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At least 343 records · Page 19Linked to original sources
PubMed1998

Interactive effects of c-myc and transforming growth factor alpha transgenes on liver tumor development in simian virus 40 T antigen transgenic mice.

To analyze the effects of c-myc and transforming growth factor alpha (TGFalpha) on hepatocarcinogenesis induced by simian virus 40 T antigen (TAg), livers from single and bitransgenic mice, 3 to 11 mice per line, were examined morphologically 1 to 8 weeks after birth. Mice carrying c-myc or TGFalpha alone exhibited centrilobular hypertrophy and increased apoptosis (c-myc mice only) of hepatocytes after 3 or 4 weeks of age, but no detectable changes in cell proliferation or proliferative lesions were observed in either line during the 8 weeks. Mice carrying TAg alone exhibited increased cell proliferation, apoptosis, and dysplasia of hepatocytes with notably high mitotic and apoptotic indices as major changes before development of putative preneoplastic lesions after 4 weeks of age and neoplastic lesions after 6 weeks. In bitransgenic mice coexpressing c-myc or TGFalpha with TAg, nonproliferative lesions and mitotic and apoptotic indices were similar to those in mice carrying TAg alone. In TAg x c-myc bitransgenic mice, however, both preneoplastic and neoplastic lesions developed sooner and grew more rapidly than those in TAg mice, whereas in TAg x TGFalpha bitransgenic mice, rapid tumor growth was the principle observation. Because of the effects of transgene coexpression, livers from TAg x c-myc and TAg x TGFalpha mice had multiple tumors as early as 3 and 6 weeks of age, respectively. The results indicate cooperative functions of c-myc and TGFalpha with TAg during development and/or growth of liver tumors in vivo.

Animals↗
PubMed1990

[Evaluation of separating X- and Y-sperms by percoll density gradient centrifugation using sperms of transgenic mice carrying a transgene on Y-chromosome].

Using sperms of the transgenic mice carrying a human A gamma/beta-globin gene on Y-chromosome, we attempted to separate X- and Y-bearing sperms by the Percoll density gradient centrifugation. The ratio of X- and Y-sperms was determined by DNA dot blot hybridization procedure with sperm DNA. Sperm suspension collected from cauda epididymidis was loaded on the gradient composed of 7 Percoll concentrations (35-84%) and was centrifuged at 300 x g for 10, 15 or 20 minutes, respectively, at room temperature. After centrifugation, sperms were collected from each gradient fraction and washed with 0.85% saline solution. DNA was extracted from sperms, dotted and fixed on nitrocellulose filter, and was hybridized with the 32P-labeled DNA probe derived from the beta-globin gene. Each DNA spot was cut out, immersed in the liquid scintillator and was counted for radioactivity. There was no difference among the radioactivities in the DNA spots, indicating that the ratio of X- and Y-sperms was the same in all the gradient fractions of three different centrifugal conditions. The results suggests to be difficult to separate X- and Y-sperms by Percoll density gradient centrifugation, at least, using sperms from cauda epididymidis of mouse.

Animals↗
PubMed2003

IL-23 production by cosecretion of endogenous p19 and transgenic p40 in keratin 14/p40 transgenic mice: evidence for enhanced cutaneous immunity.

p40, the common subunit of the proinflammatory cytokines IL-12 and IL-23, is produced by resident skin cells. Whereas the in vivo effects of IL-12 are well established, little is known about the role of IL-23 in cutaneous immune responses. In this study we show that p40 transgenic (TG) mice constitutively produce IL-23 (p19/p40), but not IL-12 (p35/p40), in basal keratinocytes by cosecretion of TG p40 with endogenous p19. Repeated injections of rIL-23 in littermate (LM) mice result in an inflammatory skin disease similar to that of p40 TG mice, confirming the proinflammatory activity of IL-23. Furthermore, IL-23 secretion by p40 TG keratinocytes induces elevated numbers of Langerhans cells (LC) with a marked up-regulation of costimulatory molecules, indicating advanced maturation of keratin 14 (K14)/p40 LC when compared with LM LC. At the functional level, freshly isolated K14/p40 LC greatly exceeded LC from LM animals in their capacity to stimulate allogeneic T cell proliferation. To assess whether IL-23 regulates cutaneous immune responses in vivo, we used an allogeneic skin transplantation model. Full thickness skin grafts from K14/p40 donors (H-2(q)) transplanted across a MHC class I and class II barrier onto BALB/c (H-2(d)) recipients were rejected in a significantly accelerated fashion (mean survival time: 8.8 days) when compared with skin grafts from non-TG LM (H-2(q)) (mean survival time: 10.7 days, p < 0.01). Based on these results we propose that IL-23-induced changes of LC may be an important mechanism in directing the outcome of cutaneous immune responses.

Animals↗
PubMed1990

Specificity and frequency of primary anti-HLA cytotoxic T lymphocytes in normal and HLA-B27.2-, HLA-B27.5-, and HLA-Cw3-transgenic mice. A transgenic model for MHC xenoantigen recognition.

Previous studies have shown that the lymphocytes of naive mice produce a strong primary CTL responses in vitro to human MHC class I Ag presented by HLA-transgenic mouse (TGM) cells. A limiting dilution (LD) assay was used to analyze this xenoreactive CTL repertoire in mice. Frequencies of HLA class I-specific CTL precursors (CTLp) were estimated in naive normal and HLA-B27.2-, -B27.5- and HLA-Cw3-double TGM (i.e., mice expressing HLA and human beta 2-microglobulin (hu beta 2m]. The xenoreactive CTLp frequencies were compared to frequencies of CTLp to H-2 alloantigens estimated in naive normal mice. The results showed that the frequencies of HLA class I-specific CTLp are comparable with those of alloreactive CTLp. This overlap in CTLp frequencies suggests that HLA class I xenoantigens are recognized by primary mouse CTL as allelic variants of H-2K and H-2D. This was confirmed in split well analysis by the observation that the xenoreactive response was not restricted by self-MHC of the responding mouse. Thus, primary HLA class I-specific mouse CTL clones recognized their target Ag regardless of whether they were expressed on H-2-mismatched mouse cells or on human cells. The frequencies of HLA class I-specific CTLp in HLA-TGM were comparable to those in normal mice. We propose that MHC allo- and xenoreactive CTL responses are not caused by the activation of CTLp specific for self-MHC plus peptide but to the activation of CTLp recognizing MHC allo- and xenoantigens directly or as peptides presented by their native MHC molecules.

Animals↗
PubMed2004

Production of transgenic chimeric rabbits and transmission of the transgene through the germline.

Here we report that improved reproductive technologies combined with an efficient microinjection method and in vitro cultivation medium enabled us to create germ line chimeric rabbits. To follow the fate of the chimeric embryo a blastomere marked with the human blood coagulation factor VIII (hFVIII) transgene was microinjected into a morula stage wild type embryo. The degree of chimerism in different tissues was estimated by real-time PCR and was found to be in the range of 0.1-42%. Among the four chimeric animals, one was identified as a chromosomal intersex and two were germline chimeras.

Animals↗
PubMed1993

Transgene copy number can be positively or negatively associated with transgene expression.

Two different types of T-DNA insert were found in tobacco plants transformed with Agrobacterium tumefaciens. High-expressing (H) types had one copy of the T-DNA at a locus and produced high expression of the transgene uidA, as measured by uidA RNA levels and beta-glucuronidase activity; low-expressing (L) types had inverted repeats of the T-DNA at a locus and produced low uidA expression. H-types from different transformants acted additively, and cross-fertilization between two different homozygous transformants with H-type inserts produced F1 plants with GUS activity that equalled the parents and individual F2 plants with 50%, 100%, 150% and 200% of parental values. However, the L-type inserts worked in trans to suppress uidA expression from H-type inserts when both were present in the same genome. Hence when a transformant homozygous for the L-type insert was crossed to one homozygous for the H-type, all plants in the F1 and F2 generations with both types of insert had low GUS activity while F2 segregants that only had the H-type inserts had high GUS activity again. Suppression of the H-type gene was associated with increased methylation of the insert. Particle acceleration was used to introduce further copies of uidA into tissues of the transformants. Regardless of the promoter used, those plants with endogenous L-type inserts showed none of the distinct loci of GUS activity readily visible in material with no inserts, showing that L-type inserts could suppress not only the uidA expression of genomic homologues, but also of copies added in vitro.

Agrobacterium tumefaciens↗
PubMed2005

Transgenic cucumbers harboring the 54-kDa putative gene of Cucumber fruit mottle mosaic tobamovirus are highly resistant to viral infection and protect non-transgenic scions from soil infection.

Cucumber fruit mottle mosaic tobamovirus (CFMMV) causes severe mosaic symptoms and yellow mottling on leaves and fruits and, occasionally, severe wilting of cucumber (Cucumis sativus L.) plants. No genetic source of resistance against this virus has been identified in cucumber. The gene coding for the putative 54-kDa replicase gene of CFMMV was cloned into an Agrobacterium tumefaciens binary vector, and transformation was performed on cotyledon explants of a parthenocarpic cucumber cultivar. R1 seedlings were screened for resistance to CFMMV by symptom expression, back inoculation on an alternative host and ELISA. From a total of 14 replicase-containing R1 lines, eight resistant lines were identified. Line 144--homozygous for the putative 54-kDa replicase gene--was immune to CFMMV infection by mechanical and graft inoculation, and to root infection following planting in CFMMV-infested soil. A substantial delay of symptom appearance was observed following infection by three additional cucurbit-infecting tobamoviruses. When used as a rootstock, line I44 protected susceptible cucumber scions from soil infection by CFMMV. This paper is the first report on protection of a susceptible cultivar against a soil-borne viral pathogen, by grafting onto a transgenic rootstock.

Base Sequence↗
PubMed2003

Reciprocal control of flowering time by OsSOC1 in transgenic Arabidopsis and by FLC in transgenic rice.

In a screen for MADS box genes which activate and/or repress flowering in rice, we identified a gene encoding a MADS domain protein (OsSOC1) related to the Arabidopsis gene AtSOC1. AtSOC1 and OsSOC1 show a 97% amino acid similarity in their MADS domain. The rice gene contains a large first intron of 27.6 kb compared to the 1 kb intron in Arabidopsis. OsSOC1 is located on top of the short arm of chromosome 3, tightly linked to the heading date locus, Hd9. OsSOC1 is expressed in vegetative tissues, and expression is elevated at the time of floral initiation, 40-50 days after sowing, and remains uniformly high thereafter, similar to the expression pattern of AtSOC1. The constitutive expression of OsSOC1 in Arabidopsis results in early flowering, suggesting that the rice gene is a functional equivalent of AtSOC1. We were not able to identify FLC-like sequences in the rice genome; however, we show that ectopic expression of the Arabidopsis FLC delays flowering in rice, and the up-regulation of OsSOC1 at the onset of flowering initiation is delayed in the AtFLC transgenic lines. The reciprocal recognition and flowering time effects of genes introduced into either Arabidopsis or rice suggest that some components of the flowering pathways may be shared. This points to a potential application in the manipulation of flowering time in cereals using well characterized Arabidopsis genes.

Journal Article↗
PubMed2006

Muscle atrophy in transgenic mice expressing a human TSC1 transgene.

Muscle mass is regulated by a wide range of hormonal and nutritional signals, such as insulin and IGF. Tuberous sclerosis complex (TSC) is an inherited hamartoma disease with tumor growth in numerous organs. TSC is caused by mutation in either TSC1 or TSC2 tumor suppressor genes that negatively regulate insulin-induced S6K activation and cell growth. Here we report that expression of human TSC1 (hTSC1) in mouse skeletal muscle leads to reduction of muscle mass. Expression of hTSC1 stabilizes endogenous TSC2 and leads to inhibition of the mTOR signaling. The hTSC1-mTSC2 hetero-complex and its downstream components remain sensitive to insulin stimulation and nutrition signals. This study suggests that an increase in the steady state level of resident TSC1-TSC2 complex is sufficient to reduce muscle mass and cause atrophy.

Animals↗
PubMed2004

Long term transgene expression by hepatocytes transduced with retroviral vectors requires induction of immune tolerance to the transgene.

BACKGROUND/AIMS: Gene therapy for inherited liver diseases requires permanent expression of the therapeutic gene. However, in vivo liver transduction with retroviral vectors triggers an immune elimination of transduced hepatocytes. Here we investigated whether immune response could be prevented by treatment with compounds known to induce tolerance in organ transplantation: CTLA4Ig and LF-15-0195. METHODS: CTLA4Ig was administered either via i.p. injection of the drug or by i.m. injection of recombinant adenoviruses encoding CTLA4Ig. LF-15-0195 was administered i.p. All animals were subjected to partial hepatectomy and received beta-galactosidase retroviral vectors intravenously. Appearance of anti-beta-galactosidase antibodies was monitored and the number of positive hepatocytes was assessed at day 7 and at sacrifice. RESULTS: No beta-galactosidase antibodies were detected as long as CTLA4Ig was detectable in serum. Short-term treatment with CTLA4Ig induced tolerance in a significant proportion of animals only at high dose (1 mg/kg). Administration of CTLA4Ig adenovectors resulted in prolonged secretion of CTLA4Ig and permanent absence of anti-beta-galactosidase antibodies. LF-15-0915 administration achieved tolerance in some animals. CONCLUSIONS: In conclusion, manipulation of the immune system at the time of virus delivery using clinically relevant tolerance-inducing protocols is a promising approach to achieve long term expression after retrovirus-mediated gene transfer to the liver.

Abatacept↗