自噬活性的降低增加人鼻咽癌CNE-2细胞的放射敏感性

目的 研究自噬与人鼻咽癌CNE-2细胞放射敏感性之间的关系。方法 采用慢病毒介导的RNA干扰技术建立稳定沉默自噬相关基因ATG5的人鼻咽癌CNE-2细胞系,实验分为未转染的CNE-2细胞组(对照组)、转染NC-shRNA的CNE-2细胞组(NC组)及转染ATG5-shRNA的CNE-2细胞组(ATG5组),应用CCK-8法、流式细胞术及克隆形成实验检测细胞增殖、凋亡及放射敏感性的变化。结果 CCK-8实验结果显示,与对照组和NC组相比,各剂量点ATG5组的细胞存活率均显著降低(F=3.755、46.086、8.609、44.160,P<0.05),绘制细胞生存曲线可见下调ATG5的表达后可以增加CNE-2细胞的放射敏感性;流式细胞术结果显示,经6 Gy X射线照射后,ATG5组细胞的凋亡率较NC组及对照组明显升高(F=394.876,P<0.05);克隆形成实验结果提示沉默ATG5基因可增加鼻咽癌CNE-2细胞的放射敏感性。结论 降低鼻咽癌CNE-2细胞的自噬活性可以增强其放射敏感性。     

自噬——脑缺血损伤中的双刃剑

近来研究表明,自噬可能成为卒中治疗过程中的新靶点,但是自噬在脑缺血过程中的激活是否提升神经元存活率一直存在争议,关于其对于脑缺血后神经元发挥的作用是保护还是加重损伤尚不明确。本文主要综述脑缺血后自噬在缺血/低氧损伤中可能发挥的双重作用及其可能的信号通路。     

细胞自噬在脊髓损伤中作用的研究进展

近年来,细胞自噬在脊髓损伤中的研究逐渐成为热点,但脊髓损伤后早期自噬激活所起的作用尚有争议。其原因在于细胞自噬在脊髓损伤中的作用具有两面性:一方面自噬能诱导自噬性细胞死亡的发生并参与细胞凋亡的发生,另一方面自噬能促进受损变性蛋白的代谢以及抑制细胞凋亡。然而究其对脊髓损伤后修复的利弊作用,早期自噬激活的程度具有决定作用,脊髓损伤后适当地上调自噬水平可促进受损变性蛋白的代谢并抑制细胞凋亡,而过度激活自噬可能引发自噬性细胞死亡。     

Delayed cardioprotection by sevoflurane preconditioning: a novel mechanism via inhibiting Beclin 1-mediated autophagic cell death in cardiac myocytes exposed to hypoxia/reoxygenation injury

Sevoflurane preconditioning has shown to exert delayed caridioprotection against subsequent ischemia and reperfusion injury, but the mechanisms underlying is unclear. Inhibition of autophagy by 3-methyladenine (3-MA) or knockdown of Beclin 1 leads to enhanced cardiac myocyte survival. Our study aimed to test whether sevoflurane preconditioning provides a second window of anesthetic preconditioning (SWOP) via inhibit Beclin 1-mediated autophagic cell death. H9c2 rat cardiomyocytes were randomly divided into five groups: Control (CON) group; hypoxia/reoxygenation (H/R) group, rat cardiomyocytes was exposed in the airtight container for 2 h followed by 1 h of reoxgenation; SWOP group, rat cardiomyocytes was exposed to 1 h of 2.5% sevoflurane 24 h before H/R; Autophagic inhibitors, 3-methyladenine (3-MA, 10 mM) was added to culture medium 15 min before sevoflurane exposure (3-MA+SWOP group) or cells were treated by 3-MA alone (3-MA group). The cell proliferation was significantly increased in SWOP group (79.49 ± 1.37%, P < 0.05) when compared to H/R group (62.2 ± 6.49%, P < 0.05). 3-MA administered before SWOP significantly attenuated the H/R induced autophagy and cell death. H/R injury up-regulated the expression of LC3-II and Beclin 1 proteins (342 ± 66% and 163 ± 18%, respectively, P < 0.05) compared to the CON group (100%), which were increased in SWOP group (202 ± 77% and 128 ± 8%, respectively, P < 0.05). The expression of LC3-II and Beclin 1 proteins was decreased in 3-MA group (110 ± 28% and 97 ± 6%, respectively) and 3-MA+SWOP group (93 ± 7% and 98 ± 6%, respectively) compared with H/R group, but Bcl-2 was upregulated in 3-MA group (158 ± 4%) and 3-MA+SWOP group (156 ± 5%) compared to H/R group (103 ± 7%). In conclusion, sevoflurane preconditioning confers delayed cardioprotection via inhibition Beclin 1-mediated autophagic cell death in cardiac myocytes 24 h before exposed to H/R injury.     

Hepatic autophagy fluctuates during the development of non-alcoholic fatty liver disease

Introduction and objectivesAutophagy has emerged as a critical regulatory pathway in non-alcoholic fatty liver disease (NAFLD). However, the variability of hepatic autophagy during NAFLD development remains controversial. This study aimed to elucidate the dynamics of hepatic autophagy and its underlying mechanism during NAFLD development both in vivo and in vitro.Materials and methodsAutophagy markers were evaluated in the livers of mice fed a high fat diet or a methionine-choline-deficient diet and in HepG2 cells treated with palmitic acid (PA) by western blotting. Intrahepatic and intracellular triacylglycerol levels were assessed using biochemical quantification and lipid staining. Autophagic flux was monitored using an LC3 turnover assay and tandem mRFP-GFP-LC3 fluorescence analysis.ResultsHepatic autophagy was enhanced in early stages but blocked at later stages of NAFLD development both in vivo and in vitro. Analysis of autophagic flux revealed that both autophagic synthesis and degradation were initially activated and progressively inhibited afterwards. The activation of mammalian target of rapamycin complex 1 (mTORC1), a central regulator of autophagy, was found to be negatively correlated with autophagic synthesis; moreover, pharmacological inhibition of mTORC1 by rapamycin alleviated hepatic steatosis through recovery of autophagic flux in hepatocytes with prolonged PA treatment.ConclusionsHepatic autophagy fluctuates during the development of NAFLD in which mTORC1 signalling plays a critical regulatory role, suggesting a therapeutic potential of autophagy modulation by targeting the mTORC1 signalling pathway in NAFLD.     

自噬与心肌病相关性的研究进展

自噬这个词来源于希腊语,原意为“吃自己”和“精确的细胞作用”。自噬从最初发现到如今经历了近50年,研究发现自噬可以被许多刺激所激活,包括饥饿、毒素、氧化应激和感染。在正常情况下,心肌细胞自噬维持在较低的情况,但在应激反应的高度激活下,自噬活动增强并在调节心脏稳态和功能中起重要作用。该文对自噬与心肌病相关性的研究进展进行综述。     

Autophagy related protein 9A increase in hepatitis B virus-associated hepatocellular carcinoma and the role in apoptosis

The majority of hepatocellular carcinoma (HCC) cases are associated with the hepatitis B virus (HBV) infection. Autophagy related protein 9A (ATG9A) is a transmembrane protein required for autophagosome formation. In order to investigate the role of ATG9A in HBV-associated HCC, ATG9A protein expression was determined in tumor liver tissues and compared with adjacent nontumor tissues from HCC patients with or without HBV infection. In HBV-associated HCC tissues, ATG9A protein level was increased in tumor liver tissues, but not in cases of non-HBV HCC. Our findings suggested that ATG9A might be involved in HBV and cancer cell survival. Therefore, we aimed to analyze the function of ATG9A in HBV replication using RNA interference to evaluate the HBV DNA level using real-time PCR. In the present study, there were no significant differences between shATG9A-transfected HepG2.2.15 cells and the mock control. However, we found that silencing ATG9A affected apoptosis in HepG2.2.15 and HepG2 cell lines. Our results indicated that ATG9A might be partly involved in the survival of HCC. Thus, the inhibition of ATG9A together with other targets might be a potential drug target for HCC treatment.     

微管末端结合蛋白1在Siha细胞自噬时的表达和意义

目的 探讨宫颈癌Siha细胞自噬过程中微管末端结合蛋白1（EB1）基因的表达变化。 方法 Hank平衡盐溶液（HBSS）和秋水仙素处理体外培养的宫颈癌Siha细胞,分别采用实时定量PCR和Western blotting检测EB1基因、LC3和p62的表达,荧光显微镜检测特异性绿色荧光蛋白（GFP)-LC3以证实自噬体形成。结果 宫颈癌Siha细胞随HBSS作用时间延长,LC3 mRNA、EB1 mRNA、LC3-Ⅱ蛋白和EB1蛋白的表达均呈时间依赖性增加,差异具有统计学意义(P<0.05)。EB1 mRNA和LC3 mRNA表达呈正相关,具有统计学意义(P<0.05)。p62 mRNA和蛋白在HBSS作用后的表达呈时间依赖性降低,差异具有统计学意义(P<0.05),EB1 mRNA和p62 mRNA表达呈负相关,具有统计学意义(P<0.05)。GFP-LC3结果显示,在HBSS作用12 h后,Siha细胞胞质中GFP-LC3强度和数目明显增加,含有GFP信号的细胞数量也明显增加。秋水仙素处理后,LC3、p62和EB1 mRNA及蛋白均未发生显著改变,差异无统计学意义(P>0.05),但此时几乎检测不到含GFP-LC3荧光信号的细胞。 结论 EB1在饥饿状态Siha细胞中高表达,此时伴随LC3表达增加、p62表达降低以及自噬体形成增加,而用秋水仙素破坏EB1赖以作用的微管时,上述现象消失,充分表明EB1参与细胞自噬的可能。     

微管相关蛋白1轻链3及Beclin-1在硅沉着病大鼠肺泡巨噬细胞中的表达

目的观察自噬相关蛋白——微管相关蛋白1轻链3(LC-3)、Beclin-1在硅沉着病大鼠肺泡巨噬细胞中的表达,从细胞自噬角度探讨硅沉着病形成的分子机制。方法 50只成年雄性SD大鼠随机分为2组(n=25):对照组和硅沉着病模型组,每组再分5个时相组。采用非暴露气管灌注二氧化硅(SiO2)粉尘混悬液法(50g/L)建立大鼠硅沉着病模型。分别于造模后1、3、7、14及28 d分批处死5只大鼠,进行原位支气管肺泡灌洗,获取肺泡巨噬细胞,进行培养纯化和富集后用于后续研究。HE染色及透射电子显微镜观察肺泡巨噬细胞形态学改变;免疫细胞化学法检测LC-3、Beclin-1的表达及分布;免疫印迹法检测LC-3、Beclin-1的蛋白表达量。结果与对照组相比模型组肺泡巨噬细胞体积较大,胞质丰富,部分细胞内可见硅沉着吞噬颗粒,电镜下可见自噬体形成;模型组LC-3、Beclin-1在各时间点的表达较对照组均增多(P0.05),1 d即开始增多,随着时间的延长表达逐渐增多,至14 d时达高峰(P0.05),28d时回落,但仍高于对照组的表达。结论在硅沉着病大鼠肺泡巨噬细胞中有自噬的激活,肺泡巨噬细胞自噬参与了大鼠硅沉着病的病理进程。