siRNA介导Sry基因沉默对小鼠胚胎性别决定基因表达的影响

为研究Sry基因的调控网络, 采用siRNA表达载体介导的RNAi技术, 特异性地抑制睾丸决定因子Sry在小鼠胚胎中的表达, 并观察Sry基因沉默后对在两性性腺分化中起重要作用的Wt1, Sf1, Dax1, Gata4, Sox9及Amh基因表达的影响。利用本课题组先前构建的siRNA重组表达载体(pSilencer4.1/Sry217及pSilencer4.1/Sry565), 通过尾静脉注射法导入妊娠9.5天(9.5 dpc)的母鼠体内, 在11.5 dpc时取胚胎, 对性别鉴定为雄性的胚胎以RT-PCR法和Western-blot检测Sry基因的表达抑制效果, 并同时用定量PCR法检测Wt1等上述性别决定相关基因表达变化情况。结果表明, 注射干扰质粒后48 h Sry基因的mRNA和蛋白表达水平均降低, 其中siRNA表达质粒pSilencer 4.1/Sry 565的抑制效果显著, 可达到80%的抑制率。Sry基因沉默后, Wt1基因表达量显著升高; Sf1, Dax1, Gata4, Sox9基因表达水平没有明显变化; Amh基因无表达。试验结果表明, Sry基因表达抑制会导致Wt1基因表达升高; 另外, Sry基因激活Sox9基因的表达可能需要其他的辅助因子协同作用。     

牛c-myc基因的克隆及其在皮肤成纤维细胞中的表达

为了构建包含牛c-myc基因编码序列的重组载体,以胎牛原始生殖嵴为材料,用RT-PCR方法克隆出牛c-myc 基因的编码序列,将其亚克隆至pMD19-T载体,再从酶切鉴定和测序正确的质粒上切下目的片段,定向克隆到pIRES2-AcGFP1-Nuc表达载体上,挑选序列正确的重组真核表达质粒转染牛皮肤成纤维细胞,用RT-PCR和Western blotting分别检测c-myc mRNA和蛋白的表达。结果表明,从胎牛原始生殖嵴中正确克隆了c-myc基因的全长编码序列,所构建的重组质粒能够在皮肤成纤维细胞中有效     

Sox8基因过表达诱导中华鳖ZW性腺的雄性分化

为了研究Sox8基因在中华鳖性别分化中的功能,研究利用慢病毒介导的过表达载体,在性别分化前的雌性中华鳖中过表达Sox8。通过组织学分析和生殖细胞标记蛋白VASA的免疫荧光染色发现在Sox8过表达后,50%的ZW性腺髓质区发育出睾丸特有的、含有生殖细胞的性索结构; qRT-PCR和免疫荧光结果显示雌性特异性基因Foxl2和Cyp19a1表达量显著降低,而调控睾丸发育的Dmrt1、Sox9和Amh基因表达上调。实验结果表明Sox8的过表达诱导ZW胚胎性腺往雄性方向分化,揭示了Sox8在中华鳖睾丸分化过程中的作用。     

牦牛FAF1基因的分子特征及其在不同阶段卵巢、输卵管、子宫中的表达

FAF1(Fas-associated factor-1)在多种细胞中可与Fas蛋白结合,介导细胞凋亡的启动,其基因突变可导致分裂期胚胎死亡。旨在探索牦牛FAF1基因的分子特征及其在不同阶段的生物学作用。试验选取雌性牦牛3个不同时期(卵泡期、黄体期和妊娠期第3个月,以下将妊娠期第3个月简称为妊娠期)的卵巢、输卵管和子宫,克隆牦牛FAF1基因,采用实时荧光定量PCR(qRT-PCR)、免疫组织化学和Western blot(WB)方法对其基因和蛋白的表达水平进行检测和定位。成功克隆出牦牛FAF1基因的编码区(CDS),长度为1 953 bp(GenBank登录号:MK416195),编码650个氨基酸,基因特征分析显示该基因具有高度保守性,其编码的蛋白为含5个蛋白结合位点的非跨膜、可溶性蛋白,主要分布于细胞核(52.2%)、线粒体(26.1%)、细胞质(13.0%)、高尔基体(4.3%)、细胞骨架(4.3%)。qRT-PCR结果显示:卵巢中FAF1基因在卵泡期表达最高,妊娠期次之,黄体期最低;输卵管中黄体期最高,子宫中卵泡期最高,妊娠期次之,黄体期最低;蛋白水平显示:妊娠期输卵管和子宫FAF1蛋白相对表达量显著高于卵泡期和黄体期,卵巢在黄体期的表达量最高,卵泡期次之,妊娠期最低。免疫组织化学(Immunohistochemistry,IHC)结果显示不同阶段FAF1蛋白在同一组织中表达部位并无明显的差异,在卵巢中主要表达部位为卵巢生殖上皮、颗粒细胞、卵泡膜细胞和黄体细胞(黄体期);在输卵管中主要表达部位为黏膜上皮细胞;在子宫中主要表达部位为子宫内膜细胞、子宫腺。FAF1基因和蛋白的表达存在显著差异,揭示其对牦牛的生殖生理调控具有重要意义。     

哺乳动物的性别决定相关基因的作用机理

哺乳动物的性别决定是以Sry基因为主导,其它多个基因参与的级联调控的机制。近年来的研究表明,Sry、Sox9、Wt1、Sf1、Amh、Dax1、Dmrt1、Wnt4等基因都参与性别决定的级联过程。哺育动物性别决定相关基因的研究,对性分化与生殖发育过程的了解具有十分重要的意义。主要论述了参与哺乳动物性别决定与调控的相关基因、可能作用机制及其研究进展等。     

赤链蛇不同组织Sox基因表达的RT-PCR分析

采用RT-PCR技术,研究了赤链蛇不同组织Sox基因的表达。通过PCR产物直接克隆法和SSCP技术筛选阳性克隆,分析了雄性睾丸和雌性卵巢组织中的Sox基因序列。结果显示,在赤链蛇雌雄成体组织中,Sox基因在睾丸、卵巢、脑和脾组织中均有不同程度的表达,而在雌雄成体肌肉组织中均无表达,显示该基因表达有一定的组织特异性。序列分析显示睾丸组织中表达的是DRSox3,卵巢组织中表达的是DRSox22。在Sox家族中,Sox3表达于中枢神经系统和尿生殖嵴的发育过程中;Sox22则表达于多种组织和神经系统中,可横跨CNS和PNS的整个过程。此结果表明Sox基因不仅在性别决定中起作用,还可能在胚胎发育过程中担负重要功能。     

拟南芥血红蛋白1的亚细胞定位

为研究拟南芥的血红蛋白1(AtGLB1)基因的亚细胞定位,该实验构建了拟南芥血红蛋白1基因与绿色荧光蛋白基因融合的植物表达载体pUCGFP/ AtGLB1.利用基因枪转化法将重组载体转入洋葱表皮细胞瞬时表达,通过检测融合蛋白在洋葱表皮细胞中的分布来确定拟南芥血红蛋白1在细胞中的定位.荧光显微镜检测结果表明,AtGLB1基因表达产物主要定位在细胞核中,少量定位在细胞质中.     

史氏鲟Sox9基因cDNA的克隆及在早期发育过程不同组织中的表达

利用RT-PCR和RACE的方法从史氏鲟(Acipenser schrenchii)中克隆了Sox9基因cDNA的部分序列(1140bp)。组织特异性表达分析表明Sox9基因在1^ ～3^ 年龄史氏鲟的大脑、心脏、肝脏、眼睛、胰脏、肾脏、精巢和卵巢等8种组织中均有表达,只是表达量随发育阶段和组织的不同而稍有差异。刚孵出1日龄的史氏鲟鱼苗中Sox9微量表达,而孵出15日龄的鱼苗中表达量上升。1^ ～3^ 年龄的史氏鲟精巢和卵巢中Sox9基因均表达,说明Sox9基因在史氏鲟性别分化过程中所起的作用不明显。Sox9基因在史氏鲟不同发育时期的8种组织中广泛表达,这可能与Sox9基因在脊椎动物软骨分化过程中的功能保守性有关。     

小鼠胚胎干细胞中天然反义转录物的表达及功能研究

非编码RNA(ncRNA),如小分子RNA和基因间长链非编码RNA在调控多能性方面发挥着重要的作用.然而,天然反义转录物(NAT)在胚胎干细胞中的作用并不清楚.本研究首先通过数字基因表达谱发现在小鼠胚胎干细胞中存在广泛的NAT表达,随后证实了Oct4,Nanog和Sox2这3个关键的多能性基因存在NAT的表达.并且,过表达Sox2的NAT可以在蛋白水平上降低Sox2的表达,同时在转录水平上对Sox2有轻微的上调作用.总之,本研究数据表明,NAT和其他的ncRNA一样,参与了多能性的维持.     

拟南芥谷氧还蛋白GRXC9负调控叶片大小

谷氧还蛋白(GRX)是一类以CXXC/S基序为活性位点的小分子热稳定蛋白,参与多种谷胱甘肽依赖的氧化还原反应。通过对该家族的GRXC9基因进行克隆、表达、亚细胞定位及功能分析,结果表明,GRXC9基因表达无组织特异性,在拟南芥(Arabidopsis thaliana)的根、茎、叶、花和角果中均能表达,此结果与GUS显色结果基本一致。GRXC9-GFP定位于细胞质和细胞核中,过表达GRXC9的株系叶片明显小于野生型;进一步观察发现,其叶片栅栏细胞明显变小,而细胞总数与野生型差距不大。叶片大小相关基因的表达分析结果表明,过表达株系中AN、LNG1和LNG2的表达量明显下降,说明GRXC9可能通过抑制这些基因的表达从而导致叶片短小。综上所述,GRXC9可能在调控叶片发育方面发挥关键作用。     

SOX9 regulates prostaglandin D synthase gene transcription in vivo to ensure testis development

In mammals, male sex is determined by the Y-chromosomal gene Sry (sex-determining region of Y chromosome). The expression of Sry and subsequently Sox9 (SRY box containing gene 9) in precursors of the supporting cell lineage results in the differentiation of these cells into Sertoli cells. Sertoli cells in turn orchestrate the development of all other male-specific cell types. To ensure that Sertoli cells differentiate in sufficient numbers to induce normal testis development, the early testis produces prostaglandin D(2) (PGD(2)), which recruits cells of the supporting cell lineage to a Sertoli cell fate. Here we show that the gene encoding prostaglandin D synthase (Pgds), the enzyme that produces PGD(2), is expressed in Sertoli cells immediately after the onset of Sox9 expression. Promoter analysis in silico and in vitro identified a paired SOX/SRY binding site. Interestingly, only SOX9, and not SRY, was able to bind as a dimer to this site and transactivate the Pgds promoter. In line with this, a transgenic mouse model showed that Pgds expression is not affected by ectopic Sry expression. Finally, chromatin immunoprecipitation proved that SOX9 but not SRY binds to the Pgds promoter in vivo.     

In vitro Cre/loxP system in cells from developing gonads: investigation of the Sry promoter

There have been few studies on the regulatory elements of the Sry gene, mainly because no Sry-expressing cell lines have yet been established. This paper describes a useful tool for investigating the regulation and upstream region of Sry by means of the in vitro Cre/loxP system. Using plasmids containing the 9.9 kb mouse genomic Sry previously shown to induce testis development in XX transgenic mice, we constructed a Sry/Cre fusion gene plasmid in which Cre expression is controlled by the 5' and 3' untranslated regions of mouse Sry. To distinguish between male and female gonads of 11.5 days post-coitus (d.p.c.) fetuses, double transgenic fetuses carrying both the CAG (cytomegalovirus enhancer and beta-actin promoter)/loxP/lacZ transgene on the autosome and the green fluorescent protein transgene ubiquitously expressed on the Y chromosome were produced by crossing between two transgenic mouse lines. When Sry/Cre plasmids were transfected into the cells that had been prepared from the gonads, brains and livers of double transgenic fetuses, only a small number of X-gal-stained cells were detected among the primary cultured cells from male and female gonads, and none were detected among the cells from the other tissues. The X-gal-positive cells were negative for alkaline phosphatase, indicating that these cells were somatic cells expressing Sry. The Sry/Cre plasmids with a 0.4 kb upstream region of Sry yielded a large number of X-gal-positive cells in the cells from gonads, including various tissues of 11.5 d.p.c. fetuses, indicating the loss of the tissue-specific expression of Sry. The Sry/Cre with a 1.4 kb upstream region maintained tissue-specific activity of Sry. The results indicate that the present in vitro Cre/loxP system using transgenic mice is a simple and useful system for investigating the regulatory element of sex determination-related genes, including Sry.     

From SRY to SOX9: mammalian testis differentiation

Sry (sex-determining region on the Y chromosome) is a master gene that initiates testis differentiation of the bipotential indifferent gonad in mammals. In mice, Sry expression is transiently activated in a center-to-pole wave along the anteroposterior (AP) axis of developing XY gonads. Shortly after the onset of Sry activation, Sox9 (Sry-related HMG box-9), a fundamental testis-differentiation gene common to all vertebrates, is also activated in a center-to-pole pattern similar to the initial Sry expression profile. Several male-specific cellular events, such as glycogenesis, coelomic epithelium proliferation, mesonephric migration and vasculogenesis, are induced in XY gonads following the onset of Sry and Sox9 expression. This paper mainly focuses on recent advances in elucidating the regulatory mechanisms of Sry and Sox9 expression and male-specific cellular events immediately downstream of SRY action during the initial phases of testis differentiation.     

DNA methylation-mediated control of Sry gene expression in mouse gonadal development

DNA methylation at CpG sequences is involved in tissue-specific and developmentally regulated gene expression. The Sry (sex-determining region on the Y chromosome) gene encodes a master protein for initiating testis differentiation in mammals, and its expression is restricted to gonadal somatic cells at 10.5-12.5 days post-coitum (dpc) in the mouse. We found that in vitro methylation of the 5'-flanking region of the Sry gene caused suppression of reporter activity, implying that Sry gene expression could be regulated by DNA methylation-mediated gene silencing. Bisulfite restriction mapping and sodium bisulfite sequencing revealed that the 5'-flanking region of the Sry gene was hypermethylated in the 8.5-dpc embryos in which the Sry gene was not expressed. Importantly, this region was specifically hypomethylated in the gonad at 11.5 dpc, while the hypermethylated status was maintained in tissues that do not express the Sry gene. We concluded that expression of the Sry gene is under the control of an epigenetic mechanism mediated by DNA methylation.