Genetic causes of Parkinson’s probed

A mutation in the gene for the protein synaptojanin 1 (SJ1) is associated with the development of Parkinson’s disease in early adulthood—a handful of patients who showed symptoms of the disease in their 20s and 30s were previously found to share the same SJ1 mutation, called R258Q. A new study, led by Pietro De Camilli, M.D., chair and John Klingenstein Professor of Neuroscience and professor of cell biology, reveals how the R258Q mutation may cause disease.

When brain cells send a signal to neighboring neurons, they release signaling molecules called neurotransmitters. Researchers already knew that SJ1 is required to recapture those neurotransmitters after the signal has been sent, for later reuse.

In the new work, De Camilli’s group created mice with the R258Q mutation in SJ1. As do humans with the mutation, the mice had movement problems as well as epilepsy.

The researchers found that neurons from the affected mice were defective in recycling neurotransmitters, accumulating the molecules outside the cell instead of recapturing them.

The results, published on Feb. 22 in Neuron, add to a growing body of evidence that various defects in this cellular recycling pathway—known as endocytosis—lead to Parkinson’s.