If you call to say that you’re having car trouble, your boss will most likely assume there’s a mechanical problem. It might be, though, that your car has been stolen. Likewise, most mutations cause disease by altering a crucial protein’s function. But in some diseases, such as cystic fibrosis, the problem seems to be that a functioning protein goes astray. Ways to shepherd these missing proteins back into place may offer novel treatments for these diseases.
In the United States, about 30,000 people have cystic fibrosis. The disease can be caused by thousands of different mutations within a gene that encodes a cell-membrane channel for the chloride ion. The ensuing faulty intercellular movement of chloride, as well as sodium, somehow produces abnormally thick, sticky mucus that can clog organs such as the lungs and pancreas.
More than 70 percent of people with cystic fibrosis have a single mutation that causes the chloride channel protein to go astray before it reaches its place in the cell membrane, says Pamela Zeitlin of the Johns Hopkins Medical Institutions in Baltimore. Her test tube studies suggest that a drug called buphenyl could guide the protein to where it belongs.
She and her colleagues tested the drug in 19 adults with cystic fibrosis caused by this common mutation. After a week of thrice-daily pills, chloride-ion movement improved slightly in some of the volunteers and in the rest, reached almost healthy measures, Zeitlin reports in the July Molecular Therapy. “The next question is whether these changes in chloride transport translate into clinical effect,” she says. Such studies are now under way.