Gene Silencing : Rna Interference

Researchers affirm that RNAi exterminated unwanted viral RNA, and RNAi-based drugs are being tested for treating certain conditions. Initially, a good part of our genes is inherited by our parents. Chromatins, a long string of DNA spooled around histones, controls the access to genes. Likewise, the histones in chromatins have “special chemical tags that act like switches to control the access of DNA” (Chapter 2, Page 31). Expressly, an embryo is able to determine which genes came from which parents, so it knows what genes should be turned on or

In 1956, Francis Crick first described what he called “The central dogma of molecular biology.” This essentially describes the flow of genetic information within cells. It states that DNA is transcribed into RNA with the help of an RNA polymerase enzyme. The RNA is then translated into a protein by protein synthesis. One thing that could drastically alter the genetic information within cells is a process called gene silencing. This process regulates the gene expression of certain genes and can occur in either transcription or translation. The process has been coined RNA interference and dsRNA gene silencing (Davidson and McCray Jr. 2011). Since direct evidence of double stranded RNA’s role in gene silencing was found in 1998 by researchers Fire and Mello, this topic has been the focus of much research in areas such as biomedical research, health care, and even agriculture. Double stranded RNA has been found to play a crucial role in things such as pest control, vector borne disease prevention, crop improvement, and in the development of therapeutics for different diseases through gene silencing. Although much research has been focused on the effects of gene silencing, there is still much more needing to be done.

MicroRNAs (miRNA) are small noncoding RNA, usually 17-25 nucleotides long that are able to bind complementary sequences of target messenger RNA (mRNA) and to induce both their degradation and translational repression (Fortunato, et al 2014). They are one of the most significant classes of non-coding RNA molecules (eg. small interfering RNA (siRNA) and ribozymes) that act within the cell. MiRNAs are also evolutionary conserved in different species from plants to humans and are encoded by their respective genes (Bader, 2012).

When scientists know what gene they want to manipulate they 'introduce double stranded DNA, or dsRNA to the cell.' The dsRNA produce small double-stranded interfering RNAs, or siRNA into the cytoplasm of the cell.5 from this the expression of the gene decreases drastically but does not get entirely eliminated, therefore showing the role of the targeted gene.

RNA interference takes advantage of an intermediate step between DNA and protein. DNA acts as a blueprint for the final protein by using messenger RNA (mRNA) . The mRNA is a messenger molecule between DNA and protein synthesis. There is a two steps process need to be completed in order to go from gene to protein. The first step in protein synthesis is transcription, it takes place in a cell’s nucleus, where the DNA template is used to make a single strand of mRNA. Then, the messenger RNA exits the nucleus and enters the cytoplasm. Now it serves as the template for making the protein. After that, with the help of several different molecules, a string of amino acids forms due to the order of the mRNA bases. This process is called translation

It is greatly involved in immunity. Mostly in plants, it is greatly involved in the immune response system to prevent viruses and harmful genetic material from damaging the cell. In animals, the RNAi pathway serves an antiviral purpose, providing protection against pathogens, bacteria, and other harmful organisms that could potentially put the cell in danger. Jaronczyk’s findings exaplain that RNAi pathways also play a large role in the regulation of development of cell growth and development. It regulates the timing of morphogenesis, a process which organizes the special distribution of cells during its embryotic development stages. It also regulates the maintenance of undifferentiated cell types, or those who are not yet specialized. Finally, RNAi pathways help in RNA activation, and event in which specific short dsRNA molecules bring about the targeted gene expression. Even evidence of RNA interference pathways are relevant in the everyday lives of humans such as insecticides, genetically engineered foods, and new treatments for cancer as described by Hannon in RNAi: A Guide to Gene Silencing

Post-transcriptional gene regulation by sRNAs may occurs in various patterns of base-pairing with a target RNA resulting in different outcomes or by directly binding to proteins to modulate their function.12-14 Two classes of sRNAs are identified: trans-encoded RNAs which are transcribed from intergenic regions of the genome, and cis-encoded RNAs which are encoded on the strand complementary to coding sequences or the 5′ or 3′ untranslated region (5′ UTR, 3′ UTR) of transcripts.15-17 The family of trans-encoded sRNAs usually requires the chaperone Hfq to stabilize the often imperfect base-pairing interaction with target mRNA.18 In contrast, cis-encoded sRNAs possess a region of perfect complementarity to their target mRNA and Hfq is not needed for target binding. It shows that sRNAs are involved in many important physiological processes including anaerobic growth, nutrient availability, iron homeostasis and the response to oxidative, envelope and osmotic

The two most common methods of genes silencing are ASOs and RNAi. Literature searches have led to commonalities in challenges faces when implementing gene silencing making them a useful laboratory tool but not quite an efficient therapeutic tool yet. [1] There are multiple disease phenotypes that have shown improvement when utilizing these methodologies, a much needed reassurance of the potential of gene silencing. There is a fear that the uncovering of more problems than solutions could to reduction of both funding and interest in this emerging field. [3] Overriding the current successes and the unknown of this technology is the hope that gene silencing can replace current therapies and open the door to more personalized genomic answers to disease. [12] The process of drug development could be simplified by starting with a specific mutated gene and developing a drug targeted to that

miRs constitute a large class of phylogenetically conserved single-stranded RNA molecules of 19 to 25 nucleotides that are implicated in post-transcriptional gene silencing. They arise from exonic and intronic genomic regions that are transcribed by RNA polymerase II as long primary RNA transcripts. These primary transcripts undergo processing steps that produce a short “mature” molecule. Approximately 70-bp precursor miR product is processed by the enzymes Drosha and Dicer in conjuction with DGCR8/Pasha to

Almost all biology students learn the fundamentals of gene expression, DNA contains information which is transcribed into RNA to create protein. Students however, are not taught of RNA Interference, the biological process where RNA molecules inhibit a gene’s expression, RNAi for short. While RNAi is a fairly new discovery, its use in modern biological research is groundbreaking. RNA Interference works by binding Double-stranded RNA molecules (siRNA) to a complementary messenger RNA. The enzymes Dicer and Slicer then cleave the chemical bonds which hold the messeger RNA in place and prevent it from delivering protein silencing instructions thus, the term, Gene Silencing. This phenomenon was first discovered by Richard Jorgensen in 1990 when

The IRES mediated translation initiation, although initially observed in viral mRNAs, has also been identified in many cellular mRNAs.12 The 5′-UTR of human vascular endothelial growth factor (hVEGF) encompasses IRES elements.

Gene therapy has been around for over two decades. It has had setbacks, but thanks to the advancement of technology and medical understanding, has become more effective in

Gene therapy is described as the transplantation of normal genes into cells in place of missing or defective ones in order to correct genetic disorders. 1 During the 1960’s and early 70’s the actual concept of what is now known to be gene therapy arose. Many new practices including the development of genetically marked cell lines and the delineation of cells transformation by the papaovaviruses polyoma were in the works. Cloned genes became a product of this new DNA technique and were used to prove that foreign genes could actually correct genetic disorders.2 This new technology in the medical field has a wide range of uses that is constantly growing larger as scientists continue to study and experiment with it. As of right now, the uses of gene therapy in the medical field consist of replacing missing or defective genes, delivering genes that speed the destruction of cancer cells, supplying genes that cause cancer cells to revert to their normality, delivering bacterial or viral genes as a form of vaccination, providing genes that promote or impede the growth of new tissue and delivering genes that stimulate the healing of damaged tissue.3 With this information, a wide variety of genes are now being used for testing within gene therapy. In the mid 1980’s the first use of gene therapy was practiced and then seen in a four-year old girl when she became the first gene therapy patient on September 14, 1990 at the NH Clinical Center. This four-year

Ribonuclease P is a type of ribonuclease which cleaves RNA. Its function is to cleave off an extra, or precursor, sequence of RNA on tRNA molecules (Stark et al., 1978). It is an essential ubiquitous enzyme, present in all cells and cellular compartments that synthesize tRNA (Gopalan et al., 2002). RNase P is a ribonucleoprotein complex and is responsible for the 5’ maturation of tRNAs (Frank and Pace, 1998). RNase P has been proposed as a novel RNA-based gene interference strategy for down regulating gene expression.

The next technique discussed in the film, RNA interference, can be used as a means of silencing gene expression. This can be harnessed to allow specific inhibitions of the function of any chosen target genes, including those