Pathological α-Synuclein Transmission Initiates Parkinson-like Neurodegeneration in Nontransgenic Mice

Synthetic Parkinson's Parkinson's disease (PD) and related α-synucleinopathies are defined by the accumulation of α-synuclein (α-Syn)–containing intraneuronal inclusions—Lewy bodies (LBs) and Lewy neurites (LNs)—in association with the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and other brain regions. However, a cause-and-effect relationship between LB/LN formation and neurodegeneration remains unclear. Indeed, whether LB/LNs are toxic or represent a neuroprotective response has been contentious. Luk et al. (p. 949 ) injected α-Syn fibrils generated from recombinant mouse α-Syn protein into the dorsal striatum of wild-type mice and found that misfolded α-Syn caused the formation…