Role of MEK1/ERK1, 2 pathways in the calcium-sensing receptor mediation of hypoxia-induced proliferation of rat pulmonary artery smooth muscle cells

Abstract

To explore the cell signal transduction pathway of calcium-sensing receptor (CaSR) mediated hypoxia-induced proliferation of rat pulmonary artery smooth muscle cells (PASMCs). The expressions of proliferating cell nuclear antigen (PCNA) and extracellular signal-regulated protein kinase 1, 2 (ERK1, 2) were analyzed by Western blot. Cell proliferation was tested by a 5-bromo-2-deoxyuridine (BrdU) incorporation assay. Cell cycle and proliferation index (PI) were analyzed by flow cytometry. Hypoxia significantly increased the expression of PCNA (0.528 ± 0.028), p-ERK1, 2 (1.12 ± 0.05, 0.91 ± 0.06), BrdU incorporation (143.3 ± 4.2) and cell proliferation index (12.5 ± 0.9) (all P < 0.05, versus control group, 0.243 ± 0.025, 0.47 ± 0.03, 0.40 ± 0.03, 100.0 ± 5.4, 7.5 ± 1.2). Gadolinium chloride (GdCl3, a CaSR agonist) amplified the effect of hypoxia (0.770 ± 0.039, 1.50 ± 0.06, 1.61 ± 0.05, 187.4 ± 3.9, 19.8 ± 0.6, all P < 0.05). PD98059 (a MEK1 inhibitor) decreased the up-regulation of PCNA expression, BrdU incorporation and the increase of cell proliferation index induced by hypoxia and GdCl3 in PASMCs (0.441 ± 0.020, 0.71 ± 0.07, 0.72 ± 0.06, 115.5 ± 4.0, 9.3 ± 1.1, all P < 0.05). Calcium-sensing receptor mediates hypoxia-induced proliferation of rat pulmonary artery smooth muscle cells through ERK1, 2 pathways.