Fig. 4: Drosophila lipoprotein receptor LpR2 mediates transcellular passage of the SPG by GBS through endocytosis. | Nature Communications

Fig. 4: Drosophila lipoprotein receptor LpR2 mediates transcellular passage of the SPG by GBS through endocytosis.

From: An original infection model identifies host lipoprotein import as a route for blood-brain barrier crossing

Fig. 4

a A knockdown screen for Drosophila E-cadherin (Shotgun) and lipoprotein receptors (LpR1, LpR1; LpR2, LpR2; Arrow, arr and Megalin, mgl) identified LpR2 as crucial for BBB crossing by GBS. A Kruskal–Wallis test followed by Dunn’s multiple comparisons test generated adjusted p-values. Control (n = 20); shg, p > 0.9999 (n = 5); LpR1, p > 0.9999 (n = 11); LpR2, p = 0.0003 (n = 18); arr, p > 0.9999 (n = 5); mgl, p > 0.9999 (n = 6). n represents the number of larvae analysed. b Schematic representation of LpR2 structure. c Confocal image (top and orthogonal views) of LpR2::GFP genomic knock-in line (green) showing colocalisation of LpR2 on SPG membranes (mdr65-mtd-Tomato, red) in a larval brain. d Confocal image (median cut and orthogonal close-up) showing a lack of colocalisation between LpR2::GFP and SPG membranes (mdr65-mtd-Tomato, red) in an adult ventral nerve cord. LpR2::GFP was also detected in neurons. e Co-immunoprecipitation experiment between LpR2::GFP immobilised on beads and bacterial lysates of WT GBS, (Δblr + blr) GBS and Δblr GBS, detected with an antibody against Blr. A robust Blr-LpR2 interaction was revealed. f GBS brain invasion is endocytosis-dependent. GBS entry at 6 h post-infection was significantly decreased by either knocking down LpR2 or blocking endocytosis (dynamints and dynaminDN) specifically in the SPG. Two-tailed Mann–Whitney tests were performed between control and each condition: p(control vs SPG > LpR2 RNAi) = 0.0162; p(control vs SPG > dynamints) = 4.25 * 10−6; p(control vs SPG > dynaminDN) = 1.04 * 10−5. Control (n = 25); SPG > LpR2 RNAi (n = 10); SPG > dynamints (n = 12) and SPG > dynaminDN (n = 7). g, h Colocalisation of GBS (white) with g a marker for early endosome (Rab5-GFP) and h LpR2::GFP (green) within the SPG membrane (mdr65-mtd-Tomato, red). Box and whisker plots: whiskers mark the minimum and maximum, the box includes the 25th–75th percentile, and the line in the box is the median. n represents the number of larvae analysed. *p ≤ 0.05; ***p ≤ 0.001; ****p ≤ 0.0001; ns, not significant. Source data are provided as a Source Data file for a and e, f.

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