Fig. 4

Microglial CD2AP haploinsufficiency reduces their phagocytosis of Aβ without affecting Aβ plaques in 5xFAD mice. A Representative images of Aβ plaques stained with Thioflavin S (ThioS, in green) and immunostained with an antibody against Aβ (6E10, in red) in the brain of 7-month-old 5xFAD;Cd2ap^fl/+ and 5xFAD;Cd2ap^fl/+;Cx3cr1-cre mice. Scale bars: 500 μm. Percentages of 6E10-immunostained and ThioS-stained areas in the cortex and hippocampus (Hip) were quantified for comparison. n = 7 mice per genotype. Unpaired Student’s t test. B Aβ42 levels in TBS-extractions, TBSX-extractions, and GuHCl-extractions of the hippocampal tissues from 7-month-old 5xFAD;Cd2ap^fl/+ and 5xFAD;Cd2ap^fl/+;Cx3cr1-cre mice were analyzed by ELISA. n = 5 mice per genotype. Unpaired Student’s t test. C Primary microglia from Cd2ap^fl/+ and Cd2ap^fl/+;Cx3cr1-cre mice were treated with TAMRA-oAβ and analyzed by flow cytometry. Untreated WT microglia were used as a negative control. The Mean fluorescence intensity (MFI) of TAMRA-oAβ⁺ primary microglia was used to indicate the ability of TAMRA-oAβ uptake and compared between different genotype groups. Cd2ap^fl/+ group, n = 7; Cd2ap^fl/+;Cx3cr1-cre group, n = 8. Unpaired Student’s t test. D Representative images and analysis of FAM-oAβ (in green) engulfed by Iba1⁺ microglia (in red) pretreated with MG132 and chloroquine. The Nuclei were stained with DAPI (in blue). The fluorescence intensity of FAM-oAβ in Iba1⁺ microglia and cell density were quantified for comparison. Scale bars for regular and zoom in images are 50 μm and 5 μm, respectively. n = 4. An average of data from approximately 12 cells in each replicate was indicated. Unpaired Student’s t test. Data are presented as mean ± SEM. *P < 0.05; **P < 0.01; ****P < 0.0001; ns, not significant