Alternative splicing (AS) is an evolutionarily conserved mechanism that removes introns and ligates exons to generate mature messenger RNAs (mRNAs), extremely improving the richness of transcriptome and proteome. Both mammal hosts and pathogens require AS to maintain their life activities, and inherent physiological heterogeneity between mammals and pathogens makes them adopt different ways to perform AS. Mammals and fungi conduct a two-step transesterification reaction by spliceosomes to splice each individual mRNA (named cis -splicing). Parasites also use spliceosomes to splice, but this splicing can occur among different mRNAs (named trans -splicing). Bacteria and viruses directly hijack the host's splicing machinery to accomplish this process. Infection-related changes are reflected in the spliceosome behaviors and the characteristics of various splicing regulators (abundance, modification, distribution, movement speed, and conformation), which further radiate to alterations in the global splicing profiles. Genes with splicing changes are enriched in immune-, growth-, or metabolism-related pathways, highlighting approaches through which hosts crosstalk with pathogens. Based on these infection-specific regulators or AS events, several targeted agents have been developed to fight against pathogens. Here, we summarized recent findings in the field of infection-related splicing, including splicing mechanisms of pathogens and hosts, splicing regulation and aberrant AS events, as well as emerging targeted drugs. We aimed to systemically decode host-pathogen interactions from a perspective of splicing. We further discussed the current strategies of drug development, detection methods, analysis algorithms, and database construction, facilitating the annotation of infection-related splicing and the integration of AS with disease phenotype.
Animals ; Alternative Splicing/genetics* ; RNA Splicing ; Spliceosomes/metabolism* ; RNA, Messenger/metabolism* ; Communicable Diseases/genetics* ; Mammals/metabolism*

Recent anti-cancer approaches have been based to target tumor-specifically associated and/or causative molecules such as RNAs or proteins. As this specifically targeted anti-cancer modulator, we have previously described a novel human cancer gene therapeutic agent that is Tetrahymena group I intron-based trans-splicing ribozyme which can reprogram and replace human telomerase reverse transcriptase (hTERT) RNA to selectively induce tumor-specific cytotoxicity in cancer cells expressing the target RNA. Moreover, the specific ribozyme has been shown to efficiently retard tumor tissues in xenograft mice which had been inoculated with hTERT-expressing human cancer cells. In this study, we assessed specificity of trans-splicing reaction in cells to evaluate the therapeutic feasibility of the specific ribozyme. In order to analyze the trans-spliced products by the specific ribozyme in hTERT-positive cells, RT, 5'-end RACE-PCR, and sequencing reactions of the spliced RNAs were employed. Then, whole analyzed products resulted from reactions only with the hTERT RNA. This study suggested that the developed ribozyme perform highly specific RNA replacement of the target RNA in cells, hence trans-splicing ribozyme will be one of specific agents for genetic approach to revert cancer.
Animals ; Genes, Neoplasm ; Heterografts ; Humans ; Introns* ; Mice ; RNA ; Sensitivity and Specificity* ; Telomerase ; Tetrahymena ; Trans-Splicing*

Fusion proteins resulting from chimeric sequences are excellent targets for therapeutic drug development. We developed a database of chimeric sequences by examining the genomic alignment of mRNA and EST sequences in the GenBank. We identified 688 chimeric mRNA and 20,998 chimeric EST sequences. Including EST sequences greatly expands the scope of chimeric sequences even though it inevitably accompanies many artifacts. Chimeric sequences are clustered according to the ECgene ID so that the user can easily find chimeric sequences related to a specific gene. Alignments of chimeric sequences are displayed as custom tracks in the UCSC genome browser. ChimerDB, available at http://genome.ewha.ac.kr/ECgene/ChimerDB/, should be a valuable resource for finding drug targets to treat cancers.
Artifacts ; Databases, Nucleic Acid* ; Genome ; RNA, Messenger ; Trans-Splicing ; Translocation, Genetic

The acquisition of somatic mutations is the most common event in cancer. Neoantigens expressed from genes with mutations acquired during carcinogenesis can be tumor-specific. Since the immune system recognizes tumor-specific peptides, they are potential targets for personalized neoantigen-based immunotherapy. However, the discovery of druggable neoantigens remains challenging, suggesting that a deeper understanding of the mechanism of neoantigen generation and better strategies to identify them will be required to realize the promise of neoantigen-based immunotherapy. Alternative splicing and RNA editing events are emerging mechanisms leading to neoantigen production. In this review, we outline recent work involving the large-scale screening of neoantigens produced by alternative splicing and RNA editing. We also describe strategies to predict and validate neoantigens from RNA sequencing data.
Alternative Splicing ; Carcinogenesis ; Humans ; Immune System ; Immunotherapy ; Mass Screening ; Peptides ; RNA Editing ; RNA ; Sequence Analysis, RNA

To analyze the expression of splicing factors in gastric cancer using bioinformatics methods and investigate the effect of aberrantly expressed serine/arginine-rich splicing factor(SRSF10)on the phenotype of gastric cancer cells. The RNA-seq data of gastric cancer and paracancerous tissues were downloaded from The Cancer Genome Atlas(TCGA)cancer database,and bioinformatics analysis was performed to obtain the splicing factors differentially expressed in gastric cancer.The splicing factor SRSF10 was selected to investigate its effect on the development of gastric cancer.RNA interference technology was used to construct SRSF10 knockdown gastric cancer cells.MTS,Transwell,and cell scratches were used to study the effect of SRSF10 knockdown on gastric cancer cell phenotype. A total of 48 splicing factors were identified in gastric cancer by a series of bioinformatics techniques,of which 35 were up-regulated and 13 were down-regulated.The splicing factor SRSF10,which was up-regulated,was selected for further study.It was found that the gastric cancer cells after SRSF10 knockdown proliferated more slowly and had lower migration ability than normal gastric cancer cells. Multiple splicing factors are found in gastric cancer and may play an important role in the development of gastric cancer.The splicing factor SRSF10 may contribute to the pathogenesis of gastric cancer.
Alternative Splicing ; Cell Cycle Proteins ; Computational Biology ; Gene Expression Regulation, Neoplastic ; Humans ; RNA Splicing Factors ; Repressor Proteins ; Serine-Arginine Splicing Factors ; Stomach Neoplasms

Alternative splicing (AS) is an important mechanism of producing transcriptome diversity and microarray techniques are being used increasingly to monitor the splice variants. There exist three types of microarrays interrogating AS events-junction, exon, and tiling arrays. Junction probes have the advantage of monitoring the splice site directly. Johnson et al., performed a genome-wide survey of human alternative pre-mRNA splicing with exon junction microarrays (Science 302:2141-2144, 2003), which monitored splicing at every known exon-exon junctions for more than 10,000 multi-exon human genes in 52 tissues and cell lines. Here, we describe an algorithm to deduce the relative concentration of isoforms from the junction array data. Non-negative Matrix Factorization (NMF) is applied to obtain the transcript structure inferred from the expression data. Then we choose the transcript models consistent with the ECgene model of alternative splicing which is based on mRNA and EST alignment. The probe-transcript matrix is constructed using the NMF-consistent ECgene transcripts, and the isoform abundance is deduced from the non-negative least squares (NNLS) fitting of experimental data. Our method can be easily extended to other types of microarrays with exon or junction probes.
Alternative Splicing ; Cell Line ; Exons* ; Humans ; Least-Squares Analysis ; Protein Isoforms ; RNA Precursors ; RNA, Messenger ; Transcriptome

Alternative splicing of pre-mRNA is an important mechanism for regulating gene function at the post-transcription level and for producing proteomic diversity in higher eukaryotes. The alternative splicing is regulated by the interaction between diverse cis-acting elements and trans-acting factors. Alternative splicing events of oncogenes, tumor suppressor genes and metastasis suppressor genes are associated with the initiation and development of human neoplasms. The protein isoforms sourced from alternative splicing take part in regulating the gene transcription, cell cycle, apoptosis of cells, and playing a role in tumor growth. It is possible for molecular therapy to target directly isoforms of protein produced by alternative splicing or to interfere with the process of alternative splicing.
Alternative Splicing ; genetics ; Humans ; Neoplasms ; genetics ; RNA Precursors ; metabolism ; RNA, Neoplasm ; analysis ; Transcription, Genetic

Telomerase reverse transcriptase (TERT) is an enzymatic ribonucleoprotein that prolongs the replicative life span of cells by maintaining protective structures at the ends of eukaryotic chromosomes. Telomerase activity is highly up-regulated in 85-90% of human cancers, and is predominately regulated by hTERT expression. In contrast, most normal somatic tissues in humans express low or undetectable levels of telomerase activity. This expression profile identifies TERT as a potential anticancer target. By using an RNA mapping strategy based on a trans-splicing ribozyme library, we identified the regions of mouse TERT (mTERT) RNA that were accessible to ribozymes. We found that particularly accessible sites were present downstream of the AUG start codon. This mTERTspecific ribozyme will be useful for validation of the RNA replacement as cancer gene therapy approach in mouse model with syngeneic tumors.
Animals ; Catalytic Domain* ; Codon, Initiator ; Genes, Neoplasm ; Genetic Therapy ; Humans ; Mice* ; Ribonucleoproteins ; RNA* ; RNA, Catalytic ; Telomerase* ; Trans-Splicing

The self-splicing group I intron from Tetrahymena thermophila has been demonstrated to perform splicing reaction with its substrate RNA in the trans configuration. In this study, we explored the potential use of the trans-splicing group I ribozymes to replace a specific RNA with a new RNA that exerts any new function we want to introduce. We have chosen thymidine phosphorylase (TP) RNA as a target RNA that is known as a valid cancer prognostic factor. Cancer-specific expression of TP RNA was first evaluated with RT-PCR analysis of RNA from patients with gastric cancer. We determined next which regions of the TP RNA are accessible to ribozymes by employing an RNA mapping strategy, and found that the leader sequences upstream of the AUG start codon appeared to be particularly accessible. A specific ribozyme recognizing the most accessible sequence in the TP RNA with firefly luciferase transcript as a 3' exon was then developed. The specific trans-splicing ribozyme transferred an intended 3' exon tag sequence onto the targeted TP transcripts, resulting in a more than two fold induction of the reporter activity in the presence of TP RNA in mammalian cells, compared to the absence of the target RNA. These results suggest that the Tetrahymena ribozyme can be a potent anti-cancer agent to modify TP RNAs in tumors with a new RNA harboring anti-cancer activity.
Codon, Initiator ; Exons ; Fireflies ; Humans ; Introns ; Luciferases ; RNA* ; RNA, Catalytic ; Stomach Neoplasms ; Tetrahymena ; Tetrahymena thermophila ; Thymidine Phosphorylase ; Trans-Splicing*

Nanog, a homeodomain (HD) transcription factor, plays a critical role in the maintenance of embryonic stem (ES) cell self-renewal. Here, we report the identification of an alternatively-spliced variant of nanog. This variant lacked a stretch of amino acids (residues 168-183) located between the HD and tryptophan-repeat (WR) of the previously-reported full length sequence, suggesting that the deleted sequence functions as a linker and possibly affects the flexibility of the C-terminal transactivation domain relative to the DNA binding domain. Expression of mRNA encoding the splice variant, designated as nanog-delta 48, was much lower than that of the full length version in human ES cells. The ratio of nanog-delta 48 transcript to full length transcript increased, however, in multipotent adult progenitor cells. EMSA analysis revealed that both forms of Nanog were able to bind a nanog binding sequence with roughly the same affinity. A reporter plasmid assay also showed that both variants of nanog modestly repressed transactivation of gata-4, whose expression is proposed to be inhibited by nanog, with comparable potency. We conclude that, despite the difference in primary structure and expression pattern in various stem cells, the alternatively-spliced variant of Nanog has similar activity to that of the full length version.
Alternative Splicing/*genetics ; Amino Acid Sequence ; Base Sequence ; Cell Nucleus ; Cells, Cultured ; DNA-Binding Proteins/chemistry/*genetics/metabolism ; Exons/*genetics ; GATA4 Transcription Factor/metabolism ; Gene Expression Profiling ; Genes, Reporter ; Homeodomain Proteins/chemistry/*genetics/metabolism ; Humans ; Introns/genetics ; Molecular Sequence Data ; Promoter Regions (Genetics) ; RNA, Messenger/genetics/metabolism ; Research Support, Non-U.S. Gov't ; Trans-Activation (Genetics) ; Transfection