Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Transgenic mouse model”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,117 records · Page 62Linked to original sources
PubMed2004

Transgenic mouse with human mutant p53 expression in the prostate epithelium.

BACKGROUND: Apoptosis is disrupted in prostate tumor cells, conferring a survival advantage. p53 is a nuclear protein believed to regulate cancer progression, in part by inducing apoptosis. To test this possibility in future studies, the objective of the present study was to generate a transgenic mouse model expressing mutant p53 in the prostate (PR). METHODS: Transgene incorporation was tested using Southern analysis. Expression of mutant p53 protein was examined using immunofluorescence microscopy. Apoptosis in the PR was evaluated using the Tunnel method. RESULTS: A construct, consisting of the rat probasin promoter and a mutant human p53 fragment, was prepared and used to generate transgenic mice. rPB-mutant p53 transgene incorporation, as well as nuclear accumulation of mutant human p53 protein, was demonstrated. Prostatic intraepithelial neoplasia (PIN) III and IV were found in PR of 52-week old transgenic mice, whereas no pathological changes were found in the other organs examined. PR ability to undergo apoptosis following castration was reduced in rPB-mutant p53 mice as compared to non transgenic littermates. CONCLUSIONS: Transgenic rPB-mutant p53 mice accumulate mutant p53 protein in PR, resulting in neoplastic lesions and reduced apoptotic potential in the PR. Breeding rPB-mutant p53 mice with mice expressing an oncogene in their PR will be useful in examining interactions of multiple genes that result in progression of slow growing prostate tumors expressing oncogenes alone to metastatic cancer.

Animals↗
PubMed2000

Hepatocytes of double-transgenic mice expressing high levels of hepatitis B virus e antigen and interferon-gamma are not injured by HBeAg specific autoantibodies.

Seroconversion from HBeAg to alphaHBe of persons chronically infected by HBV is usually associated with a transient exacerbation of liver disease and subsequent normalization of liver histology. It is speculated that these clinico-pathological features may be due to the activation of cytodestructive mechanisms by alphaHBe antibodies. The aim of the present study was to investigate the pathogenic potential of alphaHBe antibodies in a transgenic mouse model. Therefore, alphaHBe autoantibodies were elicited in double-transgenic mice expressing high amounts of HBeAg and interferon-gamma in the liver. Interferon-gamma has reviously been shown to play an important role in the development of hepatic necroinflammation associated with hepadnaviral infection, probably via tumor-necrosis-factor-alpha secreted by activated macrophages. We found no evidence that alphaHBe antibodies have the potential to destroy HBeAg-secreting hepatocytes even if the cells were predisposed to injury due to high-level interferon-gamma expression. We conclude that seroconversion from HBeAg to alphaHBe of persons chronically infected with HBV seems to be an immunological epiphenomenon without pathogenic significance.

Animals↗
PubMed1997

Animal models of cerebral beta-amyloid angiopathy.

Cerebral amyloid angiopathy (CAA) is a significant risk factor for hemorrhagic stroke in the elderly, and occurs as a sporadic disorder, as a frequent component of Alzheimer's disease, and in several rare, hereditary conditions. The most common type of amyloid found in the vasculature of the brain is beta-amyloid (A beta), the same peptide that occurs in senile plaques. A paucity of animal models has hindered the experimental analysis of CAA. Several transgenic mouse models of cerebral beta-amyloidosis have now been reported, but only one appears to develop significant cerebrovascular amyloid. However, well-characterized models of naturally occurring CAA, particularly aged dogs and non-human primates, have contributed unique insights into the biology of vascular amyloid in recent years. Some non-human primate species have a predilection for developing CAA; the squirrel monkey (Saimiri sciureus), for example, is particularly likely to manifest beta-amyloid deposition in the cerebral blood vessels with age, whereas the rhesus monkey (Macaca mulatta) develops more abundant parenchymal amyloid. These animals have been used to test in vivo beta-amyloid labeling strategies with monoclonal antibodies and radiolabeled A beta. Species-differences in the predominant site of A beta deposition also can be exploited to evaluate factors that direct amyloid selectively to a particular tissue compartment of the brain. For example, the cysteine protease inhibitor, cystatin C, in squirrel monkeys has an amino acid substitution that is similar to the mutant substitution found in some humans with a hereditary form of cystatin C amyloid angiopathy, possibly explaining the predisposition of squirrel monkeys to CAA. The existing animal models have shown considerable utility in deciphering the pathobiology of CAA, and in testing strategies that could be used to diagnose and treat this disorder in humans.

Alzheimer Disease↗
PubMed2006

Conversion to the amyotrophic lateral sclerosis phenotype is associated with intermolecular linked insoluble aggregates of SOD1 in mitochondria.

Twenty percent of the familial form of amyotrophic lateral sclerosis (ALS) is caused by mutations in the Cu, Zn-superoxide dismutase gene (SOD1) through the gain of a toxic function. The nature of this toxic function of mutant SOD1 has remained largely unknown. Here we show that WT SOD1 not only hastens onset of the ALS phenotype but can also convert an unaffected phenotype to an ALS phenotype in mutant SOD1 transgenic mouse models. Further analyses of the single- and double-transgenic mice revealed that conversion of mutant SOD1 from a soluble form to an aggregated and detergent-insoluble form was associated with development of the ALS phenotype in transgenic mice. Conversion of WT SOD1 from a soluble form to an aggregated and insoluble form also correlates with exacerbation of the disease or conversion to a disease phenotype in double-transgenic mice. This conversion, observed in the mitochondrial fraction of the spinal cord, involved formation of insoluble SOD1 dimers and multimers that are crosslinked through intermolecular disulfide bonds via oxidation of cysteine residues in SOD1. Our data thus show a molecular mechanism by which SOD1, an important protein in cellular defense against free radicals, is converted to aggregated and apparently ALS-associated toxic dimers and multimers by redox processes. These findings provide evidence of direct links among oxidation, protein aggregation, mitochondrial damage, and SOD1-mediated ALS, with possible applications to the aging process and other late-onset neurodegenerative disorders. Importantly, rational therapy based on these observations can now be developed and tested.

Amyotrophic Lateral Sclerosis↗
PubMed2002

Pathogenic effects of cerebral amyloid angiopathy mutations in the amyloid beta-protein precursor.

Cerebral amyloid beta-protein angiopathy (CAA) is a key pathological feature of patients with Alzheimer's disease and certain related disorders. Several mutations have been identified within the Abeta region of the Abeta protein precursor (AbetaPP) gene that appear to enhance the severity of CAA. A new mutation has been identified within the Abeta region (D23N) of AbetaPP that is associated with severe CAA in an Iowa kindred. Recently, we showed that E22Q Dutch, D23N Iowa, and E22Q/D23N Dutch/Iowa double-mutant Abeta40 peptides rapidly assemble in solution to form fibrils compared to wild-type Abeta40. Similarly, the E22Q Dutch and D23N Iowa Abeta40 peptides were found to induce robust pathologic responses in cultured human cerebrovascular smooth muscle (HCSM) cells, including elevated levels of cell-associated AbetaPP, proteolytic breakdown of actin, and cell death. Double-mutant E22Q/D23N Dutch/Iowa Abeta40 was more potent than either single-mutant form of Abeta in causing pathologic responses in HCSM cells. These in vitro data suggested that the E22Q Dutch and D23N Iowa substitutions promote fibrillogenesis and the pathogenicity of Abeta towards HCSM cells. Moreover, the presence of both CAA substitutions in the same Abeta peptide further enhances the fibrillogenic and pathogenic properties of Abeta. We also have generated transgenic mouse models to examine the effects of single and double CAA mutations in AbetaPP in vivo. Preliminary analysis of transgenic mouse brains indicates that expression of double-mutant E22Q/D23N Dutch/Iowa AbetaPP leads to robust deposition of Abeta in a vascular-weighted manner.

Amino Acid Sequence↗
PubMed1998

Recent advances in transgenic model development for Alzheimer's disease.

The lack of a small animal model that represents major features of Alzheimer's disease has long been considered a major handicap for research and drug development. Transgenic technology has been used to introduce potential pathological start points as well as established genetic causes of the disease to trigger pathogenesis in a small animal model. This review describes various approaches, discusses the available transgenic mouse models and compares their similarities and differences, and their applicability for the testing of drugs aiming at a causal treatment of the disease.

Journal Article↗
PubMed2003

Regulation of GLUT4 expression in vivo and in vitro.

The GLUT4 gene is subject to complex tissue-specific and metabolic regulation that has a profound impact on insulin-mediated glucose disposal. The regulation of this gene is of special clinical interest because insulin-mediated glucose homeostasis is highly sensitive to the levels of GLUT4 protein in muscle and adipose tissue. For this reason, the mechanisms of regulated expression of the GLUT4 gene have been intensively studied over the past decade. Understanding the transcriptional mechanisms that underlie the regulated expression of this highly differentiated gene have been slow to emerge, due to the paucity of suitable model systems available for detailed investigation. The development of transgenic mouse models to understand the mechanisms of transcriptional regulation has greatly enhanced our understanding of this gene. Information gained about the regulation of the GLUT4 gene has provided insight into mechanisms by which complex gene regulation occurs through a small number of cis-acting regulatory elements.

Animals↗
PubMed2003

Understanding the physiological role of retinol-binding protein in vitamin A metabolism using transgenic and knockout mouse models.

Retinoids (vitamin A and its derivatives) play an essential role in many biological functions. However mammals are incapable of de novo synthesis of vitamin A and must acquire it from the diet. In the intestine, dietary retinoids are incorporated in chylomicrons as retinyl esters, along with other dietary lipids. The majority of dietary retinoid is cleared by and stored within the liver. To meet vitamin A requirements of tissues, the liver secretes retinol (vitamin A alcohol) into the circulation bound to its sole specific carrier protein, retinol-binding protein (RBP). The single known function of this protein is to transport retinol from the hepatic stores to target tissues. Over the last few years, the generation of knockout and transgenic mouse models has significantly contributed to our understanding of RBP function in the metabolism of vitamin A. We discuss below the role of RBP in maintaining normal vision and a steady flux of retinol throughout the body in times of need.

Animals↗
PubMed1999

Autoaggression and tumor rejection: it takes more than self-specific T-cell activation.

Establishment of self-tolerance prevents autoaggression against organ-specific self-antigens. This beneficial effect, however, may in turn be responsible for tumor immune evasion. Thus, dissecting the mechanisms leading to the breakdown of self-tolerance in autoimmune diseases might provide insights for successful antitumor immune therapies. In a variety of animal models, organ- or tumor-specific immunity has been described, focusing on antigen-specific T-cell activation. Here, we discuss two transgenic mouse models which demonstrate that both autoaggression and tumor rejection require more than activated, self-reactive T cells. TCR transgenic mice, which are tolerant to a liver-specific MHC class I antigen, Kb, can be activated to reject Kb-positive grafts, but fail to attack Kb-expressing liver. However, autoaggression occurs when activated T cells are combined with "conditioning" of the target organ by irradiation or infection with a liver-specific pathogen. Similarly, in a mouse model of islet cell carcinoma, neither co-stimulatory tumor cells nor highly activated antitumor lymphocytes provoke an effective immune response against the tumor. Instead, a combination of activated lymphocytes and irradiation is required for lymphocyte infiltration into solid tumors. Both model systems provide evidence that although activated antigen-specific lymphocytes are a prerequisite for autoaggression, effector cell extravasation and appropriate interaction with the target organ/tumor are equally important. Thus, we propose that the organ/tumor microenvironment is a critical parameter in determining the effectiveness of an anti-self immune response.

Adenoma, Islet Cell↗
PubMed2002

Alcohol suppresses insulin-like growth factor-1 gene expression in prepubertal transgenic female mice overexpressing the bovine growth hormone gene.

BACKGROUND: Alcohol (ALC) delays puberty in female rats and alters the development of a normal menstrual pattern in rhesus monkeys. These actions are associated with depressed serum levels of growth hormone (GH), luteinizing hormone and insulin-like growth factor-1 (IGF-1). The mechanism of this ALC-induced depression in IGF-1 is not known, however, could be due to depressed GH and, possibly, to an alteration in the hepatic GH receptor. To assess whether ALC has a direct action at the liver, we used a transgenic mouse model that overexpresses GH, allowing assessment of potential direct actions of ALC on the level of either the GH receptor or the IGF-1-synthesizing machinery within the hepatocyte. METHODS: One group of transgenic mice was fed a liquid diet containing ALC. The second group was pair-fed the companion isocaloric control liquid diet. The third group of transgenic mice was fed Lab Chow and water. The fourth group consisted of normal (nontransgenic) littermates fed Lab Chow and water. Animals received their respective diets for 5 days. Mice were killed during their late juvenile stage of development, and tissues and blood collected and frozen. RESULTS: The ALC-fed transgenic mice showed a decrease (p < 0.01) in hepatic IGF-1a and IGF-1b messenger RNA levels compared with transgenic controls, and this paralleled a decrease (p < 0.01) in serum IGF-1. ALC did not alter the circulating levels of bovine GH held constant by the promotor and did not alter mouse GH receptor protein levels as analyzed by Western blotting. CONCLUSIONS: Using this transgenic animal model that maintains circulating GH in the presence of ALC, we found that the ability of ALC to suppress prepubertal Igf1 gene expression can also occur independently of any alterations in the level of circulating GH. This direct effect on the hepatocyte is a postreceptor event because the GH receptor protein levels were not altered by ALC exposure.

Aging↗
PubMed2006

Altered responses to dopaminergic D2 receptor activation and N-type calcium currents in striatal cholinergic interneurons in a mouse model of DYT1 dystonia.

Early-onset torsion dystonia (DYT1) is an autosomal dominant disease caused by a deletion in the gene encoding the protein torsinA. Recently, a transgenic mouse model of DYT1 has been described, expressing either the human wild-type torsinA (hWT) or mutant torsinA (hMT). We recorded the activity of striatal cholinergic interneurons of hWT, hMT, and control mice. In slice preparations, no significant differences were observed in resting membrane potential (RMP), firing activity, action potential duration or Ih current. Quinpirole, a D2-like dopamine receptor agonist, did not produce detectable effects on RMP of cholinergic interneurons in control mice and hWT mice, but in the hMT mice caused membrane depolarization and an increase in the firing rate. D2 receptor activation inhibits N-type high-voltage-activated calcium currents. We found that, in isolated interneurons from hMT mice, the quinpirole-mediated inhibition of N-type currents was significantly larger than in hWT and controls. Moreover, the N-type component was significantly over-represented in hMT mice. The altered sensitivity of N-type channels in hMT mice could account for the paradoxical excitatory effect of D2 stimulation. Our data support the existence of an imbalance between striatal dopaminergic and cholinergic signaling in DYT1 dystonia.

Acetylcholine↗
PubMed1998

Increased vulnerability to 3-nitropropionic acid in an animal model of Huntington's disease.

There is substantial evidence for both metabolic dysfunction and oxidative damage in Huntington's disease (HD). In the present study, we used in vivo microdialysis to measure the conversion of 4-hydroxybenzoic acid to 3,4-dihydroxybenzoic acid (3,4-DHBA) as a measure of hydroxyl radical production in a transgenic mouse model of HD, as well as in littermate controls. The conversion of 4-hydroxybenzoic acid to 3,4-DHBA was unchanged in the striatum of transgenic HD mice at baseline. Following administration of the mitochondrial toxin 3-nitropropionic acid (3-NP), there were significant increases in 3,4-DHBA generation in both control and transgenic HD mice, and the increases in the transgenic HD mice were significantly greater than those in controls. Furthermore, administration of 3-NP produced significantly larger striatal lesions in transgenic HD mice than in littermate controls. The present results show increased sensitivity to the mitochondrial toxin 3-NP in transgenic HD mice, which suggests metabolic dysfunction in this mouse model of HD.

Animals↗
PubMedDate not supplied

Renal expression of two 'thyroid-specific' genes: thyrotropin receptor and thyroglobulin.

Numerous renal abnormalities accompany thyroid disease, most of which have been ascribed to the effects of thyroid hormone on renal metabolism. In the present report, we investigate the renal expression of the nominally thyroid-specific proteins, thyroid-stimulating hormone (TSH) receptor (TSHR) and thyroglobulin (Tg), as potential links between renal and thyroid function. The expression of TSHR has been identified in several extrathyroidal tissues, but its presence in the kidney remains controversial. We have used reverse-transcriptase polymerase chain reaction and DNA sequencing to demonstrate the presence of TSHR transcript in human and mouse kidney, in a primary culture of human kidney, and in a green monkey kidney epithelioid cell line. Furthermore, human kidney cells responded to TSH with a 2.5- fold increase in intracellular cyclic adenosine monophosphate, suggesting the presence of functional TSHR protein. Comparison of renal expression of TSHR in a bovine growth hormone transgenic mouse model of progressive glomerulosclerosis with control mice suggested increased TSHR transcript in the renal cortex of transgenic animals. TSHR transcript was also detected in mouse mesangial cells in vitro which responded to TSH with significant increases in the formation of three-dimensional hillhocks. Polymerase chain reaction also confirmed the presence of Tg transcript in human and mouse kidneys and in mouse mesangial cells, but no effect of either TSH or cyclic adenosine monophosphate on Tg transcript levels could be discerned. Immunofluorescent staining with a monoclonal anti-Tg antibody identified positive staining in the cytoplasm of mesangial cells. These data suggest that the kidney is capable of expressing the thyroid-specific genes, TSHR and Tg, which could conceivably mediate effects of thyroid disease in the kidney.

Animals↗
PubMed1994

Effects of human class I transgenes on Toxoplasma gondii cyst formation.

MHC class I genes are important in the regulation of cyst number in mice perorally infected with Toxoplasma gondii. Since human MHC class I molecules may be capable of functioning as restriction elements in mice, to determine whether class I genes also control outcome of T. gondii infection for humans, a transgenic mouse model was developed using human class I genes in mice. Human HLA-B27 and Cw3 transgenic mice, with the cyst-susceptible B10 mouse background, were tested for resistance to cyst formation after peroral infection with the Me49 strain of T. gondii. Introduction of the B27 gene into susceptible mice made them even more susceptible to T. gondii brain cyst formation. In contrast, HLA-DB27 transgenic mice that have a substitution of the alpha 3 portion of the human class I molecule with the alpha 3 portion of the mouse Kd molecule had the same number of brain cysts as susceptible B10 control mice when perorally infected. Similarly, HLA-Cw3 transgenic mice had the same number of brain cysts as the susceptible B10 controls. These results indicate that the interaction between CD8 on mouse T cells and the human class I molecule in transgenic mice does not always occur, and sometimes may hinder a normal response. Furthermore, B27 and Cw3 transgenes did not generate resistance to cyst formation in infection by T. gondii.

Animals↗
PubMed2006

Mitochondrial dysfunction and Alzheimer's disease.

Mitochondrial dysfunction has been implicated in causing metabolic abnormalities in Alzheimer's disease (AD). The searches for mitochondrial DNA variants associated with AD susceptibility have generated conflicting results. The age-related accumulation of somatic mitochondrial DNA deletion has been suggested to play a pathogenic role in the development of AD. Recent studies have demonstrated that amyloid-beta peptide (Abeta) progressively accumulates in mitochndrial matrix, as demonstrated in both transgenic mice over-expressing mutant amyloid precursor protein (APP) and autopsy brain from AD patients. Abeta-mediated mitochondrial stress was evidenced by impaired oxygen consumption and decreased respiratory chain complexes III and IV activities in brains from AD patients and AD-type transgenic mouse model. Furthermore, our studies indicated that interaction of intramitochondrial Abeta with a mitochondrial enzyme, amyloid binding alcohol dehydrogenase (ABAD), inhibits its enzyme activity, enhances generation of reactive oxygen species (ROS), impairs energy metabolism, and exaggerates Abeta-induced spatial learning/memory deficits and neuropathological changes in transgenic AD-type mouse model. Interception of ABAD-Abeta interaction may be a potential therapeutic strategy for Alzheimer's disease.

Alzheimer Disease↗
PubMed2005

Antiapoptotic and anti-inflammatory mechanisms of heat-shock protein protection.

We and others have previously shown that heat-shock proteins (HSPs) are involved in protecting the brain from a variety of insults including stroke, epilepsy, and other related insults. While the mechanism of this protection has largely been thought to be due to their chaperone functions (i.e., preventing abnormal protein folding or aggregation), recent work has shown that HSPs may also directly interfere with other cell death pathways such as apoptosis and inflammation. Using models of cerebral ischemic and ischemia-like injury, we overexpressed the 70-kDa heat-shock protein (HSP70) using gene transfer or by studying a transgenic mouse model. HSP70 protected neurons and astrocytes from experimental stroke and stroke-like insults. HSP70 transgenic mice also had better neurological scores following experimental stroke compared to their wild-type littermates. Overexpressing HSP70 was associated with less apoptotic cell death and increased expression of the antiapoptotic protein, Bcl-2. Furthermore, HSP70 suppressed microglial/monocyte activation following experimental stroke. HSP70 overexpression also led to the reduction of matrix metalloproteinases. We suggest that HSPs are capable of protecting brain cells from lethal insults through a variety of mechanisms and should be explored as a potential therapy against stroke and other neurodegenerative diseases.

Animals↗
PubMed2002

Lens defects and age-related fiber cell degeneration in a mouse model of increased AbetaPP gene dosage in Down syndrome.

Early-onset cataract and Alzheimer's disease occur with high frequency in Down syndrome (trisomy 21), the most common chromosome duplication in human live births. Previously, we used in vivo and lens organ culture models to demonstrate Alzheimer pathophysiology in oxidative stress-related lens degeneration. Currently, well-characterized Alzheimer transgenic mouse models are used to extend these findings. Here, we report on mice carrying a complete copy of a wild-type human AbetaPP (hAbetaPP) gene from the Down syndrome critical region on chromosome 21. hAbetaPP mice produce fiber cell membrane defects similar to those described in human cataracts and increased age-related lens degeneration. hAbetaPP expression and mRNA alternative splicing in human and mouse lens and cornea favor longer, potentially more amyloidogenic forms. Endogenous mouse AbetaPP expression is increased in transgenic lenses, consistent with the cycle of oxidative stress proposed in the mechanism of Alzheimer pathophysiology. Alternative splicing previously designated as neuron-specific occurs in human lens and cornea, and is maintained by hAbetaPP expressed in mouse tissues. These present data implicate AbetaPP in fiber cell formation and in early-onset cataracts in Down syndrome. Finally, our findings provide further support for our hypothesis that Alzheimer pathophysiology contributes to the cataract formation that is increasing in the aging population.

Alternative Splicing↗
PubMed2006

Prothrombotic factors enhance heparin-induced thrombocytopenia and thrombosis in vivo in a mouse model.

BACKGROUND: Heparin-induced thrombocytopenia/thrombosis (HIT/T) is a common cause of life- and limb-threatening thrombosis. The development of antibodies that react with complexes of heparin and platelet factor 4 (PF4) is fundamental to the development of the disease. However, anti-PF4/heparin antibodies are far more common than is HIT/T and there is less understanding of the factors that contribute to thrombosis in only a subset of patients. OBJECTIVES: Both qualitative and quantitative differences in multiple factors (e.g. antibodies, heparin and platelets) may influence the clinical course of patients who develop anti-PF4/heparin antibodies. We examined the hypothesis that host-specific factors, such as comorbid prothrombotic conditions, would exacerbate the pathologic effects of anti-PF4/heparin antibodies. METHODS AND RESULTS: A mouse model transgenic for human Fcgamma RIIa and PF4 and null for mouse PF4 was used to study the influence of prothrombotic conditions on the effects of anti-PF4/heparin antibodies in vivo. To simulate a prothrombotic milieu, mice were fed a hypercholesterolemic diet (HD). HD-fed mice had elevated plasma cholesterol, increased platelet reactivity and increased endothelial activation relative to mice fed a standard diet (SD). Age- and sex-matched mice from each diet group were treated with an anti-PF4/heparin antibody and heparin. HD-fed mice developed more severe thrombocytopenia than similarly treated SD-fed mice. Mice with moderate to severe thrombocytopenia had elevated plasma levels of thrombin-antithrombin complexes, indicative of increased thrombin generation in vivo. Platelet-fibrin thrombi were observed in multiple organs of HD-fed mice that developed severe thrombocytopenia. CONCLUSIONS: Host-specific factors, such as prothrombotic changes in platelet reactivity and/or endothelial activation, may influence the development of thrombosis in a subset of patients who develop anti-PF4/heparin antibodies.

Animals↗