猪Oct4-EGFP多能性报告载体的构建与验证

本研究旨在构建一套猪Oct4-EGFP多能性报告载体,可在不破坏细胞的前提下研究Oct4的表达规律,从而有利于早期胚胎发育研究及干细胞的研究。试验采用无缝克隆(In-Fusion PCR cloning)技术,将Oct4启动子序列直接重组到pEGFP-N1载体上,用Oct4代替质粒pEGFP-N1中增强型绿色荧光蛋白(EGFP)原有的CMV启动子构建出Oct4-EGFP报告载体,并用脂质体转染技术转染入大白猪胎儿成纤维细胞中,分析Oct4-EGFP报告载体,表达情况。结果发现,经PCR及测序验证,成功构建了Oct4-EGFP多能性报告载体,并在孤雌囊胚上初步验证了载体的有效性;经过脂质体转染,经筛选及PCR鉴定,获得了8株整合有Oct4-EGFP多能性报告载体的转基因细胞。研究结果表明,运用无缝克隆技术可高效率构建Oct4-EGFP多能性报告载体,且获得的转基因阳性细胞可为猪胚胎早期发育和胚胎干细胞研究奠定技术基础。     

miRNA对干细胞重编程的影响

miRNA在胚胎干细胞(ES)细胞的自我更新及多能性中扮演重要角色,国内外研究结果表明,在体细胞形成诱导性多能干细胞(IPS)的过程中,许多miRNA与Sox2、Oct4和Nanog等调控因子组成调控网络。miRNA在细胞周期、重编程及表型建立过程中也起着重要的调控作用。另外,在IPS细胞形成中,miRNA很有可能代替关键转录因子。     

水牛Smad4基因的克隆及其真核表达载体的构建

为了阐明Smad4基因在水牛卵巢颗粒细胞增殖及胚胎发育中的分子机制,试验采用RT-PCR扩增并克隆水牛Smad4基因,对其核苷酸序列和蛋白质序列进行生物信息学分析,构建Smad4基因的真核表达载体,通过脂质体转染法转染体外培养的牛卵巢颗粒细胞。结果表明,试验克隆得到水牛Smad4基因编码序列,编码区全长为1 662 bp,编码553个氨基酸。通过BLAST对水牛Smad4基因的核苷酸序列进行同源性比对,结果显示,水牛Smad4基因与牛的同源性为99%,与绵羊、猪、马、人的同源性分别为98%、96%、96%和95%。系统进化树分析表明,Smad4基因在不同物种的进化过程中具有高度的保守性。试验成功构建了水牛Smad4基因的真核表达载体pEGFP-N1-Smad4,并在水牛卵巢颗粒细胞中表达出较强的绿色荧光蛋白Smad4-EGFP融合蛋白。本研究成功克隆了水牛Smad4基因,并成功构建了Smad4基因的真核表达载体,为进一步研究Smad4基因在水牛胚胎发育过程中的分子机制奠定基础。     

Cloning and Construction of Eukaryotic Expression Vector of Buffalo Smad4 Gene

This study was aimed to elucidate the molecular mecbanisms of Smad4 gene on granulose cells proliferation and embryonic development in buffalo. The Smad4 gene was amplified by RT-PCR, analyzed by bioinformatics, studied with eukaryotic vector construction, and used liposome transfection skill to transfect into the buffalo granulose cells. The results showed that Smad4 gene was cloned, the coding region was 1 662 bp, and encoded 553 amino acids. BLAST analysis showed that the buffalo Smad4 gene shared 99% of similar nucleotide sequence with Bos taurus, and shared 98%, 96%, 96% and 95% of similar nucleotide sequence with Ovis aries, Sus scrofa, Equues caballus and Homo sapiens, respectively. Phylogenetic tree analysis showed that Smad4 gene was highly conserved in different species. The buffalo pEGFP-N1-Smad4 eukaryotic expression vector was successfully constructed, and transferred into the buffalo granulose cells, and the Smad4-EGFP fusion protein was detected in the cells. The results suggested that the success cloning and construction vector of buffalo Smad4 gene laid the foundation for the research of Smad4 gene on embryo development.     

鸡RORα真核表达载体的构建及其在MSB1细胞中的表达

为构建鸡维甲酸相关孤核受体α（retinoid acid receptor related orphan receptor α,RORα）的真核表达载体,并检测其在MSB1细胞中的表达效果,本研究参照GenBank中鸡RORα基因序列（登录号：NM_001289887.1）设计特异性引物,从鸡肝脏组织中提取总RNA,经反转录合成cDNA,以此为模板进行PCR扩增,将扩增的特异性RORα基因片段连接pMD18-T载体,构建克隆载体pMD18-T-RORα,再用Sal Ⅰ和BamH Ⅰ双酶切克隆载体pMD18-T-RORα和真核表达载体pEGFP-N1,将酶切回收的RORα与pEGFP-N1片段进行连接,构建重组真核表达载体pEGFP-N1-RORα,经PCR、酶切和测序验证准确性后,将其转染MSB1细胞,于转染后48 h荧光显微镜下观察EGFP的表达情况,并采用实时荧光定量PCR检测鸡RORα在MSB1细胞中的表达水平。结果显示,从构建的重组质粒pEGFP-N1-RORα中可扩增出大小约1 600 bp的特异性片段,用Sal Ⅰ和BamH Ⅰ可切出大小约4 700和1 600 bp的两条带。实时荧光定量PCR结果显示,转染MSB1细胞48 h后,与对照组相比,重组真核表达载体转染组中鸡RORα基因mRNA水平显著增加（P<0.05）。表明本试验成功构建了鸡RORα的真核表达载体,该载体可在MSB1细胞中表达鸡RORα,为进一步研究鸡RORα对MSB1细胞增殖的影响奠定基础。     

Nanog基因的生物学功能研究进展

胚胎干细胞具有无限增殖能力和多向分化潜能决定了它在医学及生物学基础研究中具有巨大的应用潜力。探索维持胚胎干细胞特性的分子机制成为胚胎干细胞的生物学研究中的热点。研究发现与维持胚胎干细胞多能性相关的基因有Oct4、Nanog、Sox2等，其中Nanog是2003年5月末发现的一个基因，它对维持胚胎干细胞多能性起关键性作用，能够独立于L1F/Stats维持ICM和ES细胞的多能性。几年来，Nanog的生物学功能及其与Oct4、Sox2等多能性维持基因之间的相互作用关系已有较为深入的研究。作者在综述Nanog基因的表达特征和功能的基础上，重点探讨Nanog基因表达调控以及Oct4、Sox2等多能性维持基因之间的相互作用关系，并展望其应用前景。     

干细胞中两个关键细胞因子Oct4和Sox2

胚胎干细胞(ESC)在谱系特异性标志被激活前,Oct4和Sox2蛋白水平是细胞向谱系选择发展过程中的连续临时性标志。Oct4和Sox2转录因子在启动细胞重编程、维持ESC多能性和决定其是否走向分化方面具有关键作用。它通过与靶基因调控区结合,选择性地抑制分化基因或者激活多能性基因的表达而达到调控目的。干细胞共激活复合物(SCC)是Oct4和Sox2在Nanog基因协同激活时所需要的,它直接与Oct4和Sox2相互作用并集中在Nanog和Oct4启动子部位以及大部分被Oct4和Sox2占据的基因组区域,在维持ES细胞多能性和保持基因组完整性方面发挥着重要功能。因此,对Oct4、Sox2这两个关键性细胞因子作用机制深入了解,有助于细胞重编程分子机制的进一步阐明,为干细胞的相关研究奠定基础。     

双基因共表达的"自杀性"DNA疫苗载体的改造及其体外表达特性

PCR扩增西门利克森林病毒（SFV）亚基因组启动子26S序列及人工合成Linker，将其插入基于SFV复制子的“自杀性”DNA疫苗表达载体pSCA1的多克隆位点，获得舍2个26S启动子并能同时驱动双基因共表达的“自杀性”DNA疫苗表达载体pSCA2。为了验证pSCA2的表达能力，PCR扩增绿色荧光蛋白基因EGFP和红色荧光蛋白基因DsRed2，分别插入pSCA2的2个26s启动子下游，获得EGFP和DsRed2双基因共表达的“自杀性”DNA疫苗pSCA2-EGFP／RFP。将pSCA2-EGFP／RFP转染BHK-21细胞，转染后24h，可同时观察到被转染细胞发绿色荧光和红色荧光，证实EGFP和DsRed2均获得表达。     

Sox2基因真核表达载体的构建及转Sox2基因绵羊骨髓间充质干细胞系的建立

Sox2是多能干细胞的主要标记之一,有研究发现高表达Sox2基因的神经干细胞作为供体细胞进行核移植时具有较高的重编程能力。本研究旨在通过对绵羊骨髓间充质干细胞(bonemarrowmesenchymal stem cells,BMSC) Sox2基因进行外源性增强表达,以期提高其重编程能力,从而改善动物体细胞克隆效率。试验提取绵羊胎儿生殖腺组织RNA,以其为模板克隆Sox2基因cDNA序列,装入真核表达载体pEGFP-N1,构建出pEGFP-N1-Sox2表达载体。经脂质体转染将重组质粒转染入绵羊BMSC,经G418与荧光标记双筛选后挑选单克隆并扩增培养。测序鉴定表明,克隆得到绵羊Sox2基因CDS区全长,重组质粒构建成功;荧光检测表明,成功建立表达Sox2基因的绵羊BMSC系。本研究得到了高表达Sox2基因的绵羊BMSC系,为提高体细胞克隆过程中的重编程效率提供了新思路。     

Construction of Eukaryotic Expression Vector of Sox2 Gene and Establishment of Sheep Bone Marrow Mesenchymal Stem Cell Lines Transfected with Sox2 Gene

Sox2 is one important marker of pluripotent stem cells, a study found that neural stem cells with high expression of Sox2 as donor cells showed higher reprogramming ability in nuclear transplantation.In this study, through enhancing exogenous Sox 2 gene expression of sheep bone marrow mesenchymal stem cells, in order to raise their reprogramming ability, and improve the efficiency of somatic cell cloning in animal.Total RNA was extracted from sheep testicular tissue, and with this template, Sox2 cDNA sequence was amplified and inserted into the eukaryotic expression vector pEGFP-N1 to build a recombinant vector pEGFP-N1-Sox2.The vector was transfected into the sheep bone marrow mesenchymal stem cells by liposome method, and through G418 and fluorescence screening to obtain and amplify monoclone.DNA sequencing showed that sheep Sox 2 gene CDS sequence was obtained, and recombinant plasmid was successfully constructed.Identification of fluorescence confirmed that stable sheep bone marrow mesenchymal stem cell lines transfected with Sox2 were established.This study obtained the sheep bone marrow mesenchymal stem cell lines with high expression of Sox2, and provided a new idea for raising reprogramming efficiency in the process of somatic cell cloning.     

猪RUVBL2真核表达载体的构建及其在CHO细胞中的表达

RUVBL2(RuvB-like 2)蛋白是进化上高度保守AAA+(ATPases Associated With Diverse Cellular Activities,AAA)家族成员之一,CHO(Chinese Hamster Ovary)细胞被广泛地用于表达重组DNA蛋白。为探究猪睾丸组织的RUVBL2基因是否能够在CHO细胞中表达,本实验以猪睾丸组织的cDNA为模板,PCR扩增RUVBL2目的基因,并将其克隆至pIRES2-EGFP(Mammalian Expression Vectors pIRES2-EGFP)载体上,进一步转化到DH5α中,再进行PCR、酶切及测序鉴定;将重组质粒转染到CHO细胞中,再进行荧光、RT-PCR、Western blot检测。结果显示:PCR、酶切及测序都证实了RUVBL2基因正确地插入到了载体质粒pIRES2-EGFP的多克隆位点;荧光、RT-PCR、Western blot也证实了RUVBL2基因在CHO细胞中的成功表达。本实验成功构建了猪的pIRES2-EGFP-RUVBL2真核表达载体,并证实了猪睾丸组织中的RUVBL2基因能够在CHO细胞中表达。     

关岭牛pEGFP-N3-UCP3重组真核表达载体的构建

旨在构建不含CMV启动子的pEGFP-N3-UCP3重组真核表达载体。利用PCR技术克隆UCP3基因启动子,扩增不含CMV区的pEGFP-N3载体片段,将UCP3启动子与该载体经连接、转化后,挑取阳性克隆进行PCR鉴定及测序鉴定。结果表明,成功地构建了重组载体pEGFP-N3-UCP3,为UCP3基因转录调控机制的研究奠定了基础。     

猪多潜能干细胞系的研究进展

猪多潜能干细胞是在体外建立起来的具有自我更新及三胚层分化潜能的一类干细胞,可应用于发育生物学研究、基因组编辑和疾病模型建立等各方面,在畜牧业生产及再生医学研究中具有重要的应用价值。培养体系对多潜能干细胞的成功构建具有重要意义,其包含多种成分,包括基础培养液、氨基酸等营养成分、小分子化合物(信号通路激活剂/抑制剂及细胞因子)共同维持细胞的多能性并抑制其分化。目前已有诸多关于猪多潜能干细胞的报道,但尚未获得高效的培养体系可以维持猪多潜能干细胞的长期传代并完成生殖嵌合。猪多潜能干细胞可分为原始态(Na6ve)、形成态(Formative)及始发态(Primed)3种不同多能性的状态特点,根据建系来源的不同分为猪扩展多潜能干细胞、猪胚胎干细胞、猪前原肠胚上胚层干细胞、猪诱导多能干细胞4种干细胞类型。作者综述了猪多潜能干细胞培养体系中常用的细胞因子和信号通路激活剂/抑制剂对猪多潜能干细胞的多能性和分化能力的影响和作用,为进一步建立具有真正生殖嵌合能力的Na6ve多能性的猪多潜能干细胞系提供研究思路。     

Expression of the embryonic transcription factor Oct4 in canine neoplasms: a potential marker for stem cell subpopulations in neoplasia

Neoplastic cells and stem cells share several phenotypic characteristics. Recently, numerous studies have identified adult stem cells that have been hypothesized to be the cellular origin for cancer in several tissues. Oct4 has been consistently associated with pluripotent or stemlike cells, and it is hypothesized that Oct4 is necessary for the maintenance of pluripotency. We hypothesize that Oct4-positive cells are present in all canine neoplasms and that these subpopulations of neoplastic cells might represent "cancer stem" cells. To test this hypothesis, 83 canine neoplasms representing 21 neoplastic diseases were evaluated for Oct4 expression using immunohistochemistry. The results of this study showed that all tumors included in this study contained a subpopulation of Oct4-positive cells, although the proportion of Oct4-positive cells and the intensity of immunoreactivity varied both within and between tumor types. Subpopulations of Oct4-positive cells identified in these tumors are likely to represent "cancer stem" cells and therefore might be responsible for the maintenance and propagation of the tumors. If these cells represent cancer stem cells, and are therefore responsible for the maintenance and growth of the neoplastic cellular population, then these cells should serve as relevant therapeutic targets and offer the greatest potential for curative treatment.     

Livestock induced pluripotent stem cells

Chimeric animals generated from livestock-induced pluripotent stem cells (iPSCs) have opened the door of opportunity to genetically manipulate species for the production of biomedical models, improving traits of agricultural importance and potentially providing a system to test novel iPSC therapies. The potential of pluripotent stem cells in livestock has long been recognized, with many attempts being chronicled to isolate, culture and characterize pluripotent cells from embryos. However, in most cases, livestock stem cells derived from embryonic sources have failed to reach a pluripotent state marked by the inability to form chimeric animals. The in-depth understanding of core pluripotency factors and the realization of how these factors can be harnessed to reprogram adult cells into an induced pluripotent state has changed the paradigm of livestock stem cells. In this review, we will examine the advancements in iPSC technology in mammalian and avian livestock species.     

广西巴马小型猪Oct4基因克隆及其在成纤维细胞中的表达

根据GenBank中公布的猪Oct4核苷酸序列设计合成1对引物,采用RT-PCR方法从巴马小型猪睾丸组织扩增Oct4基因编码全序列。然后将该基因重组于含有绿色荧光报告基因的真核表达载体pEGFP-N1中,构建成pEGFP-Oct4重组质粒,通过酶切电泳鉴定和DNA测序证明重组质粒构建成功。使用脂质体2000将pEGFP-Oct4转染巴马小型猪肾脏成纤维细胞,荧光显微镜下可观察到绿色荧光,转染细胞株中可检测到Oct4的转录。结果表明,成功构建了真核表达载体pEGFP-Oct4,并可在巴马小型猪肾脏成纤维细胞中表达,为进一步研究Oct4基因生物学功能奠定了基础。     

泛素化调节因子2真核表达质粒的构建及其在原代肾小管上皮细胞的表达

本试验旨在构建带有增强型绿色荧光蛋白报告基因EGFP及目的基因泛素化调节因子2(Smurf2)的真核表达载体pEGFP-N3-Smurf2,并转染小鼠肾小管上皮细胞检测其表达情况。用RT-PCR法扩增小鼠肾小管上皮细胞Smurf2的CDS区,构建克隆载体pEASY-Zero-Smurf2和真核表达载体pEGFP-N3-Smurf2,酶切并测序鉴定。运用脂质体转染法将pEGFP-N3-Smurf2真核表达载体转染小鼠肾小管上皮细胞,实时荧光定量PCR、免疫印迹检测Smurf2的表达。PCR结果显示扩增出Smurf2基因片段大小约为2247 bp;重组质粒pEGFP-N3-Smurf2的酶切鉴定及测序结果均表明Smurf2基因成功克隆到真核表达载体中;脂质体转染后检测结果显示,转染pEGFP-N3-Smurf2表达载体的肾小管上皮细胞中Smurf2基因mRNA表达量升高且EGFP-Smurf2重组蛋白有表达。本试验成功构建了含有增强型绿色荧光蛋白标记的Smurf2真核表达质粒,转染后能明显提高细胞内Smurf2的表达,为研究Smurf2基因的功能奠定了基础。     

禽类多能性干细胞研究进展

胚胎干细胞是未分化的具有增殖和自我更新能力的细胞,并且能分化成所有类型的体细胞以及生殖细胞。它们提供了早期胚胎分化的体外模型,也是基因操作的重要靶细胞。禽类多能性干细胞培养最重要的应用领域是以干细胞体外遗传修饰、鉴定为技术平台的家禽转基因技术。通过此技术对禽类基因进行遗传修饰与操作,在胚胎发育基础研究、转基因禽类生产及家禽育种等方面有巨大的应用前景。但是禽类多能性干细胞培养的许多基本问题仍亟待解决,如探索其建系的培养条件、揭示其维持多能性和增殖能力的分子机制等。文章综述了禽类多能性干细胞的分离方法、体外分化能力、嵌合体形成以及基因修饰方面的研究进展及目前的研究局限。