Mechanisms of focal adhesion kinase in the proliferation of human pulmonary artery smooth cells under hypoxia

Abstract

To explore the mechanisms of focal adhesion kinase (FAK) in the proliferation of human pulmonary artery smooth muscle cells (HPASMCs) under hypoxia. Cultured HPASMCs were passively transfected with FAK oligonucleotides (ODNS) and under normoxia or hypoxia condition. They were divided into four groups: normoxia without fibronectin (FN), normoxia with FN, hypoxia without FN, hypoxia with FN in vitro respectively. Cytoplasmic FAK, Grb2 and paxillin were observed simultaneously by immunoprecipitation and Western blot. In addition, the expressions of cytoplasmic FAK, Grb2 and paxillin were detected by immunocytochemical staining. Immunoprecipitation and Western blot demonstrated that cytoplasmic expressions of FAK, Grb2 and paxillin in HPASMCs increased in hypoxia with FN from 43.4 ± 1.4, 69.7 ± 1.9, 59.3 ± 1.6 to 35.7 ± 1.2, 48.7 ± 1.3, 33.2 ± 1.8 at 1.5 h (all P < 0.05), from 41.3 ± 1.3, 71.3 ± 1.5, 59.4 ± 1.8 to 41.3 ± 1.3, 50.2 ± 1.7, 38.9 ± 1.9 at 24 h respectively (P < 0.01, P < 0.05, P < 0.05). Immunocytochemistry staining showed that the cytoplasmic expressions of FAK, Grb2 and paxillin were enhanced in hypoxia with FN versus normoxia with FN. There were significant differences. Hypoxia can induce the activation of cytoplasmic FAK, Grb2 and paxillin so as to regulate the migration, survival and proliferation of HPASMCs.