抑制PI3K/Akt/mTOR信号通路对兔原代巨噬细胞自体吞噬的影响及机制

目的 探讨抑制PI3K/Akt/mTOR信号通路对兔原代巨噬细胞自体吞噬中的影响。方法 分离培养纯种新西兰兔腹腔原代巨噬细胞并分为4组,加入磷脂酰肌醇3激酶（PI3K）抑制剂LY294002（10 μmol/L）组、哺乳动物雷帕霉素靶蛋白（mTOR）抑制剂雷帕霉素（10 nmol/L）组、蛋白激酶B（Akt）抑制剂曲西立滨组（20 μmol/L）以及空白对照组。共培养4 h、12 h后分别收集细胞,运用透射电镜观察巨噬细胞自噬体的变化,细胞免疫荧光法检测微管相关蛋白轻链3Ⅱ（LC3Ⅱ）分子的表达,Western blot检测 Akt、mTOR、磷酸化Akt（p-Akt）、磷酸化mTOR（p-mTOR）及自噬相关蛋白Beclin-1和自噬蛋白Atg5-Atg12连接体的表达,单丹酰尸胺（MDC）染色法观察自噬溶酶体的变化。结果 与空白对照组相比,透射电镜下LY294002组自噬体、自噬空泡、髓磷脂图像等自噬标记物明显减少,雷帕霉素组、曲西立滨组明显增多;激光共聚焦显微镜下LY294002组LC3Ⅱ表达显著减少,雷帕霉素组、曲西立滨组表达显著增多;Western blot结果显示LY294002组Beclin-1及Atg5-Atg12蛋白表达水平显著下降,p-mTOR、p-Akt蛋白表达显著减少;雷帕霉素组、曲西立滨组Beclin-1及Atg5-Atg12蛋白表达水平明显上调,共培养4 h后p-Akt表达增多,雷帕霉素组p-mTOR表达增多,曲西立滨组减少;共培养12 h后雷帕霉素组、曲西立滨组p-mTOR表达显著减少,雷帕霉素组p-Akt表达显著增多,曲西立滨组显著减少;MDC染色显示LY294002组自噬溶酶体明显减少,雷帕霉素组、曲西立滨组明显增多。结论 抑制PI3K/Akt/mTOR信号通路能促进兔原代巨噬细胞自体吞噬,抑制PI3K能减少兔原代巨噬细胞自体吞噬,可能是不同类型的PI3K分子通过其他通路起作用。     

针刺通过调节自噬反应对脑卒中大鼠的神经元损伤的影响

目的 探讨针刺通过腺苷酸活化蛋白激酶(AMPK)、哺乳动物雷帕霉素靶蛋白(mTOR)、UNC-51样自噬激活激酶(ULK)1/2介导的自噬对脑卒中大鼠神经元的影响。方法 50只SD大鼠随机分为假手术组、模型组、针刺组、3-甲基腺嘌呤(3-MA)组、针刺+5-氨基-4-甲酰胺咪唑核糖核苷酸(AICAR)组，每组10只，除假手术组其他4组采用中动脉栓塞法构建模型，并给予相应治疗。治疗后24 h,对各组大鼠神经功能缺损程度进行评分。结果 与假手术组比较，模型组治疗后神经功能缺损评分、海马组织AMPK、磷酸化ULK1(p-ULK1)/ULK1、微管相关蛋白1轻链3(LC3)B/A、Beclin-1表达升高，mTOR表达降低(P<0.05);与模型组比较，针刺组和3-MA组大鼠神经元损伤、自噬减轻，神经功能缺损评分、海马组织AMPK、p-ULK1/ULK1、LC3B/A、Beclin-1表达降低，mTOR表达升高(P<0.05);针刺+AICAR组治疗后神经功能缺损评分、海马组织AMPK、p-ULK1/ULK1、LC3B/A、Beclin-1表达明显高于针刺组(P<0.05),...     

替米沙坦诱导大鼠肝细胞自噬促进肝脏胆固醇代谢的机制研究

目的探讨替米沙坦诱导大鼠肝细胞自噬对肝脏胆固醇代谢的影响及作用机制。方法将肝脏原代细胞分为正常对照组(Con)、替米沙坦1μmol/L组(Tel 1组)、替米沙坦3μmol/L组(Tel 3组)、替米沙坦10μmol/L组(Tel 10组)、替米沙坦10μmol/L联合PPARγ抑制剂GW 9662组(Tel+G组)。Tel 1、Tel 3、Tel 10组分别按1、3、10μmol/L浓度加入替米沙坦,Tel+G组加入10μmol/L替米沙坦及PPARγ抑制剂GW9662,培养24 h。检测肝细胞胆固醇浓度,Western blot法检测微管相关蛋白轻链3(LC3)、自噬蛋白区域(Beclin-1)、腺苷酸活化蛋白激酶(AMPK)、雷帕霉素靶分子(mTOR)表达水平。结果 Tel 3、Tel 10组胆固醇水平低于Con、Tel 1组(P<0.05)。Tel 1、Tel 3、Tel 10组LC3Ⅱ/Ⅰ比值、Beclin-1蛋白水平依次升高(P<0.05)。与Con、Tel 1组比较,Tel 3、Tel 10组p-AMPK/AMPK蛋白比值升高(P<0.05),p-mTOR/mTOR蛋白比值降低(P<0.05)。与Tel 10组比较,Tel+G组胆固醇水平、p-mTOR/mTOR蛋白比值升高(P<0.05),LC3II/I比值、p-AMPK/AMPK蛋白水平降低(P<0.05)。结论替米沙坦可通过诱导大鼠肝细胞自噬影响肝脏细胞胆固醇代谢,其机制可能与激活AMPK/mTOR途径和上调PPARγ有关。     

半胱氨酸蛋白酶抑制剂C对缺氧/复氧诱导的心肌细胞凋亡和自噬的影响

目的探究半胱氨酸蛋白酶抑制剂C(CYSC)与自噬相关通路磷酸腺苷蛋白激酶(AMPK)在缺氧/复氧(H/R)状态下对心肌细胞凋亡/自噬的影响。方法用H9C2细胞为模型,建立H/R诱导的损伤模型,以正常培养的H9C2为对照组,检测CYSC表达与AMPK磷酸化水平变化的关系。用RNAi抑制CYSC或外源过表达CYSC,提取细胞全蛋白,在蛋白水平上检测AMPK信号通路变化及细胞自噬、凋亡水平的变化。结果与对照组细胞相比,在H/R损伤后细胞中CYSC及P-AMPK表达量上升(P 0.01),磷酸化的雷帕霉素靶蛋白激酶(P-mTOR)表达量下降。与H/R损伤组细胞相比,敲降CYSC后促进细胞凋亡而抑制自噬,敲降CYSC使凋亡相关蛋白Bax表达升高,而抑制了Bcl-2、LC3-2/LC3-1及自噬相关蛋白Beclin-1的表达,而过表达CYSC与对照组细胞相比促进自噬及自噬相关蛋白表达。此外,敲降CYSC可通过降低P-AMPK信号促进m TOR信号活化,过表达则相反。结论 CYSC在H/R诱导的心肌损伤中可以通过促进AMPK激活抑制m TOR信号通路促进保护性的自噬来抑制心肌损伤。     

重复异丙酚麻醉通过mTOR通路诱导大鼠海马细胞凋亡及自噬

目的 探究重复异丙酚麻醉对大鼠海马神经细胞凋亡和自噬的影响及雷帕霉素靶蛋白(mTOR)通路的影响。方法 将72只SPF级7 d龄大鼠随机分为4组，每组18只：对照组(A组)腹腔注射脂肪乳剂7.5 ml/kg, 1次/d,连续7 d;单次注射异丙酚组(B组)腹腔注射脂肪乳剂7.5 ml/kg, 1次/d,连续6 d,第7天注射异丙酚75 mg/kg;重复注射异丙酚组(C组)腹腔注射异丙酚75 mg/kg, 1次/d,连续7 d;异丙酚+雷帕霉素组(D组，雷帕霉素为mTOR抑制剂)腹腔注射雷帕霉素2.0 mg/kg和异丙酚75 mg/kg, 1次/d,连续7 d。第7天麻醉后每组随机选取12只大鼠于苏醒后抽取动脉血进行血气分析；苏木素-伊红(HE)染色观察大鼠海马组织病理学变化；原位末端标记技术(Tunel)检测海马组织神经细胞凋亡；Western印迹法检测海马组织mTOR、自噬相关蛋白Beclin-1和微管相关蛋白轻链(LC3)-Ⅱ/LC3-Ⅰ、p62及凋亡相关蛋白B细胞淋巴瘤(Bcl)-2/Bcl-2相关X蛋白(Bax)、含半胱氨酸的天冬氨酸蛋白水解酶(Caspase)-3的表达。结果...     

芪苈强心提取物阻断Smad3信号通路抑制血管紧张素Ⅱ诱导的心脏成纤维细胞转分化

目的观察芪苈强心提取物对血管紧张素II（Angiotensin II,Ang II）诱导的心脏成纤维细胞转分化的影响,探讨芪苈强心胶囊在改善心肌重构方面的分子机制。方法采用胰酶消化法培养新生SD大鼠的心脏成纤维细胞（Cardiac fibroblasts,CFs）,传代后将CFs细胞随机分为：对照组,Ang II（10-6mol/l）组,芪苈强心提取物（0.5mg/ml）组和Ang II＋芪苈强心提取物组。以芪苈强心预处理CFs细胞1h,再以Ang II干预6h,采用免疫荧光和Western Blot等方法分别检测α-SMA,TGF-βl以及TGF-βl下游信号通路中Smad3和Smad6蛋白及磷酸化表达水平。结果与对照组相比,Ang II组CFs的α-SMA、TGF-βl蛋白表达增加。与Ang II组比较,芪苈强心提取物能减少Ang II诱导的α-SMA、TGF-βl蛋白表达,同时降低Smad3蛋白的磷酸化水平,增加Smad6蛋白的表达。结论芪苈强心提取物通过调控TGF-βl/Smads信号通路,实现抑制Ang II诱导的CFs转分化,这可能是芪苈强心改善心肌重构的重要分子机制之一。     

红景天苷对高海拔缺氧条件下大鼠心肌自噬相关通路AMPK的影响

目的 探讨红景天苷保护高海拔缺氧损伤大鼠心脏的可能分子机制。 方法 将40只Wistar大鼠随机分为5组:空白对照组（1 500 m）、缺氧生理盐水组（6 500 m+NS）、缺氧Compound C组（6 500 m+comC）、缺氧红景天苷组（6 500 m +Sal）、缺氧红景天苷+Compound C组（6 500 m +comC+Sal）。造模完成后进行血气分析、HE染色、荧光TUNEL检测及Western blot检测。 结果 ①缺氧后大鼠心肌结构发生变化,心肌凋亡加重（P<0.05）,红景天苷治疗可改善心肌细胞病理性损伤,减少心肌细胞凋亡（P<0.05）;②缺氧后磷酸化AMPK水平上升,磷酸化mTOR水平降低（P<0.05）。而Compound C组AMPK及mTOR表现呈相反趋势,红景天苷治疗后AMPK及mTOR的表达水平介于Compound C组与红景天苷组之间,但是自噬蛋白Beclin-1的表达较Compound C组增加（P<0.05）。 结论 红景天苷可以正向调节AMPK信号通路激活自噬,对缺氧损伤的大鼠心脏起保护作用。     

金丝桃苷对H9C2细胞缺血再灌注损伤的作用机制

目的探讨金丝桃苷对H9C2细胞缺血再灌注损伤的作用及可能机制。方法采用H9C2细胞模拟缺血再灌注模型,缺血液培养45min,再恢复正常达尔伯克改良伊格尔培养液培养4h。将H9C2细胞随机分为对照组,金丝桃苷组,缺血再灌注组,金丝桃苷处理+缺血再灌注组(联合组)。光镜观察细胞形态变化,CCK-8法检测细胞活力,Western blot检测磷酸化腺苷酸活化蛋白激酶(AMPK)和磷酸化哺乳动物雷帕霉素靶蛋白(mTOR)蛋白水平,自噬相关蛋白LC3Ⅱ、Beclin1和P62以及凋亡相关蛋白裂解的半胱氨酸天冬氨酸蛋白酶(caspase-3)活性水平,TUNEL染色观察凋亡变化。结果金丝桃苷组与对照组各项指标比较,差异无统计学意义(P0.05)。与对照组比较,缺血再灌注组凋亡指数、caspase-3活性、LC3Ⅱ和Beclin1明显增高,细胞活力、磷酸化AMPK、磷酸化mTOR和P62蛋白明显降低,差异有统计学意义(P0.05)。与缺血再灌注组比较,联合组细胞活力、磷酸化AMPK、磷酸化mTOR和P62蛋白明显增高,凋亡指数、caspase-3活性、LC3Ⅱ和Beclin1明显降低[(11.7±2.8)%vs(27.6±4.5)%,1.4±0.1 vs 2.1±0.3,1.35±0.04 vs 2.17±0.07,1.30±0.18 vs 2.20±0.20,P0.05]。结论金丝桃苷通过激活AMPK/mTOR信号降低自噬减轻H9C2细胞缺血再灌注损伤。     

PI3K-AKT-mTOR信号通路在大鼠肺性脑病模型神经元自噬中的作用

目的探讨PI3K-AKT-m TOR信号通路在肺性脑病神经元自噬中的作用。方法对36只新生健康SD大鼠乳鼠建立离体培养大鼠皮层神经元,随机分为空白对照组、肺性脑病组、自噬抑制剂3-MA组后进一步建立了大鼠肺性脑病细胞模型,借助该模型运用CCK8法检测神经元活力、MDC染色观察神经元自噬泡数量、Western印迹法检测自噬相关蛋白LC3、Beclin-1及PI3K蛋白表达。结果与空白对照组比较,肺性脑病组神经元活力降低(P0.05);神经元自噬泡数量增多;LC3-Ⅱ/Ⅰ的比值、Beclin-1及磷酸化PI3K表达水平增加(P0.05)。使用自噬抑制剂3-MA预处理后,神经元活力降低更明显、自噬泡数量明显减少;缺氧诱导的自噬水平明显受到抑制,LC3-Ⅱ/Ⅰ的比值、Beclin-1及磷酸化PI3K表达水平明显降低。结论缺氧和二氧化碳潴留的信号使Beclin-1表达增加、LC3-Ⅰ向LC3-Ⅱ转化增加,加速PI3K磷酸化,使PI3K-AKT-m TOR信号通路失活,从而激活自噬信号通路,导致大脑神经元自噬增强。     

激活葡萄糖脑苷脂酶对不同H-Y分期的帕金森病患者皮肤成纤维细胞自噬活性的影响

目的探讨激活葡萄糖脑苷脂酶(GBA)对不同H-Y分期的帕金森病(PD)患者皮肤成纤维细胞自噬活性的影响。方法纳入36例帕金森病患者,按照H-Y分期标准将其分为早期及中晚期两组,取皮肤标本,运用含有雷帕霉素的GBA培养基进行体外培养,蛋白印迹法检测出早期及中晚期PD患者的自噬相关基因Beclin 1和自噬体的经典标记物微管相关蛋白LC3-Ⅱ(microtubule-associated protein 1light chain 3-Ⅱ)/LC3-I(microtubule-associated protein1light chain 3-l)蛋白的表达量。结果中晚期PD患者与早期PD患者表皮Beclin 1、LC3-II/LC3-l的水平差异有统计学意义(P 0. 05);中晚期PD患者的Beclin-1的水平(0. 58±0. 04) ng/ml及LC3-II/LC3-I比值(2. 58±0. 27)明显高于早期PD患者(0. 17±0. 05) ng/ml、(1. 49±0. 16)。结论通过雷帕霉素激活GBA诱导自噬,H-Y分期越高,细胞自噬水平越强,自噬可能与PD的疾病严重程度相关。     

促红细胞生成素抑制血管紧张素Ⅱ诱导的大鼠心脏成纤维细胞中转化生长因子β1和胶原的表达

目的 探讨促红细胞生成素(EPO)对血管紧张素Ⅱ(AngⅡ)诱导的心脏成纤维细胞(CF)中转化生长因子(TGF)-β1蛋白表达和胶原生成的影响,以及磷脂酰肌醇-3-激酶(PD-K)/Akt信号途径和一氧化氮合酶(NOS)在其中的作用.方法 应用胰酶和胶原酶双酶法分离培养新生大鼠CF细胞,应用EPO、Ang Ⅱ、PI3-K抑制剂LY294002、NOS抑制剂L-NAME等不同因素干预.ELISA法检测CF中Ⅰ型和Ⅲ型胶原的浓度.化学酶法检测CF培养液中的NO浓度以及NOS总的活性及其亚型的活性.Western blot检测Akt、p-Akt、内皮型一氧化氮合酶(eNOS)、iNOS和TGF-β1蛋白的表达.结果 EPO剂量依赖性的抑制Ang Ⅱ诱导的CF培养液中Ⅰ型和Ⅲ型胶原表达以及提高NO的浓度.10 U/ml的EPO对Ⅰ型和Ⅲ型胶原浓度的抑制分别达到了28%和46%,同时NO浓度则提高了154%.EPO也显著抑制了Ang Ⅱ促CF中TGF-β1蛋白的表达,同时Akt的磷酸化水平显著提高,并促进eNOS蛋白的表达.应用LY294002使eNOS蛋白表达水平明显下降,培养液中的NO浓度也随之下降.L-NAME不能降低eNOS蛋白表达,但抑制了NO的生成.EPO抑制Ang Ⅱ诱导的CF中TGF-β1蛋白的表达以及Ⅰ型和Ⅲ型胶原合成作用均能被二者阻断.结论 EPO可抑制Ang Ⅱ诱导的新生大鼠CF中TGF-β1的表达以及Ⅰ型和Ⅲ型胶原表达,可能是通过激活PI3-K/Akt信号途径促使CF中eNOS表达,从而促进NO的表达来实现.     

Intermittent hypoxia-induced autophagy via AMPK/mTOR signaling pathway attenuates endothelial apoptosis and dysfunction in vitro

Purpose

The aim of this study was to examine whether or not intermittent hypoxia (IH) upregulated autophagy and the contributions of autophagy to endothelial apoptosis and dysfunction in human umbilical vein endothelial cells (HUVECs).

Method

HUVECs were incubated under normoxia and IH conditions. After 3-, 6-, 12-, and 24-h exposure, the autophagic vacuoles and autophagosomes were observed by transmission electron microscopy and monodansylcadaverine staining. The protein levels of autophagy-related biomarkers and AMPK/mTOR pathway were measured by Western blot. The apoptosis-related proteins and the percentage of apoptotic cells were evaluated by Western blot and flow cytometry, respectively, while the levels of endothelial function biomarkers were assessed by ELISA.

Results

IH induced autophagy, as determined by the increased numbers of the autophagic vacuoles, autophagosomes, and by the elevated levels of Beclin-1 protein, the LC3II/LC3I ratio, and p62 degradation. IH-induced autophagic flux peaked at 12-h duration and weakened at 24 h. IH increased the ratio of p-AMPK/AMPK and decreased the ratio of p-mTOR/mTOR, while compound C restored the alteration. A significant decrease in the Bcl-2 level and the Bcl-2/Bax ratio and a significant increase in the protein expression levels of Bax and cleaved caspase 3 and in the percentage of apoptosis were observed under IH exposure. Moreover, the NO level was reduced, while the ET-1 and VEGF levels were raised under IH condition. These alterations were suppressed by the pretreatment of 3-methyladenine.

Conclusions

IH upregulates autophagy through AMPK/mTOR pathway in HUVECs in vitro, which might be protective against endothelial apoptosis and dysfunction caused by IH.

     

The preventive effect of liraglutide on the lipotoxic liver injury via increasing autophagy

Introduction and objectivesThe incidence of non-alcoholic fatty liver disease (NAFLD) is increasing. Previous studies indicated that Liraglutide, glucagon-like peptide-1 analogue, could regulate glucose homeostasis as a valuable treatment for Type 2 Diabetes. However, the precise effect of Liraglutide on NAFLD model in rats and the mechanism remains unknown. In this study, we investigated the molecular mechanism by which Liraglutide ameliorates hepatic steatosis in a high-fat diet (HFD)-induced rat model of NAFLD in vivo and in vitro.Materials and methodsNALFD rat models and hepatocyte steatosis in HepG2 cells were induced by HFD and palmitate fatty acid treatment, respectively. AMPK inhibitor, Compound C was added in HepG2 cells. Autophagy-related proteins LC3, Beclin1 and Atg7, and AMPK pathway-associated proteins were evaluated by Western blot and RT-PCR.ResultsLiraglutide enhanced autophagy as showed by the increased expression of the autophagy markers LC3, Beclin1 and Atg7 in HFD rats and HepG2 cells treated with palmitate fatty acid. In vitro, The AMPK inhibitor exhibited an inhibitory effect on Liraglutide-induced autophagy enhancement with the deceased expression of LC3, Beclin1 and Atg7. Additionally, Liraglutide treatment elevated AMPK levels and TSC1, decreased p-mTOR expression.ConclusionsLiraglutide could upregulate autophagy to decrease lipid over-accumulation via the AMPK/mTOR pathway.     

氧化型低密度脂蛋白通过Akt/mTOR/p70S6K通路诱导血管内皮细胞自噬

目的 探讨氧化型低密度脂蛋白(oxidized low-density lipoprotein, oxLDL)对人脐静脉内皮细胞(human umbilical vein endothelial cells, HUVECs)自噬和Akt/mTOR/p70S6K信号通路的影响.方法 将培养的HUVECs分为oxLDL组和对照组,分别用100 μg/ml oxLDL和等体积磷酸盐缓冲液处理.在培养6 h和12 h后收集细胞.应用透射电子显微镜观察自噬小体,实时荧光定量聚合酶链反应检测微管相关蛋白1轻链3(microtubule-associated protein 1 light chain 3, LC3)和p62 mRNA表达,应用蛋白质印迹法检测LC3、p62、p-Akt/Akt、p-mTOR/mTOR和p-p70S6K/p70S6K蛋白表达.结果 与对照组相比,oxLDL处理组细胞内的自噬小体数量明显增多(P<0.05),LC3 mRNA及蛋白表达水平均显著增高(P均<0.05),而p62 mRNA和蛋白表达水平均显著降低(P均<0.05).此外,oxLDL处理组Akt、mTOR、p70S6K磷酸化蛋白表达水平均较对照组显著降低(P均<0.01),但Akt、mTOR和p70S6K总蛋白表达水平与对照组无显著差异.结论 oxLDL可通过抑制Akt/mTOR/p70S6K信号通路诱导HUVECs自噬.     

Chronic resistance training activates autophagy and reduces apoptosis of muscle cells by modulating IGF-1 and its receptors,Akt/mTOR and Akt/FOXO3a signaling in aged rats

Resistance exercise training (RET) remains the most effective treatment for the loss of muscle mass and strength in elderly people. However, the underlying cellular and molecular mechanisms are not well understood. Recent evidence suggests that autophagic signaling is altered in aged skeletal muscles. This study aimed to investigate if RET affects IGF-1 and its receptors, the Akt/mTOR, and Akt/FOXO3a signaling pathways and regulates autophagy and apoptosis in the gastrocnemius muscles of 18–20 month old rats. The results showed that 9 weeks of RET prevented the loss of muscle mass and improved muscle strength, accompanied by reduced LC3-II/LC3-I ratio, reduced p62 protein levels, and increased levels of autophagy regulatory proteins, including Beclin 1, Atg5/12, Atg7, and the lysosomal enzyme cathepsin L. RET also reduced cytochrome c level in the cytosol but increased its level in mitochondrial fraction, and inhibited cleaved caspase 3 production and apoptosis. Furthermore, RET upregulated the expression of IGF-1 and its receptors but downregulated the phosphorylation of Akt and mTOR. In addition, RET upregulated the expression of total AMPK, phosphorylated AMPK, and FOXO3a. Taken together, these results suggest that the benefits of RET are associated with increased autophagy activity and reduced apoptosis of muscle cells by modulating IGF-1 and its receptors, the Akt/mTOR and Akt/FOXO3a signaling pathways in aged skeletal muscles.     

丹参多酚酸盐保护体外循环后心脏功能的研究

目的探讨细胞自噬参与体外循环术(cardiopulmonary bypass,CPB)后心脏功能减退的主要分子机制及丹参多酚酸盐治疗对CPB后心脏功能的改善。方法健康雄性中华小型猪15只,随机分为CPB组6只、治疗组6只和对照组3只。监测各组小型猪心功能、血流动力学及炎性因子的变化,以及免疫组织化学测定的凋亡指数和心肌、肾小球超微结构的改变。应用Western blot法定量分析各组细胞自噬通路相关信号的改变。结果与对照组比较,CPB组CPB后2h白细胞介素(IL)1β、TNF-α、IL-10水平明显升高,伴随有心脏功能的减退。与CPB组比较,治疗组CPB后2hIL-1β、IL-2、TNF-α水平明显下降,心脏功能明显好转,差异有统计学意义(P<0.05)。CPB后2h,CPB组哺乳动物雷帕霉素靶蛋白(mTOR)信号通路活性增强,但LC3-Ⅱ/LC3-Ⅰ比值仍较对照组明显增高,而治疗组mTOR信号通路活性较CPB组进一步增强,伴LC3-Ⅱ/LC3-Ⅰ比值较CPB组明显下降。结论丹参多酚酸盐能保护CPB后心脏功能,这与其参与AMP蛋白激酶和mTOR信号通路调控抑制CPB后心肌细胞自噬活性有关,也与其抗炎症和氧化应激相关。     

ATF3转录调控HSP110对低氧诱导的肺动脉平滑肌细胞自噬和增殖的影响

目的 探讨ATF3调控HSP110表达对低氧刺激下人肺动脉平滑肌细胞增殖及自噬的影响。 方法 体外培养人肺动脉平滑肌细胞，单独感染ATF3沉默腺病毒或共感染HSP110过表达腺病毒，48 h后加入自噬激活剂雷帕霉素预处理3 h，建立缺氧细胞模型，24 h后，CCK-8法检测细胞增殖能力，流式细胞术分析细胞凋亡，Real-time PCR检测ATF3、HSP110 mRNA的表达，Western blot检测ATF3、HSP110、LC3Ⅱ/Ⅰ、Beclin-1、p62蛋白的表达，免疫荧光观察LC3斑点形成，荧光素酶报告系统鉴定ATF3对HSP110的调控作用。 结果 缺氧组ATF3和HSP110的表达显著增加（P<0.01），ATF3沉默后，细胞增殖能力下降，凋亡率增加（P<0.01），同时自噬蛋白LC3 Ⅱ/Ⅰ、Beclin-1的表达及LC3荧光斑点显著减少(P<0.01)，自噬降解底物p62的表达明显增加(P<0.01)，而加入雷帕霉素或共感染HSP110过表达腺病毒后，ATF3沉默对细胞增殖和自噬的抑制作用显著减弱(P<0.01)。双荧光素酶报告基因检测结果显示，ATF3可上调HSP110启动子活性。 结论 ATF3调控HSP110表达增加而促进人肺动脉平滑肌细胞增殖，其机制可能与介导细胞自噬有关。     

Reactive nitrogen species regulate autophagy through ATM-AMPK-TSC2–mediated suppression of mTORC1

Reactive intermediates such as reactive nitrogen species play essential roles in the cell as signaling molecules but, in excess, constitute a major source of cellular damage. We found that nitrosative stress induced by steady-state nitric oxide (NO) caused rapid activation of an ATM damage-response pathway leading to downstream signaling by this stress kinase to LKB1 and AMPK kinases, and activation of the TSC tumor suppressor. As a result, in an ATM-, LKB1-, TSC-dependent fashion, mTORC1 was repressed, as evidenced by decreased phosphorylation of S6K, 4E-BP1, and ULK1, direct targets of the mTORC1 kinase. Decreased ULK1 phosphorylation by mTORC1 at S757 and activation of AMPK to phosphorylate ULK1 at S317 in response to nitrosative stress resulted in increased autophagy: the LC3-II/LC3-I ratio increased as did GFP-LC3 puncta and acidic vesicles; p62 levels decreased in a lysosome-dependent manner, confirming an NO-induced increase in autophagic flux. Induction of autophagy by NO correlated with loss of cell viability, suggesting that, in this setting, autophagy was functioning primarily as a cytotoxic response to excess nitrosative stress. These data identify a nitrosative-stress signaling pathway that engages ATM and the LKB1 and TSC2 tumor suppressors to repress mTORC1 and regulate autophagy. As cancer cells are particularly sensitive to nitrosative stress, these data open another path for therapies capitalizing on the ability of reactive nitrogen species to induce autophagy-mediated cell death.Autophagy is a self-digestion process by which a eukaryotic cell degrades and recycles aggregate-prone proteins, macromolecules, and organelles. During autophagy, cytoplasmic contents are sequestered in double-membrane bound vesicles called autophagosomes and delivered to lysosomes for degradation, thereby allowing cells to eliminate and recycle the contents (1–3). Autophagy participates in both prosurvival (recycling of cellular building blocks) and prodeath (excess catalysis) pathways. A comprehensive understanding of signaling pathways that regulate autophagy holds great promise for new therapeutic opportunities by opening the possibility to compromise prosurvival autophagic pathways that enable tumor cells to evade therapy, or by promoting prodeath autophagic pathways to kill cancer cells.The classical pathway regulating autophagy in mammalian cells involves the serine/threonine kinase, mammalian target of rapamycin (mTOR). Active mTOR kinase in the mTORC1 complex phosphorylates and inhibits ULK1, a key proautophagy adapter involved in nucleation of the autophagophore membrane. Inactivation of mTORC1, either pharmacologically with rapamycin or via activation of the tuberous sclerosis complex (TSC) tumor suppressor, leads to downstream dephosphorylation events, including loss of ULK1 phosphorylation at S757. The TSC1/2 heterodimer is itself regulated by upstream kinases, including the AMP-activated protein kinase (AMPK), which regulates several metabolic processes and activates the TSC to repress mTORC1 under conditions of energy stress (4–6). AMPK also directly regulates autophagy by phosphorylating and activating ULK1 at S317 (7).Nitric oxide (NO) is a pleiotropic regulator, critical to numerous biological processes extending from its role as a chemical messenger and antibacterial agent to an integral component of the cardiovascular system and immune response to pathogens (8). NO has also been documented to play both promotional and inhibitory roles in cancer etiology. NO is produced endogenously by tumor cells of various histogenetic origins and has been associated with tumor proliferation and resistance to anticancer drugs. Although cancer cells may maintain endogenous NO at elevated levels that facilitate tumor growth, this strategy carries a survival liability, as high levels of NO can cause cytostasis or cytotoxicity (9). Thus, cancer cells may be more sensitive to NO-induced nitrosative stress, which could potentially provide a therapeutic avenue for modulating nitrosative stress to induce cell death. However, understanding at the molecular level regarding how NO participates in regulation of either prosurvival or prodeath autophagic pathways is limited.Recently, a novel signaling pathway involving activation of ATM to suppress mTORC1 in response to oxidative damage was identified (10). In the study reported here, we demonstrate that NO engages this pathway to suppress mTORC1 and promote autophagy. In response to nitrosative stress induced by steady-state exposure to NO, ATM is activated, signaling to AMPK via LKB1 to activate the TSC tumor suppressor and suppress mTORC1. Concomitant with suppression of mTORC1, autophagy is induced, accompanied by loss of cell viability. Our data provide strong evidence that NO regulates autophagy, with implications both for understanding the physiological role of NO-induced signaling and the development of therapies that can modulate nitrosative stress to kill cancer cells.