Fig. 4

The Atg5 and Atg12 autophagy linked proteins were affected by CTEP and rapamycin treatments in the context of exogenous α-syn fibril exposure (black bars). A. Atg5 levels were significantly reduced by exogenously applied α-syn preformed fibrils (fib). The CTEP and rapamycin (rap) treatments reversed this α-syn fibril Atg5 reduction, as well as increasing Atg12 levels in the context of the α-syn PFFs. The A53T AV treated cells did not differ whatsoever between the groups (grey bars). (* p < 0.05, difference compared to vehicle control (ctrl); # p < 0.05, difference compared α-syn fibril (fib) treatment). Presented data are the result of three separate experiments (n = 3/group) with each carried out in triplicate. All blot signals were normalized to total protein content. Following significant ANOVAs, Tukey’s pairwise comparison was used for post hoc comparisons. B. The bottom schematic depicts the possible route through which CTEP and rapamycin may influence autophagic functioning. The interaction of CTEP with the mGlur5 receptor is posited to reduce AKT, mTOR and p70S6 activity. This in turn, disinhibits ULK1 and subsequently catalyzes PI3K-dependent interactions with the Atg5-Atg12 complex. The Atg12–Atg5-Atg16 complex is then essential for autophagosome formation. Rapamycin ultimately would result in basically the same outcome as CTEP; however, rapamycin would interact downstream of mGlur5 at the level of mTOR