An RNase P ribozyme library has been developed as a tool for functional genomics studies. Each clone of this library contains a random 18-mer and the sequence of M1 RNA, the catalytic subunit of RNase P. Repression of target gene expression is thus achieved by the complementary binding of mRNA to the random guide sequence and the successive target cleavage via M1 RNA. Cellular expression of the ribozyme expression was confirmed, and EGFP mRNA was used as a model to demonstrate that the RNase P ribozyme expression system can inhibit the target gene expression. The constructed RNase P ribozyme library has a complexity of 1.4x10(7). This novel library system should become a useful in functional genomics, to identify novel gene functions in mammalian cells.
Catalytic Domain ; Clone Cells ; Gene Expression ; Genomics* ; Repression, Psychology ; Ribonuclease P* ; Ribonucleases* ; RNA ; RNA, Messenger

Hepatitis C virus (HCV), one of the major pathogens of viral hepatitis, causes significant hazards in humans. Interferon treatment in combination with ribavirin is used as the first line clinical treatment for HCV infection. However, good response to this treatment has only been observed in few patients and repeated recurrence has also been reported frequently. Therefore, new antiviral agents and therapies are in urgent demand. Here, we report a newly constructed Escherichia coli RNase P based M1GS ribozyme that can specifically and efficiently target the core gene of HCV. The guide sequence (GS) of this M1IGS was designed according to the sequence of the core coding region of HCV genome. The GS was then covalently linked to the 3' terminus of M1 RNA, the catalytic subunit of RNase P from Escherichia coli. The specification of this sequence-specific ribozyme, M1GS, was then examined using an in vitro cleavage assay. The cytotoxicity and its activity in inhibition of HCV gene expression and viral proliferation were further studied in vivo. Our results show that the reconstructed M1GS ribozyme displayed obvious catalytic activity in cleaving target mRNAs fragment in vitro. Notable reduction in the expression of HCV core protein and a 1 000-fold reduction in viral growth were also observed in cultured HCV infected Huh7.5.1 cells expressing the functional M1GS ribozyme. This study demonstrated a direct evidence for the antiviral activity of the customized M1GS-HCV/C141 ribozyme, and thus provided a promising new strategy for clinical treatment of HCV infection.
Antiviral Agents ; pharmacology ; Escherichia coli ; genetics ; Genetic Engineering ; Hepacivirus ; genetics ; physiology ; RNA, Catalytic ; genetics ; pharmacology ; RNA, Guide ; genetics ; Ribonuclease P ; genetics ; Viral Core Proteins ; genetics

<p>OBJECTIVETo determine the effects of M1-GS RNA (M1 RNA) on bcr-abl mRNA and oncoprotein after M1 RNA with guide sequence (M1-GS RNA) targeting the oncogene was transfected into K562 cells.p><p>METHODSpAVGS4 (an eukaryocyte expression vector containing M1-GS RNA sequence) and pNAV-1 (as the control) were transfected into K562 cells by X-tremeGENE Q2. Total RNA was extracted at 24, 48, 72 and 96 hours after transfection. Then RT-PCR was done to compare the products at different time point. After collecting pAVGS4-transfected cells and the control cells at 48 and 96 hours after transfection, total protein was extracted and quantified. Change of P210 was determined by Western blot. Colony formation was analyzed at 96 hours after transfection.p><p>RESULTSRT-PCR based on transfected cells at different time point showed that the amount of bcr-abl mRNA began to decrease at 24 hours and reduced to 9.2% and 2.5% respectively at 48 and 72 hours after transfection. Western blot showed that the expression of P210 in the pAVGS4 group reduced to 10.4% of the control at 48 hours and 6.7% of the control at 96 hours after transfection. The inhibition rate of colony formation was 81.3% after K562 cells were transfected by pAVGS4.p><p>CONCLUSIONpAVGS4 can efficiently destroy bcr-abl mRNA in K562 cells. The transcript level of bcr-abl mRNA was reduced with the time after transfection. The expression of P210 was decreased significantly at 48 and 96 hours after transfection. K562 cell colony formation was prominently inhibited.p>
Escherichia coli Proteins ; genetics ; Fusion Proteins, bcr-abl ; genetics ; metabolism ; Genetic Vectors ; Humans ; K562 Cells ; RNA, Bacterial ; genetics ; RNA, Catalytic ; genetics ; RNA, Messenger ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Ribonuclease P ; genetics ; Time Factors ; Transfection ; methods

Group Ⅱ introns are self-splicing ribozymes, which insert directly into target sites in DNA with high frequency through "retrohoming". They specifically and efficiently recognize and splice DNA target sites, endowing themselves with great potential in genetic engineering. This paper reviewed the gene targeting principle of group Ⅱ introns and the application in microbial genetic modification, and then analyzed the limitations of them in multi-functional gene editing and eukaryotes based on the "retrohoming" characteristics and the dependence on high Mg²⁺ concentration. Finally, we dissected the potential of group Ⅱ introns in the development of novel gene editing tools based on our previous research outcome and the structural characteristics of the introns, hoping to provide a reference for the application of group Ⅱ introns in biotechnology.
DNA ; Eukaryota ; Gene Targeting ; Introns/genetics* ; RNA, Catalytic/genetics*

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

Overexpression of procollagen gene can cause the extraordinary increase of collagen's synthesis and therefore lead to the keloid and hypertrophic scar. To utilize ribozyme to suppress the expression of procollagen genes, a eukaryotic expression recombinant plasmid containing a dual-ribozyme gene against alpha 1 (I) and alpha 1 (III) procollagen genes was constructed. The ribozyme from in vitro transcription was incubated with target transcripts from recombinant plasmids which separately contained the fragments of the second exons of pro alpha 1 (I) and pro alpha 1 (III) collagen genes under various experimental conditions. The results showed that the dual-ribozyme could efficiently catalyze the specific cleavage of the target RNAs at 37 degrees C, 42 degrees C, 50 degrees C and Mg2+ concentration from 10 mmol/L to 20 mmol/L. This work provided a basis for further study on the ribozyme to suppress the expression of procollagen genes and control the cicatrization.
Base Sequence ; Exons ; Molecular Sequence Data ; Procollagen ; genetics ; RNA ; metabolism ; RNA, Catalytic ; genetics ; metabolism ; Temperature

A self-cleaving hammerhead ribozyme gene containing a 14nt target sequence of ASSVd at the 3' end of hammerhead ribozyme was synthesized, amplified and cloned at the Xho I-Hind III site of pGEM7Zf(+). The ends produced by Xho I or Sal I can link together, thus the recognition sites of both enzymes vanish and can't be cut by either one. We used this property to get the recombinant plasmid bearing 2, 4, 6, 8, 10 and 12 copies of self-cleavable ribozyme respectively after successively sub-cloning five times. Linearized recombinat plasmid model catalyzed by T7 RNA polymerase was transcribed in vitro. The multimeric ribozyme molecules efficiently self-cleaved via cis-acting to release many ribozyme molecules It indicates that the concentration of ribozyme transcripts has been enhanced during transcription. Trans-cleavage reaction was carried out by incubating monomeric and multimeric ribozymes with same mol concentration and 32P labeled target ASSVd. Both ribozymes and target transcripts were mixed in 1:1 ratio. Autoradiograms showed the transcripts of multimeric ribozyme were substantially more effective against the ASSVd target RNA than the monomeric ribozymes. We confer that the multimeric self-clevable ribozyme is likely to provide more valuable application in vivo.
Malus ; virology ; RNA, Catalytic ; chemistry ; genetics ; metabolism ; RNA, Viral ; metabolism ; Viroids ; metabolism

Hepatitis C ; genetics ; Humans ; RNA, Catalytic ; genetics ; RNA, Small Nuclear ; genetics

Myotonic dystrophy type 1 (DM1), which is a dominantly inherited neurodegenerative disorder, results from a CTG trinucleotide repeat expansion in the 3'-untranslated region (3'-UTR) of the myotonic dystrophy protein kinase (DMPK) gene. Retention of mutant DMPK (mDMPK) transcripts in the nuclei of affected cells has been known to be the main cause of pathogenesis of the disease. Thus, reducing the RNA toxicity through elimination of the mutant RNA has been suggested as one therapeutic strategy against DM1. In this study, we suggested RNA replacement with a trans -splicing ribozyme as an alternate genetic therapeutic approach for amelioration of DM1. To this end, we identified the regions of mDMPK 3'-UTR RNA that were accessible to ribozymes by using an RNA mapping strategy based on a trans - splicing ribozyme library. We found that particularly accessible sites were present not only upstream but also downstream of the expanded repeat sequence. Repair or replacement of the mDMPK transcript with the specific ribozyme will be useful for DM1 treatment through reduction of toxic mutant transcripts and simultaneously restore wild-type DMPK or release nucleus-entrapped mDMPK transcripts to the cytoplasm.
Cytoplasm ; Myotonic Dystrophy ; Neurodegenerative Diseases ; Protein Kinases ; Protein-Serine-Threonine Kinases ; Retention (Psychology) ; RNA ; RNA, Catalytic ; Trinucleotide Repeat Expansion

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*