Elevated protein arginine methyltransferase 1 expression regulates fibroblast motility in pulmonary fibrosis

• Expression of PRMT1 was elevated in IPF lung fibroblasts and IPF lungs.
• PRMT1 protein level was elevated in lungs of bleomycin-treated mice.
• IL-4 enhanced PRMT1 expression and migration of human lung fibroblasts.
• PRMT1 knockdown or inhibition of PRMT activity reduced IPF fibroblast motility.

ObjectiveIdiopathic pulmonary fibrosis (IPF) is a devastating disease characterized by epithelial cell injury, fibroblast activation and excessive extracellular matrix deposition. Although protein arginine methyltransferase 1 (PRMT1) was found to regulate cell proliferation, differentiation and migration, its role in the development/progression of IPF has not yet been described.ResultsExpression of PRMT1 was elevated in lung homogenates from IPF patients. Significant upregulation of PRMT1 expression was also observed in the lungs of bleomycin-treated mice. Immunohistochemical analysis revealed PRMT1-positive staining in fibroblasts/myofibroblasts and alveolar type II cells of IPF lungs and in fibrotic lesions of bleomycin-injured lungs. Fibroblasts isolated from IPF lungs demonstrated increased PRMT1 expression. Interleukin-4 (IL-4), a profibrotic cytokine, enhanced the expression of PRMT1 and the migration of donor and IPF fibroblasts. Interference with the expression or the activity of PRMT1 diminished the migration of the cells in response to IL-4. Strikingly, even though the incubation of donor and IPF fibroblasts with IL-4 did not affect their proliferation, depletion, but not blockage of PRMT1 activity suppressed cell growth.ConclusionsPRMT1 can contribute to the development of pulmonary fibrosis by regulating fibroblast activities. Thus, interference with its expression and/or activity may provide a novel therapeutic option for patients with IPF.