核糖体失活蛋白研究新进展

核糖体失活蛋白是一类可使真核细胞核糖体失活而抑制蛋白质合成的植物毒蛋白。它广泛存在于植物界,具有抗肿瘤、抗病毒、免疫调节、骨髓净化等多种生物活性。本文就核糖体失活蛋白在植物中的分类、分布和性质、功能特性、在生物医学中应用及其应用前景等作简要全面的阐述。     

苦瓜的核糖体失活蛋白

核糖体失活蛋白是一类专一修饰核糖体的大亚基rRNA从而抑制蛋白质生物合成的蛋白毒素,可分为Ⅰ-型和Ⅱ-型两种类型。苦瓜中含有多种Ⅰ-型核糖体失活蛋白,如α-苦瓜素,β-苦瓜素和MAP30等,这些蛋白成分具有抗肿瘤、抗病毒和抗艾滋病等功能,因而近年来引起人们广泛的关注。对苦瓜核糖体失活蛋白的研究进展和应用前景进行了综述。     

核糖体失活蛋白研究进展

核糖体失活蛋白是一类毒蛋白, 主要存在于植物当中, 在真菌和细菌中也有发现。其共同特点是具有N-糖苷酶活性, 能水解生物核糖体大亚基rRNA颈环结构上特定位点的腺嘌呤, 使核糖体失活, 从而抑制了蛋白质合成。本文对核糖体失活蛋白的主要性质、应用以及国内外有关这类蛋白的研究进展加以概述。     

核糖体失活蛋白研究进展

核糖体失活蛋白是一类毒蛋白,主要存在于植物当中,在真菌和细菌中也有发现.其共同特点是具有N-糖苷酶活性,能水解生物核糖体大亚基rRNA颈环结构上特定位点的腺嘌呤,使核糖体失活,从而抑制了蛋白质合成.本文对核糖体失活蛋白的主要性质、应用以及国内外有关这类蛋白的研究进展加以概述.     

植物中的核糖体失活蛋白及其抗病毒机制

植物中的核糖体失活蛋白是一类分布于植物体内的毒蛋白,其作用于真核细胞大亚基28S导致核糖体失活,抑制蛋白质的生物合成,从而对细胞产生毒害作用.文章简述了植物核糖体失活蛋白的酶活性和抗病毒的可能分子机制.     

植物单链核糖体失活蛋白的研究概况

本文扼要地介绍了单链核糖体失活蛋白的植物学分布和一般性质,特别是对无细胞系核糖体蛋白合成的抑制作用,并对其应用和研究前景提出初步看法。     

单链核糖体失活蛋白的核糖核酸酶活性

以芹菜4.5SRNA为底物, 在pH5.0的条件下, 5种纯核糖体失活蛋白:天花粉蛋白、苦瓜子蛋白、肥皂草蛋白、丝瓜素毒蛋白和多花白树毒蛋白均显示出核糖核酸酶活性, 放射自显影图显示出它们对RNA分子中的各种碱基具有不同的敏感性.     

核糖体单链失活蛋白在无细胞体系中的活性

核糖体单链失活蛋白是一类广泛分布于植物中的蛋白质,它能使真核细胞核糖体60S亚基失活。本文报道了一些核糖体单链失活蛋白的制备、纯化以及在兔网织红细胞裂解液中对蛋白质生物合成的抑制活性及它们对完整细胞的毒性。其中多数的核糖体单链失活蛋白是首次被分离纯化并对其毒性进行研究的。     

RIP5 is a RIP-homologous inducer of cell death

Members of the RIP serine/threonine kinase family are involved in activation of NF-kappaB, JNK, and p38, and induction of apoptosis. Here we report the identification of a novel RIP-homologous protein designated as RIP5. The C-terminus of RIP5 contains a kinase domain, which is mostly homologous with the kinase domain of RIP. RIP5 also contains a large unconserved N-terminal domain. Overexpression of RIP5 induces cell death with characteristic apoptotic morphology. Overexpression of RIP5 also induces DNA fragmentation and this is blocked by the caspase inhibitor crmA. However, RIP5-induced apoptotic morphology is not blocked by crmA. These findings suggest that RIP5 may induce both caspase-dependent apoptosis and caspase-independent cell death.     

褐藻裙带菜孢子叶粗提物体外抗单纯疱疹病毒Ⅱ型活性研究

从药物对细胞的保护、对HSV-2增殖的影响及对HSV-2感染细胞的综合作用三个方面研究不同稀释度的裙带菜孢子叶粗提物抑制单纯疱疹病毒Ⅱ型对Vero细胞的感染作用,细胞病变效应法(Cytopathogenic effect,CPE)观察和MTT法测定裙带菜多糖抗HSV-2活性,结果表明裙带菜多糖能明显抑制HSV-2对Vero细胞的致病变作用,使细胞存活率升高,其水提醇沉法所得裙带菜多糖的IC50为6.49μg/mL,并初步推测其抗HSV-2活性是作用在HSV-2和受体结合,侵入Vero细胞阶段,为筛选新型抗病毒药物、研究海藻多糖抗HSV-2活性机理及优化裙带菜孢子叶的提取工艺提供参考依据。     

RIP3 beta and RIP3 gamma, two novel splice variants of receptor-interacting protein 3 (RIP3), downregulate RIP3-induced apoptosis

Breast cancer resistance protein (Bcrp/Abcg2) is a member of the ABC transporter family. The purpose of this study was to quantify Bcrp mRNA in rat and mouse tissues, and to determine whether there are gender differences in Bcrp mRNA expression. Rat Bcrp mRNA levels were high in intestine and male kidney, and intermediate in testes. Mouse Bcrp expression was highest in kidney, followed by liver, ileum, and testes. Male-predominant expression of Bcrp was observed in rat kidney and mouse liver. Furthermore, gonadectomy and hypophysectomy experiments were conducted to determine whether sex steroids and/or growth hormone are responsible for Bcrp gender-divergent expression patterns. Male-predominant expression of Bcrp in rat kidney appears to be due to the suppressive effect of estradiol, and male-predominant expression of Bcrp in mouse liver appears to be due to the inductive effect of testosterone.     

甘遂根提取物对人上皮样肝癌BEL-7402的体外实验研究

通过体外培养人上皮样肝癌BEL-7402细胞,分别以加入PBS液为对照组,加人5-FU(10ug/mL)为阳性对照,加入甘遂根提取物(浓度分别为0.1、1.0、10.0、50.0、100.0ug/mL)为实验组,采用台盼蓝染色法、MTT比色法、克隆形成法以及流式细胞仪进行检测分析,以明确甘遂根提取物对BEL一7402细胞的抑制作用.结果显示,几种方法测定的结果一致,甘遂根提取物对BEL-7402细胞的生长抑制率随处理浓度的增高呈上升趋势,其中台盼蓝染色法测定的抑制率分别为71.9%、81.3%、84.4%、86.8%、100%;MTT比色法测定的抑制率分别为50.8%、52.4%、55.6%、57.1%、74.6%;克隆形成实验对克隆形成抑制率分别为44.9%、53.9%、58.1%、79.6%、86.8%.流式细胞仪测定的凋亡率分别为0、24.3%、26.5%、32.9%、100%.实验表明,甘遂根提取物对人上皮样肝癌BEL-7402细胞生长具有显著的抑制作用,而且抑制效果随提取物浓度的增加而递增.     

受体相互作用蛋白3——细胞凋亡与坏死的调节阀

综述了受体相互作用蛋白(RIPs)蛋白结构和RIP3调控细胞凋亡与坏死机制的研究进展．受体相互作用蛋白3(receptor-interacting protein 3, RIP3)是丝/苏氨酸蛋白激酶家族成员之一,该蛋白质家族包含一类高度保守的丝/苏氨酸激酶结构域．RIP家族激酶作为细胞应激传感分子,在调控细胞凋亡、细胞坏死和存活通路中发挥重要作用．近年发现,RIP3参与肿瘤坏死因子TNFα诱导的细胞程序化坏死的生物学过程．认识RIP3调控TNFα诱导的细胞凋亡与坏死不同死亡途径转换的分子机制,有助于发现肿瘤治疗的新策略．     

RIP1-dependent linear and nonlinear recruitments of caspase-8 and RIP3 respectively to necrosome specify distinct cell death outcomes

There remains a significant gap in our quantitative understanding of crosstalk between apoptosis and necroptosis pathways.By employing the SWATH-MS technique,we quantified absolute amounts of up to thousands of proteins in dynamic assembling/de-assembling of TNF signaling complexes.Combining SWATH-MS-based network modeling and experimental validation,we found that when RIP1 level is below～1000 molecules/cell(mpc),the cell solely undergoes TRADD-dependent apoptosis.When RIP1 is above～1000 mpc,pro-caspase-8 and RIP3 are recruited to necrosome respectively with linear and nonlinear dependence on RIP1 amount,which well explains the co-occurrence of apoptosis and necroptosis and the paradoxical obser-vations that RIP1 is required for necroptosis but its increase down-regulates necroptosis.Higher amount of RIP1(＞～46,000 mpc)suppresses apoptosis,leading to necroptosis alone.The relation between RIP1 level and occurrence of necroptosis or total cell death is biphasic.Our study provides a resource for encoding the com-plexity of TNF signaling and a quantitative picture how distinct dynamic interplay among proteins function as basis sets in signaling complexes,enabling RIP1 to play diverse roles in governing cell fate decisions.     

RIP3蛋白的研究进展

受体相互作用蛋白-3是丝/苏氨酸蛋白激酶家族成员（RIPs）之一,该蛋白家族作为细胞重要应激传感分子,在调控细胞存活、细胞凋亡和细胞坏死通路中发挥重要作用.近年研究发现,RIP3参与肿瘤坏死因子TNF-α诱导的细胞程序性坏死生物学过程,是TNF-α诱导的细胞凋亡与坏死不同死亡途径转换的关键开关分子.本文就RIP3分子的发现、结构特点、细胞亚定位、生理功能及其分子机制进行综述,并对RIP3分子的研究进行了展望.     

Caspase blockade induces RIP3-mediated programmed necrosis in Toll-like receptor-activated microglia

Microglia are the resident immune cells in the central nervous system and key players against pathogens and injury. However, persistent microglial activation often exacerbates pathological damage and has been implicated in many neurological diseases. Despite their pivotal physiological and pathophysiological roles, how the survival and death of activated microglia is regulated remains poorly understood. We report here that microglia activated through Toll-like receptors (TLRs) undergo RIP1/RIP3-dependent programmed necrosis (necroptosis) when exposed to the pan caspase inhibitor zVAD-fmk. Although zVAD-fmk and the caspase-8 inhibitor IETD-fmk had no effect on unstimulated primary microglia, they markedly sensitized microglia to TLR1/2,3,4,7/8 ligands or TNF treatment, triggering programmed necrosis that was completely blocked by R1P1 kinase inhibitor necrostatin-1. Interestingly, necroptosis induced by TLR ligands and zVAD was restricted to microglial cells and was not observed in astrocytes, neurons or oligodendrocytes even though they are known to express certain TLRs. Deletion of genes encoding TNF or TNFR1 failed to prevent lipopolysaccharide- and poly(I:C)-induced microglial necroptosis, unveiling a TNF-independent programmed necrosis pathway in TLR3- and TLR4-activated microglia. Microglia from mice lacking functional TRIF were fully protected against TLR3/4 activation and zVAD-fmk-induced necrosis, and genetic deletion of rip3 also prevented microglia necroptosis. Activation of c-jun N-terminal kinase and generation of specific reactive oxygen species were downstream signaling events required for microglial cell death execution. Taken together, this study reveals a robust RIP3-dependent necroptosis signaling pathway in TLR-activated microglia upon caspase blockade and suggests that TLR signaling and programmed cell death pathways are closely linked in microglia, which could contribute to neuropathology and neuroinflammation when dysregulated.