Researchers discover critical detail of cellular defense against geneti...( Researchers are closing in on a comp...)

Researchers are closing in on a completed diagram of how human cells protect themselves against constant genetic mistakes that contribute to most diseases, according to a study to be published in the April 18 edition of the journal Cell.

The blueprint for the human body is encoded in genes. Gene expression is the process by which those blueprints are converted into proteins that make up the bodys structures and send its signals. When molecular biologists began analyzing the complete set of human genes (the human genome) in 2001, one surprise was that humans have as few as 30,000 genes when, given their complexity, they should have more than 100,000. How can humans have one-fifth as much genetic material as wheat, for instance, or share one quarter of their genes with fish?

One answer is that humans do more with fewer genes. While genes consist of chains of deoxyribonucleic acids (DNA), they are put into practice by chains of ribonucleic acid chains (RNA), which are modified copies of DNA. Messenger RNA (mRNA) is transported to cellular factories called ribosomes that receive instructions for building proteins by reading mRNA templates, a process called translation. Remarkably, about 75 percent of human genes code for more than one protein through a process called alternate RNA splicing. Unfortunately, the more intricate the splicing process, the greater the opportunity for error. More than one-third of alternatively spliced mRNAs are flawed, and must be destroyed before they can cause harm. Thus, cellular processes that detect and eliminate processing errors are vitally important to effective gene expression.

In recent years, researchers at the University of Rochester Medical Center have revealed the existence of a natural surveillance system called nonsense-mediated mRNA decay (NMD) that determines which mRNAs are fit to serve as protein templates and sees to the destruction of those with flaws. Researchers hope to tweak the proc
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