The RNA paradigm is due for another correction. Once, RNA seemed a mere conduit between genes and proteins. Its status expanded with reports of catalytic RNA 20 years ago and of endogenous RNA interference 10 years later. Now microRNAs, the 20- to 24-nucleotide transcripts that underlie much of that endogenous interference, appear to be more biologically significant than first suspected.
Until April, studies implicated microRNAs in development of the worm Caenorhabditis elegans and differentiation in the plant Arabidopsis thaliana. Papers published in the past two months, however, report that microRNAs also affect apoptosis, tissue growth, fat metabolism, and nervous system patterning.1-4 These papers are the first fruits of a new focus in this small but expanding field. Having located hundreds of microRNA-encoding genes, investigators are seeking microRNA targets and functions with tools ranging from traditional genetics to computer-based genome scanning.
This time, the RNA paradigm should accommodate unusual findings more ...
