Volume 83, Issue 3, Pages 404-413 (March 2013) The histone deacetylase, SIRT1, contributes to the resistance of young mice to ischemia/reperfusion-induced acute kidney injury  Hong Fan, Hai-Chun Yang, Li You, Ying-Ying Wang, Wen-Juan He, Chuan-Ming Hao  Kidney International  Volume 83, Issue 3, Pages 404-413 (March 2013) DOI: 10.1038/ki.2012.394 Copyright © 2013 International Society of Nephrology Terms and Conditions

Figure 1 Age-related susceptibility to kidney injury following ischemia–reperfusion injury. (a) Body weights of the mice used in the experiment (*ADT I/R vs. YNG I/R, $ADT sham vs. YNG sham). (b) The blood urea nitrogen (BUN) levels were determined following ischemia–reperfusion injury (*ADT I/R vs. YNG I/R, #ADT I/R vs. ADT sham). (c) The serum creatinine levels were examined 48h after surgery. (d) A semiquantitative assessment of the lesion was performed by a pathologist in a blinded manner. Every tubular segment visible in the cortex and outer medulla was evaluated. (e) Hematoxylin and eosin (H&E)–stained sections of the kidney are shown at both low and high magnification. The left panel shows a low-magnification photomicrograph encompassing the entire cortex and outer medulla. The right panel shows a high-magnification photomicrograph of a kidney from an adult ischemia–reperfusion (I/R) mouse. d, day. Kidney International 2013 83, 404-413DOI: (10.1038/ki.2012.394) Copyright © 2013 International Society of Nephrology Terms and Conditions

Figure 2 Apoptotic cell death and the level of activated caspase-3 were increased in 4-month-old mice after ischemia–reperfusion (I/R) injury. (a) Representative terminal deoxynucleotidyl transferase–mediated dUTP nick-end labeling (TUNEL) images of the kidney 48h after surgery. Apoptotic cells were quantified by counting TUNEL-positive cells in 10 random high-power fields (HPFs, × 400). (b) Western blotting for the apoptotic marker cleaved caspase-3 in the kidneys 48h following surgery (n=4–6, densitometry). Kidney International 2013 83, 404-413DOI: (10.1038/ki.2012.394) Copyright © 2013 International Society of Nephrology Terms and Conditions

Figure 3 SIRT1 expression in the mouse kidney. (a) Western blotting of SIRT1. The 4-month-old mice showed low protein levels at baseline, which remained unchanged after ischemia–reperfusion (I/R) injury, whereas the younger mice exhibited a twofold induction after I/R injury. (b) SIRT1 mRNA expression in the four groups was examined by quantitative real-time PCR; no difference was observed. (c) Immunohistochemistry for SIRT1 expression in the mouse kidney. SIRT1 expression was found in some newly generated tubular cells (red arrow). Kidney International 2013 83, 404-413DOI: (10.1038/ki.2012.394) Copyright © 2013 International Society of Nephrology Terms and Conditions

Figure 4 Effect of SRT-1720 treatment on ischemia–reperfusion (I/R)-induced renal injury in adult mice. The effects of SRT-1720 on the (a) blood urea nitrogen (BUN) and (b) creatinine levels were determined relative to the effects of vehicle alone. (c) Quantification of the tubular injury score in the cortex and outer medulla (*P<0.05, **P<0.01, ***P<0.001). d, day. Kidney International 2013 83, 404-413DOI: (10.1038/ki.2012.394) Copyright © 2013 International Society of Nephrology Terms and Conditions

Figure 5 Effect of SIRT1 deficiency in kidneys subjected to ischemia–reperfusion (I/R). (a) The SIRT1 mRNA expression levels in the kidneys of wild-type mice (SIRT1+/+) and heterozygous SIRT1 knockout mice (SIRT1+/-) were examined by quantitative real-time PCR. (b) The SIRT1 protein expression levels in the kidneys of SIRT1+/+ mice were examined by western blotting. The (c) blood urea nitrogen (BUN) and (d) serum creatinine (d) levels were determined after I/R. (e) Semiquantitative assessment of the level of tubular lesions (*P<0.05, **P<0.01, ***P<0.001). Kidney International 2013 83, 404-413DOI: (10.1038/ki.2012.394) Copyright © 2013 International Society of Nephrology Terms and Conditions

Figure 6 p53 expression in kidneys 48h after surgery. (a) Quantification of western blotting. (b) The effect of the SIRT1 activator SRT on p53 expression. The effect of the genetic ablation of one allele of SIRT1 on (c) p53 and (d) acetylated p53 expression (**P<0.01, ***P<0.001). Kidney International 2013 83, 404-413DOI: (10.1038/ki.2012.394) Copyright © 2013 International Society of Nephrology Terms and Conditions

Figure 7 Injury-induced apoptosis was associated with p53 levels. Apoptotic cell death was assessed by a terminal deoxynucleotidyl transferase–mediated dUTP nick-end labeling (TUNEL) assay and analysis of activated caspase-3 expression. (a, c) The SIRT1 activator SRT reduced kidney p53 expression; a lower p53 level was associated with reduced apoptosis in the kidney following ischemia–reperfusion (I/R). (b, d) The genetic ablation of one allele of SIRT1 increased p53 expression, which was accompanied by an increased number of apoptotic cells in SIRT1+/- mice (*P<0.05, **P<0.01, ***P<0.001). HPF, high-power field. Kidney International 2013 83, 404-413DOI: (10.1038/ki.2012.394) Copyright © 2013 International Society of Nephrology Terms and Conditions

Figure 8 Tubular cell proliferation after ischemia–reperfusion (I/R) kidney injury. (a) Representative images and analysis of proliferating cell nuclear antigen (PCNA) staining. (b) Western blotting of PCNA expression in the kidney following I/R. (c) The p21 protein level in kidneys after I/R injury. Red boxes in (a) indicate areas that are shown in 400 × magnification on the right panel. HPF, high-power field. Kidney International 2013 83, 404-413DOI: (10.1038/ki.2012.394) Copyright © 2013 International Society of Nephrology Terms and Conditions

Figure 9 Effect of SIRT1 on cell proliferation after ischemia–reperfusion (I/R) injury. Cellular proliferation was assessed by proliferating cell nuclear antigen (PCNA). (a) The effect of the SIRT1 activator SRT on cell proliferation. (b) The effect of the genetic ablation of one allele of SIRT1 on cell proliferation (*P<0.05, ***P<0.001). HPF, high-power field. Kidney International 2013 83, 404-413DOI: (10.1038/ki.2012.394) Copyright © 2013 International Society of Nephrology Terms and Conditions

Figure 10 p21 expression in kidneys 48h after surgery. (a) The effect of the SIRT1 activator SRT on p21 expression. (b) The effect of the genetic ablation of one allele of SIRT1 on p21 expression (**P<0.01, ***P<0.001). Kidney International 2013 83, 404-413DOI: (10.1038/ki.2012.394) Copyright © 2013 International Society of Nephrology Terms and Conditions