锌金属蛋白酶家族介绍及结构机理研究进展

锌金属蛋白酶是一类分布广泛,种类繁多的水解酶家族,是近年来人们研究的热点．一般来说,HEXXH保守序列一直都作为锌金属蛋白酶家族分类的依据．除此之外,不同种类的酶还有一些其它的序列特征．谷氨酸锌蛋白（gluzincin）在锌离子配体处共有2组保守区域;甲硫氨酸锌蛋白（metzincin）则拥有1个延长的保守序列HEBXHXBGBXH,里面包含了第3个His配体．大量的金属蛋白酶晶体结构被解析出来,从中可以发现该类酶的活性中心都包含有1个锌离子．锌金属蛋白酶的催化机理通常认为是锌离子与1个水分子结合活化而成．但是,最近的发现证实了并不是所有的锌金属蛋白酶催化都需要水分子参与活化．在本文中,综述了这些已发表的锌金属蛋白酶家族的分类、结构特征、底物特异性识别和催化机理．     

昆虫基质金属蛋白酶研究进展

经过长期的进化,昆虫已形成了完善的变态发育和天然免疫机制以适应自然界环境变化。在昆虫变态发育和免疫过程中产生的冗余蛋白质和瞬时蛋白质需要及时地降解,以保证变态发育和免疫反应的平衡。基质金属蛋白酶(matrix metalloproteases, MMPs)是一类能够降解基底膜和胞外基质中多数蛋白质的蛋白水解酶,也是一类参与昆虫变态发育和天然免疫调节的重要锌离子依赖型蛋白酶。MMPs可降解关键的胞外基质和肽类激素,参与变态发育过程中的组织重构及天然免疫反应强度的调节。本文重点综述了基质金属蛋白酶参与调控昆虫发育和免疫的功能,并对昆虫基质金属蛋白酶研究中存在的问题、潜在的研究方向进行了探讨。     

微生物金属蛋白酶的研究进展

金属蛋白酶分布广泛,性质特异,对微生物金属蛋白酶的研究具有很大的现实意义。本文着重综述了金属蛋白酶的特点和分布,微生物金属蛋白酶的结构、来源,性质及其应用等方面的研究现状。     

创伤弧菌金属蛋白酶的研究进展

研究表明创伤弧菌产生的金属蛋白酶(Vibrio vulnificus protease,VVP)与创伤弧菌的致病性密切相关。经过纯化的VVP能加强血管的渗透性,而且能破坏血管基底膜而导致严重的出血。VVP能使再生基底膜的胶化下降,使出血组织损伤。VVP前体经过水解氨基末端终止信号肽和前肽而成为成熟蛋白酶。成熟的VVP包含两个功能区域,分别是介导蛋白水解反应的氨基末端多肽片段和介导与靶目标有效连接的羧基末端片段。创伤弧菌有LuxS/AI-2和SmcR两种群体感应(Quorum sensing,QS)系统,均能调控蛋白酶的表达,并且二者之间可能存在相互作用或等级反应。LuxS对创伤弧菌的致病力是必需的,但SmcR却是非必需的。     

微生物金属蛋白酶的研究进展

金属蛋白酶分布广泛 ,性质特异。对微生物金属蛋白酶的研究具有很大的现实意义。本文着重综述了金属蛋白酶的特点和分布 ,微生物金属蛋白酶的结构、来源、性质及其应用等方面的研究现状。     

基质金属蛋白酶及其组织抑制剂研究进展

基质金属蛋白酶家族是细胞外基质降解过程中的重要酶类,组织金属蛋白酶抑制剂是基质金属蛋白酶的天然抑制物。研究证实,细胞外基质中基质金属蛋白酶及其组织抑制剂的失衡与多种病理机制有关,尤其与肿瘤的侵袭和转移密切相关。本就基质金属蛋白酶及其组织抑制剂的性质、结构以及功能进行了综述。     

基质金属蛋白酶

基质金属蛋白酶是一类分解细胞外基质组分的锌蛋白酶⒚它们在有机体生长发育中的细胞外基质逆转与重塑以及疾病中的病理损害起着极为重要的作用⒚基质金属蛋白酶的表达和活性在不同细胞水平受到严密调控,如细胞因子、生长因子以及激素的调节⒚基质金属蛋白酶以酶原形式分泌,随后被其它蛋白酶如胞浆素或非蛋白酶类化学物质如有机汞所激活⒚所有基质金属蛋白酶都受到天然抑制剂 金属蛋白酶组织抑制剂所抑制⒚两者的不平衡导致许多疾病的发生,如肿瘤侵入及转移⒚合成基质金属蛋白酶组织抑制剂所抑制,如 Ｍ ａｒｉｍ ａｓｔａｔ 能控制肿瘤转移的发生及进一步扩散⒚本文将对基质金属蛋白酶的特征、分子区域结构、底物特性、激活机制、调控方式等方面进行最新概述⒚     

基质金属蛋白酶与体外循环肺损伤研究进展

肺泡 毛细血管基底膜损伤是体外循环 (CPB)术后肺损伤发生和发展的主要病理过程 ,基质金属蛋白酶 (MMPs)可能通过降解细胞外基质、调节细胞因子而参与CPB所致肺损伤的发生 ,研究MMPs在CPB肺损伤中的作用机制 ,对于防治CPB术后肺损伤的发生和发展具有重要意义     

植物基质金属蛋白酶的研究进展

基质金属蛋白酶(MMPs)是高度保守的锌依赖型内肽酶家族.医学研究表明,人体MMPs不仅在一系列生理过程中发挥关键作用,而且与很多重大疾病关联.例如,MMPs在恶性肿瘤组织中的表达量大幅度上升,和肿瘤的侵袭转移密切相关.MMPs也广泛存在于高等植物,它可能参与植物发育调控、免疫应答及非生物逆境胁迫响应等多个方面.该文对近年来国内外有关植物MMPs的分布、结构特点、活性调节以及生物学功能等方面的研究进展进行综述,并对该领域的研究趋势和重点问题进行了讨论.     

新型金属蛋白酶ADAMTS家族的研究进展

含Ⅰ型血小板结合蛋白基序的解聚蛋白样金属蛋白酶ADAMTSs(a disintegrin and metallo-proteinase with thrombospondin motifs)是一类新的Zn2 依赖的金属蛋白酶家族,广泛存在于哺乳动物和无脊椎动物体内.从1997年发现第一个ADAMTSs家族成员以来,迄今共有19个成员被发现,在保持凝血系统的稳态、器官生成、炎症、生育等方面有重要作用.尽管其中大部分酶的功能尚不清楚,但已有研究显示该家族成员与多种疾病密切相关.ADAMTSs与基质金属蛋白酶MMPs、解聚蛋白样金属蛋白酶ADAMs同属金属蛋白酶家族,但在结构组成、组织细胞分布、底物作用的特异性、酶活性的调节等方面有明显差别.本文综述了其在结构功能及与疾病关系的研究进展.     

Mining oomycete proteomes for metalloproteases leads to identification of candidate virulence factors in Phytophthora infestans

Pathogens deploy a wide range of pathogenicity factors, including a plethora of proteases, to modify host tissue or manipulate host defences. Metalloproteases (MPs) have been implicated in virulence in several animal and plant pathogens. Here we investigated the repertoire of MPs in 46 stramenopile species including 37 oomycetes, 5 diatoms, and 4 brown algae. Screening their complete proteomes using hidden Markov models (HMMs) trained for MP detection resulted in over 4,000 MPs, with most species having between 65 and 100 putative MPs. Classification in clans and families according to the MEROPS database showed a highly diverse MP repertoire in each species. Analyses of domain composition, orthologous groups, distribution, and abundance within the stramenopile lineage revealed a few oomycete-specific MPs and MPs potentially related to lifestyle. In-depth analyses of MPs in the plant pathogen Phytophthora infestans revealed 91 MPs, divided over 21 protein families, including 25 MPs with a predicted signal peptide or signal anchor. Expression profiling showed different patterns of MP gene expression during pre-infection and infection stages. When expressed in leaves of Nicotiana benthamiana, 12 MPs changed the sizes of lesions caused by inoculation with P. infestans; with 9 MPs the lesions were larger, suggesting a positive effect on the virulence of P. infestans, while 3 MPs had a negative effect, resulting in smaller lesions. To the best of our knowledge, this is the first systematic inventory of MPs in oomycetes and the first study pinpointing MPs as potential pathogenicity factors in Phytophthora.     

昆虫天然免疫相关基因研究进展

在长期进化过程中,昆虫形成了强大的天然免疫防御系统,即体液免疫和细胞免疫。体液免疫主要包括Toll、IMD和JAK/STAT 3条信号通路,通过信号转导及免疫途径调控免疫相关基因的表达,诱导产生抗菌肽和其他效应分子。细胞免疫由血细胞介导,主要完成对病原物的包裹、吞噬和集结等。近年来,昆虫基因组学快速发展,通过生物信息学等方法从昆虫基因组数据中已鉴定到大量免疫相关基因,对这些基因的研究加深了人们对昆虫天然免疫分子机制的认识和理解。根据基因功能,免疫相关基因分为识别、信号转导、调制器、效应分子、黑化反应、RNA干扰和其他基因等7类,这些基因通过互作来调控体液免疫和细胞免疫。本文对昆虫免疫相关基因的分类、功能及家族进化等方面的研究成果进行总结,并对今后昆虫免疫的研究重点进行了展望,以期为昆虫免疫分子机制的研究及开发新的害虫防治策略提供依据。     

Matrix metalloproteases and TIMPs as prognostic biomarkers in breast cancer patients treated with radiotherapy: A pilot study

Breast cancer (BC) is the most common tumour in women and one of the most important causes of cancer death worldwide. Radiation therapy (RT) is widely used for BC treatment. Some proteins have been identified as prognostic factors for BC (Ki67, p53, E‐cadherin, HER2). In the last years, it has been shown that variations in the expression of MMPs and TIMPs may contribute to the development of BC. The aim of this pilot work was to study the effects of RT on different MMPs (‐1, ‐2, ‐3, ‐7, ‐8, ‐9, ‐10, ‐12 and ‐13) and TIMPs (‐1 to ‐4), as well as their relationship with other variables related to patient characteristics and tumour biology. A group of 20 BC patients treated with RT were recruited. MMP and TIMP serum levels were analysed by immunoassay before, during and after RT. Our pilot study showed a slight increase in the levels of most MMP and TIMP with RT. However, RT produced a significantly decrease in TIMP‐1 and TIMP‐3 levels. Significant correlations were found between MMP‐3 and TIMP‐4 levels, and some of the variables studied related to patient characteristics and tumour biology. Moreover, MMP‐9 and TIMP‐3 levels could be predictive of RT toxicity. For this reason, MMP‐3, MMP‐9, TIMP‐3 and TIMP‐4 could be used as potential prognostic and predictive biomarkers for BC patients treated with RT.     

Effects of maternal marginal zinc deficiency on myelin protein profiles in the suckling rat and infant rhesus monkey

In the current study, the effects of marginal Zn deficiency on myelin protein profiles in neonatal rats and rhesus monkeys were investigated. Following mating, rats were fed a Zn-adequate diet,ad libitum (50 μg Zn/g; 50 Zn AL), or a marginal Zn diet (10 μg Zn/g) from day 0 (10 Zn d0) or day 14 (10 Zn d14) of gestation to day 20 postnatal. An additional group of dams was restricted-fed the control diet to the food intake of the 10 Zn d0 group (50 Zn RF). Day 20 pup plasma and liver Zn concentrations in the 10 Zn groups were lower than in the 50 Zn groups. In a parallel experiment, rhesus monkeys were fed a Zn-adequatead libitum diet (100 μg Zn/g) or a marginal Zn diet (4 μg Zn/g diet; MZD) throughout gestation and lactation. Day 30 monkey infant plasma and liver Zn levels were similar in the MZD and control groups. Rat brain and monkey brain cortex weights were similar among the dietary groups. The amount of myelin recovered (mg protein/g brain) from day 20 rat pups from the 10 Zn groups was lower than that recovered from the 50 Zn rat pups. Myelin recovery from the MZD and control monkey infants was similar. When myelin protein profiles were characterized, it was found that the percentages of high-molecular-weight (HMW) proteins and Wolfgram protein were higher, whereas the percentages of small and large basic proteins were lower in myelin from the 10 Zn d0 and 50 Zn RF pups compared to the distribution in the 50 Zn AL rat pups. Results for the 10 Zn d0 and 10 Zn d14 pups were similar for all of the parameters studied. The percentage of HMW proteins was higher and that of basic protein lower in myelin from MZD monkey infants compared to the percentage of these proteins in myelin from controls. Although the interpretation of the rat data is complicated because of the anorexia associated with the Zn deficiency, the observed changes in monkey myelin protein profiles provide strong evidence that maternal Zn deficiency affects myelination in the offspring.     

Development of wheat roots under zinc deficiency

Summary Wheat seedlings were cultured in nutrient solutions with and without zinc supply. Shoot: root ratio was reduced in plants without zinc and the greater biomass of –Zn roots was a result of enhanced 1st order lateral root numbers and length. The implications of morphological changes under zinc stress are discussed in relation to knowledge of ion absorption pathways across roots.     

Immunolocalization of venom metalloproteases in venom glands of adult and of newborn snakes of Bothrops jararaca

Using immunoelectronmicroscopy we analyzed qualitative and quantitatively the intracellular distribution of bothropasin, hemorrhagic factor 2 (HF2) and hemorrhagic factor 3 (HF3) in the venom secretory cells from adult snakes in the active (7 days after venom extraction) and in the resting (without venom extraction for 40 days) stages of protein synthesis. Glands from the newborn Bothrops jararaca were also studied. The results lead to the conclusion that all the secretory cells and the secretory pathway in the cells are qualitatively alike in regard to their content of the three metalloproteases. Secretory cells from the resting glands, unlike the active ones and the newborn glands, did not present immunolabeling in the narrow intracisternal spaces of the rough endoplasmic reticulum (RER). The label intensity for bothropasin was greater than that for the other proteins in the adults. HF3 and HF2 labeling densities in the newborn were higher than in the adults and HF3 labeling was not different from that of bothropasin. Co-localization of the three metalloproteases was detected in the RER cisternae of the active gland secretory cells, implying that mixing of the proteases before co-packaging into secretory vesicles occurs at the beginning of protein synthesis in the RER cisternae.     

Redistribution of tissue zinc pools during lactation and dyshomeostasis during marginal zinc deficiency in mice

Zinc (Zn) requirements are increased during lactation. Increased demand is partially met through increased Zn absorption from the diet. It is estimated that 60–80% of women of reproductive age are at risk for Zn deficiency due to low intake of bioavailable Zn and increased demands during pregnancy and lactation. How Zn is redistributed within the body to meet the demands of lactation, and how Zn deficiency affects this process, is not understood. Female C57bl/6J mice were fed a control (ZA; 30 mg Zn/kg) or a marginally Zn deficient (ZD; 15 mg Zn/kg) diet for 30 days prior to mating through mid-lactation and compared with nulliparous mice fed the same diets. While stomach and plasma Zn concentration increased during lactation in mice fed ZA, mice fed ZD had lower stomach Zn concentration and abrogated plasma Zn levels during lactation. Additionally, femur Zn decreased during lactation in mice fed ZA, while mice fed ZD did not experience this decrease. Furthermore, red blood cell, pancreas, muscle and mammary gland Zn concentration increased, and liver and adrenal gland Zn decreased during lactation, independent of diet, while kidney Zn concentration increased only in mice fed ZD. Finally, maternal Zn deficiency significantly increased the liver Zn concentration in offspring but decreased weight gain and survival. This study provides novel insight into how Zn is redistributed to meet the increased metabolic demands of lactation and how marginal Zn deficiency interferes with these homeostatic adjustments.     

Regulation of zinc transporters by dietary zinc supplement in breast cancer

Zinc is essential for cell growth and is a co-factor for more than 300 enzymes, representing over 50 different enzyme classes. Two gene families have been identified involved in zinc homeostasis. ZnT transporters reduce intracellular zinc while ZIP transporters increase intracellular zinc. Previous studies have shown that zinc concentration in breast cancer tissues is higher than that in normal breast tissues. However, the mechanisms involved and the relations to zinc transporters are still unknown. A series of zinc transporters are characterized in this article and several of that are emphasized in view of their unique tissue-specific expressions. Established human breast cancer in a nude mice model is used. With a dietary zinc supplement treatment, ZnT-1 mRNA expression in established human breast cancer is raised by 24%, and is nearly 2 times of that in basal diet. ZIP1, ZIP2 and LIV-1 mRNA are the same between two treatment groups. Moreover, no significant changes of these zinc transporters expressions are found between differential breast cancer cell lines in the nude mice model. This is the first report, which detects the zinc transporters expressions in established human breast cancer in nude mice model. These results lead to the constitutive expression and response to zinc in different tissues. In addition to that, ZnT-1 seems to have played an important role in zinc homeostasis, even in breast cancer.     

Phylogenetic analysis of the plant-specific zinc finger-homeobox and mini zinc finger gene families

Zinc finger-homeodomain proteins (ZHD) are present in many plants; however, the evolutionary history of the ZHD gene family remains largely unknown. We show here that ZHD genes are plant-specific, nearly all intronless, and related to MINI ZINC FINGER ( MIF ) genes that possess only the zinc finger. Phylogenetic analyses of ZHD genes from representative land plants suggest that non-seed plant ZHD genes occupy basal positions and angiosperm homologs form seven distinct clades. Several clades contain genes from two or more major angiosperm groups, including eudicots, monocots, magnoliids, and other basal angiosperms, indicating that several duplications occurred before the diversification of flowering plants. In addition, specific lineages have experienced more recent duplications. Unlike the ZHD genes, MIF s are found only from seed plants, possibly derived from ZHD s by loss of the homeodomain before the divergence of seed plants. Moreover, the MIF genes have also undergone relatively recent gene duplications. Finally, genome duplication might have contributed substantially to the expansion of family size in angiosperms and caused a high level of functional redundancy/overlap in these genes.