Overexpression of human KCNA5 increases IK V and enhances apoptosis.
ABSTRACT Apoptotic cell shrinkage, an early hallmark of apoptosis, is regulated by K+ efflux and K+ channel activity. Inhibited apoptosis and downregulated K+ channels in pulmonary artery smooth muscle cells (PASMC) have been implicated in development of pulmonary vascular medial hypertrophy and pulmonary hypertension. The objective of this study was to test the hypothesis that overexpression of KCNA5, which encodes a delayed-rectifier voltage-gated K+ (Kv) channel, increases K+ currents and enhances apoptosis. Transient transfection of KCNA5 caused 25- to 34-fold increase in KCNA5 channel protein level and 24- to 29-fold increase in Kv channel current (I(K(V))) at +60 mV in COS-7 and rat PASMC, respectively. In KCNA5-transfected COS-7 cells, staurosporine (ST)-mediated increases in caspase-3 activity and the percentage of cells undergoing apoptosis were both enhanced, whereas basal apoptosis (without ST stimulation) was unchanged compared with cells transfected with an empty vector. In rat PASMC, however, transfection of KCNA5 alone caused marked increase in basal apoptosis, in addition to enhancing ST-mediated apoptosis. Furthermore, ST-induced apoptotic cell shrinkage was significantly accelerated in COS-7 cells and rat PASMC transfected with KCNA5, and blockade of KCNA5 channels with 4-aminopyridine (4-AP) reduced K+ currents through KCNA5 channels and inhibited ST-induced apoptosis in KCNA5-transfected COS-7 cells. Overexpression of the human KCNA5 gene increases K+ currents (i.e., K+ efflux or loss), accelerates apoptotic volume decrease (AVD), increases caspase-3 activity, and induces apoptosis. Induction of apoptosis in PASMC by KCNA5 gene transfer may serve as an important strategy for preventing the progression of pulmonary vascular wall thickening and for treating patients with idiopathic pulmonary arterial hypertension (IPAH).
- Frontiers in Bioscience 01/2008; Volume(13):3825. · 4.25 Impact Factor
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ABSTRACT: Hypertrophic scar (HS) is an abnormally proliferative disorder characterized by excessive proliferation of fibroblasts and redundant deposition of extracellular matrix. An unbalance between fibroblast proliferation and apoptosis has been assumed to play an important role in HS formation. To explore the regulative effects of dracorhodin perchlorate (Dp), one of the derivants of dracorhodin that is a major constituent in the traditional Chinese medicine, on primary fibroblasts from human skin hypertrophic scars, 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay and flow cytometric analysis were respectively used to evaluate the inhibitory effect of Dp on the cells and to determine cell cycle distribution. Additionally, cellular apoptosis was separately detected with Hoechst 33258 staining and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay. The expression levels of caspase-3 mRNA and protein were respectively measured with reverse transcription-polymerase chain reaction and western blot analysis, and caspase-3 activity was determined using a colorimetric assay kit. The results showed that Dp significantly inhibited cell growth, and induced apoptosis in fibroblasts in a dose-and time-dependent manner, arresting cell cycle at G1 phase. Additionally, Dp slightly up-regulated caspase-3 mRNA expression in fibroblasts, but significantly down-regulated caspase-3 protein expression in a dose- and time- dependent manner, and concurrently elevated caspase-3 activity. Taken together, these data indicated that Dp could effectively inhibit cell proliferation, and induced cell cycle arrest and apoptosis in fibroblasts, at least partially via modulation of caspase-3 expression and its activity, which suggests that Dp is an effective and potential candidate to develop for HS treatment.European journal of pharmacology 04/2014; · 2.59 Impact Factor
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ABSTRACT: Spanning the plasmalemmal membrane of all cells are many ion channels, exchangers, and transporters, all interacting to control vascular tone via the regulation of cytosolic Ca2+ concentration. Among these channels are voltage-gated K+, Na+, and Ca2+ channels, voltage-independent Ca2+ and nonselective cation channels, Cl− channels, and ligand-gated ion (K+, Ca2+, and Na+) channels. Plasmalemmal Ca2+–Mg2+ -ATPase (or Ca2+ pump) and Na+–K+ -ATPase (or Na+ pump) and an array of exchangers – the Na+–Ca2+ exchanger (NCX), Na+–H+ exchanger (NHE), and Na+–Mg2+ exchanger – all coexist to maintain ionic homeostasis in the cell. Comprehensive studies of ion channel function under both normal and pathophysiological conditions have been made possible owing to the development of cell isolation and electrophysiological techniques. This chapter introduces the ion channels and transporters present in the pulmonary vasculature (focusing on their expression and function) and discusses the potential pathogenic role of ion channels and transporters in the development of pulmonary hypertension.01/2011;