过表达鸡Gata2或Gata3基因抑制Pparγ基因的转录

脂肪细胞分化是脂肪组织发育的一个重要过程. 目前,鸡脂肪细胞分化的分子调控机制还不十分清楚. 哺乳动物的研究结果表明,转录因子GATA结合蛋白2(Gata2)和GATA结合蛋白3(Gata3)具有抑制脂肪细胞分化的功能,它们在白色脂肪组织和棕色脂肪组织中的表达模式不同. 鸡没有棕色脂肪组织,目前还没有关于Gata2 和Gata3作用于鸡脂肪细胞分化的研究报道. 本研究利用半定量RT PCR的方法分析了Gata2和Gata3基因在鸡腹部脂肪组织和前脂肪细胞中的表达规律,发现鸡腹部脂肪组织中高水平表达Gata2 基因,低水平表达Gata3基因|鸡前脂肪细胞中Gata2 基因的表达水平远高于Gata3基因的表达水平,油酸诱导分化后的鸡前脂肪细胞Gata2基因的表达水平明显下调.此外,鸡过氧化物酶体增殖体激活受体γ(Pparγ)启动子（－1985/－89）报告基因荧光素活性分析和半定量RT PCP发现,在DF1细胞中过表达Gata2 或Gata3抑制鸡PPARγ基因的转录. 本研究结果为进一步研究鸡脂肪细胞分化的分子调控机制和Gata2和Gata3基因的生物学功能提供了参考.     

Krüppel样因子7的研究进展

Krüppel样因子7(Krüppel-like factor 7,KLF7)是一个羧基端具有3个高度保守的C2H2锌指结构的转录因子,因最早发现在成人多种组织中广泛表达,又被叫做普遍存在的Krüppel样因子(ubiquitous KLF,UKLF)。功能研究表明转录因子KLF7在神经系统发育、脂肪组织形成和2型糖尿病发生中发挥重要作用。此外,KLF7对神经外胚层和中胚层的发育以及干细胞的全能性也具有一定的调控作用。近年来的表观遗传学和整合基因组学研究提示,KLF7可能在弥漫型胃腺癌和心血管疾病的发生和治疗中发挥功能。本文从遗传特性、蛋白质结构和基因功能三个方面综述了转录因子KLF7的研究进展。     

Krüppel样因子7(KLF7)生物学功能研究进展

Krüppel样因子7(Krüppel-like factor 7,KLF7)是Sp1样或Krüppel样转录因子家族(specificity protein/Krüppel-like factor,SP/KLF)成员,在多种生物学过程中发挥重要作用,该基因完全敲除小鼠出生时大部分死亡.KLF7是肥胖症、Ⅱ型糖尿病、心血管疾病、癌症、面部发育异常、氧化磷酸化缺陷和Ⅰ型自身免疫性胰腺炎等疾病的相关基因.功能分析显示,KLF7是神经系统发育和脂肪形成的关键因子,同时也在肌肉再生和造血作用中发挥功能.在SP/KLF家族中,KLF7研究相对较少,大部分作用机制尚不清楚.本文从结构和功能方面详述了KLF7的最新研究进展,为其和KLFs家族深入研究提供重要的科学依据.     

转录因子KLF5调控宫颈癌细胞上皮-间充质转化的分子机制

上皮-间充质转化(epithelial-mesenchymal transition, EMT)是上皮细胞来源的恶性肿瘤细胞获得迁移和侵袭能力的重要生物学过程。为了探究Krüppel样因子5 (Krüppel-like factor 5, KLF5)调控宫颈癌细胞发生EMT过程的分子机制,首先在宫颈癌HeLa细胞瞬时转染Flag-KLF5质粒进行KLF5过表达,并通过MTT法、细胞划痕和Transwell实验证实, KLF5可以显著地抑制HeLa细胞的侵袭和迁移能力。然后采用Western-blot和实时定量PCR技术检测HeLa细胞中EMT相关基因的表达水平,结果显示E-cadherin表达升高, N-cadherin和MMP9表达降低;而且, E-cadherin基因的上游调控因子如SNAI1、SLUG、ZEB1/2和TWIST1等的m RNA表达下降。进一步开展对比研究,在Si Ha细胞中用si RNA沉默KLF5基因,再次验证了KLF5对EMT相关基因表达水平的影响。随后构建不同长度的SNAI1启动子截短体,用荧光素酶报告基因实验检测KLF5对SNAI1启动子活性的影响,结果显示KLF5可以抑制SNAI1启动子区域的活性,并且在HeLa细胞中过表达SNAI1基因后,可显著地促进细胞的EMT过程。以上结果表明, KLF5可通过调控SNAI1基因的表达来调节宫颈癌细胞的EMT过程,进而抑制宫颈癌细胞的迁移和侵袭能力。     

KLF8表达修饰及致瘤机制研究进展

KLF8(Krüppel-like factor 8)是Krüppel 样转录因子家族最新成员。KLF8广泛表达于皮肤、脂肪、食道等组织中。早期研究表明,KLF8蛋白具有转录抑制活性,在胚胎发育过程中起重要作用。而近些年大量的研究发现KLF8在多种肿瘤组织中异常高表达,具有转录活化因子活性,可通过对细胞增殖、迁移、侵袭、EMT、细胞干性等多项生理过程调控促进肿瘤发生发展。综述了近年来KLF8研究进展,系统阐述了KLF8表达修饰调控及致瘤机制,为全面深入了解KLF8在肿瘤中作用及后续相关研究提供参考。     

KLF9通过上调CD36调节肝脏脂代谢

非酒精性脂肪性肝病(nonalcoholic fatty liver disease, NAFLD)的发生和发展与脂肪酸的摄取密切相关。本研究旨在探索Krüppel样转录因子9 (Krüppel-like factor 9, KLF9)对脂肪酸转位酶CD36、肝细胞的脂代谢以及非酒精性脂肪肝的发生和发展所产生的影响。采用高脂饮食构建的高脂模型C57BL/6J小鼠和db/db糖尿病小鼠,检测其肝脏内Klf9和Cd36基因和蛋白表达水平的变化。分离C57BL/6J小鼠原代肝细胞进行体外培养,分别给予Ad-GFP、Ad-Klf9、Ad-shCtrl或Ad-shKlf9处理,然后利用油酸和棕榈酸进行24 h的诱导;同时构建肝脏特异性Klf9基因敲除小鼠,采用Western blot检测KLF9蛋白表达水平的变化,real-time PCR检测Klf9和Cd36 mRNA表达水平的变化,试剂盒测定甘油三酯含量的变化,油红O染色检测脂质含量的变化。结果显示:(1)与对照组相比,高脂饮食诱导的肥胖小鼠或db/db糖尿病小鼠肝脏Klf9的表达显著增加;(2)在小鼠原代肝脏细胞中过量表达Klf9会增加Cd36表达水平,导致细胞脂肪含量增加;(3)相反,在小鼠原代肝脏细胞中敲低Klf9的表达则降低Cd36表达水平,从而减少肝细胞脂肪含量;(4)小鼠肝脏Klf9敲除能降低肝脏Cd36表达,改善高脂饮食诱导的脂肪肝表型。上述结果表明,肝脏KLF9通过促进CD36的表达影响肝脏的脂代谢。     

KLF7通过抑制缺氧诱导因子1α转录影响肉鸡脂肪组织发育

Krüppel样转录因子7(Krüppel-like factor 7, KLF7)是脂肪形成的负调控因子,而缺氧诱导因子1(hypoxia-inducible factor 1, HIF1)促进缺氧诱导的哺乳动物脂肪组织发育。本实验室前期利用ChIP-seq技术,发现在鸡的缺氧诱导因子1α(hypoxia-inducible factor 1 alpha, HIF1α)基因上游存在1个KLF7的结合峰,提示KLF7可能调控HIF1α基因转录。为此,本研究首先利用ChIP-PCR技术验证ChIP-seq结果,发现KLF7能够与HIF1α基因5′侧翼区结合。双荧光素酶报告基因与qRT-PCR结果显示,过表达KLF7能够显著下调HIF1α(-4 432/-4 182)的荧光素酶报告基因活性（P<0.01）,抑制HIF1α基因表达。与野生型质粒相比,将生物信息学预测的KLF7结合基序“TGCGCAGCAA”(-4 300/-4 290)缺失突变后, HIF1α(-4 432/-4 182)报告基因活性显著增强（P<0.01）。此外,选取第19代1～7周龄东北农业大学高、低脂双向选择品系肉鸡(Northeast Agricultural University broiler lines divergently selected for abdominal fat content, NEAUHLF)作为实验材料,利用qRT-PCR检测HIF1α基因在肉鸡腹部脂肪组织中的表达规律。结果显示,HIF1α在1～7周龄高脂系肉鸡中的相对表达量均高于低脂系,提示HIF1α对鸡脂肪组织发育具有促进作用。在永生化鸡前体脂肪细胞系(immortalized chicken preadipocyte cell line, ICP1)诱导分化过程中,HIF1α相对表达量逐渐升高。综上所述,HIF1α是转录因子KLF7的一个靶基因,KLF7可能通过抑制HIF1α基因转录参与鸡脂肪组织发育过程。     

饥饿对尼罗罗非鱼肌肉和肝KLF15基因节律性表达的影响

Krüppel样转录因子15 (Krüppel-like factors,KLF15)是Krüppel样转录因子家族的一员。Krüppel样转录因子家族的特征是含有3个高度保守的Cys2His2锌指结构,与DNA的CACCC元件和富含GC区连接,从而调控转录激活或抑制。KLF15在糖、脂肪酸、氨基酸代谢过程中发挥重要的调控作用。本研究克隆了尼罗罗非鱼(Oreochromis niloticus) KLF15基因全长cDNA序列,根据推测的氨基酸序列分析,发现其具有KLF15的两个典型结构域zf-H2C2-2和zf-C2H2。系统进化树的比较分析表明,尼罗罗非鱼KLF15与雪鲷(Maylandia zebra) KLF15亲缘关系最为接近。尼罗罗非鱼短期饥饿实验结果显示:正常进食状态时尼罗罗非鱼肌肉、肝中KLF15基因都呈现明显的昼夜节律性,均为昼低夜高;饥饿7 d后KLF15基因依然有显著昼夜节律性,但振幅降低,且在肝中表现出昼高夜低现象。以上结果说明尼罗罗非鱼的营养变化在一定程度上直接或间接影响KLF15基因节律性表达。     

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.