Posts Tagged "Rnai"
RNA Interference
RNA interference (RNAi) or double-stranded RNA (dsRNA) is a system within living cells that helps to control which genes are active and how active they are. siRNAs were first discovered by David Baulcombe’s group in Norwich, England, as part of post-transcriptional gene silencing (PTGS) in plants1 and later independently identified in wide variety of eukaryotic organisms. These dsRNAs are rapidly processed into short RNA duplexes of 21 to 28 nucleotides in length, which then guide the recognition and ultimately the cleavage of complementary single-stranded RNAs, such as messenger RNAs or viral genomic/antigenomic RNA (Fig. 1). According to their origin or function, naturally occurring small RNA have been described: short interfering RNAs (siRNA), repeat-associated short interfering RNA (rasiRNA or shRNA) and microRNA (miRNA). RNA interference has many biological functions – it is a vital part of the immune response against viruses and also downregulates gene expression by transcriptional silencing of genes or upregulates promoting by RNA activation. Finally, artificial introduction of long dsRNA or siRNA has been adopted as a tool to inactivate gene expression, both in cultured cells and in living organisms.http://www.biosyn.com/TEWdetail.aspx?TEWid=180
A biochemical understanding of the RNAi pathway was crucial to realizing that dsRNAs shorter than 30 base pairs (bp) could be used to trigger an RNAi response in mammals. Tuschl and colleagues showed that transfection of mammalian cells with short RNAs could induce the sequence-specific RNAi pathway, and so overcame the barrier to the use of RNAi as a genetic tool in mammals2. The impetus to use siRNAs and other small RNAs in mammalian cells also came from the long-standing view that protein kinase receptor (PKR) activation3 and similar responses were not effectively triggered by short dsRNAs. Following the initial reports, it took a remarkably short period of time for siRNAs triggers to be adopted as a standard component of the molecular biology toolkit. siRNAs can be introduced into mammalian cells using a variety of standard transfection methods. The strength and duration of the silencing response is determined by several factors: on a population basis, the silencing response is affected mainly by the overall efficiency of transfection, which can be addressed by optimizing conditions. In each cell, silencing depends on the amount of siRNA that is delivered and on the potential of each siRNA to suppress its target, or its potency. Even a relatively impotent siRNA can silence its target provided that sufficient quantities of the siRNA are delivered. However, essentially ‘forcing’ the system by delivering large amounts of reagent is likely to lead to numerous undesired effects.
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Biotechnology -rna Genes
messenger RNA (mRNA) is generated in order to be translated into protein, numerous classes of “noncoding” RNAs also exist; these complex molecules all share the property of being nontranslatable. The classic categories of noncoding RNAs include ribosomal RNA and transfer RNA, both of which are involved in the translation process.
ver the past decade RNA interference (RNAi) has emerged as a natural mechanism for silencing gene expression. This ancient cellular antiviral response can be exploited to allow specific inhibition of the function of any chosen target gene. RNAi is proving to be an invaluable research tool, allowing much more rapid characterization of the function of known genes. More importantly, RNAi technology considerably bolsters functional genomics to aid in the identification of novel genes involved in disease processes. This review briefly describes the molecular principles underlying the biology of RNAi phenomenon and discusses the main technical issues regarding optimization of RNAi experimental design.
RNAi is a mechanism in molecular biology where the presence of certain fragments of double-stranded RNA (dsRNA) interferes with the expression of a particular gene which shares a similar sequence with the dsRNA.
This study defines the dollar volume of sales, both worldwide and in the U.S., and analyzes the factors that influence market size and growth for RNAi testing. The main objectives of this study are to:
1) understand the different sectors of RNAi testing market and to look at a description of the instruments, reagents and supplies marketed by major companies in each segment;
2) obtain a complete understanding of the individual RNAi-testing platforms-from basic principles to clinical applications;
3) discover feasible market opportunities by identifying high-growth applications in different analytical diagnostic areas, with a focus on the biggest and expanding markets;
4) focus on global industry developments and trends through an in-depth analysis of the major world markets for RNAi measurement technology, including growth forecasts; and
5) present market figures related to the current value of RNAi testing, market projections, market share, key players and sector growth rates.
Read more: biotechnology-online.blogspot.com
Reference: findarticles, Market Wire
, Internal Medicine News
Rna Interference: Imgenex Launched the Psuppressoradeno Construction Kit for Adenovirus Mediated Gene Knockdown
RNA interference (RNAi) is the process of mRNA degradation that is induced by double-stranded RNA in a sequence-specific manner. RNAi has been observed in all eukaryotes, from yeast to mammals. The RNAi pathway is thought to be an ancient mechanism for protecting the host and its genome against viruses and rogue genetic elements that use double-stranded RNA (dsRNA) in their life cycles. They have also been shown to play a role not only in mRNA and dsRNA stability/degradation, but also in regulation of translation, transcription, chromatin structure, and genome integrity. In plants and animals, RNA silencing has been adapted to play a critical role in regulation of cell growth and differentiation using a class of small RNAs. In the RNA interference process, the dsRNAs get processed into 20-25 nucleotide (nt) small RNAs by an RNase III-like enzyme called Dicer. Then, the small RNAs assemble into endoribonuclease-containing complexes known as RNA-induced silencing complexes (RISCs), unwinding in the process. The small RNA strands subsequently guide the RISCs to complementary RNA molecules, where they cleave and destroy the cognate RNA (effecter step). Cleavage of cognate RNA takes place near the middle of the region bound by the siRNA strand. The small RNAs that provide target specificity to the silencing machinery includes short interfering RNAs (siRNAs), repeat-associated siRNAs (rasiRNAs), and microRNAs (miRNAs) and is distinguished by their origin. siRNAs are processed from dsRNA precursors made up of two distinct strands of perfectly base-paired RNA, while miRNAs originate from a single, long transcript that forms imperfectly base-paired hairpin structures. siRNAs were originally identified as intermediates in the RNAi pathway after induction by exogenous dsRNA; however, endogenous sources of siRNAs have now been recognized. The endogenous siRNAs are derived from repetitive sequences within the genome, and are termed repeat-associated siRNAs, or rasiRNAs. miRNAs were discovered through their critical roles in development and cellular regulation, and represent a large class of evolutionarily conserved RNAs. miRNAs have always been recognized as being of endogenous origin. RNA interference has emerged as a natural mechanism for silencing gene expression over the past decade. This ancient cellular antiviral response can be harnessed to allow specific inhibition of the function of any chosen target genes, including those involved in causing diseases such as cancer, AIDS, and hepatitis. It is already proving to be an invaluable research tool, allowing much more rapid characterization of the function of known genes. More importantly, the technology considerably bolsters functional genomics to aid in the identification of novel genes involved in disease processes. Last but not the least the technology can be harnessed as a novel therapeutic agent and is suitable for combating viral diseases, cancers and inflammatory diseases.
Imgenex (San Diego) recently launched the pSuppressorAdeno construction kit for adenovirus mediated gene knockdown. The kit provides the ability to infect a broad range of cell types, including many primary cell lines as well as dividing and nondividing cells, according to a company official. The kit also offers the flexibility to validate sequences using the nonviral expression plasmid prior to construction of adenoviruses, notes Sujay K. Singh, Ph.D., president and CEO of Imgenex, which markets plasmid-based RNA interference (RNAi) products. “One of the greatest advantages is the ability of recombinant adenovirus vectors to reduce gene expression both in vitro and in vivo,” he adds. RNAi, initially considered a bizarre attribute of petunias and later a gene-silencing mechanism in worms, is creating a stir as one of the hottest new technologies in molecular biology. It is revolutionizing the field of functional genomics.
For more information about“RNA interference” please visit www.imgenex.com/rna_interference.php
IMGENEX India Pvt Ltd. the only biotech company in Orissa and one of its kinds in Eastern India. IMGENEX India started in Oct as an outsourcing branch of IMGENEX Corporation, San Diego, USA. Find out more information about RNA interference.
RNAi Medicine
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Welcome to RNAi Medicine. RNA interference (RNAi) is a system within living cells that helps to control which genes are active and how active they are. Two types of small RNA molecules – microRNA (miRNA) and small interfering RNA (siRNA) – are central to RNA interference. RNAs are the direct products of genes, and these small RNAs can bind to specific other RNAs and either increase or decrease their activity, for example by preventing a messenger RNA from producing a protein. RNA interference has an important role in defending cells against parasitic genes, as well as gene expression in general. Therein lies the medical promise of RNAI Medicine.
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Among the first applications via RNAi to reach clinical trials are the treatment of macular degeneration and a particular respiratory syncytial virus. RNA interference is also often seen as a promising way to treat cancer by silencing genes differentially upregulated in tumor cells or genes involved in cell division.
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RNAi Medicine is your portal for RNAi videos, rnai articles, and general conversation about RNA interference and genetic therapies.
Video
How Short Is Short In Rnai Research
The original work of Mello and Fire from the Univ. of Massachusetts demonstrated in C. elegans, that gene expression is controlled by RNA interference (RNAi) . The initial patent applications filed by the Univ. of Massachussetts, with both Mello and Fire as the inventors, and covering this use of RNAi, clained only dsRNA longer than 25 bp’s. Later on, work done in mamalians showed that the long ds RNA was capable of inducing the release of IFN and other pro-inflammatory cytokines, causing dangerous reactions in the animals we tested. We now know that long dsRNA is recognized in the endosomes by TLRs, inducing an undesirable immune response in the animals; a situation that created a new challenge in the study of RNAi. Subsequently other researchers, such as Tuschl et.al. now at Rockefeller Univ, realized that shorter dsRNAi fragments of 25bp of smaller, while still capable of inhibiting the expression of a targeted gene, failed to induce an innate immunity response. In other words, the mammalian system is still capable of utilizing the diced dsRNA produced by the enzyme Dicer, which normally chops down the long dsRNA to sizes of 21-23 nts with 2 bases overhanging at the 3’ends of each strand. These 2 bases overhanging in dsRNA suggests that perhaps Dicer cleaves the long dsRNA in a fashion analogous to restriction enzymes. This short dsRNA can then interact with the RISC complex, where the guide strand is prepared and readied up to base pair with the target mRNA for its cleavage.
The RNAi situation is a good example of the unexpected in science. Although at the time of the initial discovery it was hard to predict that very small fragments of RNA could be pivotal in such important newly found mechanism, currently, even shorter dsRNA fragments, e.g. 15-18 bps’ are being tested. These new third generation modifiers such as LNA’s, UNA’s and others, because of their size have significant therapeutic potential.
There is a significant amount of ongoing research to elucidate the fine details of this novel gene control mechanism, including but not limited to studies of how miRNA precursors are transported to specific compartments of the cell, as these events may play important roles in the processing of the precursor by Dicer to render the active mature form of dsRNA.
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