| About Gene Knockdown The sequence-specific interaction of short nucleic acids with target RNAs or DNAs can be exploited as a tool to specifically suppress gene expression. These methods have found utility in a wide variety of applications ranging from understanding the function of newly discovered genes to medical therapeutics. It is important to have a variety of techniques available; both antisense and RNAi are subject to artifacts such as off-target effects and CpG motif immunostimulation. It may be necessary to validate findings made using one method through use of a second approach. IDT therefore offers a wide variety of products that span the spectrum of available technologies. RNA interference is a method where double-stranded RNA is used to reduce gene expression in a sequence-specific fashion. While this method has only been in routine use in mammalian systems since 2001, it is already being successfully used in thousands of labs and ambitious whole genome screening projects. The duplex RNA effector molecules can be synthetic oligonucleotides or can be made as transcripts from DNA templates (ddRNAi). The most straightforward approach to RNAi is use of duplex RNAs made by chemical synthesis. IDT has been making synthetic RNA since 1987 and offers a full line of RNA products ranging from microgram to gram scale. Developed as a collaborative effort between John Rossi (Beckman Research Institute of the City of Hope) and IDT, Dicer-substrate RNAs (DsiRNAs) are chemically synthesized 27-mer duplex RNAs that have increased potency in RNA interference.1 Traditional 21-mer siRNAs are designed to mimic Dicer products and therefore bypass interaction with Dicer. The enzyme Dicer has been recently shown to be involved with entry of the siRNA duplex into RISC. In fact, Dicer is a component of RISC. Dicer-substrate siRNAs are designed to be optimally processed by Dicer and show increased potency by engaging this natural processing pathway. Using this approach, sustained knockdown has been regularly achieved using sub-nanomolar concentrations. New design rules specific to DsiRNAs have been developed and are available only from IDT.2 DNA-Directed RNAi (ddRNAi) uses DNA oligos as template for RNA synthesis. RNA synthesis can be achieved using in vitro transcription (IVT) or in vivo if the oligos are cloned into an appropriate expression vector. IDT offers high quality oligos in tubes or plates for this application. Antisense is a method where single-stranded DNA or RNA, in antisense configuration to a target sense mRNA, is used to reduce gene expression in a sequence-specific fashion. Synthetic antisense DNA oligonucleotides were first used over 25 years ago. Antisense methods have been used to modulate expression of single genes, thousands of genes in high-throughput screening programs, and are under active development as drugs. IDT has been involved in antisense research since the company was founded in 1987. We currently offer antisense oligos synthesized using DNA, 2'-O-methyl RNA, or LNA bases with either phosphorothioate or unmodified internucleoside bonds. The current preferred design is an LNA phosphorothioate chimera. Micro RNAs are a novel class of regulatory molecules which are naturally occurring cellular products. These short RNA species can be a challenge to study. IDT offers a variety of products that are useful in miRNA research. |