Figure 4

MPP⁺ inhibited TRPC1 expression, and TRPC reduction decreases SOCE, dopamine release and cell viability. Immunofluorescence was used to probe for endogenous TH (left) or TRPC1 (middle) or Orai1 (right) proteins in untreated (top) or MPP⁺ (500 µM for 24 hours; bottom) treated MSC-derived dopaminergic neurons (A). Tg (1 µM) induced average currents (from 7–9 cells) were measured in cells treated with 0 (A) or 500 µM MPP⁺ for 24 hours (B). The holding potential for current recordings was −80 mV. Relative current-voltage (I–V) curves (developed from maximum currents) and expressed as mean ± SE for each group, are graphically represented in C. ELISA was used to measure dopamine release from MSC-derived dopaminergic neurons that were either untreated or treated with SKF 96365 (100 µM for 30 mins), a non-specific TRPC channel blocker (D). MTT assay measured survival of MSC-derived dopaminergic neurons that were either untreated or treated with SKF 96365 (100 µM for 30 mins). *p value < 0.05, as compared with differentiated MSCs that were not treated with MPP⁺.