Latrepirdine stimulates autophagy and reduces accumulation of α-synuclein in cells and in mouse brain

Latrepirdine (Dimebon; dimebolin) is a neuroactive compound that was associated with enhanced cognition, neuroprotection and neurogenesis in laboratory animals, and has entered phase II clinical trials for both Alzheimer's disease and Huntington's disease (HD). Based on recent indications that latrepirdine protects cells against cytotoxicity associated with expression of aggregatable neurodegeneration-related proteins, including A beta 42 and gamma-synuclein, we sought to determine whether latrepirdine offers protection to Saccharomyces cerevisiae. We utilized separate and parallel expression in yeast of several neurodegeneration-related proteins, including alpha-synuclein (alpha-syn), the amyotrophic lateral sclerosis-associated genes TDP43 and FUS, and the HD-associated protein huntingtin with a 103 copy-polyglutamine expansion (HTT gene; htt-103Q). Latrepirdine effects on alpha-syn clearance and toxicity were also measured following treatment of SH-SY5Y cells or chronic treatment of wildtype mice. Latrepirdine only protected yeast against the cytotoxicity associated with alpha-syn, and this appeared to occur via induction of autophagy. We further report that latrepirdine stimulated the degradation of alpha-syn in differentiated SH-SY5Y neurons, and in mouse brain following chronic administration, in parallel with elevation of the levels of markers of autophagic activity. Ongoing experiments will determine the utility of latrepirdine to abrogate alpha-syn accumulation in transgenic mouse models of alpha-syn neuropathology. We propose that latrepirdine may represent a novel scaffold for discovery of robust proautophagic/anti-neurodegeneration compounds, which might yield clinical benefit for synucleinopathies including Parkinson's disease, Lewy body dementia, rapid eye movement (REM) sleep disorder and/or multiple system atrophy, following optimization of its pro-autophagic and pro-neurogenic activities.