Rewriting the Central Dogma with Synthetic Genetic Polymers.

DNA and RNA are ubiquitous molecules responsible for storage and transmission of genetic information and together comprise the central dogma of molecular biology. However, the recent emergence of synthetic genetic polymers is providing an opportunity to challenge the fundamental principles of life. Herein, we describe the ongoing attempts to rewrite the central dogma with 4'-thioDNA and 4'-thioRNA, which feature a sulfur instead of an oxygen atom in the furanose ring moiety. Using reconstituted Escherichia coli gene expression machinery, studies have shown that the genetic information conserved in 4'-thioDNA can be transcribed to 4'-thioRNA and eventually translated into protein, mirroring the processes that occur in nature. Such studies underscore the feasibility of controlling life by substances other than DNA and RNA.

A Unique Gene-Silencing Approach, Using an Intelligent RNA Expression Device (iRed), Results in Minimal Immune Stimulation When Given by Local Intrapleural Injection in Malignant Pleural Mesothelioma.

BACKGROUND: We have recently introduced an intelligent RNA expression device (iRed), comprising the minimum essential components needed to transcribe short hairpin RNA (shRNA) in cells. Use of iRed efficiently produced shRNA molecules after transfection into cells and alleviated the innate immune stimulation following intravenous injection. METHODS: To study the usefulness of iRed for local injection, the engineered iRed encoding luciferase shRNA (Luc iRed), complexed with cationic liposomes (Luc iRed/liposome-complexes), was intrapleurally injected into an orthotopic mesothelioma mouse model. RESULTS: Luc iRed/liposome-complexes markedly suppressed the expression of a luciferase marker gene in pleurally disseminated mesothelioma cells. The suppressive efficiency was correlated with the expression level of shRNA within the mesothelioma cells. In addition, intrapleural injection of iRed/liposome-complexes did not induce IL-6 production in the pleural space and consequently in the blood compartment, although plasmid DNA (pDNA) or dsDNA (the natural construct for iRed) in the formulation did. CONCLUSION: Local delivery of iRed could augment the in vivo gene silencing effect without eliciting pronounced innate immune stimulation. Our results might hold promise for widespread utilization of iRed as an RNAi-based therapeutic for intracelial malignant cancers.

In vitro optimization of 2'-OMe-4'-thioribonucleoside-modified anti-microRNA oligonucleotides and its targeting delivery to mouse liver using a liposomal nanoparticle.

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression post-transcriptionally. Previous studies, which characterized miRNA function, revealed their involvement in fundamental biological processes. Importantly, miRNA expression is deregulated in many human diseases. Specific inhibition of miRNAs using chemically modified anti-miRNA oligonucleotides (AMOs) can be a potential therapeutic strategy for diseases in which a specific miRNA is overexpressed. 2'-O-Methyl (2'-OMe)-4'-thioRNA is a hybrid type of chemically modified oligonucleotide, exhibiting high binding affinity to complementary RNAs and high resistance to nuclease degradation. Here, we evaluate 2'-OMe-4'-thioribonucleosides for chemical modification on AMOs. Optimization of the modification pattern using a variety of chemically modified AMOs that are perfectly complementary to mature miR-21 revealed that the uniformly 2'-OMe-4'-thioribonucleoside-modified AMO was most potent. Further investigation showed that phosphorothioate modification contributed to long-term miR-122 inhibition by the 2'-OMe-4'-thioribonucleoside-modified AMO. Moreover, systemically administrated AMOs to mouse using a liposomal delivery system, YSK05-MEND, showed delivery to the liver and efficient inhibition of miR-122 activity at a low dose in vivo.

The systemic administration of an anti-miRNA oligonucleotide encapsulated pH-sensitive liposome results in reduced level of hepatic microRNA-122 in mice.

Efficient delivery continues to be a challenge in microRNA (miRNA) therapeutics. We utilized a pH-sensitive multifunctional envelope-type nano device (MEND) containing a pH-sensitive lipid YSK05 (YSK05-MEND) to regulate liver specific miRNA-122 (miR-122). Anti-microRNA oligonucleotides including 2'-OMe and phosphorothioate modifications against miR-122 (AMO122) were encapsulated in the YSK05-MEND. Despite the lower uptake, the YSK05-MEND showed a higher activity in liver cancer cells than Lipofectamine2000 (LFN2k) due to efficient endosomal escape. Cytotoxicity was minimal at 100 nM of AMO122 in YSK05-MEND treated cells, but LFN2k showed toxicity at 50 nM. When mice were administrated with free AMO122, it was eliminated via the kidney due to its molecular weight, and lesser amounts were detected in the liver. Conversely, the YSK05-MEND delivered higher amounts of the AMO122 to the liver. Systemic administration of YSK05-MEND induced the knockdownofmiR-122andan increase in target genes inthe liver, and a subsequent reduction in plasma cholesterol at a dose of 1mgAMO/kgwhile free AMO122 showed no activity at the same dose. The effect ofAMO122 delivered by YSK05-MEND persisted for over 2 weeks. These results suggest that YSK05-MEND is a promising system for delivering AMOs to the liver.