Reduced YB-1 expression abolishes the protective effect of aPC in renal IRI. (A)–(F) Renal IRI was induced in WT and heterozygous YB-1 (YB-1+/−) mice. BUN (A), creatinine (Crea) (B), exemplary images of H&E-stained kidney section (C), bar graph summarizing results of pathologic scores (D), representative immunoblots of kidney lysates (E), and bar graph (F) summarizing results of KIM1 protein levels normalized to β-actin in control (Sham) (open bars) and experimental mice without (IRI) (black bars) or with aPC pretreatment (IRI+aPC) (striped bars; aPC: 0.5 mg/kg i.p.). Treatment with aPC normalizes BUN, Crea, tissue injury, and KIM1 expression in WT mice, but not in YB-1+/− mice. (G) and (H) Expression of KIM1 in BUMPT cells stably expressing control (shRNAc) or YB-1-specific (shRNA YB-1) shRNA after HR. Pretreatment of cells with aPC (aPC) (20 nM, 30 minutes before hypoxia) normalizes KIM1 expression in controls, but not in YB-1 knockdown cells exposed to 6 hours of hypoxia (1% O2) followed by 6 hours of reoxygenation (21% O2). Representative immunoblot of KIM1 and β-actin in whole-cell lysates (G) and bar graphs (H) summarizing results. Mean±SD value of at least six mice per group [(A), (B), (D), and (F)] or of at least three independent experiments (H); *P<0.05; **P<0.01 (ANOVA). H&E, hematoxylin and eosin.