Xu Z D, Li H S, Wang S, He W F, Wu J, Luo G X
Institute of Burn Research, Southwest Hospital, State Key Laboratory of Trauma, Burns and Combined Injury, the Third Military Medical University, Chongqing 400038, China.
Zhonghua Shao Shang Za Zhi. 2017 May 20;33(5):287-294. doi: 10.3760/cma.j.issn.1009-2587.2017.05.007.
To explore the effects of hypoxia inducible factor-1α (HIF-1α) on P311 and its influence on the migration of murine epidermal stem cells (ESCs) under hypoxia in vitro. Two kinds of murine ESCs were isolated and obtained from 15 neonatal wild-type C57BL/6J mice and 5 congeneric source P311 gene knock-out mice, respectively. The first passage of cells were used in the following experiments after morphologic observation and detection of expression of cell surface markers CD71 and CD49f with flow cytometer. (1) After cell scratch assay, according to the random number table (the same dividing method below), ESCs of P311 gene knock-out mice were divided into normoxia group (cells were cultured with complete medium in normoxic carbon dioxide incubator, and the subsequent normoxic treatments were the same) and hypoxia group (cells were cultured in hypoxic carbon dioxide incubator containing 1% oxygen, and the subsequent hypoxic treatments were the same), with 12 inserts in each group. ESCs of wild-type mice were divided into normoxia group, pure hypoxia group, dimethyl sulfoxide (DMSO) control group (2 μL DMSO solvent was added for 1 h of normoxia treatment before hypoxia treatment), HIF-1α inhibitor group (cells were treated with 11 μmol/L HIF-1 inhibitor of 2 μL under normoxia condition for 1 h before hypoxia treatment), HIF-1α stabilizer group (the cells were treated with 2 μmol/L FG-4592 of 2 μL under normoxia condition for 1 h before hypoxia treatment), with 12 inserts in each group. Three inserts of each time point in each group were adopted respectively to measure the residual width of scratch under inverted phase contrast microscope at post scratch hour (PSH) 0 (immediately), 12, 24, and 48. (2) After hypoxia treatment, the protein level of HIF-1α in ESCs of wild-type mice was detected by Western blotting at post hypoxia hour (PHH) 0, 12, 24, and 48. (3) ESCs of wild-type mice were divided into pure hypoxia group, DMSO control group, HIF-1α inhibitor group, and HIF-1α stabilizer group as that of experiment (1) with the same treatment. The mRNA expression of P311 and expression of P311 in ESCs were determined by real-time fluorescent quantitative reverse transcription polymerase chain reaction and immunocytochemical staining, respectively, at PHH 0 (immediately), 12, 24, and 48 (with sample numbers of 12). (4) The second passage of human embryonic kidney 293 (HEK-293) cells were divided into empty vector hypoxia group (cells were cultured under hypoxia condition after being transfected with empty vector plasmid), P311 normoxia group (cells were cultured under normoxia condition after being transfected with P311 reporter gene plasmid), P311 hypoxia group (cells were cultured under hypoxia condition after being transfected with P311 reporter gene plasmid), P311 hypoxia+ HIF-1α inhibitor group (cells which were incubated with HIF-1α inhibitor were cultured under hypoxia condition after being transfected with P311 reporter gene plasmid). The luciferase activity was detected at post culture hour (PCH) 0 and 12, respectively, and then the P311 transcriptional regulatory binding site of HIF-1α and the promoter sequence of P311 were predicted and searched by bioinformatics methods. Data were processed with factorial design variance analysis, one-way analysis of variance, LSD test and Bonferroni correction. (1) The results of ESCs. The cells showed cobblestone-like pattern and different clonal morphology due to the different cell proliferation potential. The proportion of CD71(-)CD49f(+) cells accounted for about 85%. The identification results indicated that the cells showed strong stem cell properties and high purity. Compared with those in cells of normoxia group of P311 gene knock-out mice, the residual widths of scratch of cells in pure hypoxia group were smaller at PSH 12 and 24 (with values below 0.05), and those in hypoxia group, normoxia group of wild-type mice, DMSO control group, HIF-1α inhibitor group, and HIF-1α stabilizer group were smaller at PSH 12 (with values below 0.05). Compared with those in cells of normoxia group of wild-type mice, the residual widths of scratch of cells in hypoxia group, pure hypoxia group, and DMSO control group were smaller at PSH 12 and 24 (with values below 0.05), and the residual width of scratch of cells in HIF-1α stabilizer group was smaller at PSH 12 (<0.05). Compared with those of cells in pure hypoxia group, the residual widths of scratch of cells in hypoxia group were wider at PSH 12 and 24 (with values below 0.05), and the residual width of scratch of cells in HIF-1α inhibitor group was wider at PSH 12 (<0.05), and those of cells in HIF-1α stabilizer group were smaller at PSH 12 and 24 (with values below 0.05). There was no obvious difference in the width of scratch in cells among the 7 groups (=19.02, >0.05). The protein levels of HIF-1α in ESCs of wild-type mice at PHH 0, 12, 24, and 48 were respectively 1.02±0.05, 2.56±0.09, 1.60±0.17, and 1.17±0.03. Compared with that at PHH 0, the protein level of HIF-1α at PHH 12 was significantly enhanced (<0.01). It began to decline at PHH 24 but was still higher than that at PHH 0 (<0.05), and the protein level of HIF-1α at PHH 48 was close to the normoxia level (>0.05). Compared with those of cells in pure hypoxia group, the mRNA expressions of P311 of cells in HIF-1α inhibitor group were significantly decreased at each time point (with values below 0.05), and those in HIF-1α stabilizer group were significantly increased at PHH 12 and 24 (with values below 0.05). Compared with those of cells in HIF-1α inhibitor group, the mRNA expressions of P311 of cells in DMSO control group and HIF-1α stabilizer group were significantly increased at PHH 0, 12, and 24 (with values below 0.05). Compared with those of cells in pure hypoxia group, the expressions of P311 of cells in HIF-1α inhibitor group were significantly decreased at each time point (with values below 0.05), while those in HIF-1α stabilizer group were significantly increased at PHH 12 and 24 (with values below 0.05). Compared with those of cells in HIF-1α inhibitor group, the expressions of P311 of cells in DMSO control group and HIF-1α stabilizer group were significantly increased at PHH 12 and 24 (with values below 0.05). (2) The results of HEK-293 cells. At PCH 0, there was no significant difference in the luciferase activity among cells of empty vector hypoxia group, P311 normoxia group, P311 hypoxia group, and P311 hypoxia+ HIF-1α inhibitor group (=13.33, >0.05). At PCH 12, the luciferase activity of cells in P311 hypoxia group was higher than that in empty vector hypoxia group (<0.01). The luciferase activity of cells in hypoxia group was higher than that in P311 normoxia group (<0.05), while that of cells in P311 hypoxia+ HIF-1α inhibitor group was lower than that in P311 hypoxia group (<0.01). HIF-1α may increase the migration of murine ESCs through inducing the expression of P311 at the early stage of hypoxia.
为探讨缺氧诱导因子-1α(HIF-1α)对P311的影响及其在体外缺氧条件下对小鼠表皮干细胞(ESCs)迁移的影响。分别从15只新生野生型C57BL/6J小鼠和5只同基因来源的P311基因敲除小鼠中分离并获得两种小鼠ESCs。经形态学观察并用流式细胞仪检测细胞表面标志物CD71和CD49f的表达后,取第一代细胞进行以下实验。(1)细胞划痕实验后,根据随机数字表(以下分组方法相同),将P311基因敲除小鼠的ESCs分为常氧组(细胞在常氧二氧化碳培养箱中用完全培养基培养,后续常氧处理相同)和缺氧组(细胞在含1%氧气的缺氧二氧化碳培养箱中培养,后续缺氧处理相同),每组12个孔板。将野生型小鼠的ESCs分为常氧组、单纯缺氧组、二甲基亚砜(DMSO)对照组(缺氧处理前常氧处理1小时,加入2 μL DMSO溶剂)、HIF-1α抑制剂组(缺氧处理前常氧条件下用2 μL 11 μmol/L HIF-1抑制剂处理细胞1小时)、HIF-1α稳定剂组(缺氧处理前常氧条件下用2 μL 2 μmol/L FG-4592处理细胞1小时),每组12个孔板。每组在划痕后小时(PSH)0(即刻)、12、24和48分别取3个孔板,在倒置相差显微镜下测量划痕残余宽度。(2)缺氧处理后,在缺氧后小时(PHH)0、12、24和48通过蛋白质免疫印迹法检测野生型小鼠ESCs中HIF-1α的蛋白水平。(3)将野生型小鼠的ESCs按实验(1)分为单纯缺氧组、DMSO对照组、HIF-1α抑制剂组和HIF-1α稳定剂组,处理相同。分别在PHH 0(即刻)、12、24和48(样本数为12)通过实时荧光定量逆转录聚合酶链反应和免疫细胞化学染色检测ESCs中P311的mRNA表达和P311的表达。(4)将人胚肾293(HEK-293)细胞的第二代分为空载体缺氧组(转染空载体质粒后在缺氧条件下培养)、P311常氧组(转染P311报告基因质粒后在常氧条件下培养)、P311缺氧组(转染P311报告基因质粒后在缺氧条件下培养)、P311缺氧 + HIF-1α抑制剂组(转染P311报告基因质粒后用HIF-1α抑制剂孵育,然后在缺氧条件下培养)。分别在培养后小时(PCH)0和12检测荧光素酶活性,然后通过生物信息学方法预测和搜索HIF-1α的P311转录调控结合位点及P311的启动子序列。数据采用析因设计方差分析、单因素方差分析、LSD检验和Bonferroni校正进行处理。(1)ESCs实验结果。细胞呈鹅卵石样形态,因细胞增殖潜能不同而克隆形态各异。CD71(-)CD49f(+)细胞比例约为85%。鉴定结果表明细胞具有较强的干细胞特性且纯度高。与P311基因敲除小鼠常氧组细胞相比,单纯缺氧组细胞在PSH 12和24时划痕残余宽度更小(P值均<0.05),野生型小鼠缺氧组、常氧组、DMSO对照组、HIF-1α抑制剂组和HIF-1α稳定剂组细胞在PSH 12时划痕残余宽度更小(P值均<0.05)。与野生型小鼠常氧组细胞相比,缺氧组、单纯缺氧组和DMSO对照组细胞在PSH 12和24时划痕残余宽度更小(P值均<0.05),HIF-1α稳定剂组细胞在PSH 12时划痕残余宽度更小(P<0.05)。与单纯缺氧组细胞相比,缺氧组细胞在PSH 12和24时划痕残余宽度更宽(P值均<0.05),HIF-1α抑制剂组细胞在PSH 12时划痕残余宽度更宽(P<0.05),HIF-1α稳定剂组细胞在PSH 12和24时划痕残余宽度更小(P值均<0.05)。7组细胞划痕宽度差异无统计学意义(F=19.02,P>0.05)。野生型小鼠ESCs在PHH 0、12、24和48时HIF-1α的蛋白水平分别为1.02±0.05、2.56±0.09、1.60±0.17和1.17±0.03。与PHH 0时相比,PHH 12时HIF-1α蛋白水平显著升高(P<0.01)。PHH 24时开始下降,但仍高于PHH 0时(P<0.05),PHH 48时HIF-1α蛋白水平接近常氧水平(P>0.05)。与单纯缺氧组细胞相比,HIF-1α抑制剂组细胞在各时间点P311的mRNA表达均显著降低(P值均<0.05),HIF-1α稳定剂组细胞在PHH 12和24时P311的mRNA表达显著升高(P值均<0.05)。与HIF-1α抑制剂组细胞相比,DMSO对照组和HIF-1α稳定剂组细胞在PHH 0、12和24时P311的mRNA表达显著升高(P值均<0.05)。与单纯缺氧组细胞相比,HIF-1α抑制剂组细胞在各时间点P311的表达均显著降低(P值均<0.05),HIF-1α稳定剂组细胞在PHH 12和24时P311的表达显著升高(P值均<0.05)。与HIF-1α抑制剂组细胞相比,DMSO对照组和HIF-1α稳定剂组细胞在PHH 12和24时P311的表达显著升高(P值均<0.05)。(2)HEK-293细胞实验结果。在PCH 0时,空载体缺氧组、P311常氧组、P311缺氧组和P311缺氧 + HIF-1α抑制剂组细胞的荧光素酶活性差异无统计学意义(F=13.33,P>0.05)。在PCH 12时,P311缺氧组细胞的荧光素酶活性高于空载体缺氧组(P<0.01)。缺氧组细胞的荧光素酶活性高于P311常氧组(P<0.05),而P311缺氧 + HIF-1α抑制剂组细胞的荧光素酶活性低于P311缺氧组(P<0.01)。HIF-1α可能在缺氧早期通过诱导P311的表达增加小鼠ESCs的迁移。