Lysyl hydroxylase 3 increases collagen deposition and promotes pulmonary fibrosis by activating TGFβ1/Smad3 and Wnt/β-catenin pathways

Introduction: Lysyl hydroxylase 3 (LH3) is a collagen post-translational modifying enzyme; it is abnormally activated during the formation of collagen cross-links. iCRT3 is an inhibitor of both Wnt and beta-catenin responsive transcription. We hypothesized that LH3 is regulated by TGFbeta1/Smad3 signaling and Wnt/beta-catenin signaling pathways. Some evidence suggested that there is complicated cross-talk between the two signal pathways in the genesis of pulmonary fibrosis. Material and methods: The normal culturing human lung cancer cell line A549 was derived from pulmonary epithelial cells. Transforming growth factor-beta1 (TGF-beta1) was induced A549 cells of pulmonary fibrosis. MTT assays detected cell growth stimulation by TGF-beta1; collagen pyridine-crosslinking contents were detected by ELISA kits. Immunofluorescence were used to evaluate expression of key molecules in PLOD3 (LH3), Wnt/beta-catenin and TGFbeta1/Smad3 pathways. Results: Our findings suggested that iCRT3 could decrease LH3 protein expression (p < 0.01), Wnt1, beta-catenin and p-Smad3 protein expression (p < 0.05). Knock-down PLOD3 could decrease LH3, collagen I gene and protein expression (p < 0.05). These effects were associated with decreasing collagen pyridine-crosslinking production (p < 0.05). However, ovexpression PLOD3 could increase LH3, collagen I gene and protein expression (p < 0.05). The result showed that LH3 plays an important role in collagen post-translational modifications, and it is regulated by Wnt/beta-catenin and TGFbeta1/Smad3 pathways. Conclusions: This study suggests that PLOD3 (LH3) represents a target to prevent pulmonary fibrosis.