Figure 6.

Ectopic phosphorylated Creb (p-Creb), Pax2, and Ncam1 expression in proximal tubule–derived cystic segments with decreased or absent lotus tetragonolobus lectin (LTL) staining in P1 Six2crePKD1 knock-out (KO) kidneys. A–F: Representative co-immunofluorescence images for p-Creb (red) and LTL (green) (A and B), Pax2 (red) and LTL (green) (C and D), or Ncam1 (red) and LTL (green) (E and F) in control and Six2crePkd1KO kidneys. A: In controls, p-Creb signal is absent in all LTL-positive proximal tubules (arrowhead) and is present in LTL-negative interstitium (I) and tubules (likely collecting ducts) (arrow). B: In Six2crePkd1KO kidneys, p-Creb is absent in most cells with strong LTL staining, but is expressed ectopically in proximal tubule–derived cystic segments with reduced or absent LTL expression (concave arrowheads) and in LTL-negative interstitium (arrow). C: In controls, Pax2 is absent in LTL-positive proximal tubules (arrowhead) and present in LTL-negative tubules (likely collecting ducts) (arrow) (yellow-labeled cells are red blood cells). D: In Six2crePkd1KO kidneys, Pax2 is expressed ectopically in cystic cells with low or absent LTL expression (concave arrowhead). E: In controls, Ncam1 is present in early epithelial nephron derivatives (arrow), but absent in LTL-positive proximal tubules (arrowhead). F: In Six2crePkd1KO kidneys, Ncam1 is expressed ectopically in cystic tubules that have reduced or absent LTL staining (concave arrowheads), and present in normal early epithelial nephron derivatives (arrow). Scale bars: 50 μm.