Gene activation influenced by DNA folding!
There is finally some insight on how the genes are activated. Recently in a research procedure made by scientists, it was found that DNA folding influenced gene activation.
Genes activation takes place when almost 3 metres of DNA is tightly folded
into the nucleus of every cell in our body. Owing to the folding of the DNA, the genes are referred to have been either ‘expressed’ or ‘activated’ leaving the others.
This new scientific theory was first analysed by Dr Tim Mercer and Professor John Mattick from Sydney`s Garvan Institute of Medical Research and Professor John Stamatoyannopoulos from Seattle`s University of Washington. This new discovery also gave an insight to the genome`s 3D structure, at high resolution.
Genes are a combination of both ‘exons’, which are expressed genes and are sequences which code for protein and ‘introns’, which are non coding in between DNA.
The role of the exons is to stick together to form a sequence that encodes a protein while the intron gets cut out during the process of the conversion of copying or transcribing the DNA to RNA. The same gene can generate different proteins depending on which of the exons are strung together.
Dr Tim Mercer and his colleagues have analysed the folding of the genome by collectively investigating the data from the ENCODE project, and found out that some of the selected exons are easily exposed even within a gene.
By giving an example of a grape wine, where in some of the grapes are easily plucked from its twisted branches and some of them are concealed and are beyond reach, Mercer and his colleagues explained their theory.
He said, “Imagine a long and immensely convoluted grape vine, its twisted branches presenting some grapes to be plucked easily, while concealing others beyond reach. At the same time, imagine a lazy fruit picker only picking the grapes within easy reach,”.
He also explained this new discovery by making us imagine a lazy fruit picker who would only pick the grapes which are within easy reach, confirming that this same principle applies to the genome as well, where in with the help DNA folding, only a certain number of specific genes and specific exons are placed within easy reach.
Using the collaborated findings of the study, it was confirmed that the research by Dr Mercer and his colleagues was the first step towards providing indication that a 3D structure of the genome could actually influence the over lapping of the genes.
The folding of the genome can happen in such a way that the region where the transcription of the genes is initiated, the ‘promoter region’ is right beside the existing exons while being presented to the transcription machinery can be inferred, added Mercer.
“This supports a new way of looking at things, one that the genome is folded around transcription machinery, rather than the other way around. Those genes that come in contact with the transcription machinery get transcribed, while those parts which loop away are ignored,” he said.
Nature Genetics published their findings online.