Cilia -- bristly, hair-like structures on the surfaces of cells -- may be the source of genetic diseases or disorders ranging from kidney disease to some types of eye disorders, researcher suggest
U.S. researchers are reporting recent discoveries regarding cilia-related diseases -- known as "ciliopathies" -- and have described "model" species that could be useful for systematic study of ciliopathies.
There is a growing body of evidence that missing or abnormal cilia can be behind a large number of human disorders, George B. Witman, a cellular biologist at the University of Massachusetts Medical School, has written in the journal BioScience.
"Kidney disease and blindness, multiple digits, shortened bones or extremities, obesity -- all of these things, it turns out, are due to defects in cilia," he says.
If a common thread linking these disorders can be identified it could lead to gene-based therapies to battle them, experts say.
In humans, cilia are found on almost every cell in the body, performing a broad range of functions. Cilia that are motile -- able to move and wiggle -- help move fluids around that body, such as cerebrospinal fluid in the brain.
In some diseases, motile cilia become dysfunctional and fail to beat to and fro to move fluid.
In addition to motile cilia, almost all human cells have a non-motile, primary cilium that acts as a "molecular antenna," detecting and conveying significant messages to the cell about its local environment.
"The signaling machinery is concentrated in the cilia," Witman says. "All in this very tightly controlled, constrained space."
The signaling function is particularly important in a developing embryo, the researchers explain, so if the signal is blocked or distorted in an embryo's early stages there is the risk of a miscommunication that can disrupt or damage organ formation.
That's why "when you have defects in these cilia, you get a lot of congenital diseases," Witman says.
While scientists have been aware of these primary cilia since the late 1800s, they were long assumed to have only minimal purposes.
With the new knowledge of the importance of the primary cilia, researchers have begun to link them to a number of ciliopathies.
Some experts even suggest some cancers might be linked to cilia.
"There's a whole series of reports that primary cilia are lost in a variety of cancers," says Peter Satir, a professor of structural biology and anatomy at the Albert Einstein College of Medicine who was not involved in the research. "It's possible that some cancers will turn out to be ciliopathies."
