RNA antisense

Many human diseases are caused when certain proteins are either over- or underexpressed. Eor example, breast cancer can be induced by overexpressing certain cellular oncogenes within mammary tissue. To study the disease, researchers produce a line of transgenic mice that synthesize an abnormal amount of the same protein. This leads to symptoms of the disease in mice that are similar to what is found in humans. A protein can be overexpressed by inserting a DNA constmct with a strong promotor. Conversely, underexpression of a protein can be achieved by inserting a DNA constmct that makes antisense RNA. This latter blocks protein synthesis because the antisense RNA binds and inactivates the sense mRNA that codes for the protein. Once a line of mice is developed, treatments are studied in mice before these therapies are appHed to humans. 

UACGGUCUAAGCUGA. What is the corresponding nucleotide sequence (5 —> 3 ) of the template strand in a DNA duplex that might be introduced into these cells so that an antisense RNA could be transcribed from it ... 

Antisense RNA that is expressed intracellularly following transfection with antisense genes. 

Pepin et al. (1992) generated transgenic mice in which antisense RNA complementary to GR cDNA led to reduced expression mostly in neuronal tissues. Consequently, this was found to result in an impaired behavior, a defective response to stress as well as in obesity. King et al. (1995) generated transgenic mice where reduced GR expression was limited to the thymus. This leads to an altered thymocyte development, changes in the T-cell repertoire, and a reduced risk to develop autoimmune diseases. 

The successful clinical application of RTK-based therapeutics in the last 8 years instigates further research to generate the next generation drugs. Thus, antisense RNAs or dominant-negative receptor mutants are being tested for their ability to reduce receptor expression. 

Knecht, D.A., Loomis, W.F. (1987). Antisense RNA inactivation of myosin heavy chain gene expression in Dictyostelium discoideum. Science 236, 1081-1086. 

Fig. 1 Antiviral genes inhibit virus replication at different stages of the viral life cycle. Early inhibitors prevent the establishment of the viral genome in the target cell (class I, e.g., entry inhibitors, RT inhibitors for HIV). Intermediate inhibitors prevent viral gene expression or amplification of the viral genome (class II, e.g., siRNAs, antisense RNAs). Late inhibitors prevent virion assembly or release, or inactivate the mature virions (class III, e.g., transdominant core proteins, capsid-targeted virion inactivation, CTVI). A list of antiviral genes in each class is found in Table 1...

Antisense RNAs, RNA decoys, ribozymes, small interfering RNAs, and RNA ap-tamers are potential tools in antiviral gene therapy. The application of the antiviral RNAs is described in detail in Chap. 9 of this volnme by J. Haasnoot and B. Berkhont. 

Nash KL, Alexander GJ, Lever AM (2005) Inhibition of hepatitis B virus by lentiviral vector delivered antisense RNA and hammerhead libozymes. J Viral Hepat 12 346-356... 

Zhu Y, CuUen JM, Aldrich CE, SaputelU J, MiUer D, Seeger C, Mason WS, JUbert AR (2004) Adenovirus-based gene therapy during clevudine treatment of woodchucks chronically infected with woodchuck hepatitis virus. Virology 327 26 0 zu Putlitz J, Wieland S, Blum HE, Wands JR (1998) Antisense RNA complementary to hepatitis B virus specifically inhibits viral replication. Gastroenterology 115 702-713... 

Recently, the related phenomenon of RNA interference (RNAi) has attracted much attention [5]. RNAi occurs when a short (generally 21 nucleotides in length) double-stranded RNA (dsRNA) catalyticaUy represses the translation of a fully complementary mRNA sequence. The process appears to proceed via a complex formed between the antisense RNA strand and a protein with RNase activity [6]. Upon binding to the target mRNA sequence, the ribonucleoprotein complex initiates cleavage of the mRNA transcript thus preventing translation of intact protein. After dissociation from the truncated mRNAs, the ribonucleoprotein complex is free to act on other intact mRNAs. Such small interfering RNAs (siRNAs) have... 

BIRD C R, RAY J A, FLETCHER J D, BONIWELL J M, BIRD A S, TEULIERES C, BLAIN I, BRAMLEY P M and SCHUCH w (1991) Using antisense RNA to study gene function inhibition of carotenoid biosynthesis in transgenic tomatoes , BioTechnology, 9, 635-9. 

Bramley, P. et al.. Biochemical characterization of transgenic tomato plants in which carotenoid synthesis has been inhibited through the expression of antisense RNA to pTOM5, Plant J. 2 (3), 343, 1992. 

Tucker,G.A.,Seymour,G.B.,Bundick,Y.,Robertson,D.,Sniith,C.J.S and Grierson,D (1992) Use of antisense RNA technology to manipulate pectin degradation in tomato fiuit. New Zealand Journal of Horticultural Crop Botany. 20.119-124... 

Smith CJS, Watson CF, Ray J, Bird CR, Morris PC, Schuch W, Grierson D (1988) Antisense RNA inhibition of polygalacturonase gene expression in transgenic tomatoes. Nature 334 724-726... 

Hunt In frogs, if you remove the B type cyclins using antisense RNA, this allows you to go straight into a premature S phase. 

A mbros Reasonably well. The basic mechanism is translational regulation of Lin-14 mRNA. lin-4 is a small antisense RNA which accumulates towards the end of the first larval stage and binds to the 3bUTR of lin-14 mRNA, inhibiting LIN-14 translational elongation. 

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