- Reporter gene
In molecular biology, a reporter gene (often simply reporter) is a gene that researchers attach to a regulatory sequence of another gene of interest in cell culture, animals or plants. Certain genes are chosen as reporters because the characteristics they confer on organisms expressing them are easily identified and measured, or because they are selectable markers. Reporter genes are often used as an indication of whether a certain gene has been taken up by or expressed in the cell or organism population.
Common reporter genes
To introduce a reporter gene into an organism, scientists place the reporter gene and the gene of interest in the same DNA construct to be inserted into the cell or organism. For bacteria or prokaryotic cells in culture, this is usually in the form of a circular DNA molecule called a plasmid. It is important to use a reporter gene that is not natively expressed in the cell or organism under study, since the expression of the reporter is being used as a marker for successful uptake of the gene of interest.
Commonly used reporter genes that induce visually identifiable characteristics usually involve fluorescent and luminescent proteins. Examples include the gene that encodes jellyfish green fluorescent protein (GFP), which causes cells that express it to glow green under blue light, the enzyme luciferase, which catalyzes a reaction with luciferin to produce light, and the red fluorescent protein from the gene dsRed. The GUS gene has been commonly used in plants but luciferase and GFP are becoming more common.
A common reporter in bacteria is the LacZ gene, which encodes the protein beta-galactosidase. This enzyme causes bacteria expressing the gene to appear blue when grown on a medium that contains the substrate analog X-gal. An example of a selectable-marker which is also a reporter in bacteria is the chloramphenicol acetyltransferase (CAT) gene, which confers resistance to the antibiotic chloramphenicol.
Transformation and transfection assays
Many methods of transfection and transformation - two ways of expressing a foreign or modified gene in an organism - are effective in only a small percentage of a population subjected to the techniques. Thus, a method for identifying those few successful gene uptake events is necessary. Reporter genes used in this way are normally expressed under their own promoter independent from that of the introduced gene of interest; the reporter gene can be expressed constitutively (that is, it is "always on") or inducibly with an external intervention such as the introduction of IPTG in the β-galactosidase system. As a result, the reporter gene's expression is independent of the gene of interest's expression, which is an advantage when the gene of interest is only expressed under certain specific conditions or in tissues that are difficult to access.
In the case of selectable-marker reporters such as CAT, the transfected population of bacteria can be grown on a substrate that contains chloramphenicol. Only those cells that have successfully taken up the construct containing the CAT gene will survive and multiply under these conditions.
Gene expression assays
Reporter genes can also be used to assay for the expression of the gene of interest, which may produce a protein that has little obvious or immediate effect on the cell culture or organism. In these cases the reporter is directly attached to the gene of interest to create a gene fusion. The two genes are under the same promoter elements and are transcribed into a single messenger RNA molecule. The mRNA is then translated into protein. In these cases it is important that both proteins be able to properly fold into their active conformations and interact with their substrates despite being fused. In building the DNA construct, a segment of DNA coding for a flexible polypeptide linker region is usually included so that the reporter and the gene product will only minimally interfere with one another.
Reporter genes can be used to assay for the activity of a particular promoter in a cell or organism. In this case there is no separate "gene of interest"; the reporter gene is simply placed under the control of the target promoter and the reporter gene product's activity is quantitatively measured. The results are normally reported relative to the activity under a "consensus" promoter known to induce strong gene expression.
- ^ Koo, J.; Kim, Y.; Kim, J.; Yeom, M.; Lee, I. C.; Nam, H. G. (2007). "A GUS/Luciferase Fusion Reporter for Plant Gene Trapping and for Assay of Promoter Activity with Luciferin-Dependent Control of the Reporter Protein Stability". Plant and Cell Physiology 48 (8): 1121–1131. doi:10.1093/pcp/pcm081. PMID 17597079.
- Research highlights and updated information on reporter genes.
- Staining Whole Mouse Embryos for β-Galactosidase (lacZ) Activity
Wikimedia Foundation. 2010.
Look at other dictionaries:
reporter gene — A gene that encodes an easily assayed product (eg. CAT) that is coupled to the upstream sequence of another gene and transfected into cells. The reporter gene can then be used to see which factors activate response elements in the upstream region … Dictionary of molecular biology
reporter gene — signalinis genas statusas T sritis augalininkystė apibrėžtis Genas, kurio paskirtis patvirtinti, kad darinys pateko į augalo genomą. Jo koduojamą produktą lengva aptikti ląstelėje. atitikmenys: angl. reporter gene rus. сигнальный ген … Žemės ūkio augalų selekcijos ir sėklininkystės terminų žodynas
reporter gene — re·port·er gene ri pōrt ər , pȯrt n a gene often of prokaryotic origin that produces a product easily detected in eukaryotic cells and that is used as a marker to determine the activity of another gene with which its DNA has been closely linked… … Medical dictionary
reporter gene — A gene that encodes a product that can be readily assayed. Used as a marker to confirm the incorporation of a transgene into a cell, organ or tissue, and as a means of testing the efficiency of specific promoters … Glossary of Biotechnology
Gene trapping — is a high throughput approach that is used to introduce insertional mutations across the mammalian genome. It is performed with gene trap vectors whose principal element is a gene trapping cassette consisting of a promoterless reporter gene… … Wikipedia
Gene expression — For vocabulary, see Glossary of gene expression terms. For a non technical introduction to the topic, see Introduction to genetics. Genes are expressed by being transcribed into RNA, and this transcript may then be translated into protein. Gene… … Wikipedia
Gene targeting — NOTOC Gene targeting (also, replacement strategy based on homologous recombination) is a genetic technique that uses homologous recombination to change an endogenous gene. The method can be used to delete a gene, remove exons, and introduce point … Wikipedia
Gene Morgan — est un acteur américain né le 12 mars 1893 à Racine, Wisconsin (États Unis), décédé le 13 août 1940 à Santa Monica (Californie). Sommaire 1 Biographie 2 Filmographie 3 … Wikipédia en Français
Gene synthesis — is the process of synthesizing an artificially designed gene into a physical DNA sequence.Gene synthesis was first demonstrated by Har Gobind Khorana in 1970 for a short artificial gene. Nowadays, commercial gene synthesis services are available… … Wikipedia
Gene London — (born Eugene Yulish in Cleveland, Ohio in 1931) was the host of a popular, long running, Philadelphia local children s show, Cartoon Corners (aka The Gene London Show ). He was tall and slender and had dark hair and a soft spoken manner. He… … Wikipedia