Abstract
Our previous study demonstrated that a large-conductance Ca2+-activated K+ current (BKCa), a voltage-gated TTX-sensitive sodium current (INa.TTX), and an inward rectifier K+ current (IKir) were heterogeneously present in most of human cardiac c-kit+ progenitor cells. The present study was designed to investigate the effects of these ion channels on cell cycling progression and migration of human cardiac c-kit+ progenitor cells with approaches of cell proliferation and mobility assays, siRNA, RT-PCR, Western blots, flow cytometry analysis, etc. It was found that inhibition of BKCa with paxilline, but not INa.TTX with tetrodotoxin, decreased both cell proliferation and migration. Inhibition of IKir with Ba2+ had no effect on cell proliferation, while enhanced cell mobility. Silencing KCa.1.1 reduced cell proliferation by accumulating the cells at G0/G1 phase and decreased cell mobility. Interestingly, silencing Kir2.1 increased the cell migration without affecting cell cycling progression. These results demonstrate the novel information that blockade or silence of BKCa channels, but not INa.TTX channels, decreases cell cycling progression and mobility, whereas inhibition of Kir2.1 channels increases cell mobility without affecting cell cycling progression in human cardiac c-kit+ progenitor cells.
Highlights
In addition to cardiac myocytes and fibroblasts, cardiac stem cells with high growth potential, clonogenicity and pluripotency have been reported in mammalian hearts
Epithelial growth factor (EGF), basic fibroblast growth factor, propidium iodide (PI), lipofectamine 2000, Triton X-100 and Tween 20 were purchased from Invitrogen (Invitrogen, Hong Kong, China). [3H]-thymidine was from GE Healthcare Life Sciences (Hong Kong, China)
It is generally recognized that ion channels play important roles in maintaining physiological homeostasis
Summary
In addition to cardiac myocytes and fibroblasts, cardiac stem cells with high growth potential, clonogenicity and pluripotency have been reported in mammalian hearts. Based on the expression of cell surface markers, cardiac stem cells have been classified into different subgroups, including side population, c-kit+, Sca-1+, Islet 1+, SSEA-1+ [1,2,3,4,5]. Human cardiac c-kit+ progenitor cells are one of the dominant members in human cardiac stem cell family. C-kit, known as CD117 or stem cell growth factor, is the cell surface marker that has been used for stem cell isolation and enrichment from different sources [3, 6,7,8,9]. It has been reported that human cardiac c-kit+ progenitor cells have the capability to differentiate into three cardiac.
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