"Almost every important gene and pathway will be regulated at multiple levels by a variety of micro RNA," predicts Deepak Srivastava of the University of California, San Francisco. "It's really an entirely new layer of biology."
Over the years, scientists and drug companies seeking genetic control over biological systems have focused their attention on proteins. But that's only one part of the picture: Recently, scientists have been accumulating evidence that non-protein-coding sequences often play the role of conductor in the body's response: it's a kind of "conductome". Now this information is becoming encyclopedic, and it is calling into question everything we thought we knew about the so-called functional genome.
In the following pages, we illustrate the roles of microRNAs - the small non-coding RNAs that regulate gene expression by interfering with messenger RNA function - in biological systems. We also present a controversial new definition of the functional genome from John Mattick, based at the University of Queensland, who argues that so-called junk DNA provides the intricate instructions for regulating the functions of complex organisms.
MicroRNAs: An emerging portrait :