Tuesday, February 26, 2013

FAQ: What is 'junk' DNA?

This image shows a DNA molecule that is methylated on both strands
on the center cytosine. DNA methylation plays an important role
 for epigenetic gene regulation in development and cancer.
Christoph Bock (Max Planck Institute for Informatics)
When the human genome was sequenced it became clear that the vast majority of the DNA contained within the human genome does not code for proteins or functional RNA's. With no explanation for the function of this non-coding DNA scientist coined the term 'junk' DNA.

However, the recently published findings of the collaborative efforts of researchers from the Karolinska Institutet in Sweden and the Scripps Research Institute in California, USA indicates that much of this sequence indeed has a function. It had been previously shown that pseudogenes, regions that do not code for proteins despite their similar sequence, are able to regulate the expression of the tumor suppressor gene PTEN. However, this report found a regulatory network of pseudogenes that alter PTEN transcription by epigenetic modification and mRNA stability by RNA-RNA pairing.

Clearly this 'junk' DNA can no longer be considered trash!

Article information:
  1. Per Johnsson, Amanda Ackley, Linda Vidarsdottir, Weng-Onn Lui, Martin Corcoran, Dan Grandér, Kevin V Morris. A pseudogene long-noncoding-RNA network regulates PTEN transcription and translation in human cells. Nature Structural & Molecular Biology, 2013; DOI: 10.1038/nsmb.2516