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 β-catenin responsive transcription. We hypothesized that LH3 is regulated by TGFβ1/Smad3 signaling and Wnt/β-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-β1 (TGF-β1) was induced A549 cells of pulmonary fibrosis. MTT assays detected cell growth stimulation by TGF-β1; collagen pyridine-crosslinking contents were detected by ELISA kits. Immunofluorescence were used to evaluate expression of key molecules in PLOD3 (LH3), Wnt/β-catenin and TGFβ1/Smad3 pathways.

RESULTS

Our findings suggested that iCRT3 could decrease LH3 protein expression ( < 0.01), Wnt1, β-catenin and p-Smad3 protein expression ( < 0.05). Knock-down PLOD3 could decrease LH3, collagen I gene and protein expression ( < 0.05). These effects were associated with decreasing collagen pyridine-crosslinking production ( < 0.05). However, ovexpression PLOD3 could increase LH3, collagen I gene and protein expression ( < 0.05). The result showed that LH3 plays an important role in collagen post-translational modifications, and it is regulated by Wnt/β-catenin and TGFβ1/Smad3 pathways.

CONCLUSIONS

This study suggests that PLOD3 (LH3) represents a target to prevent pulmonary fibrosis.