Figure 4. Overexpressed HPRT1 inhibits dopaminergic neuron loss via the Wnt/β-catenin signaling pathway in 6-OHDA-treated N27 dopaminergic neurons and mice. N27 dopaminergic neurons and mice were treated with oe-HPRT1 in the presence of the Wnt/β-catenin blocker XAV-939 or DMSO carrier. (A) The protein expression of total-β-catenin, DAT and HPRT1 as well as the extent of β-catenin phosphorylation in the N27 dopaminergic neurons detected by western blot assay. (B) The activity of the Wnt/β-catenin signaling pathway expressed by TOP/FOP ratio in the N27 dopaminergic neurons. FOP was designated as background value or as negative control due to its stability. (C) The protein expression of total-β-catenin, DAT and HPRT1 as well as the extent of β-catenin phosphorylation in the normal and 6-OHDA-lesioned PD mice. (D) TH positive neurons in the substantia nigra tissues examined by immunohistochemistry (upper × 100, lower × 400). (E–H) The mRNA expression of Nurr-1 (E), Pitx-3 (F), Ngn-2 (G) and NeuroD1 (H) in the substantia nigra tissues examined by RT-qPCR. (I) Fluoro-Jade B-stained apoptotic N27 dopaminergic neurons (scale bar = 50 μm). *p < 0.05. Measurement data are expressed by means ± standard deviation. Comparison between two groups was analyzed by unpaired t test, and comparison among multiple groups by one-way analysis of variance. n = 6.