title: The calcium-sensing receptor mediates hypoxia-induced proliferation of rat pulmonary artery smooth muscle cells through MEK1/ERK1,2 and PI3K pathways.
abstract: Activation of the calcium-sensing receptor (CaSR) leads to an increase of intracellular calcium concentration and alteration of cellular activities. High level of intracellular calcium is involved in hypoxia-induced proliferation of pulmonary arterial smooth muscle cells (PASMCs). However, whether the CaSR is expressed in PAMSCs and is related to the hypoxia-induced proliferation of PASMCs is unclear. In this study, the expression and distribution of CaSRs were detected by RT-PCR, western blotting and immunofluorescence; the intracellular concentration of free calcium ([Ca(2+) ](i) ) was determined by confocal laser scanning microscopy; cell proliferation was tested using an MTT and BrdU incorporation assay; cell cycle analysis was carried out using a flow cytometric assay; and the expression of proliferating cell nuclear antigen (PCNA), extracellular signal-regulated protein kinase 1,2 (ERK1,2) and AKT were analysed by western blotting. We observed that both CaSR mRNA and protein were expressed in rat PASMCs. Lowering of oxygen from 21% to 2.5% led to increased [Ca(2+) ](i) and CaSR expression. This condition of hypoxia also stimulated PASMCs proliferation accompanying with increased phosphorylation of ERK1,2 and AKT. GdCl(3) (an agonist of CaSR) or NPS2390 (an antagonist of CaSR) amplified or weakened the effect of hypoxia, respectively. PD98059 (a MEK1 inhibitor) or LY294002 (a PI3K inhibitors) decreased the up-regulation of PCNA expression and the increase of the cell proliferation index induced by hypoxia and GdCl(3) in PASMCs. Our results suggest that CaSR is expressed in rat PASMCs, and that CaSR activation through MEK1/ERK1,2 and PI3 kinase pathways is involved in hypoxia-induced proliferation of PASMCs.
authors.affiliation: Department of Pathophysiology, Harbin Medical University, Harbin, China.
authors.forename: Guang-Wei
authors.initials: GW
authors.lastname: Li
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Xing
authors.forename: Shu-Zhi
authors.initials: SZ
authors.lastname: Bai
authors.forename: Jing-Hui
authors.initials: JH
authors.lastname: Hao
authors.forename: Jin
authors.initials: J
authors.lastname: Guo
authors.forename: Hong-Zhu
authors.initials: HZ
authors.lastname: Li
authors.forename: Hong-Xia
authors.initials: HX
authors.lastname: Li
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Zhang
authors.forename: Bao-Feng
authors.initials: BF
authors.lastname: Yang
authors.forename: Ling-Yun
authors.initials: LY
authors.lastname: Wu
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Guang-Dong
authors.initials: GD
authors.lastname: Yang
authors.forename: Chang-Qing
authors.initials: CQ
authors.lastname: Xu
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D015687:Cell Hypoxia; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011651:Pulmonary Artery / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D044169:Receptors, Calcium-Sensing / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D000081082:Phosphoinositide-3 Kinase Inhibitors; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; D044169:Receptors, Calcium-Sensing; C473605:extracellular calcium cation-sensing receptor, rat; D058539:Phosphatidylinositol 3-Kinase; D051057:Proto-Oncogene Proteins c-akt