Fig 2: CG1/CDK5 axis regulates PTC dedifferentiation and fibrosis in CKD rodents.(A) Schematic diagram of the UUO model with CDK5 inhibitor GLX. (B) Quantitative analysis of obstructed kidney weight (KW)/body weight (mg/g BW) and obstructed/contralateral kidneys (%) following UUO with GLX or vehicle. (C) Large, scanned images of picrosirius red–stained kidneys imaged by polarized-light microscopy from UUO plus GLX or vehicle. Dashed outline indicates region of interest quantified. Scale bars: 500 µm. (D) Quantification of picrosirius red+ area/cortex (%) in C. Contralateral kidney of vehicle, n = 5; contralateral kidney of GLX, n = 5; UUO with vehicle, n = 6; UUO with GLX, n = 6. (E) Western blot analysis of SOX9 and VIM in whole-kidney lysates of UUO and contralateral kidneys with vehicle or GLX, and (F) quantification of SOX9/ß-actin and VIM/ß-actin. (G) Representative images of dedifferentiation markers (SOX9, Na+/K+-ATPase, and VIM) in kidneys from contralateral or UUO kidneys treated with vehicle or GLX. Scale bars: 25 µm. HM, high magnification. (H) Quantitative analysis of the number of SOX9+ PTCs/cortex (n/mm2), Na+/K+-ATPase+/cortex (%), or VIM+ area/cortex (%) in contralateral or UUO kidney treated with vehicle or GLX. Contralateral kidney of vehicle, n = 5; contralateral kidney of GLX, n = 5; UUO with vehicle, n = 7; UUO with GLX, n = 7–8. (I) Representative images of collagen type IV a1 chain (COL4a1) in contralateral or UUO kidney with vehicle or GLX. Scale bar: 50 µm. (J) The corresponding analysis of COL4a1+ area/cortex (%). Contralateral kidney of vehicle, n = 3; contralateral kidney of GLX, n = 3; UUO with vehicle, n = 6; UUO with GLX, n = 7. Data are presented as the mean ± SD. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001 by unpaired, 2-tailed Student’s t test (B) or 1-way ANOVA with Tukey’s post hoc test (D, F, H, and J).

Fig 3: CG1 modulates PTC dedifferentiation and proliferation in CKD.(A and B) Representative images of SOX9-labeled kidney sections from WT and CG1-KO mice in acute (day 7) and chronic (day 42) phases of AA. Scale bar: 20 µm (C) Corresponding quantification of the number of SOX9+ cells/kidney. Control (n = 5) and injured kidney (n = 3–6). (D) Western blot analysis of KIM-1, SOX9, and ß-actin in acute phase of AA, including day 7 and day 14 after administration of AA and the corresponding quantification of SOX9/ß-actin and KIM-1/ß-actin. (E and F) Representative images of SOX9- and Ki-67–labeled kidney sections from WT and CG1-KO mice on day 3 and day 9 of UUO and corresponding quantification of the number of SOX9+ or Ki-67+ cells/kidney. Control (NK; n = 5) and injured kidney (n = 5–9). Scale bar: 20 µm. (G) Representative images of LTL staining in kidneys on days 0, 14, 28, and 42 following AA and corresponding quantification. Scale bar: 50 µm. (H) Western blotting analysis of YAP in whole-kidney lysates of WT and CG1-KO mice following AA. (I) Representative images of Na+/K+-ATPase– or VIM-stained kidney sections following UUO. Scale bars: 100 µm. HM, high magnification. (J) The corresponding quantification of Na+/K+-ATPase+ or VIM+ area/cortex (%). Control (n = 4–6) and injured kidney (n = 8–9). Scale bar: 100 µm. Data are presented as the mean ± SD. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001 by 1-way ANOVA with Tukey’s post hoc test.