Fig 2: qPCR analysis in RNA isolated from the cerebral cortex. (A) PLX treatment caused a significant reduction of microglial receptors (Csf1r, P2ry12, Trem2, and Itgam) in both Sham and SCI groups. (B) Inflammatory cytokine IL-1a and Lrrc25 expression. (C-D) Astrocytes marker Gfap and the genes that are associated with astrocyte function including Vim, Gbp2, Osmr, C4a, and Entpd2 remained unchanged in both SCI and PLX groups. All data are presented as independent data points. N = 4 mice/group. *p < 0.05, ++++p < 0.0001, vs. Sham/Veh group; ####p < 0.0001 vs. SCI/WT. Two-way ANOVA following Tukey's multiple comparisons test.

Fig 3: Ablation of PGRN promoted the activation of astrocytes in aged mice. Brain sections from 12-month-old WT and Grn-/– mice were stained with anti-GFAP antibody. The accumulation of GFAP-positive cells was analyzed in two different brain regions, midbrain and cerebellum, using immunohistochemistry. (A,B) Representative images of three different brain regions from three independent WT mice or Grn-/– mice. (C) Statistical analysis of A and B. n = 3. Data presented as mean ± SD. * p < 0.05.

Fig 4: Increased MPTP vulnerability of VPS35 D620N KI mice. (a) A schematic diagram depicts the experimental design. (b–c) Exacerbated motor function deficits in VPS35D620N / D620N mice as measured by the latency to fall in rotarod test (b) and duration to cross the narrow beam (9 mm) in beam walking test (c) (n = 12–14/group). (d–g) Concentrations of DA (d), DOPAC (e), HVA (f), and DA turnover rate (DOPAC+HVA/DA) (g) in the STR of VPS35D620N / D620N and WT controls injected with MPTP/Saline as indicated (n = 10–12/group). (h) Representative images of TH, GFAP, and IBA1 immunostaining in SNpc and STR from VPS35D620N / D620N and WT mice injected with MPTP/Saline as indicated. Scale bar, 100 µm. Quantification of TH-positive neurons in SNpc (i), OD of TH-positive fibers in STR (j), GFAP-positive cells (k) and IBA1-positive cells (l,m) in SNpc (n = 9/group). Representative Western blots (n) and quantification (o) of TH in VM extracts from VPS35D620N / D620N mice and WT controls injected with MPTP/Saline as indicated (n = 7/group). Two-way ANOVA with Tukey's post hoc test; mean ± SEM; *p < 0.05, **p < 0.01, ***p < 0.001, n.s., not significant

Fig 5: The effects of microglial depletion on the expression levels of microglial receptors and biomarker genes of neuronal apoptosis and astrocytes in the spinal cord at 6 weeks post-injury. (A) Microglial receptors including Csf1r, P2ry12, Trem2, and Itgam (CD11b) were significantly upregulated following injury and reduced with PLX treatment in both Sham and SCI groups. (B-C) The markers related to the processes of neuronal apoptosis and autophagy. (D) Astrocyte marker Gfap. All data are presented as independent data points. N = 4 mice/group. * or +p < 0.05, ** or ++p < 0.01, ***p < 0.001, **** or ++++p < 0.0001, vs. Sham/Veh group; #p < 0.05, ##p < 0.01, ####p < 0.0001 vs. SCI/WT. Two-way ANOVA following Tukey's multiple comparisons test.