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Transgenic Mice (transgenic + mouse)
Kinds of Transgenic Mice Terms modified by Transgenic Mice Selected AbstractsDoubly Truncated FosB Isoform (,2,FosB) Induces Osteosclerosis in Transgenic Mice and Modulates Expression and Phosphorylation of Smads in Osteoblasts Independent of Intrinsic AP-1 Activity,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2008George Sabatakos Abstract Introduction: Activator protein (AP)-1 family members play important roles in the development and maintenance of the adult skeleton. Transgenic mice that overexpress the naturally occurring ,FosB splice variant of FosB develop severe osteosclerosis. Translation of ,fosb mRNA produces both ,FosB and a further truncated isoform (,2,FosB) that lacks known transactivation domains but, like ,FosB, induces increased expression of osteoblast marker genes. Materials and Methods: To test ,2,FosB's ability to induce bone formation in vivo, we generated transgenic mice that overexpress only ,2,FosB using the enolase 2 (ENO2) promoter-driven bitransgenic Tet-Off system. Results: Despite ,2,FosB's failure to induce transcription of an AP-1 reporter gene, the transgenic mice exhibited both the bone and the fat phenotypes seen in the ENO2-,FosB mice. Both ,FosB and ,2,FosB activated the BMP-responsive Xvent-luc reporter gene and increased Smad1 expression. ,2,FosB enhanced BMP-induced Smad1 phosphorylation and the translocation of phospho-Smad1 (pSmad1) to the nucleus more efficiently than ,FosB and showed a reduced induction of inhibitory Smad6 expression. Conclusions: ,FosB's AP-1 transactivating function is not needed to induce increased bone formation, and ,2,FosB may act, at least in part, by increasing Smad1 expression, phosphorylation, and translocation to the nucleus. [source] Inhibition of Hematopoietic Progenitor Cell Proliferation by Ethanol in Human Immunodeficiency Virus Type 1 Tat-Expressing Transgenic MiceALCOHOLISM, Issue 3 2001Om Prakash Background: A number of hematological abnormalities are associated with both human immunodeficiency virus type 1 (HIV-1) infection and alcohol abuse. There is little information on how alcohol abuse might further influence the survival and growth of hematopoietic progenitors in HIV-infected individuals in the presence of immune system abnormalities and anti-HIV drugs. Because there is evidence that viral transactivator Tat itself can induce hematopoietic suppression, in this study we examined the role of ethanol as a cofactor in transgenic mice that expressed HIV-1 Tat protein. Methods: Tat transgenic mice and nontransgenic littermates were given ethanol (20% v/v) and the anti-HIV drug 3,-azido-3,-deoxythymidine (AZT; 1 mg/ml) in drinking water. Immunosuppression in mice was induced by weekly intraperitoneal injections of anti-CD4 antibody. Hematopoiesis was examined by erythroid colony forming unit (CFU-E) and granulocyte/macrophage colony-forming unit (CFU-GM) assays of the bone marrow progenitor cells. Results: Administration of ethanol for 7 weeks resulted in a 50% decrease in the proliferative capacity of CFU-E- and CFU-GM-derived progenitors from transgenic mice compared with that of ethanol-treated nontransgenic controls. Similar decreases also were observed in transgenic mice treated with AZT or a combination of AZT and ethanol. Furthermore, ethanol and AZT were significantly more toxic to the granulopoietic progenitors (40,50% inhibition) than to the erythropoietic progenitors (10,20% inhibition) in Tat transgenic mice. Although a 10 day exposure of Tat transgenic and nontransgenic mice to a combination of ethanol and AZT had no suppressive effect on the erythropoietic and granulopoietic progenitor cells, there was a marked decrease (40,60%) in CFU-GM in mice made immunodeficient by CD4+ T-lymphocyte depletion. The ethanol-treated Tat transgenic mice but not the nontransgenic littermates also showed a significant decrease (25%) in CFU-GM. Conclusion: Our in vivo study strongly suggests that ethanol ingestion in HIV-1-infected individuals, particularly those on antiretroviral drugs, might increase bone marrow toxicity and contribute to HIV-1-associated hematopoietic impairment. [source] Biglycan Overexpression on Tooth Enamel Formation in Transgenic MiceTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 10 2008Xin Wen Abstract Previously, it was shown that the volume of forming enamel of molar teeth in biglycan-null mice was greater than that in genetically matched wild-type mice. This phenotypic change appeared to result from an increase in amelogenin expression, implying that biglycan directly influences amelogenin synthesis. To determine whether biglycan overexpression resulted in decreased amelogenin expression, we engineered transgenic mice to overexpress biglycan in the enamel organ epithelium. Biglycan overexpression did not significantly affect the amelogenin expression in incisor and molar teeth in 3-day postnatal transgenic mice. In the transgenic animals, we observed that the immature and mature enamel appeared normal. These results suggested that increasing the biglycan expression, in the cells that synthesize the precursor protein matrix for enamel, has a negligible influence on amelogenesis. Anat Rec, 2008. © 2008 Wiley-Liss, Inc. [source] Intraneuronal APP/A, Trafficking and Plaque Formation in ,-Amyloid Precursor Protein and Presenilin-1 Transgenic MiceBRAIN PATHOLOGY, Issue 3 2002Oliver Wirths Neuropil deposition of ,-amyloid peptides A,40 and A,42 is believed to be the key event in the neurodegenerative processes of Alzheimer's disease (AD). Since A, seems to carry a transport signal that is required for axonal sorting of its precursor ,-amyloid precursor protein (APP), we studied the intraneuronal staining profile of A, peptides in a transgenic mouse model expressing human mutant APP751 (KM670/671NL and V717I) and human mutant presenilin-1 (PS-1 M146L) in neurons. Using surface plasmon resonance we analyzed the A, antibodies and defined their binding profile to APP, A,40 and A,42. Immunohistochemical staining revealed that intraneuronal A,40 and A,42 staining preceded plaque deposition, which started at 3 months of age. A, was observed in the somatodendritic and axonal compartments of many neurons. Interestingly, the striatum, which lacks transgenic APP expression harbored many plaques at 10 months of age. This is most likely due to an APP/A, transport problem and may be a model region to study APP/A, trafficking as an early pathological event. [source] Mapping of Melanoma Modifier Loci in RET Transgenic MiceCANCER SCIENCE, Issue 11 2000Tommaso A. Dragani Transgenic mice carrying the RET oncogene under the control of the metallothionein promoter exhibit severe pigmentation of the whole skin and melanocytic tumors. The genetic background influences melanoma development in RET mice; founder mice crossed with BALB/c mice show decreased incidence and increased latency of melanocytic tumors, whereas progeny of C57BL/6 mice show the opposite effect. Using partially congenic RET mice on a C57BL/6 genetic background (N3/RET mice), we studied genetic linkage in (N3/RETxBALB/c)xN3/RET backcross mice. We mapped three melanoma modifier loci, on chromosome 1 (Melm1 and Melm2) and chromosome 11 (Melm3), that are linked with early melanoma incidence and latency. Mapping of Melm loci and of five additional regions on chromosomes 6, 8, 9, 12, and 13 indicated allelic imbalance in N3/RET mice, with a significant excess of BALB/c alleles, suggesting the presence of additional putative melanoma modifier loci on these chromosomes. [source] Promotion of Skin Carcinogenesis by Dimethylarsinic Acid in Keratin (K6)/ODC Transgenic MiceCANCER SCIENCE, Issue 6 2000Takashi Morikawa Dimethylarsinic acid (DMA) is a major metabolite of inorganic arsenicals in mammals, and arsenic exposure is associated with tumor development in a wide variety of human tissues, particularly the skin. Transgenic mice with ornithine decarboxylase (ODC) targeted to hair follicle keratinocytes are much more sensitive than littermate controls to carcinogens. In this study we investigated the promoting effect of DMA on skin carcinogenesis in such K6/ODC transgenic mice. The back skin of female C57BL/6J K6/ODC transgenic mice, 10 to 14 weeks old, was initiated with topical application of 7,12-dimethylbenz[,]anthracene (DMBA) at a dose of 50 ,g or acetone alone on day 1 of the experiment, followed by treatment with 3.6 mg of DMA, 5 ,g of 12-O-tetradecanoylphorbol-13-acetate (TPA) or neutral vehicle (control) twice a week for 18 weeks. Mice were killed 1 week after the end of the treatment. Induction of skin tumors was significantly accelerated in the DMA-treated group, as well as in the TPA-treated group, indicating that DMA has a promoting effect on skin tumorigenesis in K6/ODC transgenic mice. [source] Characterization of sleep,wake patterns in a novel transgenic mouse line overexpressing human prepro-orexin/hypocretinACTA PHYSIOLOGICA, Issue 3 2010K. A. Mäkelä Abstract Aim:, Orexin/hypocretin peptides are expressed in the lateral hypothalamus and involved in the regulation of autonomic functions, energy homeostasis and arousal states. The sleep disorder narcolepsy, which is characterized by excessive daytime sleepiness and occurrence of sudden rapid eye movement (REM) sleep, is associated with a loss of orexin neurones. Our study investigated the effects of orexins on sleep,wake patterns in a novel transgenic mouse line overexpressing the human prepro-orexin (hPPO) gene under the control of its endogenous promoter. Methods:, Orexin overexpression was investigated by PCR, Southern and Western blotting as well as immunohistochemistry. Polysomnographic recordings were performed for analyses of sleep,wake patterns and for electroencephalographic activity during 24 h baseline and during and after 6 h of sleep deprivation (SD). Results:, Transgenic hPPO mice had increased expression of human prepro-orexin (hPPO) and orexin-A in the hypothalamus. Transgene expression decreased endogenous orexin-2 receptors but not orexin-1 receptors in the hypothalamus without affecting orexin receptor levels in the basal forebrain, cortex or hippocampus. Transgenic mice compared with their wild type littermates showed small but significant differences in the amount of waking and slow wave sleep, particularly during the light,dark transition periods, in addition to a slight reduction in REM sleep during baseline and during recovery sleep after SD. Conclusion:, The hPPO-overexpressing mice show a small reduction in REM sleep, in addition to differences in vigilance state amounts in the light/dark transition periods, but overall the sleep,wake patterns of hPPO-overexpressing mice do not significantly differ from their wild type littermates. [source] Transgenic mice for studies of the renin,angiotensin system in hypertensionACTA PHYSIOLOGICA, Issue 4 2004J. L. Lavoie Abstract Hypertension is a polygenic and multi-factorial disorder that is extremely prevalent in western societies, and thus has received a great deal of attention by the research community. The renin,angiotensin system has a strong impact on the control of blood pressure both in the short- and long-term, making it one of the most extensively studied physiological systems. Nevertheless, despite decades of research, the specific mechanisms implicated in its action on blood pressure and electrolyte balance, as well as its integration with other cardiovascular pathways remains incomplete. The production of transgenic models either over-expressing or knocking-out specific components of the renin,angiotensin system has given us a better understanding of its role in the pathogenesis of hypertension. Moreover, our attention has recently been refocused on local tissue renin,angiotensin systems and their physiological effect on blood pressure and end-organ damage. Herein, we will review studies using genetic manipulation of animals to determine the role of the endocrine and tissue renin,angiotensin system in hypertension. We will also discuss some untraditional approaches to target the renin,angiotensin system in the kidney. [source] Ectopic activation of the transcription promoter for the testis-specific mouse Pgk-2 gene on elimination of a cis -acting upstream DNA regionDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 4 2000Hiroshi Ando Transgenic mice carrying the coding sequence of ,-galactosidase, for which expression was driven by various upstream regions including the transcription promoter of the testis-specific mouse Pgk-2 gene, were generated. Expression of ,-galactosidase mRNA driven by the region between nucleotide positions , 1404 and + 61, with respect to the transcription initiation site numbered + 1, was examined by reverse transcription-mediated polymerase chain reaction, blot hybridization and in situ hybridization, and compared with that of endogenous Pgk-2 mRNA. The results revealed that the 1.4 kb DNA region is sufficient for determining the organ-specific, developmental stage-specific and spermatogenic stage-specific transcription of the mouse Pgk-2 gene. When the region between , 684 and + 61 was used to generate transgenic mice, ,-galactosidase mRNA was detectable not only in the testis, but also in other organs such as brain and lung. However, the timing and cell-type specificity of testicular expression of ,-galactosidase mRNA were retained in these mice. Because the region between , 1404 and , 685 repressed the Pgk-2 promoter in somatic cell-derived cell lines, it is suggested that the organ specificity of Pgk-2 transcription is achieved at least partly by negative regulation. [source] Impaired lactation in mice expressing dominant-negative FADD in mammary epitheliumDEVELOPMENTAL DYNAMICS, Issue 4 2009Mark Shackleton Abstract The Fas-associated death domain (FADD/Mort1) adaptor protein was originally identified as a key mediator of apoptosis, although pleiotropic functions for FADD have also been reported. FADD-mediated tumoricidal effects have been described in breast cancer cells; however, its physiological role in normal mammary gland epithelium is not well understood. To determine the role of FADD signaling during mammary gland development, we generated transgenic mice overexpressing dominant-negative FADD (DN-FADD) in mammary epithelium, using the steroid responsive mouse mammary tumor virus promoter. Transgenic mice exhibited a perturbation in lactation resulting in impaired milk production and pup growth retardation. Reduced expansion of alveoli was evident during early lactation with extensive shedding of luminal alveolar cells. Significantly more TUNEL (terminal deoxynucleotidyl transferase,mediated deoxyuridinetriphosphate nick end-labeling)-positive cells were present at this time point and a subsequent increase in bromodeoxyuridine-positive cells was observed. These findings suggest a role for FADD in maintaining the survival of mammary secretory alveolar cells after the establishment of lactation. Developmental Dynamics 238:1010,1016, 2009. © 2009 Wiley-Liss, Inc. [source] Effect of canonical Wnt inhibition in the neurogenic cortex, hippocampus, and premigratory dentate gyrus progenitor poolDEVELOPMENTAL DYNAMICS, Issue 7 2008Nina Solberg Abstract Canonical Wnt signaling is crucial for the correct development of both cortical and hippocampal structures in the dorsal telencephalon. In this study, we examined the role of the canonical Wnt signaling in the dorsal telencephalon of mouse embryos at defined time periods by inhibition of the pathway with ectopic expression of Dkk1. Transgenic mice with the D6-driven Dkk1 gene exhibited reduced canonical Wnt signaling in the cortex and hippocampus. As a result, all hippocampal fields were reduced in size. Neurogenesis in the dentate gyrus was severely reduced both in the premigratory and migratory progenitor pool. The lower number of progenitors in the dentate gyrus was not rescued after migration to the subgranular zone and thus the dentate gyrus lacked the entire internal blade and a part of the external blade from postnatal to adult stages. Developmental Dynamics 237:1799,1811, 2008. © 2008 Wiley-Liss, Inc. [source] The role of autophagy in , -cell lipotoxicity and type 2 diabetesDIABETES OBESITY & METABOLISM, Issue 2010G. Las Autophagy, a ubiquitous catabolic pathway involved in both cell survival and cell death, has been implicated in many age-associated diseases. Recent findings have shown autophagy to be crucial for proper insulin secretion and , -cell viability. Transgenic mice lacking autophagy in their , -cells showed decreased , -cell mass and suppressed glucose-stimulated insulin secretion. Several studies showed that stress can stimulate autophagy in , -cells: the number of autophagosomes is increased in different in vivo models for diabetes, such as db/db mice, mice fed high-fat diet, pdx-1 knockout mice, as well as in in vitro models of glucotoxicity and lipotoxicity. Pharmacological and molecular inhibition of autophagy increases the susceptibility to cell stress, suggesting that autophagy protects against diabetes-relevant stresses. Recent findings, however, question these conclusions. Pancreases of diabetics and , -cells exposed to fatty acids show accumulation of abnormal autophagosome morphology and suppression of lysosomal gene expression suggesting impairment in autophagic turnover. In this review we attempt to give an overview of the data generated by others and by us in view of the possible role of autophagy in diabetes, a role which depending on the conditions, could be beneficial or detrimental in coping with stress. [source] The RhoA- and CDC42-specific exchange factor Dbs promotes expansion of immature thymocytes and deletion of double-positive and single-positive thymocytesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2004Abstract Specific members of the Rho family of GTPases exert unique influences on thymocyte proliferation, differentiation and deletion. Dbs is a guanine nucleotide exchange factor which is expressed throughout thymocyte development and is able to activate the Rho family GTPases CDC42, RhoA and RhoG. Transgenic mice expressing an activated form of Dbs had increased numbers of double-negative thymocytes. The Dbs transgene promoted expansion of double-negative thymocytes in the absence of pre-TCR, but had no effect on pre-TCR-dependent differentiation of double-negative thymocytes into double-positive thymocytes. Transgenic double-positive thymocytes were proliferative in vivo, but were also susceptible to apoptosis in vivo and in vitro. The transgenic single-positive thymocytes had attenuated proliferative responses following TCR ligation, and were depleted rather than expanded during culture in the presence of anti-CD3. When expressing a positively selectable TCR, transgenic double-positive thymocytes were increased in number and activated, but the output of single-positive thymocytes was reduced. Transgenic double-positive thymocytes were acutely sensitive to deletion by TCR ligation in vivo. These results indicate that activation of Dbs has the potential to promote proliferation throughout thymocyte development, but also sensitizes double-positive and single-positive thymocytes to deletion. [source] Olfactory deficits in mice overexpressing human wildtype ,-synucleinEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2008Sheila M. Fleming Abstract Accumulation of ,-synuclein in neurons of the central and peripheral nervous system is a hallmark of sporadic Parkinson's disease (PD) and mutations that increase ,-synuclein levels cause familial PD. Transgenic mice overexpressing ,-synuclein under the Thy1 promoter (Thy1-aSyn) have high levels of ,-synuclein expression throughout the brain but no loss of nigrostriatal dopamine neurons up to 8 months, suggesting that they may be useful to model pre-clinical stages of PD. Olfactory dysfunction often precedes the onset of the cardinal motor symptoms of PD by several years and includes deficits in odor detection, discrimination and identification. In the present study, we measured olfactory function in 3- and 9-month-old male Thy1-aSyn mice with a buried pellet test based on latency to find an exposed or hidden odorant, a block test based on exposure to self and non-self odors, and a habituation/dishabituation test based on exposure to non-social odors. In a separate group of mice, ,-synuclein immunoreactivity was assessed in the olfactory bulb. Compared with wildtype littermates, Thy1-aSyn mice could still detect and habituate to odors but showed olfactory impairments in aspects of all three testing paradigms. Thy1-aSyn mice also displayed proteinase K-resistant ,-synuclein inclusions throughout the olfactory bulb. These data indicate that overexpression of ,-synuclein is sufficient to cause olfactory deficits in mice similar to that observed in patients with PD. Furthermore, the buried pellet and block tests provided sufficient power for the detection of a 50% drug effect, indicating their usefulness for testing novel neuroprotective therapies. [source] Altered sensorimotor development in a transgenic mouse model of amyotrophic lateral sclerosisEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2004Julien Amendola Abstract Most neurodegenerative diseases become manifest at an adult age but abnormalities or pathological symptoms appear earlier. It is important to identify the initial mechanisms underlying such progressive neurodegenerative disease in both humans and animals. Transgenic mice expressing the familial amyotrophic lateral sclerosis (ALS)-linked mutation (G85R) in the enzyme superoxide dismutase 1 (SOD1) develop motor neuron disease at 8,10 months of age. We address the question of whether the mutation has an early impact on spinal motor networks in postnatal mutant mice. Behavioural tests showed a significant delay in righting and hind-paw grasping responses in mutant SOD1G85R mice during the first postnatal week, suggesting a transient motor deficit compared to wild-type mice. In addition, extracellular recordings from spinal ventral roots in an in vitro brainstem,spinal cord preparation demonstrated different pharmacologically induced motor activities between the two strains. Rhythmic motor activity was difficult to evoke with N -methyl- dl -aspartate and serotonin at the lumbar levels in SOD1G85R mice. In contrast to lumbar segments, rhythmic activity was similar in the sacral roots from the two strains. These results strongly support the fact that the G85R mutation may have altered lumbar spinal motor systems much earlier than previously recognized. [source] Stabilization of mutant Cu/Zn superoxide dismutase (SOD1) protein by coexpressed wild SOD1 protein accelerates the disease progression in familial amyotrophic lateral sclerosis miceEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2001Kei Fukada Abstract Transgenic mice carrying familial amyotrophic lateral sclerosis (FALS)-linked mutant Cu/Zn superoxide dismutase (SOD1) genes such as G93A (G93A-mice) and G85R (G85R-mice) genes develop limb paresis. Introduction of human wild type SOD1 (hWT-SOD1) gene, which does not cause motor impairment by itself, into different FALS mice resulted in different effects on their clinical courses, from no effect in G85R-mice to acceleration of disease progression in G93A-mice. However, the molecular mechanism which causes the observed difference, has not been clarified. We hypothesized that the difference might be caused by the stability of mutant SOD1 proteins. Using a combination of mass spectrometry and enzyme-linked immunosorbent assay, we found that the concentration of G93A-SOD1 protein was markedly elevated in tissues of transgenic mice carrying both G93A - and hWT-SOD1 genes (G93A/hWT-mice) compared to that in G93A-mice, and also found that the concentration of G93A-SOD1 protein had a close relation to the disease duration. The concentration of metallothionein-I/II in the spinal cord, reflecting the degree of copper-mediated oxidative stress, was highest in G93A/hWT-mice, second in G93A-mice, and normal in the mice carrying hWT-SOD1 gene. These results indicated that the increase of G93A-SOD1 protein was responsible for the increase of oxidative stress and disease acceleration in G93A/hWT-mice. We speculate that coexpression of hWT-SOD1 protein is deleterious to transgenic mice carrying a stable mutant such as G93A-SOD1, because this mutant protein is stabilized by hWT-SOD1 protein, but not to transgenic mice carrying an unstable mutant such as G85R-SOD1, because this mutant protein is not stabilized by hWT-SOD1. [source] Conditional transgene expression mediated by the mouse ,-actin locusGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 11 2007Ulrike Jägle Abstract Transgenic mice are an effective model to study gene function in vivo; however, position effects can complicate tissue-specific transgene analysis. To facilitate precise targeting of a transgenic construct into the mouse genome, we combined the Cre/lox and Flp/FRT recombination systems to allow for rapid transgene replacement and conditional transgene expression from the endogenous ,-actin locus. Flp/FRT recombination was used to rapidly exchange FRT-flanked transgene cassettes by recombinase-mediated cassette exchange in embryonic stem cells, while transgene expression can be activated in mice after Cre-mediated excision of a floxed STOP cassette. To validate our system, we analyzed the expression profile of an EGFP reporter gene after integration into the ,-actin locus and Cre-mediated excision of the floxed STOP cassette. Breeding of EGFP reporter mice with various Cre mouse lines resulted in the expected expression profiles, demonstrating the feasibility of the model to facilitate predictable and strong transgene expression in a spatially and temporally controlled manner. genesis 45:659,666, 2007. © 2007 Wiley-Liss, Inc. [source] Transgenic mice expressing a dual, CRE-inducible reporter for the analysis of axon guidance and synaptogenesis,GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 6 2007Aurora Badaloni Abstract Improved and modular tools are needed for the neuroanatomical dissection of CNS axonal tracts, and to study the cell-intrinsic and cell-extrinsic cues that govern their assembly and plasticity. Here we describe a general purpose transgenic tracer that can be used to visualize axonal tracts and synaptic terminals in any region of the embryonic neural tube or postnatal CNS, on any wild type or mutant genetic background. The construct permits CRE-inducible expression of a dicistronic axonal marker encoding two surface reporter proteins: a farnesylated GFP and the human Placental Alkaline Phosphatase (PLAP). Both proteins localize alongside the neuronal surface, permitting the concomitant detection of cell body, neurites, and presynaptic and postsynaptic sites in the same neuron. This provides a CRE-inducible dual system for imaging neural circuits in vivo, and to study their assembly and remodeling in cultured neurons, neural stem cells, and tissue explants derived from the reporter line. Unlike existing lines, this reporter does not encode a ubiquitously expressed, floxable LacZ gene, permitting the simultaneous analysis of beta galactosidase activity in mutant lines. genesis 45:405,412, 2007. © 2007 Wiley-Liss, Inc. [source] Transgenic mice for Cre-inducible overexpression of the oncogenes c-MYC and Pim-1 in multiple tissuesGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 10 2006Meejeon Roh Abstract The transcription factor c-MYC and the serine-threonine kinase Pim-1 have multiple roles in development and cancer, including in lymphomagenesis and prostate tumorigenesis. In some cancers, MYC and Pim-1 oncogenes are co-expressed and show marked cooperativity. To facilitate the analysis of the pathological roles of MYC and Pim-1 in specific cell types and developmental stages, we generated mice carrying Cre-inducible MYC/Pim-1 transgenes. The mice carry a constitutively expressed lacZ marker and silent MYC/Pim-1 genes. Cre-mediated recombination results in deletion of the lacZ marker and concurrent activation of the MYC/Pim-1 transgene. In addition, the Pim-1 mice harbor an alkaline phosphatase gene as a positive marker for recombination. Mouse lines for each gene were established, which show distinct patterns of expression in multiple tissues. In vivo recombination was confirmed for all lines by breeding to Cre transgenic mice. These mice provide a valuable resource for investigating the significance of MYC and Pim-1 overexpression in various tissues. genesis 44:447,453, 2006. © 2006 Wiley-Liss, Inc. [source] Transgenic mice expressing tamoxifen-inducible Cre for somatic gene modification in renal epithelial cellsGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 5 2006Irma S. Lantinga-van Leeuwen Abstract Gene inactivation often leads to an embryonic-lethal phenotype. In focal diseases like renal cell carcinomas and polycystic kidney disease, somatic gene inactivation in subsets of cells is likely to occur at later stages. We generated a transgenic mouse line with an inducible form of Cre recombinase for conditional gene modifications in kidney epithelial cells. To this end a 1.4-kb promoter fragment of the kidney-specific cadherin gene (KspCad) was cloned upstream of a tamoxifen-inducible Cre recombinase (CreERT2) encoding sequence. Expression and activity of Cre was evaluated using reverse transcriptase polymerase chain reaction (RT-PCR) analysis and by crossbreeding to Z/EG reporter mice. One KspCad-CreERT2 line showed kidney-specific Cre expression and mediated recombination upon tamoxifen treatment in Z/EG reporter mice. No reporter gene expression was detected in untreated animals or in extrarenal tissues upon treatment. Within the kidneys, enhanced green fluorescent protein (EGFP) fluorescence was observed in epithelial cells in several nephronic segments. In addition, the system successfully recombined a floxed Pkd1 gene. genesis 44:225,232, 2006. © 2006 Wiley-Liss, Inc. [source] Role of aquaporins in endothelial water transportJOURNAL OF ANATOMY, Issue 5 2002A. S. Verkman The aquaporins (AQP) are a family of homologous water channels expressed in many epithelial and endothelial cell types involved in fluid transport. AQP1 protein is strongly expressed in most microvascular endothelia outside of the brain as well as in endothelial cells in cornea, intestinal lacteals, and other tissues. AQP4 is expressed in astroglial foot processes adjacent to endothelial cells in the central nervous system. Transgenic mice lacking aquaporins have been useful in defining their role in mammalian physiology. Mice lacking AQP1 manifest defective urinary concentrating ability, in part because of decreased water permeability in renal vasa recta microvessels. These mice also show a defect in dietary fat processing that may involve chylomicron absorption by intestinal lacteals. There is preliminary evidence that AQP1 might play a role in tumour angiogenesis and in renal microvessel structural adaptation. However AQP1 in most endothelial tissues does not appear to have a physiological function despite its role in osmotically driven water transport. For example mice lacking AQP1 have low alveolar capillary water permeability but unimpaired lung fluid absorption, as well as unimpaired saliva and tear secretion, aqueous fluid outflow, and pleural and peritoneal fluid transport. In the central nervous system mice lacking AQP4 are partially protected from brain oedema in water intoxication and ischaemic models of brain injury. Therefore although the role of aquaporins in epithelial fluid transport is in most cases well understood there remain many questions about the role of aquaporins in endothelial cell function. It is unclear why many leaky microvessels strongly express AQP1 without apparent functional significance. Improved understanding of aquaporin endothelial biology may lead to novel therapies for human disease, such as pharmacological modulation of tumour angiogenesis, renal fluid clearance and intestinal absorption. [source] Doubly Truncated FosB Isoform (,2,FosB) Induces Osteosclerosis in Transgenic Mice and Modulates Expression and Phosphorylation of Smads in Osteoblasts Independent of Intrinsic AP-1 Activity,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2008George Sabatakos Abstract Introduction: Activator protein (AP)-1 family members play important roles in the development and maintenance of the adult skeleton. Transgenic mice that overexpress the naturally occurring ,FosB splice variant of FosB develop severe osteosclerosis. Translation of ,fosb mRNA produces both ,FosB and a further truncated isoform (,2,FosB) that lacks known transactivation domains but, like ,FosB, induces increased expression of osteoblast marker genes. Materials and Methods: To test ,2,FosB's ability to induce bone formation in vivo, we generated transgenic mice that overexpress only ,2,FosB using the enolase 2 (ENO2) promoter-driven bitransgenic Tet-Off system. Results: Despite ,2,FosB's failure to induce transcription of an AP-1 reporter gene, the transgenic mice exhibited both the bone and the fat phenotypes seen in the ENO2-,FosB mice. Both ,FosB and ,2,FosB activated the BMP-responsive Xvent-luc reporter gene and increased Smad1 expression. ,2,FosB enhanced BMP-induced Smad1 phosphorylation and the translocation of phospho-Smad1 (pSmad1) to the nucleus more efficiently than ,FosB and showed a reduced induction of inhibitory Smad6 expression. Conclusions: ,FosB's AP-1 transactivating function is not needed to induce increased bone formation, and ,2,FosB may act, at least in part, by increasing Smad1 expression, phosphorylation, and translocation to the nucleus. [source] Effect of Osteoblast-Targeted Expression of Bcl-2 in Bone: Differential Response in Male and Female Mice,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2005Alexander G Pantschenko Abstract Transgenic mice (Col2.3Bcl-2) with osteoblast-targeted human Bcl-2 expression were established. Phenotypically, these mice were smaller than their wildtype littermates and showed differential effects of the transgene on bone parameters and osteoblast activity dependent on sex. The net effect was an abrogation of sex differences normally observed in wildtype mice and an inhibition of bone loss with age. Ex vivo osteoblast cultures showed that the transgene had no effect on osteoblast proliferation, but decreased bone formation. Estrogen was shown to stimulate endogenous Bcl-2 message levels. These studies suggest a link between Bcl-2 and sex regulation of bone development and age-related bone loss. Introduction: Whereas Bcl-2 has been shown to be an important regulator of apoptosis in development, differentiation, and disease, its role in bone homeostasis and development is not well understood. We have previously showed that the induction of glucocorticoid-induced apoptosis occurred through a dose-dependent decrease in Bcl-2. Estrogen prevented glucocorticoid-induced osteoblast apoptosis in vivo and in vitro by preventing the decrease in Bcl-2 in osteoblasts. Therefore, Bcl-2 may be an important regulator of bone growth through mechanisms that control osteoblast longevity and function. Materials and Methods: Col2.3Bcl-2 mice were developed carrying a 2.3-kb region of the type I collagen promoter driving 1.8 kb of human Bcl-2 (hBcl-2). Tissue specific expression of hBcl-2 in immunoassays validated the transgenic animal model. Histomorphometry and DXA were performed. Proliferation, mineralization, and glucocorticoid-induced apoptosis were examined in ex vivo cultures of osteoblasts. The effect of estrogen on mouse Bcl-2 in ex vivo osteoblast cultures was assayed by RT-PCR and Q-PCR. Results and Conclusions: Two Col2.3Bcl-2 (tg/+) founder lines were established and appeared normal except that they were smaller than their nontransgenic wildtype (+/+) littermates at 1, 2, and 6 months of age, with the greatest differences at 2 months. Immunohistochemistry showed hBcl-2 in osteoblasts at the growth plate and cortical surfaces. Nontransgenic littermates were negative. Western blots revealed hBcl-2 only in type I collagen-expressing tissues. Histomorphometry of 2-month-old mice showed a significant decrease in tg/+ calvaria width with no significant differences in femoral trabecular area or cortical width compared with +/+. However, tg/+ males had significantly more trabecular bone than tg/+ females. Female +/+ mice showed increased bone turnover with elevated osteoblast and osteoclast parameters compared with +/+ males. Col2.3Bcl-2 mice did not show such significant differences between sexes. Male tg/+ mice had a 76.5 ± 1.5% increase in ObS/BS with no significant differences in bone formation rate (BFR) or mineral apposition rate (MAR) compared with male +/+ mice. Transgenic females had a significant 48.4 ± 0.1% and 20.1 ± 5.8% decrease in BFR and MAR, respectively, compared with +/+ females. Osteoclast and osteocyte parameters were unchanged. By 6 months, femurs from female and male +/+ mice had lost a significant amount of their percent of trabecular bone compared with 2-month-old mice. There was little to no change in femoral bone in the tg/+ mice with age. Ex vivo cultures of osteoblasts from +/+ and Col2.3Bcl-2 mice showed a decrease in mineralization, no effect on proliferation, and an inhibition of glucocorticoid-induced apoptosis in Col2.3Bcl-2 cultures. Estrogen was shown to increase mouse Bcl-2 transcript levels in osteoblast cultures of wildtype mice, supporting a role for Bcl-2 in the sex-related differences in bone phenotype regulated by estrogen. Therefore, Bcl-2 differentially affected bone phenotype in male and female transgenic mice, altered bone cell activity associated with sex-related differences, and decreased bone formation, suggesting that apoptosis is necessary for mineralization. In addition, Bcl-2 targeted to mature osteoblasts seemed to delay bone development, producing a smaller transgenic mouse compared with wildtype littermates. These studies suggest that expression of Bcl-2 in osteoblasts is important in regulating bone mass in development and in the normal aging process of bone. [source] Targeted Expression of SHH Affects Chondrocyte Differentiation, Growth Plate Organization, and Sox9 Expression,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2004Sara Tavella Abstract The role of Hedgehogs (Hh) in murine skeletal development was studied by overexpressing human Sonic Hedgehog (SHH) in chondrocytes of transgenic mice using the collagen II promoter/enhancer. Overexpression caused a lethal craniorachischisis with major alterations in long bones because of defects in chondrocyte differentiation. Introduction: Hedgehogs (Hhs) are a family of secreted polypeptides that play important roles in vertebrate development, controlling many critical steps of cell differentiation and patterning. Skeletal development is affected in many different ways by Hhs. Genetic defects and anomalies of Hhs signaling pathways cause severe abnormalities in the appendicular, axial, and cranial skeleton in man and other vertebrates. Materials and Methods: Genetic manipulation of mouse embryos was used to study in vivo the function of SHH in skeletal development. By DNA microinjection into pronuclei of fertilized oocytes, we have generated transgenic mice that express SHH specifically in chondrocytes using the cartilage-specific collagen II promoter/enhancer. Transgenic skeletal development was studied at different embryonic stages by histology. The expression pattern of specific chondrocyte molecules was studied by immunohistochemistry and in situ hybridization. Results: Transgenic mice died at birth with severe craniorachischisis and other skeletal defects in ribs, sternum, and long bones. Detailed analysis of long bones showed that chondrocyte differentiation was blocked at prehypertrophic stages, hindering endochondral ossification and trabecular bone formation, with specific defects in different limb segments. The growth plate was highly disorganized in the tibia and was completely absent in the femur and humerus, leading to skeletal elements entirely made of cartilage surrounded by a thin layer of bone. In this cartilage, chondrocytes maintained a columnar organization that was perpendicular to the bone longitudinal axis and directed toward its outer surface. The expression of SHH receptor, Patched-1 (Ptc1), was greatly increased in all cartilage, as well as the expression of parathyroid hormone-related protein (PTHrP) at the articular surface; while the expression of Indian Hedgehog (Ihh), another member of Hh family that controls the rate of chondrocyte maturation, was greatly reduced and restricted to the displaced chondrocyte columns. Transgenic mice also revealed the ability of SHH to upregulate the expression of Sox9, a major transcription factor implicated in chondrocyte-specific gene expression, in vivo and in vitro, acting through the proximal 6.8-kb-long Sox9 promoter. Conclusion: Transgenic mice show that continuous expression of SHH in chondrocytes interferes with cell differentiation and growth plate organization and induces high levels and diffuse expression of Sox9 in cartilaginous bones. [source] Osteoblast-Specific Targeting of Soluble Colony-Stimulating Factor-1 Increases Cortical Bone Thickness in Mice,,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2003SL Abboud Abstract The soluble and membrane-bound forms of CSF-1 are synthesized by osteoblasts and stromal cells in the bone microenvironment. Transgenic mice, generated to selectively express sCSF-1 in bone, showed increased cortical thickness in the femoral diaphysis caused by new bone formation along the endosteal surface. The ability of sCSF-1 to enhance bone cell activity in vivo is potentially relevant for increasing cortical bone in a variety of disorders. Introduction: The soluble form of colony-stimulating factor-1 (sCSF-1) and the membrane-bound form of CSF-1 (mCSF-1) have been shown to support osteoclastogenesis in vitro; however, the effect of each peptide on bone remodeling in vivo is unclear. To determine the effect of sCSF-1, selectively expressed in bone, the skeletal phenotype of transgenic mice harboring the human sCSF-1 cDNA under the control of the osteocalcin promoter was assessed. Methods: At 5 and 14 weeks, mice were analyzed for CSF-1 protein levels, weighed, and X-rayed, and femurs were removed for peripheral quantitative computed tomography, histology, and histomorphometry. Results: High levels of human sCSF-1 were detected in bone extracts and, to a lesser extent, in plasma. Adult transgenic mice showed normal body weight and increased circulating monocytic cells. At 5 weeks, the femoral diaphysis was similar in CSF-1T and wt/wt littermates. However, by 14 weeks, the femoral diaphysis in CSF-1T mice showed increased cortical thickness and bone mineral density. In contrast to the diaphysis, the femoral metaphysis of CSF-1T mice showed normal cancellous bone comparable with wt/wt littermates at each time point. Histological sections demonstrated increased woven bone along the endosteal surface of the diaphysis and intracortical remodeling. Fluorochrome-labeling analysis confirmed endocortical bone formation in CSF-1T, with a 3.1-fold increase in the percentage of double-labeled surfaces and a 3.6-fold increase in the bone formation rate compared with wt/wt mice. Although remodeling resulted in a slightly porous cortex, sCSF-1 preferentially stimulated endocortical bone formation, leading to increased cortical thickness. Conclusions: These findings indicate that sCSF-1 is a key determinant of bone cell activity in the corticoendosteal envelope. [source] Predominant formation of heavily pigmented dermal melanocytomas resembling ,animal-type' melanomas in hepatocyte growth factor (C57BL/6 × C3H)F1 mice following neonatal UV irradiationJOURNAL OF CUTANEOUS PATHOLOGY, Issue 9 2007Scott R. Florell Background:, Transgenic mice expressing hepatocyte growth factor (HGF) develop cutaneous melanocytic tumors following neonatal UV exposure. Here, we examined the histologic spectrum of UV-induced melanocytic tumors in HGF mice on a pigmented (C57BL/6 × C3H/HeN)F1 background. Methods:, Neonatally irradiated (4000 J/m2) mice were monitored for 43 weeks, and 31/34 (91%) animals developed a total of 163 melanocytic tumors. Results:, Of 54 primary tumors analyzed, most (49/54, 91%) demonstrated exclusively dermal collections of epithelioid cells with voluminous densely pigmented cytoplasm. Seven of these also demonstrated a population of spindled cells with mitoses. Several (3/54, 6%) tumors exhibited a junctional component with melanocytes present in the epidermis. Staining with PEP8 confirmed the presence of interfollicular melanocytes at the dermal-epidermal junction in neonatal skin. Conclusions:, In contrast to HGF animals on an albino (FVB) background, HGF animals on the pigmented (C57BL/6 × C3H/HeN)F1 background do not develop classic radial growth phase melanoma but rather predominantly develop dermal melanocytomas resembling the ,animal-type' melanoma occasionally seen in humans. These results demonstrate the influence of genetic background on histologic pattern of UV-induced melanomas in mice. [source] Transgenic mice replicating hepatitis B virus but lacking expression of the major HBsAg,JOURNAL OF MEDICAL VIROLOGY, Issue 4 2008Leonie Halverscheid Abstract Hepatitis B Virus (HBV) transgenic mice replicating the viral genome at high level but lacking expression of the small envelope protein (HBsAg) have been produced using a terminally redundant viral DNA construct (HBV 1.4). The generation of viable infectious progeny was dependent on sex and age of mice. Viral mRNA was abundant in liver and kidneys and at low levels in other organs of the mice. No viral particles or HBV envelope proteins could be detected in sera of mice. Despite expression of non-secreted LHBs and MHBs proteins in the liver, there was no accumulation of viral particles in the endoplasmic reticulum of hepatocytes and no necroinflammatory hepatitis was observed. Therefore, these mice represent an excellent model for studies of the role of HBsAg in viral assembly, antiviral immune responses, the further understanding of HBV immunopathogenesis, and the development of antiviral vaccines. J. Med. Virol. 80:583,590, 2008. © 2008 Wiley-Liss, Inc. [source] Structure of the Mouse Glutamate Decarboxylase 65 Gene and Its PromoterJOURNAL OF NEUROCHEMISTRY, Issue 4 2000Preferential Expression of Its Promoter in the GABAergic Neurons of Transgenic Mice Abstract: GABA is synthesized by glutamate decarboxylase (GAD), which has two forms, GAD65 and GAD67. To elucidate the molecular mechanisms of mouse GAD65 (mGAD65) gene expression, we isolated and characterized the mGAD65 gene. The mGAD65 gene was found to be divided into 16 exons and spread over 75 kb. The sequence of the first exon and the 5,-flanking region indicated the presence of potential neuron-specific cis -regulatory elements. We used transgenic mice to examine the expression pattern conferred by a 9.2-kb promoter-proximal DNA fragment of the mGAD65 gene fused to the bacterial lacZ reporter gene. Transgenic mice showed high ,-galactosidase activity specifically in brain and testis. They also showed characteristic patterns of transgene expression in olfactory bulb, cerebellar cortex, and spinal cord, a similar expression pattern to that of endogenous mGAD65. However, no transgene expression was observed in the ventral thalamus or hypothalamus, in which high mGAD65 gene expression levels have been observed. These results suggest that the 9.2-kb DNA fragment of the mGAD65 gene is associated with its tissue-specific expression and its targeted expression in GABAergic neurons of specific brain regions but that additional regulatory elements are necessary to obtain fully correct expression. [source] Astrocyte expression of a dominant-negative interferon-, receptorJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2005Claudia Hindinger Abstract Interferon-, (IFN-,) is a major proinflammatory cytokine, and binding to its nearly ubiquitous receptor induces a wide variety of biological functions. To explore the role(s) of IFN-, signaling in astrocytes, transgenic mice (GFAP/IFN-,R1,IC) expressing a dominant-negative IFN-, receptor alpha chain under control of the astrocyte-specific glial fibrillary acid protein (GFAP) promoter were generated. Transgenic mice developed normally, had normal astrocyte numbers and distribution, and exhibited no clinically overt phenotype. Transgene mRNA expression was detected only in the CNS, and the transgene-encoded IFN-, receptor 1 colocalized with GFAP, which is consistent with astrocyte expression. Astrocytes from transgenic mice exhibited reduced IFN-,-induced signaling as measured by major histocompatibility class II induction. Neither CNS inflammation nor perforin-mediated clearance of a neurotropic mouse hepatitis virus from astrocytes was impaired following infection. Transgenic mice with impaired astrocyte responsiveness to IFN-, provide a model for studying the selective astrocyte-dependent effects of this critical cytokine in CNS immunopathology. © 2005 Wiley-Liss, Inc. [source] Reactive site-dependent phenotypic alterations in plasminogen activator inhibitor-1 transgenic miceJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 7 2007M. EREN Summary.,Background:,Plasminogen activator inhibitor-1 (PAI-1) is the major physiological inhibitor of plasminogen activators (PAs) and plays a role in the regulation of a number of physiological processes including the degradation of extracellular matrix proteins, cell proliferation and migration, and intracellular signaling. Aim:,To characterize the effects of durable expression of a stable form of human PAI-1 and to characterize important structure,function relationships in PAI-1 in vivo.Methods:,We developed transgenic mice lines overexpressing stable variants of human PAI-1 under the control of the murine preproendothelin-1 promoter and characterized the phenotypic alterations displayed by transgenic mice. Results:,Transgenic mice expressing an active form of human PAI-1 (PAI-1-stab) display complex phenotypic abnormalities including alopecia and hepatosplenomegaly. Reactive site mutant transgenic mice expressing inactive PAI-1 exhibit complete phenotypic rescue, while transgenic mice expressing PAI-1 with reduced affinity for vitronectin manifest all of the phenotypic abnormalities present in PAI-1-stab transgenic mice. Conclusions:,The protease inhibitory activity of PAI-1 toward PAs and/or other serine proteases is necessary and sufficient to promote complex phenotypic abnormalities and mediates many of the physiological effects of PAI-1 in vivo. [source] | ||||||||||||||||||||||||||||||||||