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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Stealth RNA Protects Retina's Rods
10 August 1998 7:00 pm
Scientists have engineered a genetic weapon that, in animal models, can forestall a common form of progressive blindness. The therapy uses a designer ribozyme, a short strand of RNA that chops up other RNA, to seek and destroy mutant RNA before it can be used to build a protein that kills the eye's rod cells. The finding could pave the way for new treatments for the blinding mutations that afflict nearly 1 in 3000 North Americans with autosomal dominant retinitis pigmentosa (ADRP).
ADRP begins to take its toll in late childhood. As the mutant rhodopsin protein kills light-sensitive rod cells in the retina, the sufferer first loses night vision, then peripheral vision, and finally central vision when the lack of rod cells causes the color-sensitive cone cells to degenerate. Like almost all autosomal dominant diseases, ADRP wreaks its havoc because one copy of a gene produces a mutant--and damaging--protein, in this case a mutant rhodopsin.
In the current Nature Medicine, Alfred Lewin, a molecular geneticist and microbiologist at the University of Florida in Gainesville, and graduate student Kimberly Drenser and their colleagues report that they developed two ribozymes, one shaped like a hairpin and the other like a hammerhead, that home in on the mutant messenger rhodopsin RNA and slice through it before it can be used as a template to assemble the harmful protein. The ribozyme is delivered via a harmless recombinant virus and turned on by a promoter active only in rod cells. They tested it in a rat model of ADRP and found that after 2 to 3 months, eyes that had been injected with the virus-ribozyme combo contained 30 to 40% more rod cells than eyes that received a dummy injection.
"This is a dramatic demonstration that ribozymes may be selective enough to recognize a mutant form of a gene while potentially not interfering at all with the [nonmutant] form," says microbiologist and molecular geneticist Tom Burke of the University of Vermont in Burlington. Scientists hope that ribozymes might be effective weapons against other autosomal dominant diseases such as Huntington's disease and glaucoma. If continuing animal studies show that the method is safe and effective, the researchers hope to proceed with Phase 1 clinical trials within a few years.