21 March 2008

The first artificial transposon has been created

Inactive residues of transposons ("jumping genes") are found in the genomes of both plants and animals, including humans. Currently, scientists are attempting to create active transposons from these fragments for subsequent use in the study of gene functions.

Researchers at the Max Delbruck Center for Molecular Medicine (Berlin-Buch, Germany) have succeeded in reconstructing the first active transposon of the Harbinger transposon superfamily. In laboratory experiments on human cells, the synthetic "jumping gene" demonstrated the ability to transpose according to the "cut and paste" principle, which indicates the prospects of its use as an experimental system for studying the functioning of human genes.

Transposons make up about 50% of the human genome. They are molecular parasites, a kind of "fleas" living in the genome of an organism, not on its back. They jump, move and reproduce in the cells of the host, without which their existence is impossible. In most cases, transposons do not perform any functions in the human genome, but they are not absolutely useless. In natural conditions, the embedding of a transposon sometimes leads to the appearance of traits useful from the point of view of evolution, and such new genes can be fixed in the genome of the descendants of a mutant individual. According to modern data, it is believed that more than 100 active genes of the human body, including several genes associated with the immune system, are modified transposons.

To reconstruct the active transposon, scientists compared the DNA of various inactive transposons of the Harbinger superfamily (one of the largest families of transposons). Based on the analysis of these sequences, they constructed an artificial jumping gene. According to the authors, they were very lucky, because the first experiment turned out to be successful.

In the laboratory, the researchers embedded a transposon into the genome of human cells using a "gene shuttle". In this technique, plasmids capable of functioning in organisms of different hosts, for example, in bacterial and eukaryotic cells, are usually used as a vector (carrier). By means of the "cut and paste" mechanism, the transposon is released from the carrier and embedded in the cell genome. If at the same time it violates the sequence of an important gene, accordingly, cellular processes dependent on it are disrupted, which allows scientists to draw conclusions about the functions performed by this gene.

Using computer analysis, the authors found two new elements belonging to the Harbinger superfamily. As part of a new project, they plan to find out the role played by these DNA fragments in the human body.

Over time, experts hope to use transposons in gene therapy. With the help of transposons, intact copies of genes can be embedded in the patient's genome in order to replace defective genes. However, there is still a lot of work to be done on this, because transposons are inserted into the genome randomly, which is completely unacceptable for therapeutic purposes.

Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily  


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