Figure 3

Pax8-Vps34^Δ/Δ mice show preserved apico-basal polarity in kidney proximal tubules but increasing mislocalization of megalin and NaPi-II from P7 to P14. (a) Confocal imaging of epithelial polarity markers: ezrin (apical brush border; red), NHERF-1 (apical PDZ scaffold; cyan), Na⁺/K⁺-ATPase subunit α1 (basolateral domain; green). Almost perfect colocalization of ezrin with NHERF-1 generates an apical white layer at P7 and P14, irrespective of conditional Vps34 excision. In WT PTCs and in most Vps34^Δ/Δ PTCs up to P7, notice extensive invaginations of basal membrane labeled for Na⁺/K⁺-ATPase. These structures have vanished in Vps34^Δ/Δ PTCs at P14. (b) Confocal imaging of apical transmembrane proteins: megalin (red), NaPi-IIa (green), by reference to ezrin (cyan). In WT PTCs, NaPi-IIa perfectly colocalizes with ezrin (pale green signal) while megalin is concentrated in a subapical layer. In Vps34^Δ/Δ PTCs, megalin and NaPi-IIa are progressively mislocalized to separate (red, green) or common (yellow) deep cytoplasmic dots. Yellow dashed line indicates mosaicism with preserved cell indicated by #. For cubilin and SGLT-2, see Supplementary Fig. 5.