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In human cells

Pubblicato il 05/03/2013Read time: 2 mins

You probably don't need to be a biologist or chemist to know that DNA is a double helix molecule. Now a team of researchers from the University of Cambridge, led by Professor Balasubramanian, reported the existence of quadruple DNA helix in human cells.

G-quadruplex

The quadruple helix is technically called G-quadruplex, where "G" refers to guanine, one of the four chemical groups, or "bases", that form DNA and which encode our genetic information. These G-quadruplex structures tend to form in nucleic acid sequences (DNA or RNA) that are rich in guanine. Four-stranded G-quadruplex structures were already been observed in test tubes and in protozoan (ciliate macronuclei), but never in mammalian cells.
Giulia Biffi (the first author of the study) and her colleagues developed a highly specific DNA G-quadruplex antibody, tagged it with a fluorescent molecule and used it to visualize G-quadruplex structures in the DNA of human cells.
With this powerful and highly specific tool in their hands, they were able to demonstrate the presence of G-quadruplex structures along different sites in the chromosomes of human cells. Moreover they investigated the relationship between G-quadruplex formation and cell cycle progression and found that these four-stranded DNA structures form more frequently when cells are replicating their DNA (the S-phase of the cell cycle).
Finally, they were able to specifically target the G-quadruplex structures by using small-molecule drugs.
Although in its early stage, the discovery of the existence of four-stranded DNA structures in human cells is also particularly exciting from a therapeutic point of view. G-quadruplex structures are more likely to occur in cells that are rapidly dividing, such as cancer cells. By targeting quadruplexes with synthetic drugs that trap and contain these DNA structures, preventing tumor cells from replicating their DNA and consequently blocking cell division, scientists believe it may be possible to stop cancer proliferation.

Original article: http://www.nature.com/nchem/journal/v5/n3/full/nchem.1548.html

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di Francesca Zammarchi
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Quadruple helix DNA
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