An international team of scientists, led by researchers at the University of California, San Diego School of Medicine, have discovered a connection between mutations in the INPP5E gene and ciliopathies. Their findings, which may lead to new therapies for these diseases, will appear in the online edition of Nature Genetics on August 9.
Ciliopathies are a newly emerging group of diseases caused by defects in the function or structure of cellular primary cilia, which are small, cellular appendages of previously unknown function. Examples of ciliopathies include mental retardation, retinal blindness, obesity, polycystic kidney disease, liver fibrosis, ataxia, and some forms of cancer.
Joseph G. Gleeson, MD, professor of neurosciences and pediatrics at UC San Diego and a Howard Hughes Medical Institute investigator, and his colleagues showed that when two copies of mutated INPP5E are present in an individual, the result is Joubert syndrome, a condition marked by mental retardation and impaired balance. They linked the function of the protein that is encoded by this gene to enzymatic conversion of one of the most important signaling molecules in the body, phosphatylinositol, currently one of the main targets of the pharmaceutical industry to treat a host of diseases, including cancer.
The Gleeson team, led by UC San Diego scientists Stephanie Bielas, PhD, and Jennifer Silhavey, MS, discovered that the enzyme goes to a cellular structure known as the cilium, a long-forgotten organelle without clear function until recently. However, in the past five years, the field of cilia biology has exploded due to the recognition that many of our basic bodily functions are regulated and “fine-tuned” by the cilium.