CSPα reduces aggregates and rescues striatal dopamine release in αsynuclein transgenic mice

Synuclein aggregation at the synapse is an early event in Parkinsons disease and is associated with impaired striatal synaptic function and dopaminergic neuronal death. The cysteine string protein (CSP) and synuclein have partially overlapping roles in maintaining synaptic function and mutations in each cause neurodegenerative diseases. CSP is a member of the DNAJ/HSP40 family of co-chaperones and like synuclein, chaperones the SNARE complex assembly and neurotransmitter release. Synuclein can rescue neurodegeneration in CSPKO mice. However, whether synuclein aggregation alters CSP expression and function is unknown. Here we show that synuclein aggregation at the synapse induces a decrease in synaptic CSP and a reduction in the complexes that CSP forms with HSC70 and STGa. We further show that viral delivery of CSP rescues in vitro the impaired vesicle recycling in PC12 cells with synuclein aggregates and in vivo reduces synaptic synuclein aggregates restoring normal dopamine release in 1-120hsyn mice. These novel findings reveal a mechanism by which synuclein aggregation alters CSP at the synapse, and show that CSP rescues synuclein aggregation-related phenotype in 1-120hsyn mice similar to the effect of synuclein in CSPKO mice. These results implicate CSP as a potential therapeutic target for the treatment of early-stage PD.