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- Title
TGF-beta1 reduces Wilms' tumor suppressor gene expression in podocytes.
- Authors
Sakairi, Toru; Abe, Yoshifusa; Kopp, Jeffrey B.
- Abstract
Background. Wilms' tumor suppressor gene (WT1) is essential for normal podocyte function, and transforming growth factor (TGF)-beta contributes to focal segmental glomerulosclerosis (FSGS). We aimed to address whether TGF-beta affects WT1 expression in podocytes.Methods. A human podocyte cell line treated with TGF-beta1 and kidneys in Alb/TGF-beta1-transgenic mice were analyzed for WT1 expression.Results. In cultured podocytes, TGF-beta1 reduced WT1 protein expression determined by western blotting beginning at 8 h and decreased WT1 messenger RNA (mRNA) expression measured by quantitative reverse transcription–polymerase chain reaction beginning at 3 h. Knockdown of Smad4 by small hairpin (sh) RNA partially rescued the TGF-beta1-induced reduction of both WT1 protein and mRNA expressions in the cultured podocytes. TGF-beta1 did not alter luciferase activity of the reporter construct for a human WT1 promoter but reduced that for a human WT1 5′ enhancer construct, suggesting that TGF-beta1 may regulate WT1 expression by altering the 5′ enhancer activity. In the transgenic mice, WT1 protein expression in podocytes was decreased at 1 and 3 weeks of age, while glomeruloclerosis developed after 3 weeks.Conclusion. TGF-beta1 reduces WT1 expression in cultured human podocytes and podocytes in mice before overt glomerulosclerosis begins. The effects are at least partially Smad4 dependent. Our findings identify a novel pathway linking TGF-beta1 to podocyte injury and FSGS. The WT1 reduction may be a useful marker for early podocyte injury.
- Subjects
FOCAL segmental glomerulosclerosis; TRANSFORMING growth factors-beta; NEPHROBLASTOMA; TUMOR suppressor genes; GENE expression; MESSENGER RNA; WESTERN immunoblotting; TRANSGENIC mice
- Publication
Nephrology Dialysis Transplantation, 2011, Vol 26, Issue 9, p2746
- ISSN
0931-0509
- Publication type
Article
- DOI
10.1093/ndt/gfr061