Geng Jing, Huang Xiaoxi, Li Ying, Xu Xuefeng, Li Shuhong, Jiang Dingyuan, Liang Jiurong, Jiang Dianhua, Wang Chen, Dai Huaping
Department of Respiratory and Critical Care Medicine, Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Beijing Chao-Yang Hospital-Beijing Institute of Respiratory Medicine, Capital Medical University, Beijing, 100020, P.R. China.
Department of Medical Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, 100020, P.R. China.
Respir Res. 2015 Oct 9;16:124. doi: 10.1186/s12931-015-0286-3.
Idiopathic pulmonary fibrosis (IPF) is a fatal disease characterized by fibroblastic foci and progressive scarring of the pulmonary parenchyma. IPF fibroblasts display increased proliferation and enhanced migration and invasion, analogous to cancer cells. This transformation-like phenotype of fibroblasts plays an important role in the development of pulmonary fibrosis, but the mechanism for this is not well understood.
In this study, we compared gene expression profiles in fibrotic lung tissues from IPF patients and normal lung tissues from patients with primary spontaneous pneumothorax using a cDNA microarray to examine the mechanisms involved in the pathogenesis of IPF. In a cDNA microarray, we found that USP13 was decreased in lung tissues from patients with IPF, which was further confirmed by results from immunohistochemistry and western blot assays. Then, we used RNA interference in MRC-5 cells to inhibit USP13 and evaluated its effects by western blot, real-time RT-PCR, bromodeoxyuridine incorporation, and transwell assays. We also used co-immunoprecipitation and immunofluorescence staining to identify the correlation between USP13 and PTEN in IPF.
USP13 expression levels were markedly reduced in fibroblastic foci and primary IPF fibroblast lines. The depletion of USP13 resulted in the transformation of fibroblasts into an aggressive phenotype with enhanced proliferative, migratory, and invasive capacities. Additionally, USP13 interacted with PTEN and mediated PTEN ubiquitination and degradation in lung fibroblasts.
Down-regulation of USP13 mediates PTEN protein loss and fibroblast phenotypic change, and thereby plays a crucial role in IPF pathogenesis.
特发性肺纤维化（IPF）是一种致命性疾病，其特征为成纤维细胞灶和肺实质进行性瘢痕形成。IPF成纤维细胞表现出增殖增加以及迁移和侵袭能力增强，类似于癌细胞。成纤维细胞的这种转化样表型在肺纤维化的发展中起重要作用，但其机制尚不清楚。
在本研究中，我们使用cDNA微阵列比较了IPF患者纤维化肺组织和原发性自发性气胸患者正常肺组织中的基因表达谱，以研究IPF发病机制中涉及的机制。在cDNA微阵列中，我们发现IPF患者肺组织中USP13表达降低，免疫组化和蛋白质印迹分析结果进一步证实了这一点。然后，我们在MRC-5细胞中使用RNA干扰抑制USP13，并通过蛋白质印迹、实时RT-PCR、溴脱氧尿苷掺入和Transwell分析评估其作用。我们还使用免疫共沉淀和免疫荧光染色来确定IPF中USP13与PTEN之间的相关性。
USP13表达水平在成纤维细胞灶和原发性IPF成纤维细胞系中显著降低。USP13的缺失导致成纤维细胞转变为具有增强的增殖、迁移和侵袭能力的侵袭性表型。此外，USP13与PTEN相互作用，并介导肺成纤维细胞中PTEN的泛素化和降解。
USP13的下调介导PTEN蛋白丢失和成纤维细胞表型改变，从而在IPF发病机制中起关键作用。
