Figure 3

Brain lymphatic endothelial cells take up monomeric A?42, but not oligomeric A?42. (A) A schematic diagram of the larval brain with the dorsal view. Red lines in the dotted box depict the loop structure of the brain lymphatic endothelial cells (BLECs) in the optic tectum. (B) Quantification of the co-localization of A?42 with BLECs. Data are presented as mean ± SEM. n = 9 for mA?42 and n = 7 for oA?42. Statistical significance was determined by two-tailed unpaired t-test. (C) Quantification of the numbers of mrc1a+ BLECs in the optic tectum after mA?42 or oA?42 injection in the Tg(mrc1a:mCherry). Data are presented as mean ± SEM. n = 9 per group. (D) Quantification of the number of A?42 positive BLECs nearby (within 10 ?m) mesencephalic vein (MsV) region showing mrc1a+ positivity. Statistical significance was determined by ordinary one-way ANOVA with Tukey?s test. n = 10 for mA?42 and n = 8 for oA?42. (E,F) Confocal projections of prox1a:RFP+ BLECs and A?42-HiLyte Fluor 488. (E?,F?) High magnification of dotted boxes in (E,F) showing endocytic vesicles of BLECs. mA?42-injected BLECs showed robust uptake of mA?42 into endocytic vesicles ((E?), yellow arrows) whereas oA?42-injected did weak uptake ((F?), white arrows). Scale bars in (E?F?) = 10 ?m. (G,H) Confocal fluorescence images of the brain optic tectum region with double transgenic Tg(kdrl:EGFP); Tg(mrc1a:mCherry) larvae after A?42 injection (HiLyte Fluor 647-A?42) at 3 dpf. mA?42 fluorescence detected in the neighboring (within 10 ?m) kdrl:EGFP+ cerebrovasculature was mostly co-localized with mrc1a:mCherry+ BLECs (yellow arrowheads) (G), whereas oA?42 (H) fluorescence neighboring kdrl:EGFP+ cerebro-vasculatures was not. HB, hindbrain; OT, optic tectum; MsV, mesencephalic vein; Scale bars in (G,H) = 50 ?m. ns, not significant; **** p < 0.0001.