The discovery of RNA interference or RNAi, a natural phenomenon by which cells silence genes, was like many great moments in science—an accident.
Here’s how the story goes: Back in 1986, geneticist Rich Jorgenson tried to create a super purple petunia by inserting an extra copy of the gene that causes the purple color into the plant’s DNA. But what happened is the petunia lost its pigmentation altogether. It turned white.
What Jorgensen had stumbled upon was a natural process in the cell involving RNA, a chemical cousin of DNA in genes. RNA plays a powerful role in the creation of proteins, which are the building blocks of life, and essentially, in gene expression RNA is made up of strings of chemicals called bases—genetic instructions.
RNA is usually single stranded, but what Jorgenson discovered is that by artificially introducing a double stranded version of RNA, he could set off a cellular immune response. When a cell senses a double strand of RNA, its defenses treat it like a virus, because viruses are also double stranded. It then acts to silence any genes with the corresponding sequence of bases.
In our segment for “TechKnow,” we looked at how researchers are trying to use RNAi treatment to suppress the population of Asian citrus pysllids, which transmit a disease deadly to citrus trees. But it’s not just the psyllid population that could be controlled with RNAi. Researchers are even exploring how to kill mosquitoes , the vector for diseases like yellow fever and malaria, by shutting off the very gene which gives it the ability to digest blood. The promising early results: 90 percent die within 48 hours of feeding.
And RNAi treatment doesn’t have to spell the demise of the organism receiving it. Drug companies are interested in how to harness RNAi to treat diseases like cancer and HIV. The promise of RNAi is that virtually any disease related to genes could be inactivated—from ones that cause troublesome proteins to be made to ones that allow pathogens to thrive.
So far the biggest challenge is how to deliver RNAi treatment to cells. There are a bevy of researchers tackling that specific problem, including a team at the California Institute of Technology in Pasadena that is building tiny nanotech robots. Supposedly, these tiny polymer robots can seek out the receptor on many tumor cells in the body to deliver the gene therapy.
All very exciting stuff—but it’s likely to be five to 10 years before the first therapies in either agriculture or healthcare hit the marketplace. In the meantime, it’s getting a lot of buzz in the science world, as well as drawing criticism from those who fear the therapies could have off-target affects. Greenpeace is among the groups who are against it. And it doesn’t help that Big Ag chemical companies like Monsanto—whose presence often spurs large protests—are behind some of the research efforts.
So will the discovery of RNAi be the penicillin of our time? Or is it another technology that holds promise but can’t be practical—or palatable enough—to become part of our daily world?
Watch “TechKnow” this Sunday and then give us your take.