You could compare them with footballers who, because they can play at any position, never get given a fixed position in the team: 14-3-3 proteins form an essential link in so many processes that they have never been given a decent name. Because the names of proteins are customarily chosen to reflect their function, explains Loes Stevers, PhD candidate at Biomedical Engineering: “In the 1960s, these proteins were first seen on a gel. And 14-3-3 was simply the code for the place where they ended up.”

14-3-3 proteins are jacks of all trades, explains Stevers. “By binding to other proteins, they are able to activate or deactivate them, help fold, or play a role in the transport occurring inside the cell.” This last role, for example, 14-3-3 fulfils for the CFTR protein, which occurs in cell membranes (the cell's ‘skin’) and ensures that chlorine ions can penetrate the membrane. The symptoms of cystic fibrosis occur when the cell membrane becomes less permeable to these ions.

“People with cystic fibrosis often do make CFTR, but these molecules have errors in them. Consequently, they fail to find their place in the cell membrane. Instead, they are broken down by the body if they aren't taken to the cell membrane in good time by 14-3-3. Our approach was to assist the 14-3-3 protein with this task, by adding an assistant molecule that improves the binding of CFTR to 14-3-3. This enables more of the CFTR protein to reach and enter the cell membrane, and should cause the symptoms of the disease to diminish.”

Binding

To establish what just such an assistant should look like, Stevers first studied the structure of the CFTR molecule, in particular which parts of this elongated molecule are able to bind to 14-3-3. In so doing, she discovered that a single binding site is not enough. “14-3-3 has two groves into which CFTR fits. CFTR must evidently bind in both groves, or it doesn't work.”

Armed with this information - and which of the nine potential CFTR binding sites actually fit in the groves - the PhD candidate went in search of a small assistant molecule that could stabilize binding. In trying out thousands of different molecules, she came across a promising candidate.

“This molecule, which we want to patent, has now been tested at McGill University in Canada on cultures of diseased cells. This has revealed that the addition of this molecule enables much more CFTR to enter the cell membrane and makes this membrane much more permeable to chlorine ions.”

Side effects

Incidentally, Stevers didn't study the 14-3-3 proteins only in relation to cystic fibrosis;  she also found leads for potential medicines to combat Parkinson's disease. Hopeful results, but there may be catch, she is keen to stress. “As 14-3-3 fulfils so many roles, it is also highly likely that a medicine will have side effects. And that has not yet been tested; to do that we need to cooperate with pharmaceutical companies. They will probably be interested if the follow-up studies in Canada go well. I would  really like to stay involved in this work after I gain my doctorate.”