Mitogenic modulation of Ca2+ -activated K+ channels in proliferating A7r5 vascular smooth muscle cells

摘要: 1 Modulation of Ca2+-activated K+ channels (KCa) has been implicated in the control proliferation vascular smooth muscle cells (VSMC) and other cell types. In present study, we investigated underlying signal transduction mechanisms leading to mitogen-induced alterations expression pattern intermediate-conductance KCa VSMC. 2 Regulation IKCa/rKCa3.1 BKCa/rKCa1.1 A7r5 cells, a line derived from rat aortic VSMC, was by patch-clamp technique, quantitative RT–PCR, immunoblotting procedures, siRNA strategy. 3 PDGF stimulation for 2 48 h induced an 11- 3.5-fold increase rKCa3.1 transcript levels resulting four- seven-fold IKCa currents after 4 48 h, respectively. Upregulation channel function required phosphorylation extracellular signal-regulated kinases (ERK1/2) Ca2+ mobilization, but not activation p38-MAP kinase, c-Jun NH(2)-terminal protein kinase C, calcium-calmodulin II Src kinases. 4 In contrast rKCa3.1, mRNA functions were decreased half following mitogenic stimulation. Downregulation rKCa1.1 did require ERK1/2 or mobilization. 5 In vitro-proliferation assay, knockdown completely abolished functional mitogenesis. 6 Mitogen-induced upregulation is mediated via Raf/MEK- ERK-signaling cascade Ca2+-dependent manner. promotes VSMC may thus represent pharmacological target cardiovascular disease states characterized abnormal proliferation. British Journal Pharmacology (2006) 148, 909–917. doi:10.1038/sj.bjp.0706793