RNAi: Turning Off Genes to Treat Disease

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By Staff Reports

(DGIwire) – In high school biology class, students are taught “DNA codes for RNA codes for proteins.” These days, scientists not only have the capability to manipulate the basic molecules of life; they are also able to prevent the production of proteins that play roles in certain diseases. The way this works is through a process called RNA interference—“RNAi” for short—that can target and destroy specific RNAs before they can serve as templates for the generation of hundreds to thousands of copies of the coded protein.

RNAi was first demonstrated in 1998 by Dr. Craig Mello and Dr. Andrew Fire, who were awarded the 2006 Nobel Prize in Physiology or Medicine for their efforts, according to The Scientist. RNAi is a “gene-silencing” technology, in which RNAi compounds inhibit gene expression by targeting and destroying specific messenger RNA (mRNA) molecules, as noted in a recent article in GEN. Without those mRNAs, specific proteins are kept from forming.

The process of RNAi can be artificially induced by introducing into the cells a small double-stranded fragment of RNA that corresponds to a particular mRNA. A protein complex within the cell called RISC (RNA-Induced Silencing Complex) recognizes this double-stranded RNA fragment and uses one strand, the guide strand, to bind to and destroy its corresponding cellular mRNA target. If the mRNA is destroyed in this way, the encoded protein cannot be made. Thus, RNAi provides a way to potentially block the expression of specific proteins. Since the overexpression of certain proteins plays a role in many diseases—from lung cancer to kidney disease—the ability to inhibit gene expression with RNAi provides a potentially powerful tool to treat human disease.

“A considerable number of medical conditions are a consequence of the overexpression of specific proteins,” says Dr. Geert Cauwenbergh, President and CEO of RXi Pharmaceuticals. “For example, it is known that both hypertrophic scarring and retinal scarring are consequences of the excessive expression of connective tissue growth factor (CTGF), an extracellular matrix protein that plays a key role in tissue regeneration and repair.”

With so many potential areas of applicability in medicine, RNAi has significant potential—and the result could be improved therapies for many people experiencing a wide range of conditions.

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