Protein Expression Profile in Rat Silicosis Model Reveals Upregulation of PTPN2 and Its Inhibitory Effect on Epithelial-Mesenchymal Transition by Dephosphorylation of STAT3.

Ying Zhu,Jingxin Yao,Yuxia Duan,Fang Yang,Heliang Liu,Qiyun Cheng,Xuemin Gao,Hong Xu,Shumin Li,Juxiang Yuan

doi:10.3390/ijms21041189

Abstract

Silicosis is a chronic occupational lung disease caused by long-term inhalation of crystalline silica particulates. We created a rat model that closely approximates the exposure and development of silicosis in humans. Isobaric tags for relative and absolute quantitation (iTRAQ) technologies we used to identify proteins differentially expressed in activated rat lung tissue. We constructed three lentiviral knockdown vectors and an overexpression vector for the protein tyrosine phosphatase non-receptor type 2 (PTPN2) gene to achieve stable long-term expression. A total of 471 proteins were differentially expressed in the silicosis group compared with controls. Twenty upregulated, and eight downregulated proteins exhibited a ≥1.5-fold change relative to controls. We next found that the PTPN2, Factor B, and VRK1 concentrations in silicotic rats silicosis and SiO2-stimulated MLE-12 cells were significantly higher than control groups. More importantly, we found that overexpression of PTPN2 simultaneously decreased the expression of phospho–signal transducer and activator of transcription 3 (p-STAT3) and Vimentin, while increasing E-cadherin expression. The opposite pattern was observed for PTPN2-gene silencing. We identified three proteins with substantially enhanced expression in silicosis. Our study also showed that PTPN2 can inhibit epithelial-mesenchymal transition by dephosphorylating STAT3 in silicosis fibrosis.

Highlights

Silicosis is a highly prevalent occupational condition that is caused by chronic inhalation of crystalline silica particulates into the distal air spaces of the lung
Accumulating evidence indicates that silica particles activate macrophages and epithelial cells, causing them to release copious amounts of oxidants and cytokines, which leads to fibroblast proliferation, epithelial-mesenchymal transition (EMT), deposition of the extracellular matrix, and fibrosis [3,4,5]
Many proteins and small molecules are involved in the development of silicosis fibrosis, and they are the first to change in affected lung tissue

Summary

Introduction

Silicosis is a highly prevalent occupational condition that is caused by chronic inhalation of crystalline silica particulates (aerodynamic diameter < 5 μm) into the distal air spaces of the lung. In developing countries, such as China, the control and prevention of silicosis remain unachievable in a short time, requiring significant progress going forward [1]. The core principle of iTRAQ is polypeptide labeling and quantification, which resolves quantitative changes in protein intensities with high sensitivity, accuracy, and reproducibility [7]; it is widely used in protein biomarker validation to support preclinical and clinical studies [8].In a previous iTRAQ technology study of silicosis, researchers employed SiO2 to stimulate raw264.7 cells [9], and TGF-β to stimulate lung fibroblasts [10]. Nobody employed iTRAQ technology to screen the differential proteins in lung tissue of rats exposed to dynamically silica

Methods

Results

Conclusion