Transforming growth factor-β1/Smad3-independent epithelial–mesenchymal transition in type I collagen glomerulopathy

Figures & data

Figure 1 Col1a2-deficient (−/−) glomeruli demonstrate PEC EMT at 1 month of age.

Notes: Immunostaining of 1-week and 1-month +/+ and −/− kidneys with α-sma, desmin, vimentin, and PCNA. Immunostaining at 1 week of age demonstrates glomerular α-sma (A, B), desmin (E, F), vimentin (I, J), and PCNA (M, N) in both +/+ and −/− within the same regions, consistent with developmental expression. α-sma is seen in the vascular pole of +/+ glomeruli (C), in contrast to −/− glomeruli (D), which show α-sma staining in PECs and in the mesangium. At 1 month of age,+/+ kidneys demonstrate desmin (G) and vimentin (K) staining in podocytes, while −/− glomeruli demonstrate intense desmin (H) and vimentin (L) staining in PECs and a redistribution of positive staining in podocytes to the periphery. PCNA-positive staining was seen in +/+(O) and −/− (P) glomeruli at 1 month of age; however, there was a decrease in intraglomerular staining and an increase in PEC positivity as compared to +/+ glomeruli.
Abbreviations: EMT, epithelial–mesenchymal transition; PCNA, proliferating cell nuclear antigen; PEC, parietal epithelial cell.

Figure 2 TGF-β1 steady-state mRNA and protein are not upregulated in homotrimeric type I collagen glomerulopathy.

Notes: (A) Quantitative RT-PCR demonstrates that TGF-β1 copy number is not significantly different in glomerular isolates of 1-month-old wildtype (+/+) and Col1a2-deficient (−/−) mice. However, by 3 months of age the TGF-β1 copy number is reduced in Col1a2-deficient glomerular isolates as compared to wildtype glomerular isolates (*p≤ 0.05). (B) Although protein immunoassay demonstrated no significant difference in picograms of TGF-β1 protein per glomerulus in wildtype (+/+) and Col1a2-deficient (−/−) glomeruli at both 1 month and 3 months of age, Col1a2-deficient (−/−) glomeruli at 1 month of age exhibited a greater variability in TGF-β1 protein per glomerulus.
Abbreviations: TGF-β1, tumor growth factor β1; RT-PCR, reverse transcriptase-polymerase chain reaction.

Figure 3 Col1a2-deficient/Smad3-deficient glomeruli demonstrate homotrimeric type I collagen deposition.

Notes: (A) 1-month Col1a2-deficient glomerulus demonstrating fibrillar collagen deposition upon staining with picrosirius red. (B) 1-month Smad3-deficient glomeruli demonstrating similar intensity of picrosirius red staining. Mean lesion scores for 1-month Col1a2-deficient/Smad3-deficient animals are provided in the table and demonstrate no significant differences.