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*

Panax japonicus is a traditional Chinese medicine,and its principle components have shown certain pharmacological activities for cell damage,aging and cell apoptosis. In order to clarify the pharmacological mechanism and involved metabolic pathways of P. japonicas,the gene expression of Tetrahymena thermophila under P. japonicus treatment was analyzed through high-throughput transcriptome sequencing in this study. Based on the transcriptome analysis,3 544 differentially expressed genes were identified in control group,of which 1 945 genes showed up-regulated expression and 1 599 genes showed down-regulated expression. Under P. japonicas treatment in the experiment group,3 312 differentially expressed genes were screened,of which 1 `493 genes showed up-regulated expression and 1 819 genes showed down-regulated expression. GO enrichment analysis indicated that in control group,the genes in the cells in a series of fundamental biological process were down-regulated,such as DNA replication and protein synthesis; while the signal transduction process and fatty acids oxidizing process were enriched. Whereas in the experiment group,down-regulated genes were mainly enriched in oxidation-reduction,cofactor metabolic process and vitamin metabolic process; up-regulated genes were enriched in signal transduction process and protein modification process. In the analysis using KEGG database,cell cycle pathway was enhanced and autophagy pathway was inhibited under the condition of P. japonicas treatment. Real-time quantitative polymerase chain reaction( RT-qPCR) was used to detect the expression differences between 6 up-regulated and 4 down-regulated genes in related metabolic pathways. The RT-q PCR results and RNA-Seq data were highly correlated and consistent with each other. This study could provide important direction and basis for further study on the mechanism of cell growth regulation with the treatment of P. japonica.
Gene Expression ; Gene Expression Profiling ; Metabolic Networks and Pathways ; Panax ; chemistry ; Plants, Medicinal ; chemistry ; Tetrahymena thermophila ; drug effects ; genetics ; Transcriptome

Meiotic recombination is carried out through a specialized pathway for the formation and repair of DNA double-strand breaks (DSBs) made by the Spo11 protein. The present study shed light on the functional role of cyclin, CYC2, in Tetrahymena thermophila which has transcriptionally high expression level during meiosis process. Knocking out the CYC2 gene results in arrest of meiotic conjugation process at 2.5-3.5 h after conjugation initiation, before the meiosis division starts, and in company with the absence of DSBs. To investigate the underlying mechanism of this phenomenon, a complete transcriptome profile was performed between wild-type strain and CYC2 knock-out strain. Functional analysis of RNA-Seq results identifies related differentially expressed genes (DEGs) including SPO11 and these DEGs are enriched in DNA repair/mismatch repair (MMR) terms in homologous recombination (HR), which indicates that CYC2 could play a crucial role in meiosis by regulating SPO11 and participating in HR.
Cell Cycle Checkpoints ; Cyclins ; genetics ; metabolism ; DNA Breaks, Double-Stranded ; DNA Mismatch Repair ; DNA Repair ; Endodeoxyribonucleases ; genetics ; metabolism ; Homologous Recombination ; Meiosis ; Microscopy, Fluorescence ; Phenotype ; Protozoan Proteins ; genetics ; metabolism ; Real-Time Polymerase Chain Reaction ; Sequence Analysis, RNA ; Tetrahymena thermophila ; genetics ; metabolism ; Transcriptome