1. Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
2. Laboratory for Drug Discovery in Neurodegeneration, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
3. Electron Microscopy Laboratory, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.