Figure 3.

Decreased Skp2 expression is associated with cell senescence of PTECs in DN. (A) Decreased Skp2 mRNA expression was found in PTECs from a type 2 diabetes mellitus (DM) patient (n = 3). (B) HG decreased Skp2 mRNA expression in human PTECs after three days of treatment (n = 4). Skp2 mRNA levels were assessed by quantitative real-time polymerase chain reaction (PCR). (C) HG suppressed Skp2 protein expression in human PTECs after three and four days of treatment (D3: n = 3, D4: n = 3). Skp2 protein levels were assessed by western blot. The expression of Skp2 in the proximal tubule of kidneys of mice (D) and humans (E). The kidney sections of C57BL/6 mice, non-diabetic db/m mice, and diabetic db/db mice, and human donors (UTUC with normal kidney function and normal glomerulus and proximal tubule) and patients with DN were stained with Skp2 (brown). The images quantification was performed using the IHC Profiler Plugin of ImageJ Software. The bar graph represents the mean ± S.E.M. ^* p < 0.05, ^*** p < 0.001 by Student’s t test.