Cofilin pathology is a new player on α-synuclein-induced spine impairment in models of hippocampal synucleinopathy

Cognitive dysfunction and dementia are presently recognized as major complications in α-synucleinopathies, namely in Dementia with Lewy Bodies (DLB) and Parkinson’s disease with dementia (PDD). In these disorders, α-Synuclein (αSyn) accumulation affects severely the hippocampus by inducing synaptic dysfunction which culminates in cognitive impairment. To characterize the mechanisms underlying αSyn-induced neuronal dysfunction we analysed the effect of overexpression or extracellular administration of αSyn on hippocampal neurons. We observed that αSyn induces the dysregulation of the actin-binding protein cofilin and its assembly into rod structures in a mechanism mediated by the cellular prion protein (PrP C ). Moreover, we unraveled cofilin pathology as mediator of αSyn-induced dendritic spine impairment in hippocampal neurons. Importantly, in a synucleinopathy mouse model with cognitive impairment we validated cofilin dysregulation and synaptic dysfunction at the same age when cognitive deficits were observed. Our data supports cofilin as a novel player on hippocampal synaptic dysfunction triggered by αSyn on Lewy Body dementias.