The Low-dose Ionizing Radiation Stimulates Cell Proliferation via Activation of the MAPK/ERK Pathway in Rat Cultured Mesenchymal Stem Cells
The Low-dose Ionizing Radiation Stimulates Cell Proliferation via Activation of the MAPK/ERK Pathway in Rat Cultured Mesenchymal Stem Cells
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DOI：
10.1269/jrr.10121
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发表时间：
2011-05-01
影响因子：
2
通讯作者：
Li, Wei
中科院分区：
文献类型：
--
作者：
Liang, Xinyue;So, You Ho;Li, Wei
低剂量电离辐射（LDIR）引起的激效效应通常反映在其对细胞增殖的刺激上。已知丝裂原活化蛋白激酶(MAPK)/细胞外信号调节激酶（ERK）途径在细胞生长中起重要作用。因此，本研究旨在探讨LDIR对大鼠间充质干细胞（MSC）增殖及MAPK/ERK信号通路的影响。从6 ~ 8周龄雄性Wistar大鼠骨髓中分离大鼠间充质干细胞并进行体外培养。4-5代内呈指数增长的细胞分别接受20、50、75和100 mGy的低剂量x射线照射，剂量率为100 mGy/min。通过台盼蓝染色和MTT法计数总活细胞数，观察细胞增殖情况。流式细胞术检测细胞周期变化，Western blotting检测MAPK/ERK信号通路激活情况。结果表明，50和75 mGy的LDIR均能显著刺激大鼠间充质干细胞的增殖，其中75 mGy的刺激作用最大。在75 mGy的x射线下，MSCs中S期细胞的比例显著增加。在暴露于75 mGy x射线的细胞中观察到MAPK/ERK信号通路中的几个成员，包括c-Raf， MEK和ERK的激活。为了确定ERK激活在ldir刺激的细胞增殖中的作用，将ldir处理的MSCs与MEK特异性抑制剂U0126预孵育，该抑制剂完全消除了ldir增加的ERK磷酸化和细胞增殖。这些结果表明，在体外条件下，LDIR通过激活MAPK/ERK通路刺激MSC增殖。
Hormesis induced by low-dose ionizing radiation (LDIR) is often mirrored by its stimulation of cell proliferation. The mitogen-activated protein kinases (MAPK)/ extracellular-signal- regulated kinases (ERK) pathway is known to play important roles in cell growth. Therefore, this study was to examine the effects of LDIR on rat mesenchymal stem cell (MSC) proliferation and MAPK/ERK signaling pathway. Rat MSCs were isolated from the bone marrow from 6 to 8-week-old male Wistar rats and cultured in vitro. Exponentially growing cells within 4-5 passages were irradiated with low doses of X-rays at 20, 50, 75 and 100 mGy with a dose rate of 100 mGy/min. Cell proliferation was evaluated by counting total viable cell number with trypan-blue staining and MTT assay. Cell cycle changes were also evaluated by flow cytometry and the activation of MAPK/ERK signaling pathway was assayed by Western blotting. Results showed that LDIR at 50 and 75 mGy significantly stimulated the proliferation of rat MSCs with the most stimulating effect at 75 mGy. There was a significant increase in the proportion of S phase cells in MSCs in response to 75 mGy X-rays. Activation of several members in the MAPK/ERK signaling pathway, including c-Raf, MEK and ERK were observed in the cells exposed to 75 mGy X-rays. To define the role of ERK activation in LDIR-stimulated cell proliferation, LDIR-treated MSCs were pre-incubated with MEK specific inhibitor U0126, which completely abolished LDIR-increased phosphorylation of ERK and cell proliferation. These results suggest that LDIR stimulates MSC proliferations in the in vitro condition via the activation of MAPK/ERK pathway.