Of frogs, chicken and people

Researchers at the University of California, San Diego School of Medicine have uncovered new details of an unusual biological mechanism in the brains of diverse species that not only helps regulate how their brains develop, but also how they function later in life.

Illustration courtesy of Rachid Karam.

The discovery could lead to new biomarkers for specific neurological diseases in humans and, possibly, the development of drugs to cure them.

The research, by Miles F. Wilkinson, PhD, professor of reproductive medicine and a member of the UCSD Institute for Genomic Medicine, and colleagues, is published in the May 20 issue of the journal Molecular Cell.

Messenger ribonucleic acid (mRNA) is one of a family of molecules that help transcribe genetic information (DNA) into the construction of proteins essential to life. Nonsense-mediated mRNA decay or NMD is a sort of quality control mechanism used by cells to eliminate errant mRNAs that prematurely terminate these translations.

It's vital to the normal development of the brain and nervous system. When NMD doesn't work correctly, the result in humans can be a range of neurological conditions from mental retardation to attention-deficit disorder, schizophrenia and autism.

In recent years, scientists have discovered that NMD also regulates normal transcriptions in neural cells, suggesting it has a functional, on-going importance. ''Having a dual role is unusual. I can't really think of a known, analogous system,'' said Wilkinson. ''We don't have evidence that these roles are complementary. Rather, we think it's an instance where nature has co-opted one system to also accomplish something else. Whether quality control or regulation of gene expression came first is anybody's guess.''