Wilms tumor 1 impairs apoptotic clearance of fibroblasts in distal fibrotic lung lesions
Harshavardhana H. Ediga, … , Francis X. McCormack, Satish K. Madala
Harshavardhana H. Ediga, … , Francis X. McCormack, Satish K. Madala
Published June 10, 2025
Citation Information: J Clin Invest. 2025;135(15):e188819. https://doi.org/10.1172/JCI188819.
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Research Article Inflammation Pulmonology

Wilms tumor 1 impairs apoptotic clearance of fibroblasts in distal fibrotic lung lesions

Abstract

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease characterized by impaired fibroblast clearance and excessive extracellular matrix (ECM) protein production. Wilms tumor 1 (WT1), a transcription factor, is selectively upregulated in IPF fibroblasts. However, the mechanisms by which WT1 contributes to fibroblast accumulation and ECM production remain unknown. Here, we investigated the heterogeneity of WT1-expressing mesenchymal cells using single-nucleus RNA-Seq of distal lung tissues from patients with IPF and control donors. WT1 was selectively upregulated in a subset of IPF fibroblasts that coexpressed several prosurvival and ECM genes. The results of both loss-of-function and gain-of-function studies were consistent with a role for WT1 as a positive regulator of prosurvival genes to impair apoptotic clearance and promote ECM production. Fibroblast-specific overexpression of WT1 augmented fibroproliferation, myofibroblast accumulation, and ECM production during bleomycin-induced pulmonary fibrosis in young and aged mice. Together, these findings suggest that targeting WT1 is a promising strategy for attenuating fibroblast expansion and ECM production during fibrogenesis.

Authors

Harshavardhana H. Ediga, Chanukya P. Vemulapalli, Vishwaraj Sontake, Pradeep K. Patel, Hikaru Miyazaki, Dimitry Popov, Martin B. Jensen, Anil G. Jegga, Steven K. Huang, Christoph Englert, Andreas Schedl, Nishant Gupta, Francis X. McCormack, Satish K. Madala

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Figure 4

Loss of WT1 attenuates the expression of genes involved in fibroblast survival and ECM production.

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Loss of WT1 attenuates the expression of genes involved in fibroblast su...
(A) Quantification of both proapoptotic (BAX and BIM) and antiapoptotic (BCL2-L2, BCL-XL, and BCL3) gene transcripts using RT-PCR in IPF fibroblasts treated with either control or WT1 specific siRNA for 72 hours. Multiple unpaired, 2-tailed Student’s t tests were used for comparisons (n = 3/group). *P < 0.05, **P < 0.01, and ***P < 0.001, by multiple unpaired, 2-tailed Student’s t tests. (B) Quantification of collagen gene transcripts (COL1A1 and COL6A3) using RT-PCR in IPF fibroblasts treated with either control or WT1-specific siRNA for 72 hours (n = 3/group). *P < 0.05, and ***P < 0.001, by multiple unpaired, 2-tailed Student’s t tests. (C and D) IPF fibroblasts were treated with either control or WT1-specific siRNA for 72 hours, and cell lysates were immunoblotted with antibodies against WT1, FAS, BCL-XL, or GAPDH. Quantification of WT1, FAS, and BCL-XL protein levels normalized to GAPDH (n = 3/group). *P < 0.05, by 2-tailed Student’s t test. (E–I) IPF fibroblasts were treated with either control or WT1-specific siRNA for 72 hours, and cell lysates were immunoblotted with antibodies against COL1α1, FN1, ELN, αSMA, or GAPDH. Quantification of COL1α1, FN1, ELN, and αSMA protein levels normalized to GAPDH (n = 3/group). *P < 0.05 and ***P < 0.001, by 2-tailed Student’s t test. (J) IPF fibroblasts were treated with either control or WT1-specific siRNA for 48 hours, followed by anti-Fas antibody treatment for another 24 hours, and cells were stained to quantify total TUNEL+ cells. Representative confocal images were obtained at ×20 original magnification. Scale bars: 100 μm. (K) The percentage of TUNEL+ (red color) cells in the total DAPI-stained (blue color) cells was quantified using MetaMorph image analysis. One-way ANOVA was used for comparisons (n = 3/group). *P < 0.05, **P < 0.01, and ****P < 0.0001, by 1-way ANOVA for comparisons.