Fig. 4.

Chronic phosphate restriction reduces kidney markers of collagen deposition and myofibroblast activation in pcy/pcy mice. A: picrosirius red staining of representative sagittal kidney sections from pcy/pcy mice fed either the control or phosphate-restricted (Phos-rest) diet (scale bars = 50 µm). B: fibrosis scoring of picrosirius red-stained kidneys (n ≥ 9 per group); no statistically significant difference in kidney fibrosis scoring was observed. C–E: quantitative RT-PCR to assess gene expression of key mediators of kidney fibrosis, including collagen type I-α₁ (Col1α1) (C), transforming growth factor-β (TGFβ) (D), and α-smooth muscle actin (α-SMA; Acta2) (E), respectively. Col1α1 and Acta2 gene expression was significantly lower in kidneys from mice fed the phosphate-restricted diet, while TGFβ expression demonstrated a wide pattern of distribution with no statistically significant difference between groups (**P < 0.01 by Student’s t test; n ≥ 8 per group). F–H: quantification of kidney protein expression from Western blots for Col1α1 (F), phosphorylated (p-)SMAD3 (G), and α-SMA (H). Protein expression for all three of these targets was significantly lower in phosphate-restricted mice (*P < 0.05, **P < 0.01 by Student’s t-test; n = 5 per group. I: image of Western blots with associated Ponceau S stain to demonstrate total protein loading per lane.