. AKT1, which is involved in a variety of viral biological processes, with 3'UTR lengthening, and its protein function was activated intracellularly.
ABSTRACT
During the messenger RNA (mRNA) maturation process, RNA polyadenylation is a key step, and is coupled to the termination of transcription. Various cis-acting elements near the cleavage site and their binding factors would affect the process of polyadenylation, and AAUAAA, a highly conserved hexamer, was the most important polyadenylation signal (PAS). PAS usage is one of the critical modification determinants targeted at mRNA post-transcription. The full-length transcriptome has recently generated a massive amount of sequencing data, revealing poly(A) variation and alternative polyadenylation (APA) in Spodoptera frugiperda. We identified 50,616 polyadenylation signals in Spodoptera frugiperda via analysis of full-length transcriptome combined with expression Sequence Tags Technology (EST). The polyadenylation signal usage in Spodoptera frugiperda is conserved, and it is similar to that of flies and other animals. AAUAAA and AUUAAA are the most highly conserved polyadenylation signals of all polyadenylation signals we identified. Additionally, we found the U/GU-rich downstream sequence element (DSE) in the cleavage site. These results demonstrate that APA in Spodoptera frugiperda plays a significant role in root growth and development. This is the first polyadenylation signal usage analysis in agricultural pests, which can deepen our understanding of Spodoptera frugiperda and provide a theoretical basis for pest control.
ABSTRACT
The coronavirus disease 2019 (COVID-19) pandemic has caused many deaths worldwide. To date, the mechanism of viral immune escape remains unclear, which is a great obstacle to developing effective clinical treatment. RNA processing mechanisms, including alternative polyadenylation (APA) and alternative splicing (AS), are crucial in the regulation of most human genes in many types of infectious diseases. Because the role of APA and AS in response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains unknown, we performed de novo identification of dynamic APA sites using a public dataset of human peripheral blood mononuclear cell (PBMC) RNA-Seq data in COVID-19 patients. We found that genes with APA were enriched in innate immunity -related gene ontology categories such as neutrophil activation, regulation of the MAPK cascade and cytokine production, response to interferon-gamma and the innate immune response. We also reported genome-wide AS events and enriched viral transcription-related categories upon SARS-CoV-2 infection. Interestingly, we found that APA events may give better predictions than AS in COVID-19 patients, suggesting that APA could act as a potential therapeutic target and novel biomarker in those patients. Our study is the first to annotate genes with APA and AS in COVID-19 patients and highlights the roles of APA variation in SARS-CoV-2 infection.
Subject(s)
COVID-19/genetics , Polyadenylation , SARS-CoV-2 , Alternative Splicing , COVID-19/immunology , Female , Genome, Human , Humans , Immunity, Innate , Leukocytes, Mononuclear , Male , RNA, Messenger , TranscriptomeABSTRACT
Microbes and viruses are known to alter host transcriptomes by means of infection. In light of recent challenges posed by the COVID-19 pandemic, a deeper understanding of the disease at the transcriptome level is needed. However, research about transcriptome reprogramming by post-transcriptional regulation is very limited. In this study, computational methods developed by our lab were applied to RNA-seq data to detect transcript variants (i.e., alternative splicing (AS) and alternative polyadenylation (APA) events). The RNA-seq data were obtained from a publicly available source, and they consist of mock-treated and SARS-CoV-2 infected (COVID-19) lung alveolar (A549) cells. Data analysis results show that more AS events are found in SARS-CoV-2 infected cells than in mock-treated cells, whereas fewer APA events are detected in SARS-CoV-2 infected cells. A combination of conventional differential gene expression analysis and transcript variants analysis revealed that most of the genes with transcript variants are not differentially expressed. This indicates that no strong correlation exists between differential gene expression and the AS/APA events in the mock-treated or SARS-CoV-2 infected samples. These genes with transcript variants can be applied as another layer of molecular signatures for COVID-19 studies. In addition, the transcript variants are enriched in important biological pathways that were not detected in the studies that only focused on differential gene expression analysis. Therefore, the pathways may lead to new molecular mechanisms of SARS-CoV-2 pathogenesis.