Figure 2.

P7 and P21 Six2creFrs2α knock-out (KO) kidneys ectopically express phosphorylated Creb (p-Creb) in lotus tetragonolobus lectin (LTL)-negative segments of proximal tubule–derived cysts. A–D: Representative co-immunofluorescence images for p-Creb (red) and LTL (green) in P7 and P21 control and Six2creFrs2αKO kidneys. In P7 and P21 controls (A and C), p-Creb signal is present in stromally derived interstitium (I) and glomeruli (G) and in nondilated LTL-negative tubules (arrows), but is absent in LTL-positive proximal tubules (A and C, arrowheads). B and D: In Six2creFrs2αKO kidneys, p-Creb is absent in LTL-positive cells in both nondilated tubules and in cysts (arrowheads); however, it is expressed ectopically in LTL-negative cystic segments (concave arrowheads) and present in many nonproximal tubular cells (likely interstitium and collecting ducts). Scale bars: 50 μm.