Project description:Circular RNAs (circRNAs) constitute an abundant class of covalently closed non-coding RNA molecules that are formed by backsplicing from eukaryotic protein-coding genes. Recent studies have shown that circRNAs can act as microRNA or protein decoys as well as transcriptional regulators. However, the functions of most circRNAs are still poorly understood. Because circRNA sequences overlap with their linear parent transcripts, depleting specific circRNAs without affecting host gene expression remains a challenge. Here, we assessed the utility of LNA-modified antisense oligonucleotides (ASOs) to knock down circRNAs for loss-of-function studies. We identified 5807 circRNAs in total RNA sequencing data from 4 liver cancer cell lines and used the back splice junction (BSJ) sequences of 7 validated circRNAs as target sites for designing different LNA-modified ASOs for circRNA knockdown. We found that while most RNase H-dependent gapmer ASOs mediate effective knockdown of their target circRNAs, some gapmers reduce the levels of the linear parent transcript and may also cause degradation of unintended off-targets. The circRNA targeting specificity can be enhanced using design-optimized gapmer ASOs or LNA/DNA mixmer ASOs, which display potent and specific circRNA knockdown with a minimal effect on the host genes or predicted off-targets. In summary, our results demonstrate that LNA-modified ASOs complementary to BSJ sequences mediate robust knockdown of circRNAs in vitro and, thus, represent a useful tool to explore the biological roles of circRNAs in loss-of-function studies in cultured cells and animal models.
Project description:We identified 2 specific motifs that are enriched in GI-SINE RNA expressed in sciatic-nerve injured DRG neurons compared to non-regulated B2-SINE RNAs. We designed a mix of 5 ASOs (21nt phosphorothioate DNA with LNA-flanks) that target these motifs and transfected those into cultured dorsal root ganglia (DRG) neurons. Control ASO was based on a 21nt non-targetting sequence from shControl backbone (addgene plasmid #85741). Primary DRG neurons were transfected using Dharmafect-4 with ASO at 50nM final concentration 1 hour after plating. Cultures were processed for RNA extraction 48h after transfection for RNA sequencing to identify changes in B2-SINE expression.
Project description:Antisense oligonucleotide (ASO) has the potential to induce hybridization-dependent effects by inadvertent binding of ASOs to RNA with sequences similar to that of the target RNA. In the present study, we examined the effects of the nucleobase derivatives introduced into the gapmer ASOs on gene expression. We performed microarray analysis using NMuLi cells (mouse liver-derived cells) treated with LNA gapmer ASO containing nucleobase modification.
Project description:To investigate gene expression change induced by modified gapmer antisense oligonucleotides, we performed transcriptome analysis of Scarb1 ASO or PBS treated mouse livers.
Project description:Proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as a therapeutic target for the reduction of low-density lipoprotein cholesterol (LDL-C). PCSK9 increases the degradation of the LDL receptor, resulting in high LDL-C in individuals with high PCSK9 activity. Here, we show that two locked nucleic acid (LNA) antisense oligonucleotides targeting PCSK9 produce sustained reduction of LDL-C in nonhuman primates after a loading dose (20 mg/kg) and four weekly maintenance doses (5 mg/kg). PCSK9 messenger RNA (mRNA) and serum PCSK9 protein were reduced by 85% which resulted in a 50% reduction in circulating LDL-C. Serum total cholesterol (TC) levels were reduced to the same extent as LDL-C with no reduction in high-density lipoprotein levels, demonstrating a specific pharmacological effect on LDL-C. The reduction in hepatic PCSK9 mRNA correlated with liver LNA oligonucleotide content. This verified that anti-PCSK9 LNA oligonucleotides regulated LDL-C through an antisense mechanism. The compounds were well tolerated with no observed effects on toxicological parameters (liver and kidney histology, alanine aminotransferase, aspartate aminotransferase, urea, and creatinine). The pharmacologic evidence and initial safety profile of the compounds used in this study indicate that LNA antisense oligonucleotides targeting PCSK9 provide a viable therapeutic strategy and are potential complements to statins in managing high LDL-C.
Project description:We report the structure activity relationships of short 14-mer phosphorothioate gapmer antisense oligonucleotides (ASOs) modified with α-L-locked nucleic acid (LNA) and related modifications targeting phosphatase and tensin homologue (PTEN) messenger RNA in mice. α-L-LNA represents the α-anomer of enantio-LNA and modified oligonucleotides show LNA like binding affinity for complementary RNA. In contrast to sequence matched LNA gapmer ASOs which showed elevations in plasma alanine aminotransferase (ALT) levels indicative of hepatotoxicity, gapmer ASOs modified with α-L-LNA and related analogs in the flanks showed potent downregulation of PTEN messenger RNA in liver tissue without producing elevations in plasma ALT levels. However, the α-L-LNA ASO showed a moderate dose-dependent increase in liver and spleen weights suggesting a higher propensity for immune stimulation. Interestingly, replacing α-L-LNA nucleotides in the 3'- and 5'-flanks with R-5'-Me-α-L-LNA but not R-6'-Me- or 3'-Me-α-L-LNA nucleotides, reversed the drug induced increase in organ weights. Examination of structural models of dinucleotide units suggested that the 5'-Me group increases steric bulk in close proximity to the phosphorothioate backbone or produces subtle changes in the backbone conformation which could interfere with recognition of the ASO by putative immune receptors. Our data suggests that introducing steric bulk at the 5'-position of the sugar-phosphate backbone could be a general strategy to mitigate the immunostimulatory profile of oligonucleotide drugs. In a clinical setting, proinflammatory effects manifest themselves as injection site reactions and flu-like symptoms. Thus, a mitigation of these effects could increase patient comfort and compliance when treated with ASOs.Molecular Therapy - Nucleic Acids (2012) 1, e47; doi:10.1038/mtna.2012.34; published online 18 September 2012.
Project description:We performed RNA-seq assay in Scramble ASO and antisense Mus1_L1 ASO treated AML12 cells to reveal the trscriptiome associated with MATR3 protein. The libraries were constructed by ribosome-depleted and strand-specific kits.
Project description:The development of clinically relevant anti-microRNA antisense oligonucleotides (anti-miRNA ASOs) remains a major challenge. One promising configuration of anti-miRNA ASOs called "tiny LNA (tiny Locked Nucleic Acid)" is an unusually small (~8-mer), highly chemically modified anti-miRNA ASO with high activity and specificity. Within this platform, we achieved a great enhancement of the in vivo activity of miRNA-122-targeting tiny LNA by developing a series of N-acetylgalactosamine (GalNAc)-conjugated tiny LNAs. Specifically, the median effective dose (ED50) of the most potent construct, tL-5G3, was estimated to be ~12 nmol/kg, which is ~300-500 times more potent than the original unconjugated tiny LNA. Through in vivo/ex vivo imaging studies, we have confirmed that the major advantage of GalNAc over tiny LNAs can be ascribed to the improvement of their originally poor pharmacokinetics. We also showed that the GalNAc ligand should be introduced into its 5' terminus rather than its 3' end via a biolabile phosphodiester bond. This result suggests that tiny LNA can unexpectedly be recognized by endogenous nucleases and is required to be digested to liberate the parent tiny LNA at an appropriate time in the body. We believe that our strategy will pave the way for the clinical application of miRNA-targeting small ASO therapy.