细胞自噬研究进展

细胞自噬是真核生物在进化过程中高度保守、基于溶酶体的一种胞内降解途径,对维持细胞和生物体的稳态平衡有重要作用。研究表明,自噬参与生物体发育、免疫反应、代谢调节、细胞凋亡和衰老等多种过程。自噬功能异常与神经退行性疾病、肿瘤等的发生发展密切相关。近30年,我们对细胞自噬的认识无论是在分子机制上还是生理功能方面都有了长足的发展。为进一步加深对细胞自噬的认识,该文主要对细胞自噬的概念、自噬核心机器的组成及调控机制、自噬类型、生理功能及与疾病的关系作一简单综述。     

细胞自噬与病毒感染

自噬是广泛存在于真核细胞内的一种溶酶体依赖性降解途径,在维持细胞存活、更新、物质再利用和内环境稳定中起着重要作用。目前已经发现大量新的自噬相关基因,同时发现自噬在病毒感染过程中发挥着重要的抗病毒作用:自噬可以将胞质中的病毒转运到溶酶体中,降解病毒;也可以将病毒核酸转运至胞内感受器上激活天然免疫;还可以将病毒抗原递呈给MHCⅡ类分子激活适应性免疫。自噬参与胞内微生物感染具有双重作用。一方面,自噬能够降解入侵的微生物,即以异源吞噬(xenophagy)的方式清除胞内的病原体;另一方面,有些微生物能够通过某些机制逃避自噬而利于自身存活。本文就细胞自噬及其与不同病毒感染关系的最新研究进展进行综述。     

细胞自噬研究技术进展及其应用

在生理状态下,细胞通过自噬清除衰老细胞器和异常长寿蛋白质,维持自身结构和功能的衡定,参与胚胎发育、免疫调节和延长寿命。病理状态下细胞自噬水平显著升高,以耐受饥饿、缺血和凋亡。自噬功能障碍与某些慢性感染疾病、神经变性疾病、溶酶体贮积症和肿瘤等密切相关。掌握和合理应用自噬研究技术对于提高细胞自噬研究水平有着重要意义。该文对哺乳类细胞自噬研究技术进展及其应用作了概述。     

细胞自噬及真菌中自噬研究概述

细胞自噬是真核生物中广泛存在的、主要依赖于溶酶体或液泡的保守的降解途径,通过降解细胞内过多或异常的蛋白、细胞器等以维持正常的细胞功能。近10年来自噬研究方面的飞速进展显示出自噬与癌症、神经退行性疾病、衰老及心脏病等人类疾病相关。与此同时,自噬在丝状真菌的生长、形态和发育等方面发挥着重要作用,特别是在丝状真菌的细胞分化过程中,自噬起到了关键性作用,如致病性生长、程序性细胞死亡及孢子形成。本文主要论述了什么是自噬,自噬的检测方法及以真菌为对象的自噬研究进展。     

自噬的分子细胞机制研究进展

自噬是真核细胞中进化上高度保守的、用于降解和回收利用细胞内生物大分子和受损细胞器的过程。自噬的完成依赖于正常的溶酶体功能,与机体的多种生理和病理过程密切相关。自噬研究已成为当前生命科学研究的热点,揭示自噬的发生机制、自噬与疾病发生的关系对预防与治疗多种人类重大疾病具有重要意义。该文旨在概括目前自噬的研究进展,重点介绍细胞自噬的发生机制及其与疾病的关系。     

植物细胞自噬研究进展

细胞自噬是一类依赖于溶酶体和液泡的蛋白质降解途径。在动物细胞中, 靶物质通过自噬体包裹被运送到溶酶体中,由特定的水解酶降解; 而植物和酵母细胞中该过程在液泡内进行。近年来, 在模式植物拟南芥(Arabidopsis thaliana)中鉴定到多个关键ATG基因, 它们对植物细胞自噬体的形成及自噬调控起到关键作用。该文全面综述了植物细胞自噬的调控及其在植物逆境胁迫中的生理功能。     

细胞自噬与肿瘤耐药

细胞自噬是一种细胞自我降解的过程,在适应代谢应激、保持基因组完整性及维持内环境稳定方面发挥重要作用. 在肿瘤治疗中,凋亡耐受是产生肿瘤耐药的重要机制. 细胞自噬可防止抗肿瘤药诱导的凋亡,促进肿瘤耐药. 然而,自噬性细胞死亡可能是凋亡耐受肿瘤细胞的一种死亡方式. 因此,细胞自噬对肿瘤细胞的耐药性有双重影响. 本文综述了细胞自噬的分子机制、细胞自噬与凋亡的关系、细胞自噬与肿瘤耐药以及治疗的主要研究进展.     

溶酶体途径在细胞自噬过程中的功能意义

溶酶体具有高度保守的异质性,是细胞自噬的关键细胞器。细胞质中的蛋白质和细胞器最终在溶酶体降解,故溶酶体在维持细胞结构和功能的平衡方面起着重要生理作用。通过自噬溶酶体途径,细胞可清除某些病原体并参与抗原呈递。细胞自噬与异噬经溶酶体密切联系。自噬过程中溶酶体功能障碍与某些疾病和衰老等相关。对细胞自噬的溶酶体途径及其功能意义作了概述。     

磁性纳米粒子作用于肝癌细胞的生物学效应的研究进展

磁性纳米粒子,是一类智能型的纳米材料,因其特有的性质,被广泛应用于生物医学领域,在肝癌的治疗方面也有大量的实验性研究和成果。研究和探索磁性纳米粒子治疗肝癌的新方法和途径,有着很大的现实意义。本文就磁性纳米粒子作用于肝癌细胞的生物学效应的研究现状和进展进行总结整理,从三个方面进行了综述:磁性纳米粒子直接作用于肝癌细胞,探索磁性纳米粒子的生物相容性、在肝癌细胞的分布方式以及磁性纳米粒子本身对肝癌细胞的生物学效应的影响;磁性纳米粒子协同外加磁场(稳恒磁场、极低频交变磁场和高频交变磁场)作用于肝癌细胞;磁性纳米粒子外加修饰(磁性白蛋白纳米颗粒、纳米磁流体、磁性脂质体等),作为药物载体作用于肝癌细胞。     

自噬在发育及干细胞中的作用

自噬是亚细胞膜结构发生动态变化并经溶酶体介导的细胞内蛋白质和细胞器降解的过程。通过平衡细胞内的合成和分解代谢,自噬可以维持细胞内环境稳态。干细胞是具有自我更新能力和多向分化潜能的细胞,对组织器官再生和维持组织稳态有重要作用。近年的研究表明,自噬在维持干细胞功能方面有非常重要的作用,本文综述了自噬的形成过程和分子机制及其在发育及干细胞中的作用。     

Effects of Lipofectamine 2000/siRNA Complexes on Autophagy in Hepatoma Cells

Lipofectamine 2000 is commonly used for siRNA transfections. However, few studies have examined cellular responses to this delivery system. The purpose of this study is to evaluate the effect of siRNA transfection using Lipofectamine 2000 on cellular autophagy. Huh7.5 cells, stably transfected to express GFP–LC3, were treated with Lipofectamine 2000/negative control siRNA (NC siRNA) complexes. At different time points after treatment, cells were lysed and analyzed by immunoblotting and fluorescence spectroscopy. Cells were also observed using confocal microscopy. An increase of endogenous LC3 lipidation, GFP–LC3 fluorescence, and autophagosomal puncta was observed in cells treated with Lipofectamine 2000/NC siRNA complexes. The kinetics of the increase of GFP–LC3 fluorescence correlated with the concentration of NC siRNA transfected, where 50, 100, and 200 nM NC siRNA caused a significant increase at 72, 48, and 24 h, respectively, after transfection. A similar effect on the GFP–LC3 signal was also observed for cells treated with Lipofectamine 2000 complexed with two other NC siRNAs. The effects were also confirmed in another hepatoma cell line, H4IIE, by immunoblotting. Lipofectamine 2000-mediated transport of NC siRNAs led to an increase of autophagosomes in a dose- and time-dependent manner. Thus, this effect on cells should be taken into consideration when using this approach for intracellular delivery of siRNA.     

雷公藤甲素诱导HeLa细胞p53依赖的自噬和凋亡

自噬与凋亡被认为是细胞程序性死亡的两种重要途径,二者的交互联系对阐明药物的抗肿瘤机理有重要价值.众多的研究表明,雷公藤甲素对多种肿瘤细胞都具有显著的抑制作用.细胞凋亡与自噬可被相同的因素所诱导,p53蛋白可以同时对二者起调控作用,在自噬与凋亡的交互作用(crosstalk)中扮演着重要角色.本文以He La细胞为模型,研究雷公藤甲素诱导He La细胞发生自噬和凋亡的机制,并通过抑制p53依赖的转录,研究雷公藤甲素诱导He La细胞p53依赖的自噬和凋亡交互联系.     

PERK-mediated Autophagy in Osteosarcoma Cells Resists ER Stress-induced Cell Apoptosis

Osteosarcoma is a bone cancer that develops commonly in children and adolescents. However, osteosarcoma treatments often fail by the development of chemoresistance to apoptosis, and the molecular mechanisms remain unclear. In this study, we propose that autophagy is responsible for osteosarcomatous resistance to apoptosis. We implicate PERK-mediated autophagy as a significant contributor to apoptosis resistance due to ER stress in osteosarcoma cells. By immunostainings and western blots, we identified that PERK activated osteosarcomatous autophagy via inhibiting mTORC1 pathway, thereby preventing cell apoptosis. While using RNAi, we knocked down PERK and found that autophagy was suppressed, result in osteosarcomatous apoptosis. Our results identify a novel role of PERK-mediated autophagy as a significant mechanism for osteosarcoma cell survival. These results will help to understand the mechanism of chemoresistance in osteosarcoma cells, and indicate a novel target for improving osteosarcoma therapy.     

Selenium Nanoparticles Induce the Chemo-Sensitivity of Fluorouracil Nanoparticles in Breast and Colon Cancer Cells

Drug resistance is a major challenge of breast and colon cancer therapies leading to treatment failure. The main objective of the current study is to investigate whether selenium nanoparticles (nano-Se) can induce the chemo-sensitivity of 5-fluorouracil (FU)-encapsulated poly (D, L-lactide-co-glycolide) nanoparticles (nano-FU) in breast and colon cancer cell lines. Nano-Se and nano-FU were synthesized and characterized, then applied individually or in combination upon MCF7, MDA-MB-231, HCT 116, and Caco-2 cancerous cell lines. Cytotoxicity, cellular glucose uptake, and apoptosis, as well as malondialdehyde (MDA), nitric oxide (NO), and zinc (Zn) levels, were investigated upon the different treatments. We have resulted that nano-FU induced cell death in MCF7 and Caco-2 more effectively than MDA-MB-231 and HCT 116 cell lines. Moreover, nano-FU plus nano-Se potentiate MCF7 and Caco-2 chemo-sensitivity were higher than MDA-MB-231 and HCT 116 cancerous cell lines. It is relevant to note that Se and FU nano-formulations inhibited cancer cell bioenergetics via glucose uptake slight blockage. Furthermore, nano-FU increased the levels of NO and MDA in media over cancer cells, while their combinations with nano-Se rebalance the redox status with Zn increment. We noticed that MCF7 cell line is sensitive, while MDA-MB-231 cell line is resistant to Se and nano-Se. This novel approach could be of great potential to enhance the chemo-sensitivity in breast and colon cancer cells.

     

活性氧调控植物细胞自噬的研究进展

真核生物通过双层膜结构包裹细胞内受损的蛋白、细胞器或外源物质, 经溶酶体(或液泡)将内含物降解并进行循环利用, 这种高度保守的生物学过程称为自噬。活性氧是细胞有氧代谢的副产物, 作为一种信号分子广泛参与不同生物学过程的调控。研究表明, 真核生物中自噬与活性氧之间存在密切联系。该文结合近年的研究进展, 对植物细胞中活性氧的种类及作用和自噬的分子机制等进行概述, 旨在探讨活性氧对自噬的调控作用。     

Role of Zinc in the Regulation of Autophagy During Ethanol Exposure in Human Hepatoma Cells

Faulty autophagy has been linked to various diseases including neurodegenerative disorders, diabetes, and cancer. Increasing evidence support the notion that activation of autophagy protects against ethanol-induced steatosis and liver injury. Herein, we investigated the role of zinc in autophagy in human hepatoma cells VL-17A exposed or not to ethanol. LC3II/LC3I ratio, p62, and Beclin-1 expression and autophagosomes number were determined in cells incubated in medium containing various concentrations of zinc with or without ethanol. In addition, labile zinc and mRNA expression of metallothionein and the zinc transporters SLC39A8, SLC39A14, and SLC30A10 were evaluated in cells exposed to ethanol and the autophagy inhibitor 3-methyladenine. Zinc depletion caused a significant suppression of autophagy in cells. Conversely, zinc addition to medium stimulated autophagy in cells. Moreover, cotreatment with ethanol and excess zinc (40 μM) had an additive effect on the induction of autophagy. 3-methyadenine treatment decreased labile zinc, but this effect was more pronounced in cells exposed to ethanol. Lastly, ethanol and 3-methyladenine caused significant changes in the expression of metallothionein and zinc transporters. The results from this study support the hypothesis that zinc is critical for autophagy under basal conditions and during ethanol exposure.     

几个能量代谢相关蛋白在HeLa细胞自噬过程中表达下调

自噬是真核细胞中的一种保守的代谢信号通路。人们已经知道自噬与肿瘤发生等疾病密切相关,但对于自噬的分子机制仍然不是很清楚。鉴定更多的自噬相关蛋白对于进一步阐明自噬的分子机制具有重要意义。该研究使用饥饿法处理HeLa细胞,通过电镜观察以及检测自噬标记蛋白LC3-I的转换,证实HeLa细胞发生了明显的自噬。之后,使用双向电泳结合串联质谱分析鉴定细胞自噬时发生变化的蛋白质。结果发现果糖二磷酸醛缩酶A、GAPDH和ATP合成酶O亚基的量在HeLa细胞发生自噬后明显降低。实时定量PCR结果证明饥饿诱导后,这三种蛋白的mRNA水平都发生了明显的下降。使用自噬抑制剂3-Methyladenine预处理HeLa细胞后再行饥饿,三种蛋白mRNA的表达水平与正常细胞相当而明显高于饥饿诱导的细胞。结果表明这三种蛋白在饥饿诱导的自噬中表达下调,其分子机制还有待进一步研究。     

基于自噬与凋亡机制研究左归丸对化疗损伤颗粒细胞及膜细胞的影响

目的 探讨左归丸含药血清对化疗损伤性颗粒细胞和膜细胞的影响及作用机制。方法 制备左归丸含药血清,培养大鼠卵巢颗粒细胞和膜细胞,使用磷酰胺氮芥造模分组后给药。CCK-8法测定颗粒细胞和膜细胞存活率,实时荧光定量PCR法（RT-PCR）及蛋白质免疫印迹法（Western blot）分别检测卵巢自噬启动因子Beclin-1、微管结合蛋白轻链3（LC3B）、自噬受体蛋白p62、凋亡蛋白Bax、Caspase3在转录水平和翻译水平上的表达。结果 10%左归丸含药血清对于细胞存活的挽救率最高。Beclin-1、LC3B、Bax、Caspase3在磷酰胺氮芥作用的颗粒细胞和膜细胞中,相对于空白对照组有高表达（P<0.05）,10%左归丸含药血清可下调上述蛋白质在模型组中的表达（P<0.05）;然而受体蛋白p62较空白对照组升高（P<0.05）,10%左归丸含药血清可上调模型组p62的表达（P<0.05）。此外,在颗粒细胞实验组中,激活或抑制自噬途径后,自噬相关蛋白的表达在发生相应改变的同时,凋亡相关蛋白的表达也会发生相应改变。结论 磷酰胺氮芥可通过促进凋亡、激活自噬/溶酶体降解途径的机制损伤颗粒细胞和膜细胞。10%左归丸含药血清能缓解由此带来的损伤,同时影响了颗粒细胞和膜细胞自噬和凋亡过程。在磷酰胺氮芥损伤颗粒细胞的过程和10%左归丸含药血清缓解其损伤过程中均存在自噬与凋亡串流（cross-talk）。