Expression and regulation of hFIX minigene and cDNA driven by β-casein gene in mouse mammary gland

Mammary gland specific expression vectors for human clotting factor IX (hFIX) and LacZ reporter gene driven by bovine β-casein gene were constructed. Vectors were packaged by stearylamine (SA) liposome and were transferred to lactating mice via tail vein. Both hFIX and Lac2 gene could be expressed in the mammary gland of the treated mice. The highest production of hFIX protein was 80.28 ng per mL milk, and more than 85% of hFIX protein appeared to be γ-carboxylation and biologically active. The results suggested that the 2.0 kb sequence of β-casein gene including promoter, exon 1 was effective to drive hFIX gene expression in mammary gland and intron 1 of β-casein gene had an effect on the tissue specific expression. The expression level in mouse milk injected with hFIX minigene vector containing hFIX endogenous intron 1 was increased by above 3 times of that injected with hFIX cDNA vector.     

Transgenic Mice Can Express Mutant Human Coagulation Factor IX with Higher Level of Clotting Activity

To improve the available values of transgenic animals, we produced a mutant human coagulation factor IX minigene (including cDNA and intron I) with arginine at 338 changed to alanine (R338A-hFIX) by using a direct mutation technique. The R338A-hFIX minigene was then cloned into a plasmid carrying the goat β-casein promoter to get a mammary gland-specific expression vector. The clotting activity in the supernatant of the transfected HC-11 cells increased to approximately three times more than that of wild-type hFIX. Nine transgenic mice (three females and six males) were produced, and the copy number of the foreign gene was very different, ranging from 1 to 43 in different lines. ELISA, Western blot, and clotting assay experiments showed that the transgenic mice could express R338A-hFIX, showing higher average levels of clotting activity than wild-type hFIX in the milk (103.76% vs. 49.95%). The highest concentration and clotting activity of hFIX reached 26 μg/mL and 1287% in one founder (F₀-7), which was over 10 times higher than that in human plasma. Furthermore, RT-PCR, APTT assay, and histological analysis indicated that hFIX was expressed specifically in the mammary gland without affecting the intrinsic coagulation pathway and physiologic performance of the local tissue.     

Targeting expression to the mammary gland: intronic sequences can enhance the efficiency of gene expression in transgenic mice

We are studying the tissue-specific expression of the sheep milk-whey protein gene, β-lactoglobulin. We have used sequences derived from this gene to target the expression of biomedical proteins into milk with the intention to exploit this technology in transgenic sheep as a means of protein production. In the present study, a series of β-lactoglobulin hybrid genes and β-lactoglobulin minigenes were evaluated for expression in the mammary gland of transgenic mice. In particular, we have assessed whether there is a requirement for introns for efficient transgene expression in the mammary gland, since the coding sequences of many candidate proteins are available only as cDNAs. The results suggest that the inclusion of natural introns in constructs can enhance the efficiency of transgene expression. Thus, a hybrid construct comprising 4.3 kb of the immediate 5′ flanking sequences of β-lactoglobulin fused to a genomic minigene encoding human α-antitrypsin (α₁AT) was expressed much more efficiently than an α₁AT-cDNA construct containing the same β-lactoglobulin segment. Similarly, the intact β-lactoglobulin gene was expressed more efficiently than the corresponding intronless β-lactoglobulin minigene. This effect was not seen in transient expression expriments in baby hamster kidney cells when β-lactoglobulin-α₁AT constructs were driven by SV40 enhancer sequences. The effect cannot be explained by a simple requirement for splicing, since the inclusion of the first β-lactoglobulin intron into cDNA constructs encoding human α₁AT or β-lactoglobulin itself failed to enhance the efficiency of transgene expression. It is concluded that sequence elements within introns may interact with the upstream 5′ flanking sequences of β-lactoglobulin and enable the latter to function efficiently in the mammary gland of transgenic mice.     

人促血小板生成素在转基因小鼠乳腺中定位表达的研究(英文)

通过转基因动物乳腺生物反应器大规模生产药用蛋白质已成为现代生物技术新的生长点之一。为研制表达人促血小板生成素的哺乳动物生物反应器的转基因小鼠模型,本论文以小鼠乳清酸蛋白 (mWAP) 基因5挾说骺厍团-s1-酪蛋白基因3挾说骺厍魑鹘谠菇擞糜诒泶锶舜傺“迳伤氐娜橄僮橹匾煨员泶镌靥錺WAPTPO(Fig.1)。通过常规显微注射的方法把mWAP启动子指导的hTPO表达载体导入小鼠受精卵,获得出生小鼠16只。经PCR检测,有6只为转基因阳性(Fig.2)。G0代小鼠中转基因整合率为37.5% (6/16),用ELISA方法在G0代转基因雌鼠的乳汁中检测了促血小板生成素的表达,表达量在0.8 mg/mL以上(Table 1)。这些结果表明我们已建立了乳腺表达hTPO 的转基因小鼠模型,为以后大型家畜乳腺生物反应器的研制提供了科学依据。     

Establishment of La-tPA/G-CSF dual transgenic mice and expression in their mammary gland

Expression vectors of human granulocyte colony stimulating factor (G-CSG) and long acting tissue plasminogen activator (La-tPA) in mammary gland were constructed using promoters of mouse whey acid protein gene (WAP) and sheep β-lactoglobulin gene (BLG) with sizes of 2.6 and 5 kb respectively. Two kinds of transgenic mice of G-CSF and La-tPA were produced with microinjection. The expression of G-CSF and La-tPA was achieved in mammary glands of transgenic mice, respectively. In order to establish dual transgenic mice of La-tPA /G-CSF, transgenic mice carrying G-CSF and La-tPA gene characterized with specific expression in mammary gland were mated. La-tPA/G-CSF dual transgenic mice were screened out from the hybrid offspring by Once-PCR. The co-expression of La-tPA and G-CSF in mammary gland of the dual transgenic mice was confirmed by the milk assayed and Northern blot analysis. Some parameters about the dual transgenic mice indicated that there were fewer litters than that of normal mice. The ratio of dual transgenes was 46.1% in F1 generation, and offspring’s sex ratio was normal. Hence a dual transgenic mouse model was established for the study of co-expression foreign proteins in mammary gland.     

牛乳铁蛋白肽转基因小鼠的构建

目的:探讨牛乳铁蛋白肽在转基因鼠乳汁中的表达及其抑菌活性。方法:将实验室构建并保存的包含山羊β-酪蛋白基因启动子和牛乳铁蛋白肽基因的乳腺特异表达载体PI-bcp-LfcinB,用Xho I和Nru I双酶切,得到含有全部表达盒的显微注射DNA片段,采用常规显微注射技术获得转基因小鼠。并通过对泌乳期转基因雌鼠乳腺组织的RT-PCR检测,确定了牛乳铁蛋白肽在mRNA水平的表达,同时利用琼脂板扩散法检测了转基因鼠乳汁中表达产物的抑菌活性。结果:获得了牛乳铁蛋白肽转基因小鼠,且转基因小鼠乳汁中能够表达具有抑菌活性的牛乳铁蛋白肽。结论:通过转基因动物乳腺可以获得具有生物活性的牛乳铁蛋白肽,为进一步研究抗菌肽转基因牛、培育抗乳房炎奶牛新品种以及通过建立转基因动物生物反应器进行抗菌肽的大量生产奠定了基础。     

The use of flow cytometry and fluorescein-labeled antibodies to measure specific milk proteins in bovine mammary epithelial cells

Summary A flow cytometric technique was developed to measure the relative concentration of whey protein and β-casein in individual fixed and permeabilized bovine mammary epithelial cells. Primary bovine mammary epithelial cells were compared to mammary cells isolated from explants after a 24-h incubation and a bovine mammary epithelial transfected cell line (MAC-T). Cells were incubated with rabbit anti-bovine whey protein (α-lactalbumin + β-lactoglobulin) or β-casein primary antibodies followed by a fluorescein-labeled goat anti-rabbit IgG second antibody. The number and intensity of fluorescing cells were measured using an EPICS Profile Flow Cytometer. Primary and explant cells contained 3.3 and 2.8 times more whey protein than MAC-T cells. Explant epithelial cells contained 2.9 and 5.1 times more β-casein than primary or MAC-T cells. The higher concentrations of specific proteins within the cells was attributed to either greater synthesis or reduced secretion. These data show that flow cytometry is capable of detecting differences in milk protein concentration in different mammary epithelial cell types.     

The last intron of the human thrombopoietin gene enhances expression in milk of transgenic mice

Introns can enhance gene expression levels. This effect is known as intron-mediated enhancement, which is different from that of enhancers or promoters. In our previous study, under the control of the cytomegalovirus or goat β-casein promoter, the vector containing intron V-TPOcDNA expressed the highest thrombopoietin (TPO) level, whereas the vector containing TPOgDNA expressed the lowest level. In order to verify whether intron V also improves TPO expression in the milk of transgenic mice, rat whey acidic protein promoter was used as regulatory element to construct mammary gland expression vectors including pTPOWA (containing TPOcDNA), pTPOWB (containing intron V-TPOcDNA), and pTPOWC (containing TPOgDNA). These vectors were transfected into HC-11 cells and the supernatants were analyzed at 48 h. The highest TPO level was found in pTPOWB (795 pg/mL) and the lowest level in pTPOWC (193 pg/mL). Then, corresponding vectors were microinjected into fertilized mice zygotes. Transgenic mice were identified by polymerase chain reaction and Southern blot. Enzyme-linked immunosorbent assay was performed to measure TPO levels in the milk of lactating transgenic mice. The highest and lowest TPO levels were found in transgenic mice carrying intron V-TPOcDNA (2,307 pg/mL) and in transgenic mice carrying TPOgDNA (242 pg/mL), respectively. Thus, intron V remarkably improved TPO expression in transgenic mice.     

Developmental alterations in expression and subcellular localization of antizyme and antizyme inhibitor and their functional importance in the murine mammary gland

Ornithine decarboxylase (ODC), antizyme (AZ), and antizyme inhibitor (AIn) play a key role in regulation of intracellular polyamine levels by forming a regulatory circuit through their interactions. To gain insight into their functional importance in cell growth and differentiation, we systematically examined the changes of their expression, cellular polyamine contents, expression of genes related to polyamine metabolism, and β-casein gene expression during murine mammary gland development. The activity of ODC and AZ1 as well as putrescine level were low in the virgin and involuting stages, but they increased markedly during late pregnancy and early lactation when mammary cells proliferate extensively and begin to augment their differentiated function. The level of spermidine and expression of genes encoding spermidine synthase and AIn increased in a closely parallel manner with that of casein gene expression during pregnancy and lactation. On the other hand, the level of spermidine/spermine N ¹-acetyltransferase (SSAT) mRNA and AZ2 mRNA decreased during those periods. Immunohistochemical analysis showed the translocation of ODC and AIn between the nucleus and cytoplasm and the continuous presence of AZ in the nucleus during gland development. Reduction of AIn by RNA interference inhibited expression of β-casein gene stimulated by lactogenic hormones in HC11 cells. In contrast, reduction of AZ by AZsiRNA resulted in the small increase of β-casein gene expression. These results suggested that AIn plays an important role in the mammary gland development by changing its expression, subcellular localization, and functional interplay with AZ.     

Expression and function of leptin and its receptor in mouse mammary gland

Leptin is an autocrine and paracrine factor which affects the development of duct, formation of gland alveolus, expression of milk protein gene and onset involution of mammary gland. In order to know the function and mechanism of leptin in mammary gland, the protein expression and localization of leptin and its long form receptor (OB-Rb) were detected by a confocal laser scanning microscope. To study the impacts of leptin on mammary gland and leptin signal transduction pathway in pregnancy-, lactation-and involution-stage mammary gland, explants were cultured and Western blotting was used. The results showed that in the whole development cycle of mammary gland, the expression of leptin and OB-Rb was in positive correlation. In virgin the leptin expression was the highest and then decreased in pregnancy. In lactation the expression of leptin was low and upgraded in involution, and recovered to the original level about virgin on involution 13 d. The localization of leptin and OB-Rb revealed that leptin induced the expression of OB-Rb specifically and controlled the development and physiological function of the mammary gland by binding to OB-Rb. In pregnancy stage, leptin stimulated proliferation and differentiation of ductal epithelial cells by JAK-MAPK signal pathway. In lactation, leptin induced gene expression of β-casein by JAK-STAT5 signal pathway, and in involution leptin induced mammary epithelial cell apoptosis and mammary gland restitution by JAK-STAT3 signal pathway.     

Expression and function of leptin and its receptor in mouse mammary gland

Leptin is an autocrine and paracrine factor which affects the development of duct, formation of gland alveolus, expression of milk protein gene and onset involution of mammary gland. In order to know the function and mechanism of leptin in mammary gland, the protein expression and localization of leptin and its long form receptor (OB-Rb) were detected by a confocal laser scanning microscope. To study the impacts of leptin on mammary gland and leptin signal transduction pathway in pregnancy-, lacta-tion-and involution-stage mammary gland, explants were cultured and Western blotting was used. The results showed that in the whole development cycle of mammary gland, the expression of leptin and OB-Rb was in positive correlation. In virgin the leptin expression was the highest and then decreased in pregnancy. In lactation the expression of leptin was low and upgraded in involution, and recovered to the original level about virgin on involution 13 d. The localization of leptin and OB-Rb revealed that leptin induced the expression of OB-Rb specifically and controlled the development and physiological function of the mammary gland by binding to OB-Rb. In pregnancy stage, leptin stimulated proliferation and differentiation of ductal epithelial cells by JAK-MAPK signal pathway. In lactation, leptin induced gene expression of β-casein by JAK-STAT5 signal pathway, and in involution leptin induced mammary epithelial cell apoptosis and mammary gland restitution by JAK-STAT3 signal pathway.     

TPO内含子Ⅴ可显著增强人血小板生成素基因在乳腺细胞中的表达

人血小板生成素（thrombopoietin,TPO）基因组包括6个外显子和5个内含子,内含子在其表达过程中可能扮演着重要作用.为了研究人TPO基因组中不同内含子对TPO表达的影响,构建可在转基因动物乳腺中高水平表达人TPO的乳腺特异性表达质粒.本研究以65 kb的山羊β-casein启动子为调控元件,构建了包括人TPO cDNA(pTPOA)、TPO intronⅠ-TPO cDNA (pTPOB)、ΔTPO intronⅠ-TPO cDNA (pTPOC)、TPO intronⅤ-TPO cDNA (pTPOD)和TPO gDNA (pTPOE)等5种TPO乳腺特异性表达质粒,并在人乳腺细胞HC-11细胞上进行了瞬间表达研究.在转染48 h后,通过双抗体夹心的ELISA方法定量分析上述质粒在HC-11细胞上的表达水平.结果表明,含有内含子Ⅴ的 pTPOD的表达量最高,而含有整个基因组TPO的pTPOE表达水平最低.为了进一步证实pTPOD可在乳腺细胞中高水平表达,将pTPOD经脂质体包埋后注射到泌乳期山羊的乳腺中.结果显示,在山羊乳汁中可连续14 d检测到人TPO的表达.上述实验证实,人TPO基因组中的内含子V可显著提高TPO在HC-11细胞内的表达水平,并提示内含子Ⅴ中可能含有特殊的调控序列.     

Transferrin is a major mouse milk protein and is synthesized by mammary epithelial cells

Summary We have identified a major mouse milk protein as transferrin (Tf) using immunoprecipitation, 2-dimensional electrophoresis, Ouchterlony diffusion and V-8 protease digests. We show that Tf is synthesized by mammary epithelial cells themselves and that its synthesis and secretion is regulated distinctly from that of other milk proteins. In culture, the kinetics of Tf synthesis and secretion are distinct from that of β-casein; furthermore, Tf is relatively insensitive to lactogenic hormones whereas β-casein is hormone-dependent.In vivo, however, Tf is regulated by pregnancy. While the virgin gland produces small amounts of Tf, its production is greatly increased during pregnancy and lactation. Thus, Tf synthesis in the mammary gland is modulated by as yet unknown factorsin vivo. These observations are discussed in terms of Tf’s possible role in mammary gland growth, differentiation and function. This research was supported by the OHER office of U. S. DOE, contract DE-AC 03-76S F00098, and NIH grant BRSG RR05918. Editor’s Statement This study combines cultured cells and direct analytical approaches to show that authentic transferrin is a major mouse milk protein and is regulated differently than beta-casein in mammary epithelium. Wallace L. McKeehan     

A 3,387?bp 5′-flanking sequence of the goat alpha-S1-casein gene provides correct tissue-specific expression of human granulocyte colony-stimulating factor (hG-CSF) in the mammary gland of transgenic mice

A new expression vector containing the 1,944 bp 5'-flanking regulatory region together with exon 1 and intron 1 of the goat alpha-S1-casein gene (CSN1S1), the full-sized human granulocyte colony-stimulating factor gene (hGCSF) and the 3'-flanking sequence of the bovine CSN1S1, was created. The vector DNA was used for generation of four mouse transgenic lines. The transgene was integrated into chromosomes 8 and 12 of two founders as 2 and 5 copies, respectively. Tissue-specific secretion of hG-CSF into the milk of transgenic mice was in the range of 19-40 μg/ml. RT-PCR analysis of various tissues of the transgenic mice demonstrated that expression of hGCSF was detected in only the mammary gland in the progeny of all founders. Moreover, cells were shown to be positive for hG-CSF by immunofluorescent analysis in the mammary glands but not in any other tissues. There were no signs of mosaic expression in the mammary gland. Trace amounts of hG-CSF were detected in the serum of females of two transgenic lines during lactation only. However, no transgenic mice showed any changes in hematopoiesis based on the number of granulocytes in blood. Immunoblotting of hG-CSF in the milk of transgenic mice revealed two forms, presumably the glycosylated and non-glycosylated forms. The hematopoietic activity of hG-CSF in the milk of transgenic females is comparable to that of recombinant G-CSF. In general, the data obtained in this study show that the new expression vector is able to provide correct tissue-specific expression of hG-CSF with high biological activity in transgenic mice.     

Expression of functional recombinant human factor IX in milk of mice

Human factor IX is synthesized in the liver and secreted in the blood, where it participates in a group of reactions involving coagulation factors and proteins that permit sanguinary coagulation. In this work two lines of transgenic mice were developed to express the FIX gene in the mammalian glands under control of milk β-casein promoter. The founding females secreted the FIX in their milk (3% total soluble protein). The stable integration of transgene was confirmed by southern blot analysis. The presence of the FIX recombinant protein in the milk of transgenic females was confirmed by western blot and the clotting activity was revealed in blood-clotting assays. The coagulation activity in human blood treated with recombinant FIX increased while the time of coagulation decreased. Our results confirm the production of a large amount of recombinant biologically active FIX in the mammary gland of transgenic mice.     

Skeletal muscle-specific expression of human blood coagulation factor Ⅸ rescues factor Ⅸ deficiency mouse by AAV-mediated gene transfer

The efficacy of recombinant adeno-associated virus (AAV) vector to deliver and express human blood clotting factor DC (hFIX) gene in skeletal muscle of coagulation factor IX deficiency mouse strain (FactorIX-knockout) is e-valuated. The muscle creatine kinase enhancer (MCK) and βactin promoter ((3A) were used to drive the hFIX minigene (hFIXml), which was flanked by AAV inverted terminal repeats (ITRs). Following intramuscular injection of high liter (2.5 x 1011 vector genomes/mL) of AAV, increased hFIX expression (256 ng/mL of plasma) was achieved. The time course of hFIX expression demonstrated that the expression level gradually increased over a period of two weeks before anti-hFIX antibodies developed in mouse circulating plasma. Those results provided a promising evidence that rAAV-me-diated gene transfer and skeletal muscle-specific expression of hFIX is a feasible strategy for treating patients for hemophilia B.     

Accurate spatial and temporal transgene expression driven by a 3.8-kilobase promoter of the bovine β-casein gene in the lactating mouse mammary gland

The spatial, temporal, and hormonal pattern of expression of the β-casein gene is highly regulated and confined to the epithelial cells of the lactating mammary gland. Previous studies have shown that 1.7 kb of the bovine β-casein promoter were able to drive cell-specific and hormone-dependent expression to a mouse mammary cell line but failed to induce accurate expression to the mammary gland of transgenic mice. We investigated here the ability of 3.8 kb of the bovine β-casein gene promoter to drive the expression of the human growth hormone (hGH) gene in transgenic mice. A Northern blot analysis using total RNA obtained from different tissues of lactating and nonlactating females revealed the presence of hGH mRNA only in the mammary gland of lactating females. hGH mRNA was not detectable in the mammary gland of virgin females or males. A developmental analysis showed that hGH mRNA only peaked on parturition, resembling more closely the bovine β-casein temporal expression pattern rather than the murine. In situ hibridization studies performed on mammary gland sections showed that the cellular pattern of hGH expression was homogeneous in all lobules from heterozygous and homozygous transgenic mice. Silver grain counts on the tissue sections highly correlated with the hGH contents in the milk determined by radioimmunoassay (r = 0.996). Thus 3.8 kb of the bovine β-casein promoter direct a high-level expression of a reporter gene to the lactating mammary gland of transgenic mice in a tissue-specific and developmentally regulated manner. Mol. Reprod. Dev. 49:236–245, 1998. © 1998 Wiley-Liss, Inc.     

Maintenance of milk protein gene expression in a subpopulation of 7,12-dimethylbenz (a) anthracene-induced rat mammary carcinoma cells grown on attached collagen gels

Summary Milk protein gene expression was studied in cell subpopulations of 7,12-dimethylbenz(a)anthracene-induced rat mammary carcinoma cells enriched or depleted for casein production grown on attached collagen gels. Culture of these cells in the presence of 10% fetal bovine serum, insulin (5 μg/ml), hydrocortisone (10 μg/ml), and prolactin (5 μg/ml) maintained α-, β-, and γ-casein and whey acidic protein mRNAs at levels identical to cells isolated from perphenazine-treated rats. Whey acidic protein mRNA levels in the tumor cells relative to the 14-d lactating gland were greater than those of the casein mRNAs. Withdrawal of prolactin from the casein-producing cells resulted in the loss of all four milk protein mRNAs. Subsequent addition of prolactin to the withdrawn cells caused a rapid accumulation of these mRNAs to prewithdrawal levels. Milk protein gene expression in this tumor cell subpopulation is modulated by prolactin (in the presence of insulin and hydrocortisone) in a similar manner to that observed in the normal mammary gland when these tumor cells are cultured on attached collagen gels. This work was supported by National Institutes of Health grant CA 16303. M. L. Johnson was the recipient of NIH Fellowship, HD 06157.