硫氧还蛋白系统在COPD抗氧化中的作用研究进展

硫氧还蛋白系统是由硫氧还蛋白（thioredoxin,Trx）,硫氧还蛋白还原酶（thioredoxinreductase,TrxR）和还原型辅酶Ⅱ（NADPH）组成的多功能小分子蛋白系统,广泛表达的硫氧还蛋白作为蛋白质二硫键的还原酶,它参与很多生理过程,并发挥重要生物学功能,包括调节机体的氧化还原反应、抑制细胞凋亡、调节转录因子DNA结合活性以及免疫应答等,其中一重要作用是参与调节细胞氧化还原状态以对抗氧化应激。因此在一些炎症性疾病如慢性阻塞性肺疾病、急性呼吸窘迫综合征、肺间质疾病、哮喘、肺结节病等的发生发展中扮演重要角色,本文对硫氧还蛋白系统在慢性阻塞性肺疾病中的抗氧化作用作一综述。     

硫氧还蛋白的结构及在生物抗氧化中的功能

硫氧还蛋白(thioredoxin,Trx)是广泛存在于原核与真核生物体内的氧化还原调节蛋白。Trx通过对目标蛋白质进行还原,从而调节机体的氧化还原平衡。Trx与硫氧还蛋白还原酶(thioredoxin reductase,TrxR)及NADPH共同组成硫氧还蛋白系统参与众多生理过程。细胞中的活性氧是导致生物氧化胁迫的一个主要方面。Trx可以通过对细胞内被氧化的二硫键的还原来修复机体的氧化损伤,并通过这种方式防止机体衰老。同时,Trx系统可以与其它氧化还原系统如谷胱甘肽(GSH)系统协调配合,并消除体内过多的活性氧。     

硫氧还蛋白在凋亡途径中的作用机制

硫氧还蛋白（Trx）是体内广泛存在的氧化还原蛋白,其家族中两种重要的硫氧还蛋白：硫氧还蛋白1（thioredoxin1,Trx1）和硫氧还蛋白2（thioredoxin2,Trx2）都含有保守的-Cys-Gly-Pro-Cys-还原序列。由于Trx具有调节细胞生长增殖和抗凋亡的作用,因此Trx在凋亡途径中的作用机制就成为了对抗肿瘤的研究热点。     

TDRS与靶向性新型抗菌策略

硫醇相关的氧化还原系统(thiol-dependent redox system, TDRS)由硫氧还蛋白系统(thioredoxin system, Trx system)和谷胱甘肽系统(glutaredoxin system, GSH system)组成,存在于多种生物体内,共同维持细胞内氧化还原平衡。原核生物细胞Trx系统中的硫氧还蛋白还原酶(thioredoxin reductase, TrxR)在结构和功能上与哺乳动物TrxR存在着天然差异。这些差异导致了细胞在相同药物作用下发生截然相反的氧化还原反应,使其可以成为潜在的抗菌作用靶点。此外,TrxR作为细菌看家基因trxB编码的蛋白,难以发生突变,故不易产生耐药性,是理想的新型抗菌靶标。本文就TDRS特别是Trx系统靶向性的新型抗菌策略作一综述。     

叶绿体硫氧还蛋白系统的调节机制

硫氧还蛋白(Trx)属于巯基-二硫键氧化还原酶家族, 通过作用于底物蛋白侧链2个半胱氨酸残基之间的二硫键(还原、异构和转移)来调控胞内蛋白的结构和功能。叶绿体Trx系统包括Trx及Trx类似蛋白、铁氧还蛋白(Fd)依赖的硫氧还蛋白还原酶(FTR)和还原型烟酰腺嘌呤二核苷磷酸(NADPH)依赖的硫氧还蛋白还原酶C (NTRC)。除了基质蛋白酶类活性变化及叶绿体蛋白的转运受Trx系统调控之外, 在叶绿体中还存在1条跨类囊体膜的还原势传递途径, 把基质Trx的还原势经跨膜转运蛋白介导, 最终传递给类囊体腔蛋白。FTR和NTRC共同作用维持叶绿体的氧化还原平衡。该文对叶绿体硫氧还蛋白系统的调节机制进行了综述, 同时讨论了叶绿体硫氧还蛋白系统对维持植物光合效率的重要意义。     

硫氧还蛋白与心血管疾病

硫氧还蛋白是细胞内最重要的二硫键还原酶,对维持细胞内蛋白质的还原状态并正常发挥功能着重要的作用,此外。硫氧还蛋白、硫氧还蛋白还原酶和硫氧还蛋白过氧化物酶组成了细胞内最重要的抗氧化系统之一,在对抗细胞的氧化应激上起着重要作用。心血管疾病是威胁人类健康的主要疾病,它与炎症反应和氧化应激有着密切的联系。文章将从硫氧还蛋白的抗氧化、抗炎、抗细胞凋亡,调控与炎症基因表达有关的核转录因子的转录活性,以及调节细胞内蛋白质的亚硝基化等诸多方面阐述硫氧还蛋白在防御心血管疾病方面可能具有的生物学功能。     

硫氧还蛋白结合蛋白-2在糖和脂代谢中的作用

硫氧还蛋白结合蛋白-2(thioredoxin binding protein-2,TBP-2)属于硫氧还蛋白结合蛋白家族成员,与还原型硫氧还蛋白结合,抑制其还原活性。在生物体内,TBP-2不但参与细胞内的氧化还原调节,还具有调节细胞生长繁殖和促进细胞凋亡的作用。TBP-2在葡萄糖和脂肪代谢中的作用被广泛研究。TBP-2高表达时,胰岛细胞凋亡,与糖尿病发生相关;而TBP-2缺失,与高脂血症发病有关。本文综述了TBP-2在糖脂代谢中的作用。     

硫氧还蛋白研究进展

硫氧还蛋白(Trx)是一类广泛存在于真核及原核生物体内的小分子多功能蛋白质。Trx具有调节细胞的生长、抑制细胞凋亡及调节基因转录等功能,并且它与硫氧还蛋白还原酶(TrxR)、烟酰腺嘌呤二核苷磷酸(NADPH)共同构成了生物体内重要的硫氧还蛋白系统,对维持体内稳定的氧化还原状态具有重要的作用。以Trx为对象,综述了其结构特点、分类分布及其生物学活性等方面的研究现状,以期为相关研究提供参考。     

地钱,肾蕨和中山柏的NADP硫氧还蛋白系统

硫氧还蛋白(Td)是一类低分子量酸性蛋白,具有二硫键(-s-s-),通过氧化还原互变来参与很多反应(周志民等1986)。Td可被NADP-硫氧还蛋白还原酶(NTR)还原:     

NADPH依赖性硫氧还蛋白还原酶C在植物质体中的作用

硫氧还蛋白的氧化还原调节作用在生物界中普遍存在。它能够还原目标蛋白的二硫键,而自身的活性位点则被氧化。因此,对于新的催化循环,则需要由相应的还原酶将其再次还原成活性形式。硫氧还蛋白对维持高等植物的光合效率同样具有重要意义。叶绿体中的硫氧还蛋白分别由铁氧还蛋白依赖性硫氧还蛋白还原酶和NADPH依赖性硫氧还蛋白还原酶C(NTRC)两种酶还原。NTRC的本质是一种黄素蛋白,除了具有还原酶活性外,还整合了一个硫氧还蛋白结构域,在叶绿体和淀粉体的氧化还原调节中处于核心地位。这种特殊的双功能酶在卡尔文-本森循环、氧化戊糖磷酸途径、抗过氧化、四吡咯代谢、ATP和淀粉合成、生长素和光周期调控中扮演了多重角色。本综述总结了NTRC的生理功能,并讨论了该蛋白质对植物质体氧化还原稳态的调节机制。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.