佛手多糖对1-甲基-4-苯基-吡啶离子诱导人神经母细胞瘤(SH-SY5Y)细胞损伤的保护作用研究

陈进炫1,2,龚舒2,刘天开2,龚记熠1,乙引1*,刘文华2*

1(贵州师范大学 生命科学学院,贵州 贵阳,550025)

2(肇庆学院 生命科学学院,广东 肇庆,526061)

摘 要 该文探究佛手多糖对1-甲基-4-苯基-吡啶离子(1-methyl-4-phenyl-pyridine ion, MPP+)诱导人神经母细胞瘤(SH-SY5Y)细胞损伤的保护作用及其机制。佛手多糖经大孔吸附树脂AB-8进行纯化。体外培养SH-SY5Y细胞,构建帕金森病(Parkinson′s disease, PD)细胞模型,实验分为对照组、MPP+模型组、佛手多糖组。采用噻唑蓝(methye thiazdye telrazlium, MTT)法检测细胞存活率,Hoechst33258染色法观察细胞形态,2′,7′-二氯荧光黄双乙酸盐荧光探针检测细胞活性氧(reactive oxygen species, ROS)水平,JC-1荧光探针法检测线粒体膜电位,蛋白免疫印迹(Western blot)检测磷酸化蛋白激酶B(phosphorylated protein kinase B, p-Akt)、蛋白激酶B(protein kinase B, Akt)、磷酸化细胞外调节蛋白激酶(phosphorylated extracellular regulated protein kinases1/2, p-ERK1/2)和细胞色素c(cytochrome c, Cyt-c)蛋白表达水平。结果表明,佛手多糖的得率4.86%,纯度为44.46%,经过AB-8纯化后,纯度提高到60.81%;与对照组相比,模型组细胞的存活率显著降低,Hoechst33258染色下可见细胞破碎,细胞核皱缩,细胞内ROS显著增加,线粒体膜电位显著降低。与模型组相比,佛手多糖组的细胞存活率显著增加,细胞形态明显得到改善,ROS水平下降,线粒体膜电位升高。Western blot结果显示,佛手多糖能抑制MPP+引起的p-Akt和p-ERK1/2的降低,以及Cyt-c的上升。综上,佛手多糖对MPP+诱导SH-SY5Y细胞损伤具有保护作用,其机制可能是通过调节线粒体ROS的产生和Cyt-c的释放,进而维持线粒体稳态,激活Akt信号通路和ERK信号通路,抑制细胞的凋亡,从而起到保护作用。研究结果可为缓解帕金森病的发生发展提供理论依据,同时也能更好地开发和利用佛手资源。

关键词 佛手多糖;提取纯化;MPP+;SH-SY5Y细胞;保护作用

佛手又名佛手柑、五指柑、福寿柑等,为芸香科柑橘属植物佛手的果实,具有药食两用价值,主要产于我国的广东、广西、四川、浙江、福建等地,其主要活性成分有多糖类、挥发油类、黄酮类、香豆素类等[1]。不同产地的佛手多糖在种类、单糖组成及结构等方面存在差异,这可能与土壤、气候和栽培条件等因素有关[2]。研究显示,川佛手多糖的单糖组分为鼠李糖、木糖、甘露糖、葡萄糖和半乳糖,而金佛手和建佛手多糖的单糖组分均为甘露糖、葡萄糖和半乳糖[3]。广佛手多糖由D-木糖、D-甘露糖、D-葡萄糖、D-半乳糖和L-鼠李糖组成[4]。佛手多糖具有免疫调节[5]、抗氧化[6]、抗肿瘤[7]等生物活性。

帕金森病(Parkinson′s disease,PD)是一种中枢神经系统退行性疾病,主要以中脑黑质致密部多巴胺能神经元变性、死亡为病理特征。帕金森病的发病机制尚未完全明确[8],研究表明,氧化应激、线粒体功能障碍、细胞自噬等因素都参与了帕金森病的致病过程[9]。帕金森病多发于中老年群体,我国老龄化不断加剧,预计到2030年,全国帕金森病人数高达500万[10]。目前还没有能完全根治帕金森病的药物。研究表明,很多中药活性成分对帕金森病有较好的预防治疗效果,而且具有低毒、副作用小等优点。因此,对中药活性成分预防和治疗帕金森病的效果进行深入研究,具有重要的实际意义[11]

表1 干酪成熟过程中风味物质的变化
Table 1 Changes of flavor compounds during cheese ripening

类别RT化合物名称第0周第4周第8周第12周A组B组C组A组B组C组A组B组C组A组B组C组醇类5.803乙醇38.56±2.0447.27±2.5160.58±3.5829.41±3.441.14±5.3356.54±1.8023.46±0.5130.66±0.7025.61±1.6330.05±1.0140.43±1.6431.83±2.5513.7683-甲基-1-丁醇18.95±4.5419.04±0.82—6.92±0.0670.11±1.239.32±2.2743.13±0.4768.19±0.6250.71±4.6986.82±1.62—103.9±1.3718.4515-甲基-2-己醇—————4.16±0.271.18±0.15—5.37±0.422.77±0.07—10.98±0.3819.8021-己醇2.160±0.056.69±0.684.09±0.615.79±0.049.86±0.802.9±0.443.91±0.0810.56±0.835.65±0.207.01±0.0613.8±0.1921.9982-丙基癸-1-醇—2.59±0.03—2.28±0.223.49±0.462.17±0.03———1.60±0.72——24.0491-庚醇—0.85±0.052.09±0.342.22±0.132.53±0.032.58±0.031.57±0.08—2.19±0.191.78±0.04——25.3822-乙基-1-己醇13.08±0.245.88±0.487.33±1.887.27±0.1812.35±1.89.09±1.025.22±0.367.08±0.077.92±0.324.37±0.137.39±0.068.45±0.1128.2411-辛醇———2.31±0.01——3.2±0.315.08±0.13—1.93±0.212.14±0.04—32.1981-壬醇4.31±0.092.93±0.02—3.02±0.024.65±0.053.27±0.042.64±0.31—3.68±0.032.29±0.174.57±0.805.86±0.1341.187苯乙醇2.59±0.521.38±0.221.49±0.197.66±0.1413.16±0.273.46±0.0412.02±0.1511.49±1.574.53±0.0231.15±0.6713.72±0.348.74±0.0747.924a-雪松醇11.6±1.601.72±0.23—5.43±0.131.43±0.13—4.69±0.261.4±0.11—3.40±0.15——酮类6.522,3-丁二酮—46.69±2.93———39.77±0.6311.36±0.66—————12.6532-庚酮16.38±4.5924.13±3.7739.10±1.7325.59±0.0535.09±6.2345.07±1.8615.82±0.1526.03±0.4528.11±1.0420.87±4.427.48±0.2645.31±3.2516.7993-羟基-2-丁酮188.83±6.1258.2±14.8290.62±1.65115.96±1.55245.96±6.78274.53±0.9466.21±3.58179.27±6.35123.65±5.769.76±4.66254.31±2.8154.34±4.521.1392-壬酮45.87±2.2646.73±2.4549.19±3.0132.3±0.7868.09±0.8162.92±3.9824.4±0.2843.21±0.4646.87±0.4633.26±0.3751.39±1.8370.64±5.1029.7692-十一酮—14.57±1.1813.35±1.6813.77±0.2220.78±0.0521.21±1.8510.90±1.0814.32±0.7414.36±1.5211.26±1.0719.01±1.4426.03±0.3437.6512-十三酮3.62±0.072.95±0.14—2.15±0.073.68±0.076.85±0.082.46±0.102.92±0.022.95±0.052.44±0.043.89±0.065.09±0.03酸类23.679乙酸134.22±8.5598.87±5.81156.5±5.6960.16±0.7388.09±1.36165.71±3.2130.3±1.6655.83±0.59110.93±6.4349.21±0.762.13±0.81132.74±4.7227.287丙酸1.15±0.030.73±0.05—0.53±0.21.16±0.021.32±0.040.45±0.020.81±0.071.00±0.140.65±0.121.02±0.021.4±0.0230.813丁酸42.44±1.4443.47±3.3232.9±1.5858.48±1.1128.72±1.355.93±0.4455.55±1.13131.65±4.2769.53±5.689.61±6.2114.71±5.71123.62±3.2332.4073-甲基-丁酸15.05±1.4141.07±1.4210.21±0.2914.99±0.0546.55±2.5612.65±0.6914.9±0.6336.53±2.4712.04±0.6123.59±1.1651.57±1.9616.47±0.2735.01戊酸—2.32±0.03—0.71±0.082.04±0.03—0.92±0.022.20±0.041.20±0.031.35±0.021.67±0.341.94±0.0836.307苯乙酸—15.61±0.3233.62±2.5817.47±2.0220.76±2.0933.08±1.9712.95±0.1815.23±0.3611.82±0.1613.85±0.2618.6±0.9815.76±0.2238.841己酸92.34±11.0272.80±7.0475.57±1.7289.50±1.6307.46±1.98116.26±4.0178.54±0.54262.65±5.82139.22±4.32127.25±4.98—221.29±1.5442.542庚酸2.74±0.061.73±0.2—2.0±0.025.31±0.16—1.23±0.245.25±0.141.88±0.121.71±0.173.16±0.082.96±0.0346.016辛酸125.57±10.495.65±9.8671.79±2.3692.35±1.5257.2±2.35163.86±7.6565.88±1.86207.45±3.4899.54±6.6487.89±6.02169.37±5.76115.66±3.2349.396壬酸3.89±0.232.40±0.26.45±0.92.88±0.044.16±0.915.27±0.152.01±0.114.89±0.143.76±0.142.69±0.153.9±0.164.33±0.0552.56癸酸68.23±1.2662.51±0.7447.53±2.1457.99±1.35113.0±1.8353.98±0.6947.23±5.4788.53±4.1565.95±4.1250.48±0.5495.46±4.2490.29±1.2361.159十六烷酸5.6±0.082.36±0.1510.91±0.672.86±0.0114.67±1.41—2.52±0.028.34±0.0715.2±0.36—2.26±0.063.76±0.05酯类33.564丙酸芳樟酯40.15±2.6516.07±0.810.2±2.1425.27±3.8726.55±4.039.04±0.8510.36±0.1612.94±0.1410.37±0.8518.09±0.1745.53±1.0714.71±1.2655.639γ-十二内酯0.99±0.061.22±0.290.94±0.041.74±0.291.29±0.120.92±0.03—1.18±0.031.09±0.01—1.51±0.0257.188十三内酯5.13±0.093.21±0.112.05±0.032.92±0.074.82±0.615.12±0.062.02±0.052.32±0.212.33±0.202.3±0.023.35±0.413.35±0.0360.031邻苯二甲酸二丁酯—0.86±0.063.51±0.12——1.22±0.01—2.77±0.213.24±0.22—3.54±0.09—其他7.901甲基苯16.62±2.378.81±1.1320.03±0.7911.2±0.6925.41±2.0525.53±0.897.24±0.4712.3±0.2613.62±1.218.36±1.6411.14±1.1420.47±0.7211.0281,2-二甲基苯——3.52±0.09—6.66±1.099.64±0.22——6.14±0.42——7.9±0.344.123苯酚0.8±0.120.5±0.090.44±0.020.56±0.061.22±0.020.58±0.010.58±0.081.00±0.090.77±0.061.05±0.121.81±0.251.27±0.0124.5444-羟基-6-甲基庚醛二乙缩醛6.03±0.123.33±0.024.57±0.853.66±0.6311.15±1.915.04±0.461.80±0.075.36±0.173.38±0.162.51±0.442.77±0.034.97±0.1832.054甲基-2-丙烯基醚26.11±3.0114.57±0.0531.86±1.115.28±0.2318.38±1.4732.12±0.8810.3±1.1112.2±0.2114.85±0.1211.75±0.9414.32±0.0717.93±0.4039.935,6-二氢-4-环戊呋喃—0.43±0.02——1.05±0.10—0.61±0.030.96±0.120.64±0.051.02±0.020.93±0.021.22±0.02

目前,植物多糖对PD细胞模型和动物模型的保护作用已有不少报道[12-14],但未见有佛手多糖对PD细胞模型的保护作用方面的报道。因此,本实验采用被广泛使用的1-甲基-4-苯基-吡啶离子(1-methyl-4-phenyl-pyridine ion, MPP+)诱导人神经母细胞瘤(SH-SY5Y)细胞损伤为PD细胞模型,探究佛手多糖对神经细胞的保护作用及其机制,为缓解帕金森病的发生发展提供理论依据,同时也能更好地开发和利用佛手资源。

1 材料与方法

1.1 材料与试剂

SH-SY5Y细胞株,武汉大学保藏中心;佛手,广东省肇庆市德庆县莫村镇(2020年);无水乙醇,广东广试试剂科技有限公司;AB-8大孔树脂,郑州勤实科技有限公司;纤维素酶、果胶酶,上海源叶生物科技有限公司;木瓜蛋白酶、MPP+,上海麦克林生化科技股份有限公司;DMEM培养基、胎牛血清、0.25%胰酶,美国Gibco公司;磷酸盐缓冲溶液(PBS),大连美仑生物技术有限公司;二甲基亚砜(dimethyl sulfoxide,DMSO),天津市富宇精细化工有限公司;噻唑蓝(methye thiazdye telrazlium, MTT)、Hoechst33258染色液、活性氧(reactive oxygen species,ROS)检测试剂盒、线粒体膜电位检测试剂盒(JC-1)、BCA蛋白浓度测定试剂盒、ECL发光液,上海碧云天生物科技有限公司;蛋白激酶B(protein kinase B, Akt)抗体、磷酸化蛋白激酶B(phosphorylated protein kinase B, p-Akt)抗体、磷酸化细胞外调节蛋白激酶(phosphorylated extracellular regulated protein kinases1/2, p-ERK1/2)抗体、细胞色素c(cytochrome c, Cyt-c)抗体、美国Cell Signaling Technology公司;β-肌动蛋白(β-actin)抗体,美国Santa Cruz Biotechnology公司;Goat anti-Rabbit IgG二抗,美国Merck Millipore公司;其余试剂均为国产分析纯。

1.2 仪器与设备

DHG-9140A鼓风干燥箱、HWS-12恒温水浴锅,上海一恒科学仪器有限公司;800A多功能粉碎机,永康市红太阳机电有限公司;TDL-80-2C低速离心机,上海安亭科学仪器厂;SQP电子天平,赛多利斯科学仪器(北京)有限公司;RE-3000旋转蒸发仪,上海亚荣生化仪器厂;Smart-Q30纯水机,上海和泰仪器有限公司;ELx800酶标仪,美国Bio-Tek公司;FRESCO 21高速冷冻离心机、HEARACELL 150i CO2培养箱,美国Thermo Fisher公司;Eclipse Ts2 FL倒置荧光、Eclipse TS100F正置荧光显微镜,日本Nikon公司;ChemiDocXRS+化学发光成像分析系统,美国Bio-Rad公司;SW-CJ-2FD超净工作台,苏州安泰空气技术有限公司。

1.3 实验方法

1.3.1 标准曲线的制备

称取21 mg无水葡萄糖,定容于100 mL容量瓶,分别吸取0.2、0.4、0.6、0.8、1.0、1.5 mL于试管中,分别加入1.8、1.6、1.4、1.2、1.0、0.5 mL纯净水,另一个试管加入2.0 mL去离子水作为空白组,各试管中加入6%(质量分数)苯酚1.0 mL,摇匀,加入5.0 mL硫酸,摇匀,静置5 min,放入沸水浴加热15 min,立即冷却至室温,490 nm测吸光度,绘制标准曲线。得葡萄糖标准曲线方程y=11.669x+0.014 9,其中R2=0.999 1。

1.3.2 佛手多糖的提取

参考章斌等[15]的方法,并稍加修改:佛手片烘干,粉碎,过100目筛,5倍95%(体积分数)乙醇浸泡过夜(脱脂),过滤,烘干,酶提取[酶用量1.5%(质量分数),料液比1∶30,提取温度50 ℃,提取时间2 h],90 ℃灭酶10 min,抽滤浓缩,离心,取上清液,Sevage法除蛋白,活性炭去色素,80%乙醇沉淀,无水乙醇、丙酮、乙醚依次洗涤,烘干,去离子水重溶,离心,80%乙醇沉淀,无水乙醇、丙酮、乙醚依次洗涤,烘干,测定多糖得率。

1.3.3 佛手多糖的纯化

本研究使用AB-8大孔树脂对佛手粗多糖进行纯化,参考杨波等[16]的方法,并稍作修改。以大孔吸附树脂AB-8为填料,佛手粗多糖溶于去离子水,上样浓度为6 mg/L,先用300 mL去离子水进行洗脱,再用300 mL 40%乙醇洗脱,流速为1 mL/min,洗脱液体积为600 mL,50 mL/管进行收集,苯酚-硫酸法进行检测跟踪,浓缩,醇沉,烘干备用。

1.3.4 佛手多糖纯度测定

称取20 mg佛手粗多糖置于100 mL容量瓶中,用去离子水定容至刻度线,取1 mL多糖溶液按照1.3.1节的方法测定吸光度,计算纯度。

1.3.5 细胞培养与分组

将SH-SY5Y细胞接种于含10%(体积分数)血清的DMEM完全培养基中,在恒温37 ℃、5%(体积分数)CO2的培养箱中培养。每天观察细胞生长状况,待细胞长到80%以上即可传代,取对数生长期的细胞进行实验。将细胞分为对照组、模型组(加入1 mmol/L MPP+)和佛手多糖组(20、40、60、80、100 mg/L),佛手多糖(溶于PBS)预处理6 h,然后加入1 mmol/L MPP+处理细胞48 h。

1.3.6 细胞存活率的检测

以每孔细胞数1×104将细胞接种于96孔板中,每组5个重复,在恒温37 ℃、5% CO2的培养箱培养24 h后,各组给予相应的药物处理。加药48 h后,每孔加20 μL MTT(5 mg/mL),在培养箱继续孵育4 h,吸尽旧培养基,每孔加入DMSO 150 μL,放置37 ℃、200 r/min摇床下振荡30 min,用酶标仪在490 nm处测定吸光度值(A值)。细胞存活率计算如公式(1)所示:

细胞存活率

(1)

1.3.7 Hoechst33258染色

将细胞接种于6孔板(接种前放入盖玻片),每孔细胞数约3×105,在恒温37 ℃、5% CO2的培养箱培养24 h后,佛手多糖组加入80 mg/L佛手多糖,对照组及模型组加入相同体积PBS,6 h后佛手多糖组和模型组加入1 mmol/L MPP+,对照组加入相同体积PBS。继续培养48 h后,每孔加入Hoechst33258染色液5 μL,放入培养箱孵育20 min,用PBS洗涤2次,取出盖玻片,置于载玻片中,在荧光显微镜下随机选取视野拍照。

1.3.8 细胞ROS水平的检测

按1.3.7节分组处理细胞,培养48 h后,吸去细胞培养基,每孔加入10 μmol/L DCFH-DA 荧光染色液1 mL,放入培养箱中孵育20 min,用DMEM完全培养基清洗细胞3次,最后加入1 mL DMEM完全培养基,在荧光显微镜下随机选取视野拍照,随后使用Image J软件计算荧光强度。

1.3.9 线粒体膜电位的检测

按1.3.7节项分组处理细胞,48 h后,吸去培养基,用1 mL PBS洗涤1次,各组分别加入1 mL完全培养基,避光条件下,加入1 mL的JC-1染色工作液,摇匀,放入培养箱继续培养20 min。孵育结束后,吸走培养基,用提前预冷的1× JC-1染色缓冲液,洗涤2次,最后加入1.5 mL基本培养基,置于倒置荧光显微镜,随机选取视野拍照,并使用Image J软件测定各组细胞的红绿荧光强度。

1.3.10 Western blot检测p-Akt、Akt、p-ERK和Cyt-c蛋白表达水平

将细胞接种于6 cm培养皿,每皿细胞数约1×106,按1.3.7节分组处理细胞,培养24 h后,吸去细胞培养液,PBS清洗1次,每皿加入细胞裂解液300 μL,放于冰上,置于4 ℃摇床振荡30 min,将细胞转移至EP管,13 000 r/min离心10 min后,吸取上清液。取少量上清液,用BCA蛋白浓度试剂盒测定总蛋白含量。余下样品加适量5×loading buffer,沸水浴5 min,冷却后,将蛋白样品加入泳道,进行电泳,先恒压80 V电泳 1 h,再恒压100 V电泳至底部,随后将蛋白转至聚偏二氟乙烯膜(250 mA,100 min)。转膜完成后将膜置于5%奶粉或1×Tris缓冲盐吐温混合液(tris buffered saline tween,TBST)中封闭1 h,加一抗(p-Akt,Akt,p-ERK1/2,Cyt-c,β-actin,体积比1∶1 000) 4 ℃孵育过夜。1×TBST洗膜3次,每次10 min,然后加二抗(1∶3 000)孵育1 h,1×TBST洗膜3次后加ECL发光液显影,于化学发光成像系统成像及分析,使用Image J软件分析条带灰度值。

1.4 统计学分析

采用SPSS 25.0软件进行统计学分析,单因素方差分析(ANOVA),LSD检验以及t检验,实验数据以形式表示,以P<0.05为差异显著,P<0.01为差异极显著。

2 结果与分析

2.1 佛手多糖的提取、纯化

通过复合酶提法对佛手粗多糖进行提取,由苯酚-硫酸法测定得佛手粗多糖得率为(4.86±0.50)%,纯度为(44.46±4.64)%。与王琴等[17]的文献相比,多糖得率提高了1.68%,但纯度降低了21.4%,这可能是蛋白质等杂质去除不够干净[17]。经过AB-8大孔吸附树脂对佛手粗多糖的纯化,佛手多糖纯度达到(60.81±1.41)%,纯度提高了16.35%。

2.2 佛手多糖对MPP+损伤的细胞存活率的影响

如图1所示,SH-SY5Y细胞经MPP+作用后,细胞存活率明显下降(P<0.01)。经佛手多糖预处理后,细胞的存活率显著上升(P<0.01),在20~100 mg/L浓度内呈先上升后下降的趋势,佛手多糖组细胞存活率均高于模型组(50.58%),最高达62.24%。故选择80 mg/L的佛手多糖浓度进行后续实验。

图1 佛手多糖对MPP+诱导SH-SY5Y细胞损伤的 保护作用

Fig.1 Protective effect of bergamot polysaccharide on damaged SH-SY5Y cells induced by

注:与对照组比较,**P<0.001,与模型组比较,** P<0.01。

2.3 佛手多糖对MPP+诱导的细胞形态的影响

通过Hoechst33258染色后可见(图2),对照组细胞呈现出均匀的低强度荧光,模型组中部分细胞呈现出高强度的颗粒状蓝色荧光,出现细胞破碎、细胞核皱缩等细胞凋亡现象,佛手多糖组细胞的形态和对照组接近,荧光强度较模型组的低。

a-对照组;b-模型组;c-佛手多糖组(80 mg/L)

图2 佛手多糖对SH-SY5Y细胞形态的影响 (Hoechst33258,×400)

Fig.2 Effects of bergamot polysaccharide on the morphology of SH-SY5Y cells(Hoechst33258,×400)

2.4 佛手多糖对MPP+诱导的细胞活性氧水平的影响

如图3所示,与对照组比较,MPP+组细胞内二氯荧光素信号显著增强,绿色荧光强度大,表明细胞内活性氧水平显著增加(P<0.01)。与模型组比较,佛手多糖组的荧光强度明显降低,细胞内活性氧水平显著减少(P<0.01)。以上结果表明,佛手多糖能够抑制MPP+所导致的SH-SY5Y细胞活性氧水平增加。

图3 佛手多糖对MPP+诱导SH-SY5Y细胞ROS水平的影响 (荧光显微镜,

Fig.3 Effect of bergamot polysaccharide on ROS level in SH-SY5Y cells induced by MPP+(fluorescence

注:与对照组比较,**P<0.01,与模型组比较,##P<0.01。

2.5 佛手多糖对MPP+诱导的细胞线粒体膜电位的影响

如图4所示,对照组中的红绿荧光比值为4.44,与对照组相比,模型组中红绿荧光比值降低至0.72(P<0.01),而佛手多糖组的红绿荧光比值显著高于模型组,佛手多糖组为1.98(P<0.05),以上结果表明,佛手多糖能抑制MPP+导致的膜电位下降,从而减少线粒体损伤。

图4 佛手多糖对MPP+诱导SH-SY5Y细胞线粒体膜电位的 影响(荧光显微镜,

Fig.4 Effect of bergamot polysaccharide on mitochondrial membrane potential of SH-SY5Y cells injured by MPP+ (fluorescence microscope,×200,

注:与对照组比较,**P<0.01,与模型组比较,#P<0.05。

2.6 佛手多糖对p-Akt、p-ERK和Cyt-c表达水平的影响

如图5所示,与对照组比较,模型组p-ERK1/2和p-Akt的表达水平均极显著减少(P<0.01),Cyt-c蛋白表达水平显著增加(P<0.05)。佛手多糖能显著抑制MPP+引起p-ERK1/2和p-Akt的下降以及Cyt-c水平的增加。

a-蛋白免疫印迹中的蛋白表达水平(A-对照组;B-模型组;C-佛手多糖组(80 mg/L));b-p-Akt/Akt;c-p-ERK1/2/β-actin;d-Cyt-c/β-actin

图5 佛手多糖对SH-SY5Y细胞p-Akt、p-ERK1/2和Cyt-c蛋白表达水平的影响

Fig.5 Effects of bergamot polysaccharide on the expression of p-Akt, p-ERK1/2 and Cyt-c proteins in SH-SY5Y

注:与对照组比较,*P<0.05,**P<0.01,与模型组比较,#P<0.05。

a-模型组;b-佛手多糖组(80 mg/L)

图6 佛手多糖细胞保护作用机制图

Fig.6 The diagram of cytoprotective mechanism of bergamot polysaccharide

2.7 作用机制

佛手多糖细胞保护作用机制如图6所示。

3 结果与讨论

MPP+是一种神经毒素,是PD模型常用的诱导剂,可经多巴胺转运体转运到多巴胺能神经元后,在线粒体中积累并产生大量ROS[18],随后诱导Cyt-c从线粒体释放到细胞质中,从而触发Caspase级联反应和细胞凋亡[19]。本研究结果显示,MPP+使得细胞内ROS增加,Cyt-c从线粒体释放到细胞质,经过佛手多糖处理后,细胞内ROS减少,Cyt-c释放减少,说明佛手多糖可通过调节线粒体中ROS的产生和Cyt-c的释放来抑制MPP+诱导的细胞凋亡。

ERK1/2是指细胞外调节蛋白激酶,是丝裂原活化蛋白激酶家族重要成员之一,参与细胞生长发育,细胞形态维持,细胞死亡等生理过程。ROS能激活ERK信号通路,可进一步激活蛋白激酶、转录因子等多种下游效应因子,调控基因表达,共同作用于神经系统,反过来对细胞起到保护作用[20-21]。ERK信号通路可通过三级酶促级联反应激活,促使ERK转变成p-ERK,从而发挥神经保护作用[22]。用1 mmol/L MPP+处理SH-SY5Y细胞,24 h/48 h后,细胞内p-ERK1/2表达水平均明显下降[23-24]。本实验得到相似的结果,经1 mmol/LMPP+作用后,细胞内p-ERK1/2水平明显下降,而经佛手多糖处理后,p-ERK1/2的下降得到抑制,提示佛手多糖可能通过激活ERK信号通路,进而抑制细胞凋亡。

研究表明,Akt参与神经细胞存活、凋亡、自噬以及细胞增殖等过程[25]。另外的研究还表明,PI3K/Akt通路是细胞抗凋亡信号转导机制的重要途径,能够避免细胞受多种凋亡信号刺激[26]。当PI3K被激活后,能够催化PIP2转化为PIP3,促进Akt发生磷酸化,磷酸化的Akt可以抑制多种凋亡蛋白的表达,进而发挥抗凋亡作用[27]。CAO等[23]研究显示,MPP+能够抑制Akt信号通路,使SH-SY5Y细胞中的p-Akt表达降低从而使细胞凋亡。李鹏等[13]研究发现,枸杞多糖能通过激活PI3K/Akt通路,抑制MPP+诱导的帕金森病模型细胞凋亡。本实验结果显示,MPP+处理SH-SY5Y细胞后,p-Akt表达水平显著下降,经佛手多糖处理后,能够显著抑制p-Akt的下降,提示佛手多糖可能通过激活Akt信号通路,进而抑制细胞凋亡。

综上所述,佛手多糖对MPP+诱导的SH-SY5Y细胞损伤具有保护作用,其机制可能是通过调节线粒体ROS的产生和Cyt-c的释放,进而维持线粒体稳态,激活Akt信号通路和ERK信号通路,抑制细胞的凋亡,从而起到保护作用。本研究有助于阐明佛手多糖对细胞损伤的保护作用机制,为缓解帕金森病的发生发展提供理论依据。

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Protective effect of bergamot polysaccharide on SH-SY5Y cells injured by 1-methyl-4-phenyl-pyridine ion

CHEN Jinxuan1,2, GONG Shu2, LIU Tiankai2, GONG Jiyi1, YI Yin1*, LIU Wenhua2*

1(School of Life Science, Guizhou Normal University, Guiyang 550025, China)

2(School of Life Science, Zhaoqing University, Zhaoqing 526061, China)

ABSTRACT This study aimed to explore the protective effect and mechanism of bergamot polysaccharide on damaged SH-SY5Y cells induced by 1-methyl-4-phenyl-pyridine ion (MPP+).The bergamot polysaccharide was extracted and purified with AB-8 macroporous resin.SH-SY5Y cells were cultured in vitro to construct a Parkinson′s disease (PD) cell model.The experiment was divided into a control group, the MPP+ model group, and the bergamot polysaccharide group.The cell viability was detected with the methye thiazdye telrazlium (MTT) method, and the cell morphology was observed by the Hoechst33258 staining method.The reactive oxygen species (ROS) level was detected by the DCFH-DA fluorescence probe, and mitochondrial membrane potential was measured by the JC-1 fluorescence probe method.The protein expression levels of phosphorylated protein kinase B (p-Akt), protein kinase B (Akt), phosphorylated extracellular regulated protein kinases1/2 (p-ERK1/2), and cytochrome c (Cyt-c) were detected by Western blot.Results showed that the yield of bergamot polysaccharide was 4.86% and the purity was 44.46%.After purification by AB-8, the purity of the polysaccharide was increased to 60.81%.Compared with the control group, the cell viability of the MPP+-treated group was significantly reduced, the cells were broken and the nucleus was shrunk after Hoechst33258 staining.Meanwhile, the intracellular ROS was significantly increased, and the mitochondrial membrane potential was significantly decreased.Compared with the model group, the cell viability of the bergamot polysaccharide group was significantly increased, the cell morphology was significantly improved, the enhancement of intracellular ROS was inhibited, and the mitochondrial membrane potential was increased.The results of the Western blot showed that bergamot polysaccharide could inhibit the decrease of p-Akt and p-ERK1/2 as well as the increase of Cyt-c caused by MPP+.Based on these data, bergamot polysaccharide had a protective effect on SH-SY5Y cells against the injury induced by MPP+, which might be correlated with antioxidant activity as well as ERK and Akt activation pathway.The research results could provide a theoretical basis for alleviating the occurrence and development of Parkinson's disease, and be also beneficial for the development and utilization of bergamot resources.

Key words bergamot polysaccharide; extraction and purification; 1-methyl-4-phenyl-pyridine ion (MPP+); SH-SY5Y cells; protective effect

DOI:10.13995/j.cnki.11-1802/ts.035243

引用格式:陈进炫,龚舒,刘天开,等.佛手多糖对1-甲基-4-苯基-吡啶离子诱导人神经母细胞瘤(SH-SY5Y)细胞损伤的保护作用研究[J].食品与发酵工业,2024,50(8):17-23.CHEN Jinxuan,GONG Shu,LIU Tiankai, et al.Protective effect of bergamot polysaccharide on SH-SY5Y cells injured by 1-methyl-4-phenyl-pyridine ion[J].Food and Fermentation Industries,2024,50(8):17-23.

第一作者:硕士研究生(乙引教授和刘文华教授为共同通信作者,E-mail:100236417@qq.com;wenhualiu@hotmail.com)

基金项目:国家自然科学基金(31271124);广东省教育厅创新团队项目(2015KCXTD032);广东省普通高校青年创新人才项目(2018KQNCX291)

收稿日期:2023-02-24,改回日期:2023-03-27