Now revealed, how body's defence keeps off 'junk' DNA attack
Posted on Apr 27 2014 | IANS
New York, April 27 : Had there been no defence mechanism in operation to minimise the collateral damage of what could be termed as a civil war among the 37 trillion cells in a human body, diseases could have been much more widespread than they are today.
Scientists have now discovered how our cells fight off the effects of the rogue DNAs, called LINE-1 retrotransposons, in our cells.
The new finding gives scientists the first proof of a hypothesised defence strategy, said John Moran, a professor at the University of Michigan in the US.
"It is often hard to see what normally happens during an efficient process that occurs inside our cells," said Moran.
On one side of the battle are "regular" DNA, which provide day-to-day instructions for life.
On the other side are tiny bits of rogue DNA that hide like spies between genes in our own DNA.
From time-to-time, these rogue bits of DNA spin off a copy of themselves and "jump" to another DNA location, often causing harmful mutations when they land.
To discover the defence mechanism of the cells, the researchers focused on the defensive activity of an enzyme called APOBEC3A and showed that it can cause mutations within the LINE-1 retrotransposons as they jump to new locations.
This prevents subsequent invasions into other areas of DNA.
This defensive strike sends out a signal to other defence forces inside the cell, which neutralise the jumping gene and sweep away the destroyed copy.
The findings could also lead to the development of new cancer drugs, said the study which appeared in the journal eLife.