Fig. 6: Alterations in endo-lysosomal function and compensatory remodeling in disease.

a Plots depict fluorescence intensity in S1 segments post injection of lactoglobulin^At565. Uptake was decreased in OCRL knockout (KO) mice compared to wild type (WT) (mean value ± SEM; time × genotype ***p < 0.001; n = 3 mice per group). b Normalized raw intensity waveform derived from line scan ROIs showing intracellular evolution of fluorescence in KO mice (0 = apical, 1 = basolateral). Base vectors derived from SVD analysis in wild type (c) and KO (d). e Kinetics of SVD1-3 in WT and KO mice (mean value ± SEM; n = 3 mice per group). SVD2 shows a small delay in transition through EEs (^$$$p < 0.001). SVD3 (lysosomal protein degradation) also displays a small right shift (°°°p < 0.001). f, g Protein uptake length was increased along the proximal convoluted tubule (PCT) in KO mice. Single plane example images (representative of three independent experiments) are depicted 20 min post injection. Scale bars = 20 μm. Histogram depicts the fluorescence signal (mean value ± SD; n = 3 mice per group) in ROIs drawn around individual PCT segments, ordered from highest to lowest. Data depicted were from single plane images acquired 20 min post injection of lactoglobulin^At565. h, i Antibody staining for the late endosomal/lysosomal markers Rab7 and Lamp1. Example single plane images are depicted (representative of five independent experiments). Scale bars = 10 μm. j Intracellular signal distribution was assessed by the standard deviation (Std. Dev.). In WT mice, signal is condensed in apical vesicles in early PCT segments (high Std. Dev.), and more diffuse in late (low Std. Dev.). This axial pattern was lost in KO mice, resulting in a lack of linear correlation (R value: 0.89 in WT, 0.53 in KO; p < 0.05; n = 5 mice per group). k Summary diagram depicting axial redistribution of protein reabsorption along the PCT in KO mice; increased uptake in later segments can compensate for severe defects in endocytosis.