TGF-ß1 increases permeability of ciliated airway epithelia via redistribution of claudin 3 from tight junction into cell nuclei.

TGF-ß1 is a major mediator of airway tissue remodelling during atopic asthma and affects tight junctions (TJs) of airway epithelia. However, its impact on TJs of ciliated epithelia is sparsely investigated. Herein we elaborated effects of TGF-ß1 on TJs of primary human bronchial epithelial cells. We demonstrate that TGF-ß1 activates TGF-ß1 receptors TGFBR1 and TGFBR2 resulting in ALK5-mediated phosphorylation of SMAD2. We observed that TGFBR1 and -R2 localize specifically on motile cilia. TGF-ß1 activated accumulation of phosphorylated SMAD2 (pSMAD2-C) at centrioles of motile cilia and at cell nuclei. This triggered an increase in paracellular permeability via cellular redistribution of claudin 3 (CLDN3) from TJs into cell nuclei followed by disruption of epithelial integrity and formation of epithelial lesions. Only ciliated cells express TGF-ß1 receptors; however, nuclear accumulations of pSMAD2-C and CLDN3 redistribution were observed with similar time course in ciliated and non-ciliated cells. In summary, we demonstrate a role of motile cilia in TGF-ß1 sensing and showed that TGF-ß1 disturbs TJ permeability of conductive airway epithelia by redistributing CLDN3 from TJs into cell nuclei. We conclude that the observed effects contribute to loss of epithelial integrity during atopic asthma.

Pentachloropseudilin Inhibits Transforming Growth Factor-ß (TGF-ß) Activity by Accelerating Cell-Surface Type†II TGF-ß Receptor Turnover in Target Cells.

Pentachloropseudilin (PClP) is a chlorinated phenylpyrrole compound that was first isolated from Actinoplanes (ATCC33002), and its structure has been confirmed by chemical synthesis. PClP shows broad antimicrobial activity against Gram-negative and Gram-positive bacteria, protozoa, fungi, and yeast. In mammalian cells, PClP is known to act as a reversible and allosteric inhibitor of myosin 1c (Myo1c). Herein, we report that PCIP is a potent inhibitor of transforming growth factor-ß (TGF-ß)-stimulated signaling. PCIP inhibits TGF-ß-stimulated Smad2/3 phosphorylation and plasminogen activator inhibitor-1 (PAI-1) promoter activation with an IC50 of 0.1 µm in target cells (A549, HepG2, and Mv1Lu cells). In addition, PCIP attenuates TGF-ß-stimulated expression of vimentin, N-cadherin, and fibronectin and, thus, blocks TGF-ß-induced epithelial to mesenchymal transition (EMT) in these cells. Furthermore, cell-surface labeling and immunoblot analysis indicates that PCIP suppresses TGF-ß-stimulated cellular responses by attenuating cell-surface expression of the type II TGF-ß receptor through accelerating caveolae-mediated internalization followed by primarily lysosome-dependent degradation of the receptor, as demonstrated by sucrose density gradient analysis and immune fluorescence staining.

Transforming growth factor-ß1 (TGF-ß1) induces mouse precartilaginous stem cell differentiation through TGFRII-CK1ε-ß-catenin signalling.

Precartilaginous stem cells (PSCs) are adult stem cells which could self-renew or differentiate into chondrocytes to promote bone growth. In this study, we aimed to understand the role of transforming growth factor-ß1 (TGF-ß1) in precartilaginous stem cell (PSC) differentiation and to study the mechanisms that underlie this role. We purified PSCs from the neonatal murine perichondrial mesenchyme using immunomagnetic beads, and primary cultured them. Their phenotype was confirmed by the PSC marker fibroblast growth factor receptor-3 (FGFR-3) overexpression. TGF-ß1 was added to induce PSCs differentiation. TGF-ß1 increased mRNA expression of chondrogenesis-related genes (collagen type II, Sox 9 and aggrecan) in the cultured PSCs. This was abolished by TGF-ß receptor II (TGFRII) and Casein kinase 1 epsilon (CK1ε) lentiviral shRNA depletion. Meanwhile, we found that TGF-ß1 induced CK1ε activation, glycogen synthase kinase-3ß (GSK3ß) phosphorylation and ß-catenin nuclear translocation in the mouse PSCs, which was almost completely blocked by TGFRII and CK1ε shRNA knockdown. Based on these results, we suggest that TGF-ß1 induces CK1ε activation to promote ß-catenin nuclear accumulation, which then regulates chondrogenesis-related gene transcription to eventually promote mouse PSC differentiation.

Methylation silencing of TGF-ß receptor type II is involved in malignant transformation of esophageal squamous cell carcinoma.

BACKGROUND: Although massive studies have been conducted to investigate the mechanisms of esophageal squamous cell carcinoma (ESCC) carcinogenesis, the understanding of molecular alterations during the malignant transformation of epithelial dysplasia is still lacking, especially regarding epigenetic changes. RESULTS: To better characterize the methylation changes during the malignant transformation of epithelial dysplasia, a whole-genome bisulfite sequencing analysis was performed on a series of tumor, dysplastic, and non-neoplastic epithelial tissue samples from esophageal squamous cell carcinoma (ESCC) patients. Promoter hypermethylation in TGF-ß receptor type II (TGFBR2), an important mediator of TGF-ß signaling, was identified. Further, we evaluated the methylation and expression of TGFBR2 in tumor samples through The Cancer Genome Atlas multiplatform data as well as immunohistochemistry. Moreover, treatment of ESCC cell lines with5-Aza-2'-deoxycytidine, a DNA methyltransferase inhibitor, reactivated the expression of TGFBR2. The lentiviral mediating the overexpression of TGFBR2 inhibited the proliferation of ESCC cell line by inducing cell cycle G2/M arrest. Furthermore, the overexpression of TGFBR2 inhibited the tumor growth obviously in vivo. CONCLUSIONS: The characterization of methylation silencing of TGFBR2 in ESCC will enable us to further explore whether this epigenetic change could be considered as a predictor of malignant transformation in esophageal epithelial dysplasia and whether use of a TGFBR2 agonist may lead to a new therapeutic strategy in patients with ESCC.