Plant‐produced human growth hormone shows biological activity in a rat model

Plants have been shown to be efficient systems for expressing a wide range of recombinant proteins from various origins. Here, using a plant virus‐based expression vector to produce human growth hormone (hGH) in Nicotiana benthamiana plants, we demonstrate, for the first time, that the plant‐produced hGH (pphGH) is biologically active in a hypophysectomized rat model. We observed an average weight gain of ～17 g per animal in a group of 10 animals that were injected subcutaneously with pphGH with 60 μg/dose for 10 days. With the increasing demand for hGH, accompanied with the need to make this recombinant protein available to a wider population at a more reasonable cost, plants provide a feasible alternative to current production platforms. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Porcine growth hormone gene expression from viral promoters in transgenic swine

Abstract

The production of porcine growth hormone (pGH) from novel expression vectors containing the promoter/enhancer elements of the Moloney murine leukemia virus (MLV) LTR or the human cytomegalovirus (CMV) immediate early gene was examined in transgenic swine. Both fusion genes resulted in elevated levels of serum pGH, elevation of insulin‐like growth factor 1 (IGF‐1), and a pronounced decrease in carcass fat deposition. The two viral promoter/enhancer elements were constitutively active in the transgenic swine throughout the life of the animals. In individual swine, the CMV‐pGH transgene was expressed predominantly in the pancreas while the MLV‐pGH transgene was expressed in a wide variety of tissues. These swine were infertile, had insulin resistance, and demonstrated an accelerated form of osteochondritis dissicans. Our results show that excess pGH produces a phenotype identical to that seen in swine expressing heterologous growth hormones, and provides a baseline for assessing the overall efficiency of producing transgenic swine. Furthermore, our data suggests that unregulated pGH production, even at 15 times normal levels and independent of the tissue source, has adverse effects that outweigh the desired reduction in carcass fat deposition in transgenic swine.     

Generation of a prostate epithelial cell-specific Cre transgenic mouse model for tissue-specific gene ablation

To facilitate the elucidation of the genetic events that may play an important role in the development or tumorigenesis of the prostate gland, we have generated a transgenic mouse line with prostate-specific expression of Cre recombinase. This line, named PB-Cre4, carries the Cre gene under the control of a composite promoter, ARR2PB which is a derivative of the rat prostate-specific probasin (PB) promoter. Based on RT-PCR detection of Cre mRNA in PB-Cre4 mice or Cre-mediated activation of LacZ activity in PB-Cre4/R26R double transgenic mice, it is conclusively demonstrated that Cre expression is post-natal and prostatic epithelium-specific. Although the Cre recombination is detected in all lobes of the mouse prostate, there is a significant difference in expression levels between the lobes, being highest in the lateral lobe, followed by the ventral, and then the dorsal and anterior lobes. Besides the prostate gland, no other tissues of the adult PB-Cre4 mice demonstrate significant Cre expression, except for a few scattered areas in the gonads and the stroma of the seminal vesicle. By crossing the PB-Cre4 animals with floxed RXRalpha allelic mice, we demonstrate that mice, whose conventional knockout of this gene is lethal in embryogenesis, could be propagated with selective inactivation of RXRalpha in the prostate. Taken together, the results show that the PB-Cre4 mice have high levels of Cre expression and a high penetrance in the prostatic epithelium. The PB-Cre4 mice will be a useful resource for genetic-based studies on prostate development and prostatic disease.     

Effective gene therapy in a mouse model of prion diseases

Classical drug therapies against prion diseases have encountered serious difficulties. It has become urgent to develop radically different therapeutic strategies. Previously, we showed that VSV-G pseudotyped FIV derived vectors carrying dominant negative mutants of the PrP gene are efficient to inhibit prion replication in chronically prion-infected cells. Besides, they can transduce neurons and cells of the lymphoreticular system, highlighting their potential use in gene therapy approaches. Here, we used lentiviral gene transfer to deliver PrPQ167R virions possessing anti-prion properties to analyse their efficiency in vivo. Since treatment for prion diseases is initiated belatedly in human patients, we focused on the development of a curative therapeutic protocol targeting the late stage of the disease, either at 35 or 105 days post-infection (d.p.i.) with prions. We observed a prolongation in the lifespan of the treated mice that prompted us to develop a system of cannula implantation into the brain of prion-infected mice. Chronic injections of PrPQ167R virions were done at 80 and 95 d.p.i. After only two injections, survival of the treated mice was extended by 30 days (20%), accompanied by substantial improvement in behaviour. This delay was correlated with: (i) a strong reduction of spongiosis in the ipsilateral side of the brain by comparison with the contralateral side; and (ii) a remarkable decrease in astrocytic gliosis in the whole brain. These results suggest that chronic injections of dominant negative lentiviral vectors into the brain, may be a promising approach for a curative treatment of prion diseases.     

Sexual dimorphism and growth hormone regulation of a hybrid gene in transgenic mice.

The sexually dimorphic expression of the urinary protein genes of mice (Mup genes) in the liver is mediated by the different male and female temporal patterns of circulating GH. Normal females were induced to male levels when GH was administered by injection to mimic the male GH pattern, showing that expression at the male level does not require a male sex steroid status in addition to intermittent GH. Two Mup-alpha 2u-globulin hybrid transgenes with different Mup gene promoters showed sexually dimorphic expression, and their expression in females increased to male levels upon testosterone treatment. GH-deficient (lit/lit) mice did not express these transgenes, and GH-deficient females did not respond to testosterone treatment, showing that GH was required for induction. Both normal and GH-deficient females were induced to male levels when GH was administered by injection. This is the first report of a transgene responsive to GH. A transgene consisting of a Mup promoter fused to a Herpes simplex virus thymidine kinase reporter sequence also showed sexual dimorphism, although to a lesser degree. It was expressed at the same level in normal females and GH-deficient mice of both sexes and was induced when GH-deficient mice were treated with GH. We propose that this transgene has a basal constitutive expression, possibly due to the absence of any rodent DNA downstream of the promoter. Since expression of the transgene was significantly induced by GH, the GH response is due at least in part to sequences in the promoter region.     

The fibroblast growth factor-2 is not essential for melanoma formation in a transgenic mouse model

Fibroblast growth factor 2 (FGF2) has been assigned a role in melanocyte proliferation and in development of human cutaneous melanoma. We have used a transgenic mouse melanoma model in combination with mice lacking mouse FGF2 to analyse the possible implication of FGF2 in melanomagenesis. Tyr::N-rasQ61K transgenic mice which are deficient for FGF2 and the tumor suppressors p16INK4a and p19ARF are hyperpigmented and develop cutaneous metastasizing melanoma, with no difference to mice wildtype for FGF2. We conclude from our data, that FGF2 is not essential for melanoma progression and metastasis.     

Production of transgenic rabbits and mice carrying the gene for bovine growth hormone

The results of experiments on the transfer of bovine gene for growth hormone into mice and rabbits are presented. The gene was transferred by the technique of microinjection into the zygote. In all cases transgene in rabbits occurred to be changed. In two transgenic mice the bovine growth hormone gene represented some tandem arranged copies. One of the mice had accelerated growth. This phenotypic changes is found to be inheritable.     

A bacterial artificial chromosome transgenic mouse model for visualization of neurite growth

Class III β-tubulin(Tubb3) is a component of the microtubules in neurons and contributes to microtubule dynamics that are required for axon outgrowth and guidance during neuronal development. We here report a novel bacterial artificial chromosome(BAC) transgenic mouse line that expresses Class III β-tubulin fused to m Cherry, an improved monomeric red fluorescent protein, for the visualization of microtubules during neuronal development. A BAC containing Tubb3 gene was modified by insertion of m Cherry complementary DNA downstream of Tubb3 coding sequence via homologous recombination. m Cherry fusion protein was expressed in the nervous system and testis of the transgenic animal, and the fluorescent signal was observed in the neurons that located in the olfactory bulb, cerebral cortex, hippocampal formation, cerebellum, as well as the retina. Besides, Tubb3-m Cherry fusion protein mainly distributed in neurites and colocalized with endogenous Class III β-tubulin. The fusion protein labels Purkinje cell dendrites during cerebellar circuit formation. Therefore, this transgenic line might be a novel tool for scientific community to study neuronal development both in vitro and in vivo.     

Cryptic human growth hormone gene sequences direct gonadotroph-specific expression in transgenic mice

Our laboratory reported previously that chimeric genes encoding either rat somatostatin (SS) or human GH (hGH), but containing the identical mouse metallothionein-I (MT) promoter/enhancer sequences and hGH 3'-flanking sequences, were selectively expressed in the gonadotrophs of transgenic mice. The experiments reported here were designed to identify the DNA sequences responsible for this unexpected cell-specific expression within the anterior pituitary. We produced new transgenic mice expressing fusion genes that tested separately the requirement of the MT or 3'-hGH sequences for gonadotroph expression. A fusion gene that retained the original MT and SS sequences, with a simian virus 40 polyadenylation signal exchanged for the 3'-hGH sequences, no longer directed strong pituitary expression, but was active in the liver. In contrast, a cytomegalovirus promoter/enhancer-SS-hGH fusion gene was expressed at the same high level in the anterior pituitaries of transgenic mice as the originally studied MT-SS-hGH gene. Immunohistochemical analysis indicated that pituitary expression of the cytomegalovirus promoter/enhancer-SS-hGH fusion gene was also restricted to gonadotroph cells in adult mice. These studies indicate that sequences within the 3'-flanking region of the hGH gene can direct expression of chimeric genes to pituitary cells that do not normally produce growth hormone.     

The human growth hormone gene cluster locus control region supports position-independent pituitary- and placenta-specific expression in the transgenic mouse

The human growth hormone (hGH) cluster contains five genes. The hGH-N gene is predominantly expressed in pituitary somatotropes, whereas the remaining four genes, the chorionic somatomammotropin genes (hCS-L, hCS-A, and hCS-B) and hGH-V, are expressed selectively in the placenta. In contrast, the mouse genome contains a single pituitary-specific GH gene and lacks any GH-related CS genes. Activation of the hGH transgene in the mouse is dependent on its linkage to a previously described locus control region (LCR) located -15 to -32 kilobases upstream of the hGH cluster. The sporadic, nonreproducible expression of hCS transgenes lacking the LCR suggests that they may be dependent on hGH LCR activity as well. To determine whether the hCS genes could be expressed with appropriate placental specificity, a series of five transgenic mouse lines carrying an 87-kilobase human genomic insert encompassing the majority of the hGH gene cluster and the entire contiguous LCR was established. All of the hGH cluster genes were appropriately expressed in each of these lines. High level expression of hGH was restricted to the pituitary and hCS to the labyrinthine layer of the placenta. The expression of the GH cluster genes in their respective tissues paralleled transgene copy numbers irrespective of the transgene insertion site in the host mouse genome. These studies have extended the utility of the transgenic mouse model for the analysis of the full spectrum of hGH gene cluster activation. Further, they support a role for the hGH LCR in placental hCS, as well as pituitary hGH gene activation, and expression.     

Oxidative stress in growth hormone transgenic coho salmon with compressed lifespan - a model for addressing aging

Abstract Growth hormone (GH) transgenic fish have dramatically enhanced growth rates, increased oxygen demands and reactive oxygen species production. GH-transgenic coho salmon provide an opportunity to address effects of increased metabolism on physiological aging. The objective of this study was to compare oxidative stress in wild-type (WT) and GH-transgenic (T) coho salmon (Oncorhynchus kisutch) of different ages (1 and 2 years). Antioxidant enzyme activity, protein carbonyls (PC) and glutathione (GSH, GSSG) were measured. PC correlated to growth rates in individual fish. T fish exhibited lower antioxidant enzyme activities and GSH levels compared to the WT, while levels of PC and GSSG were higher. Age affects were observed in both WT and T fish; enzyme activities and GSH decreased while PC and GSSG increased. Our results support the metabolic rate theory of aging. This study aims to be a platform for continued studies of the theories of aging using fish as model organisms.     

Tissue-specific and expression of porcine growth hormone gene in BAC transgenic mice

One of the primary goals of traditional livestock breeding is to improve growth rate and optimise body size. Growth rate can be significantly increased by integrating a growth hormone (GH) transgene under the control of a ubiquitous promoter, but while such animals do demonstrate increased growth there are also serious deleterious side-effects to the animals health. Here we report the generation and initial characterization of transgenic mice that carried a porcine BAC encoding the porcine GH gene. We show that GH expression is restricted specifically to the pituitary, is associated with elevated IGF-1 levels, and results in growth enhancement. No negative effects to the health of the transgenic animals were detected. This initial characterisation supports the use of BAC pGH transgene in livestock studies.     

Evaluation of an antisense RNA transgene for inhibiting growth hormone gene expression in transgenic rats

We compared the levels of growth hormone (GH) mRNA in the pituitary, plasma GH concentration, and altered phenotype in rats heterozygous and homozygous for an antisense RNA transgene targeted to the rat GH gene, with those in nontransgenic rats. We initially investigated whether the transgene promoter, which is connected to four copies of a thyroid hormone response element (TRE) that increases promoter activity, affected in vivo transgene expression in the pituitary of the transgenic rats. Plasma GH concentration correlated negatively with T, injection in surgically thyroidectomized heterozygous transgenic rats. There was a reduction of about ?35–40% in GH mRNA levels in the pituitary of homozygous animals compared with those in non-transgenic rats. Plasma GH concentration was significantly ?25–32 and ?29–41% lower in heterozygous and homozygous transgenic rats, respectively, compared with that in nontransgenic animals. Furthermore, the growth rates in homozygous transgenic rats were reduced by ?72–81 and ?51–70% compared with those of their heterozygous and nontransgenic littermates, respectively. The results of these studies suggested that the biological effect of GH in vivo is modulated dose-dependently by the antisense RNA transgene. The rat GH gene can therefore be targeted by antisense RNA produced from a transgene, as reflected in the protein and RNA levels. © 1995 Wiley-Liss, Inc.     

Reproductive performance of a transgenic boar carrying the bovine growth hormone gene (bGH)

The aim of this study was to obtain information on the possible influence of the bovine growth hormone gene (bGH) on gametogenesis and reproductive parameters of a 2-year-old Polish Landrace transgenic boar. The bGH gene construct had been introduced into the zygote of the boar with the use of the microinjection technique. On the basis of the available documentation we established that the fertility of the investigated transgenic (bGH) boar was low in comparison with other animals of the Polish Landrace breed, with a poor libido, ineffective matings and, on average, 3 live piglets less per litter. Samples of testis tissue from the boar were obtained after castration. In total, we observed 100 spermatocytes and all of them had normally paired bivalents. It is possible that the boar's lower fertility was caused by some, as yet unknown factor.     

转大麻哈鱼生长激素基因鲤生态安全性检测与分析

评价了转大麻哈鱼（Oncorhynchus Suckley）生长激素基因鲤生态安全性问题及研究转基因鱼对天然野生鲤群体遗传污染程度。通过RAPD和SSLP方法,用265个RAPD标记和35对鲤的微卫星标记对受杂交鲤污染的哈尔滨江段黑龙江鲤群体、未受污染的抚远江段黑龙江鲤群体及模拟转基因鲤占普通鲤群体的1%和10%比例获得繁殖子代等实验群体的DNA样本进行全基因组扫描统计分析得出结论,即转基因鲤占普通鲤群体1%时对普通群体的基因污染程度是微乎其微的,远远低于杂交鲤对野生群体基因污染,转基因鲤占普通鲤群体10%时对普通鲤遗传背景的影响稍有升高,但仍然远远低于杂交鲤对野生群体基因污染程度。总之,在现有的检测技术条件及有效的监控条件下,与杂交鲤相比转基因鲤对鲤野生群体的遗传背景的影响是微弱的,而外来种和杂交种则对生态环境有严重威胁。     

The fibroblast growth factor‐2 is not essential for melanoma formation in a transgenic mouse model

Fibroblast growth factor 2 (FGF2) has been assigned a role in melanocyte proliferation and in development of human cutaneous melanoma. We have used a transgenic mouse melanoma model in combination with mice lacking mouse FGF2 to analyse the possible implication of FGF2 in melanomagenesis. Tyr::N‐ras^Q61K transgenic mice which are deficient for FGF2 and the tumor suppressors p16^INK4a and p19^ARF are hyperpigmented and develop cutaneous metastasizing melanoma, with no difference to mice wildtype for FGF2. We conclude from our data, that FGF2 is not essential for melanoma progression and metastasis.