Fig. 4: Microglia-specific Cx43 knockout induces microglia neuroprotective reactive state in APP/PS1 mice.

a Representative image of IBA1, Aβ and DAPI staining of mouse hippocampus. Scale bar: 20 μm. b The total number of IBA1+ microglia, periplaque microglia, and distal microglia was quantified and normalized to the area. N = 5 mice. Statistical test: two-sided t test. c Representative image of IBA1, Aβ and DAPI staining. Scale bar: 10 μm. For each plaque, the number of periplaque microglia was quantified and normalized to the plaque perimeter. N = 5 mice. Statistical test: two-sided t test. d 3D reconstruction image of panel c displaying Aβ plaque and the fraction of Aβ plaque within IBA1+ microglia domain. Scale bar: 10 μm. The ratio between plaque within microglia and total plaque volume was quantified. N = 5 mice. Statistical test: two-sided t test. e Dye uptake experiment was performed on acute brain slices and counterstained with IBA1 to analyze the microglial hemichannel opening. Scale bar: 10 μm. EtBr intensity was quantified and normalized to the WT group for each experiment. N = 5 mice. Statistical test: paired t test. f ELISA analysis of TNFα and IL1β cytokine levels in acute brain slices normalized to protein content. N = 4 mice. Statistical test: paired t test. g Bulk RNA-seq was performed on microglia isolated from WT, APP/PS1, and APP/PS1:Cx43^mgl-cKO mouse cortex and hippocampus. h Volcano plot highlighting the differentially expressed genes between APP/PS1:Cx43^mgl-cKO microglia and APP/PS1. i Heatmap shows expression of disease-associated microglia 3 (DAM3) enriched genes, which were split into 5 clusters according to their expression change in APP/PS1:Cx43^mgl-cKO microglia compared to APP/PS1. Left: normalized gene expression level of 4 clusters. Right: functional annotation and representative genes of 4 clusters. j, k Heatmap shows differentially expressed genes that are associated with Aβ recognition, as well as the neuroprotective or neurotoxic signature of microglia. Dot plots show mean ± SEM, each data point, and p-value. Box plots show minima, maxima, 25 ~ 75% percentile, and medium. Significance: *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. Source data are provided as a Source Data file.