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Results for “Transgenic mouse model”

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At least 505 records · Page 28Linked to original sources
PubMed2002

The relationship between predicted peptide-MHC class II affinity and T-cell activation in a HLA-DRbeta1*0401 transgenic mouse model.

The HLA-DRB1*0401 MHC class II molecule (DR4) is genetically associated with rheumatoid arthritis. It has been proposed that this MHC class II molecule participates in disease pathogenesis by presenting arthritogenic endogenous or exogenous peptides to CD4+ T cells, leading to their activation and resulting in an inflammatory response within the synovium. In order to better understand DR4 restricted T cell activation, we analyzed the candidate arthritogenic antigens type II collagen, human aggrecan, and the hepatitis B surface antigen for T-cell epitopes using a predictive model for determining peptide-DR4 affinity. We also applied this model to determine whether cross-reactive T-cell epitopes can be predicted based on known MHC-peptide-TCR interactions. Using the HLA-DR4-IE transgenic mouse, we showed that both T-cell proliferation and Th1 cytokine production (IFN-gamma) correlate with the predicted affinity of a peptide for DR4. In addition, we provide evidence that TCR recognition of a peptide-DR4 complex is highly specific in that similar antigenic peptide sequences, containing identical amino acids at TCR contact positions, do not activate the same population of T cells.

Aggrecans↗
PubMed1990

A transgenic mouse model for trilateral retinoblastoma.

We present a murine model of trilateral retinoblastoma. Ocular retinoblastoma and central nervous system tumors are observed in a line of mice formed by the transgenic expression of SV40 T-antigen. An oncogenic protein known to bind to the retinoblastoma gene product (p105-Rb) is specifically expressed within retinal cells in this model. All animals that carry this genetic alteration develop multifocal retinal tumors. Midbrain tumors are observed in 15% of ocular tumor-bearing animals, and these arise ventral to the cerebral aqueduct at the level of the pineal gland. Both ocular and central nervous system neoplasms are heritable in heterozygous offspring through 10 sequential generations of breeding. Retinal tumors display the gross appearance, invasive properties, light and electron microscopic features, and immunohistochemical staining characteristics of human retinoblastoma. The light and electron microscopic characteristics as well as immunocytochemical features of undifferentiated midline central nervous system neoplasms further correlate with human trilateral retinoblastoma. We postulate an alternative mechanism of retinoblastoma tumorigenesis that involves functional inactivation of retinoblastoma protein locally in the face of an intact retinoblastoma gene locus.

Animals↗
PubMed2004

Genetically decreased spinal cord copper concentration prolongs life in a transgenic mouse model of amyotrophic lateral sclerosis.

Mutations in the Cu/Zn superoxide dismutase (SOD1) gene cause familial amyotrophic lateral sclerosis (FALS) by gain of an aberrant function that is not yet well understood. The role of Cu(2+) in mediating the toxicity of mutant SOD1 has been earnestly contested. We tested the in vivo effects of genetically induced copper deprivation on the ALS phenotype of transgenic mice expressing G86R mutant mouse SOD1, a protein that fails to incorporate Cu(2+) in its active site. Genetically copper-deficient SOD1(G86R) transgenic mice were produced by mating SOD1(G86R) males to female carriers of the X-linked mottled/brindled (Mobr) mutation. We found that the Mobr allele causes a severe ( approximately 60%) depletion of spinal cord copper levels; however, despite the burden of double genetic lesions, it lengthens the lives of SOD1(G86R) transgenic mice by 9%. These findings provide evidence supporting a role for copper in the pathogenesis of FALS linked to SOD1 mutations.

Adenosine Triphosphatases↗
PubMed1995

Age-dependent penetrance of disease in a transgenic mouse model of familial amyotrophic lateral sclerosis.

The mutation gly93-->ala of Cu,Zn superoxide dismutase (SOD) is found in patients with familial amyotrophic lateral sclerosis and causes motor neuron disease when expressed in transgenic mice. The progression of clinical and pathological disease was studied in a line of mice designated G1H. Clinical disease started at 91 +/- 14 days of age with fine shaking of the limbs, followed by paralysis and death by 136 +/- 7 days of age. Pathological changes begin by 37 days of age with vacuoles derived from swollen mitochondria accumulating in motor neurons. At the onset of clinical disease (90 days), significant death of somatic motor neurons innervating limb muscles has occurred; mice at end-stage disease (136 days) show up to 50% loss of cervical and lumbar motor neurons. However, neither thoracic nor cranial motor neurons show appreciable loss despite vacuolar changes. Autonomic motor neurons also are not affected. Mice that express wild-type human Cu,Zn SOD remain free of disease, indicating that mutations cause neuron loss by a gain-of-function. Thus, the age-dependent penetrance of motor neuron disease in this transgenic model is due to the gradual accumulation of pathological damage in select populations of cholinergic neurons.

Aging↗
PubMedDate not supplied

Gastric hamartomatous tumours in a transgenic mouse model expressing an activated dioxin/Ah receptor.

BACKGROUND: The dioxin/Aryl hydrocarbon (Ah) receptor is a ligand-activated transcription factor known to mediate the toxic effects of the environmental pollutants dioxins. MATERIALS AND METHODS: Transgenic mice expressing a constitutively active Ah receptor were found to develop gastric tumours. RESULTS: Segments of the normal gastric glands of the corpus region (lined by foveolar, parietal and cardio-pyloral cells) developed cystic tumours. Tumours in the submucosa and muscularis propria consisted of large cysts surrounded by organized lymphocytic, connective, squamous and adipose tissues and vessels. Those tumours were obviously hamartomatous in nature. Despite the fact that the tumours had an inward growth and penetrated all stomach layers, no metastases developed. CONCLUSION: The model here described may open new vistas into the investigation of the role of environmental pollutants in the development of gastric hamartomas.

Animals↗
PubMed1993

An evaluation of mechanisms by which tolerance to organ-specific antigens is lost using a transgenic mouse model.

Patients with type I diabetes lose immunologic tolerance to beta cell Ag and produce anti-self (beta cell) antibodies. We have examined mechanisms by which this self tolerance is lost using transgenic mice in which islet cells express human CD4. These mice are immunologically tolerant to this human protein; the tolerance appears to be characterized by the presence of self reactive B cells and nonresponsive T cells. Autoantibodies can be induced by immunization with CD4 in CFA; this autoantibody response is accompanied by minor peri-islet inflammation but diabetes is not induced. Tolerance can also be broken by provision of an independent covalently linked T cell epitope. Although this mimic can lead to the appearance of an autoantibody response, the autoimmune response can not be maintained by the endogenous Ag. We have also demonstrated that an inflammatory lesion leading to death of the CD4-containing beta cells may not be sufficient to break tolerance. These results have implications for potential mechanisms relating to the appearance of autoantibodies in patients with type I diabetes.

Animals↗
PubMed2003

Neuromuscular accumulation of mutant superoxide dismutase 1 aggregates in a transgenic mouse model of familial amyotrophic lateral sclerosis.

Superoxide dismutase 1 (SOD1) aggregates are a histological and biochemical correlate of disease progression in neural tissues from mutant SOD1-linked forms of familial amyotrophic lateral sclerosis (FALS). In the present study, we assayed the monomeric and high molecular weight mutant SOD1 content of nervous, muscle and visceral tissues from transgenic SOD1(G93A) mice using immunoblotting and zymograms. A progressive age-dependent increase in mutant SOD1 level, aggregation and stabilisation by cross-species heterodimers was determined in lumbar spinal cord, sciatic nerve and gastrocnemius muscle. Such biochemical abnormalities were not present in cervical spinal cord, brainstem and diaphragm muscle, nor common to endogenous mouse SOD1. Mutant dismutase activity in general did not increase correspondingly with accumulating protein at later ages. These results suggest that peripheral targets such as hindlimb skeletal muscle and nerve accumulate mutant SOD1 aggregates and may therefore be susceptible to mutant SOD1-mediated toxicity, in addition to lower and upper motor neurons of the central nervous system in transgenic FALS mice.

Amino Acid Substitution↗
PubMed2001

Transgenic mouse models of tauopathies: prospects for animal models of Pick's disease.

Because filamentous neuronal tau inclusions are neuropathologic hallmarks of Pick's disease and a number of other neurodegenerative disorders known as tauopathies, the authors generated lines of transgenic (Tg) mice that overexpress the shortest human tau isoform in the CNS. These Tg mice accumulated argyrophilic and filamentous tau immunoreactive neuronal inclusions with age in cortex and brainstem as well as in spinal cord, where these inclusions were most abundant and associated with gliosis. The ventral roots of affected spinal cord segments showed axonal degeneration, whereas residual axons exhibited reduced microtubules and reduced fast axonal transport. The inclusions were composed of 10 to 20 nm tau immunopositive straight filaments. In addition, the Tg mice developed age-related motor weakness as well as progressive hyperphosphorylation and decreased solubility of brain and spinal cord tau proteins. Thus, these Tg mice recapitulate phenotypic features of human tauopathies. In this article the authors review the phenotype of these Tg mice and discuss how the availability of relevant animal model of tauopathies will facilitate discovery of more effective therapies to treat Pick's disease and related disorders characterized by filamentous tau pathology in selectively vulnerable regions of the CNS.

Animals↗
PubMed2005

Neurological and neurodegenerative alterations in a transgenic mouse model expressing human alpha-synuclein under oligodendrocyte promoter: implications for multiple system atrophy.

Multiple system atrophy (MSA) is a progressive, neurodegenerative disease characterized by parkinsonism, ataxia, autonomic dysfunction, and accumulation of alpha-synuclein (alpha-syn) in oligodendrocytes. To better understand the mechanisms of neurodegeneration and the role of alpha-syn accumulation in oligodendrocytes in the pathogenesis of MSA, we generated transgenic mouse lines expressing human (h) alpha-syn under the control of the murine myelin basic protein promoter. Transgenic mice expressing high levels of halpha-syn displayed severe neurological alterations and died prematurely at 6 months of age. Furthermore, mice developed progressive accumulation of halpha-syn-immunoreactive inclusions in oligodendrocytes along the axonal tracts in the brainstem, basal ganglia, cerebellum, corpus callosum, and neocortex. The inclusions also reacted with antibodies against phospho-serine (129) halpha-syn and ubiquitin, and halpha-syn was found in the detergent-insoluble fraction. In high-expresser lines, the white matter tracts displayed intense astrogliosis, myelin pallor, and decreased neurofilament immunostaining. Accumulation of halpha-syn in oligodendrocytes also leads to prominent neurodegenerative changes in the neocortex with decreased dendritic density and to loss of dopaminergic fibers in the basal ganglia. The oligodendrocytic inclusions were composed of fibrils and accompanied by mitochondrial alterations and disruption of the myelin lamina in the axons. Together, these studies support the contention that accumulation of alpha-syn in oligodendrocytes promotes neurodegeneration and recapitulates several of the key functional and neuropathological features of MSA.

Animals↗
PubMed2004

Diffusion tensor imaging detects age-dependent white matter changes in a transgenic mouse model with amyloid deposition.

Increasing evidence demonstrates that there is marked damage and dysfunction not only in the gray matter but also in the white matter in Alzheimer's disease (AD). In this study, transgenic mice overexpressing beta-amyloid precursor protein (APP) under control of the platelet-derived growth factor promoter (PDAPP mice) were examined using diffusion tensor magnetic resonance imaging (DTI) to evaluate the extent of white matter injury before and following the development of AD-like pathology. The profile of DTI parameters was significantly different in old PDAPP mice compared to that of old control mice following the development of AD-like pathology. No difference in DTI parameters was observed between the young PDAPP and control mice. Our results suggest that as amyloid beta (Abeta) deposition and levels increase over time in PDAPP mice, these changes lead to primary or secondary white matter injury that can be detected by DTI.

Aging↗
PubMed2000

Fumonisin toxicity in a transgenic mouse model lacking the mdr1a/1b P-glycoprotein genes.

The toxicity of fumonisin B(1) (FB(1)) was investigated in male mdr1a/1b double knockout (MDRK) mice, lacking the drug-transporting P-glycoproteins. These transgenic animals are deficient in their blood:brain barrier and accumulate different drugs in brain and other tissues. The MDRK and their wild-type counterparts, FVB mice, were injected subcutaneously with 2.25 mg/kg per day of FB(1) for 5 days and sampled one day after the last treatment in a protocol that has resulted in marked hepatic and renal damage in other strains. FB(1) caused liver enlargement in both FVB and MDRK. Hematological parameters were not affected in either strain. Plasma levels of alanine aminotransferase and aspartate aminotransferase, measures of liver damage, were increased by FB(1) in both FVB and MDRK mice. Histopathological evaluation of liver corroborated this finding. Kidney lesions were induced by FB(1) in both types of mice. Concentrations of free sphingosine and sphinganine increased in liver and kidney of both strains after the FB(1) treatment, although the increase in liver sphingoid bases was half as much in MDRK as compared to FVB. The levels of sphinganine-containing complex sphingolipids were increased in kidney. The levels of sphingosine-containing complex sphingolipids in kidney were unaffected by FB(1) treatment but were significantly lower in control MDRK than in FVB mice. The levels of neurotransmitters and their metabolites were similarly affected in both strains by FB(1), suggesting no influence of disrupted blood:brain barrier on FB(1)-induced neurotoxicity. In both strains, the liver mRNA for tumor necrosis factor alpha was increased; however, the increase was statistically significant only in FVB. It was apparent that mice deficient in P-glycoprotein do not exhibit greater sensitivity to FB(1), the cellular or brain transport of FB(1) appears to be independent of this multidrug transporting system.

Journal Article↗
PubMed2003

In vivo multiphoton imaging of a transgenic mouse model of Alzheimer disease reveals marked thioflavine-S-associated alterations in neurite trajectories.

Postmortem analyses of senile plaques reveal numerous dystrophic processes in their vicinity. We used in vivo multiphoton microscopy of a transgenic model of Alzheimer disease (AD) to simultaneously image senile plaques and nearby neuronal processes. Plaques were labeled by immunofluorescent staining or thioflavine-S and neuronal processes were labeled with a fluorescent dextran conjugate. Imaging of 3-dimensional volumes in the vicinity of plaques revealed subtle changes in neurite geometry in or near diffuse plaques. By contrast, disruptions in neurite morphology, including dystrophic neurites immediately surrounding plaques as well as major alterations in neurite trajectories, were seen in association with thioflavine-S-positive plaques. Nearly half of all labeled processes that came within 50 microm of a thioflavine-S-positive plaque were altered, suggesting a fairly large "halo" of neuropil alterations that extend beyond the discrete border of a thioflavine-S plaque. These results support the hypothesis that compact thioflavine-S-positive plaques disrupt the neuropil in AD.

Aging↗
PubMed2001

Permeability of proteins at the blood-brain barrier in the normal adult mouse and double transgenic mouse model of Alzheimer's disease.

The permeability of albumin, insulin, and human A beta 1--40 at the blood-brain barrier (BBB) was determined in the normal adult mouse (B6/SJL) and in the double transgenic Alzheimer mouse (APP, PS1) by using an I.V. bolus injection technique to quantify the permeability coefficient-surface area (PS) product for each protein after correction for the residual plasma volume (V(p)) occupied by the protein in the blood vessels of different brain regions using a second aliquot of the same protein radiolabeled with a different isotope of iodine ((125)I vs (131)I) as a vascular space marker. This technology for quantifying BBB permeability of proteins was adapted from the rat to the mouse and involved catheterizing the femoral artery and vein of the mouse instead of the brachial artery and vein as for the rat. Because of the smaller blood volume in the mouse, serial sampling (20 microl) of blood from the femoral artery of the mouse was performed and directly TCA precipitated to generate a whole blood washout curve for the intact protein. When similar blood sampling techniques were used in the rat, the PS values for albumin and insulin at the BBB were similar in these two species. In the double transgenic mouse, the V(p) values for albumin were significantly increased 1.4- to 1.6-fold in five of six brain regions compared to the normal adult mouse, which indicated increased adherence of albumin to vessel walls. As a result, the PS values were significantly decreased, from 1.4- to 3.2-fold, which likely reflected decreased transport of albumin by passive diffusion. In contrast, insulin, which is taken up into the brain by a receptor-mediated transport mechanism at the BBB, showed no significant difference in the V(p) values but a significant increase in the PS values in four of six brain regions. This suggests a compensatory mechanism in the Alzheimer's transgenic brain whereby there is an increased permeability to insulin at the BBB. Surprisingly, there was no significant difference in the V(p) or PS values for human A beta 1--40 at the BBB in the double transgenic Alzheimer mouse at 24, 32, or 52 weeks of age, when there is both significant A beta levels in the plasma and amyloid burden in the brains of these animals. These data suggest that there is not an alteration in permeability to human A beta 1--40 at the BBB with increasing amyloid burden in the double transgenic Alzheimer mouse. Although these observations suggest structural alterations at the BBB, they do not support the concept of extensive BBB damage with substantial increases in BBB permeability in Alzheimer's disease.

Age Factors↗
PubMed2000

Expression of macrophage colony-stimulating factor receptor is increased in the AbetaPP(V717F) transgenic mouse model of Alzheimer's disease.

Inflammation is an important neuropathological change in Alzheimer's disease (AD). However, the pathophysiological factors that initiate and maintain the inflammatory response in AD are unknown. We examined AbetaPP(V717F) transgenic mice, which show numerous brain amyloid-beta (Abeta) deposits, for expression of the macrophage colony-stimulating factor (M-CSF) and its receptor (M-CSFR). M-CSF is increased in the brain in AD and dramatically augments the effects of Abeta on cultured microglia. AbetaPP(V717F) animals 12 months of age showed large numbers of microglia strongly labeled with an M-CSFR antibody near Abeta deposits. M-CSFR mRNA and protein levels were also increased in brain homogenates from AbetaPP(V717F) animals. Dystrophic neurites and astroglia showed no M-CSFR labeling in the transgenic animals. A M-CSF antibody decorated neuritic structures near hippocampal Abeta deposits in transgenic animals. M-CSF mRNA was also increased in AbetaPP(V717F) animals in comparison with wild-type controls. Simultaneous overexpression of M-CSFR and its ligand in AbetaPP(V717F) animals could result in augmentation of Abeta-induced activation of microglia. Because chronic activation of microglia is thought to result in neuronal injury, the M-CSF system may be a potential target for therapeutic intervention in AD.

Alzheimer Disease↗