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Trehalose reduces aggregate formation and delays pathology in a transgenic mouse model of oculopharyngeal muscular dystrophy.

Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant disease that presents in the fifth or sixth decade with dysphagia, ptosis and proximal limb weakness. OPMD is caused by the abnormal expansion of a polyalanine tract within the coding region of polyA binding protein nuclear 1 (PABPN1). The resultant mutant PABPN1 forms aggregates within the nuclei of skeletal muscle fibres. We have previously described a transgenic mouse model of OPMD that recapitulates the human disease and develops progressive muscle weakness accompanied by the formation of aggregates in skeletal muscle nuclei. The chemical chaperone trehalose has been used effectively to alleviate symptoms in a mouse model of Huntington's disease and is thought to elicit its effect by binding and stabilizing partially folded polyglutamine proteins and inhibiting the formation of aggregates. Here, we show that trehalose reduces aggregate formation and toxicity of mutant PABPN1 in cell models. Furthermore, oral administration of trehalose attenuated muscle weakness, reduced aggregate formation and decreased the number of TUNEL-labelled nuclei in skeletal muscle in an OPMD transgenic mouse model. Thus, anti-aggregation therapy may prove effective in the treatment of human OPMD.

Analysis of Variance↗

Neuroprotective effects of creatine in a transgenic mouse model of Huntington's disease.

Huntington's disease (HD) is a progressive neurodegenerative illness for which there is no effective therapy. We examined whether creatine, which may exert neuroprotective effects by increasing phosphocreatine levels or by stabilizing the mitochondrial permeability transition, has beneficial effects in a transgenic mouse model of HD (line 6/2). Dietary creatine supplementation significantly improved survival, slowed the development of brain atrophy, and delayed atrophy of striatal neurons and the formation of huntingtin-positive aggregates in R6/2 mice. Body weight and motor performance on the rotarod test were significantly improved in creatine-supplemented R6/2 mice, whereas the onset of diabetes was markedly delayed. Nuclear magnetic resonance spectroscopy showed that creatine supplementation significantly increased brain creatine concentrations and delayed decreases in N-acetylaspartate concentrations. These results support a role of metabolic dysfunction in a transgenic mouse model of HD and suggest a novel therapeutic strategy to slow the pathological process.

Animals↗

Suppression of arthritis and protection from bone destruction by treatment with TNP-470/AGM-1470 in a transgenic mouse model of rheumatoid arthritis.

OBJECTIVE: We assessed the clinical and histologic features of angiogenesis inhibition in a transgenic mouse model of arthritis that closely resembles rheumatoid arthritis (RA) in humans. METHODS: KRN/NOD mice, which spontaneously develop arthritis, were treated with TNP-470, an angiogenesis inhibitor. Disease was monitored by use of clinical indices and histologic examinations; circulating blood levels of vascular endothelial growth factor were determined by enzyme-linked immunosorbent assay. RESULTS: In the preventive protocol, with TNP-470 administration at a dosage of 60 mg/kg of body weight, the onset of arthritis was delayed and its clinical intensity was rather mild; 100% of placebo-treated transgenic mice developed arthritis that led to severe articular destruction. At a dosage of 90 mg/kg of TNP-470, the appearance of clinical signs was delayed for a longer period of time and disease was almost abolished. The therapeutic regimen alleviated clinical signs only when given during the very early stage of disease. Reductions in cartilage and bone destruction by TNP-470 treatment were observed histologically, a feature that was still evident at 30 and 80 days after injections were withdrawn. CONCLUSION: Our demonstration that in vivo administration of an angiogenesis inhibitor suppresses arthritis and protects from bone destruction provides new insight into the pathogenesis of the disease and opens new possibilities in the treatment of RA in humans.

Angiogenesis Inhibitors↗

Neuroprotective effects of phenylbutyrate in the N171-82Q transgenic mouse model of Huntington's disease.

Huntington's disease (HD) is caused by an expansion of exonic CAG triplet repeats in the gene encoding the huntingtin protein (Htt), however, the means by which neurodegeneration occurs remains obscure. There is evidence that mutant Htt interacts with transcription factors leading to reduced histone acetylation. We report that administration of the histone deacetylase inhibitor phenylbutyrate after onset of symptoms in a transgenic mouse model of HD significantly extends survival and attenuates both gross brain and neuronal atrophy. Administration of phenylbutyrate increased brain histone acetylation and decreased histone methylation levels as assessed by both immunocytochemistry and Western blots. Phenylbutyrate increased mRNA for components of the ubiquitin-proteosomal pathway and down-regulated caspases implicated in apoptotic cell death, and active caspase 3 immunoreactivity in the striatum. These results show that administration of phenylbutyrate, at doses that are well tolerated in man, exerts significant neuroprotective effects in a transgenic mouse model of HD, and therefore represents a very promising therapeutic approach for HD.

Acetylation↗

Analysis of ubiquitination in vivo using a transgenic mouse model.

The primary pathway for the proteolytic destruction of cellular proteins is through ubiquitin-mediated targeting to the proteasome. This pathway is pivotal not only in the elimination of damaged or misfolded proteins but also in the temporal, developmental, or signal-mediated destruction of normal cellular substrates. The list of known substrates of the ubiquitin/proteasome pathway is long, but most substrates have been identified in yeast or, more recently, in cultured mammalian cells. It is likely that many mammalian substrates with developmental or disease relevance have yet to be identified because their ubiquitination occurs in tissue or organ systems that cannot be adequately modeled in vitro. We have developed a transgenic mouse model that will allow the isolation and identification of these substrates. The human UbC promoter was used to drive expression of a hexahistidine-tagged version of human ubiquitin in a variety of mouse tissues from early embryonic stages, as assessed by a green fluorescent protein marker. Cleavage of the fusion protein by endogenous enzymes produced epitope-tagged ubiquitin that was detected both in monomeric form and conjugated to cellular proteins. This mouse model should facilitate in the analysis of normal and disease-related ubiquitination events in vivo.

Animals↗

Transgenic mouse models for tumors of melanocytes and retinal pigment epithelium.

Cutaneous and ocular melanomas are due to malignant transformation of neural crest-derived melanocytes. The rising incidence of this tumor in humans has stimulated experiments to devise suitable mouse models. In the past years, transgenic mouse lines have been generated using different oncogenes - Ha-ras, SV40 T antigen (Tag), ret - which develop benign lesions of melanocytes, melanoma, and/or eye tumors. Pigment cell tumors in humans, although rather rare, can also develop from the retinal pigment epithelium (RPE), a cell layer of neuroectodermal origin. We, therefore, established transgenic models for this ocular tumor. Regulated by the promoter of tyrosinase-related protein-1 (TRP-1), two oncogenes, ret and SV40 Tag, were targeted to the developing RPE in transgenic mice. The TRP-1/ret transgenic mice displayed microphthalmia and benign tumors of the RPE. Expression of SV40 T antigen (TRP-1/Tag) led to malignant tumors, which were invasive and metastasized to inguinal lymph node and spleen.

Animals↗

Magnetic resonance imaging accurately estimates LV mass in a transgenic mouse model of cardiac hypertrophy.

Transgenic mice with a dysfunctional guanylyl cyclase A gene (GCA -/-) are unable to transduce the signals from atrial naturetic peptide and develop hypertension and cardiac hypertrophy. Magnetic resonance imaging (MRI) was performed to assess cardiac hypertrophy in these animals, using wild-type siblings as controls. Anesthetized mice were studied by gated multislice, multiphase cine MRI at 1.5 T. Simpson's rule was used to estimate left ventricle (LV) mass and volumes from short-axis images. Correlation between LV mass evaluated by MRI and at necropsy was excellent, with LVnecropsy = 1.04 x LVMRI + 4.69 mg (r2 = 0.95). By MRI, GCA -/- LV mass was significantly different when compared with isogenic controls [GCA -/-, 226 +/- 43 mg (n = 14) vs. controls, 156 +/- 14 mg (n = 10); P < 0.0001]. LV volumes and ejection fraction in the two groups were not significantly different. MRI provides an accurate means for the noninvasive assessment of murine cardiac phenotype and may be useful in following the effects of genetic modification.

Animals↗

Increased dietary fat promotes islet amyloid formation and beta-cell secretory dysfunction in a transgenic mouse model of islet amyloid.

Transgenic mice expressing the amyloidogenic human islet amyloid polypeptide (hIAPP) in their islet beta-cells are a model of islet amyloid formation as it occurs in type 2 diabetes. Our hIAPP transgenic mice developed islet amyloid when fed a breeder chow but not regular chow. Because the breeder chow contained increased amounts of fat, we hypothesized that increased dietary fat enhances islet amyloid formation. To test this hypothesis, we fed male hIAPP transgenic and nontransgenic control mice diets containing 15% (low fat), 30% (medium fat), or 45% (high fat) of calories derived from fat for 12 months, and we measured islet amyloid, islet endocrine cell composition, and beta-cell function. Increased dietary fat in hIAPP transgenic mice was associated with a dose-dependent increase in both the prevalence (percentage of islets containing amyloid deposits; 34 +/- 8, 45 +/- 8, and 58 +/- 10%, P < 0.05) and severity (percentage of islet area occupied by amyloid; 0.8 +/- 0.5, 1.0 +/- 0.5, and 4.6 +/- 2.5%, P = 0.05) of islet amyloid. In addition, in these hIAPP transgenic mice, there was a dose-dependent decrease in the proportion of islet area comprising beta-cells, with no significant change in islet size. In contrast, nontransgenic mice adapted to diet-induced obesity by increasing their islet size more than twofold. Increased dietary fat was associated with impaired insulin secretion in hIAPP transgenic (P = 0.05) but not nontransgenic mice. In summary, dietary fat enhances both the prevalence and severity of islet amyloid and leads to beta-cell loss and impaired insulin secretion. Because both morphologic and functional defects are present in hIAPP transgenic mice, this would suggest that the effect of dietary fat to enhance islet amyloid formation might play a role in the pathogenesis of the islet lesion of type 2 diabetes in humans.

Amyloid↗

Development and characterization of a progressive series of mammary adenocarcinoma cell lines derived from the C3(1)/SV40 Large T-antigen transgenic mouse model.

We have developed four new mammary adenocarcinoma cell lines from the C3(1)/SV40 Large T-antigen (Tag) transgenic mouse model: M28N2 and M27H4 (weakly tumorigenic), M6 (carcinoma), and M6C (metastatic). The C3(1) promoter directs Tag expression to the mammary epithelium and 100% of female C3(1)/Tag transgenic mice develop mammary adenocarcinoma in a predictable and progressive manner. The cell lines we developed from this model are demonstrated to be of epithelial origin and display growth rates, both in vitro and following subcutaneous inoculation into nude mice, that are consistent with their representative stage of tumor progression. The more tumorigenic cell lines, M6 and M6C, both express the sodium/iodide symporter, a mammary carcinoma cell marker with potential therapeutic and diagnostic applications. All of the cell lines express estrogen receptor (ER) alpha and ER beta mRNA, and Western blot analysis demonstrates that the ER alpha protein is down-regulated in the M6 and M6C cell lines. M28N2 cells also express progesterone receptor (PgR), which is very unusual in a mouse mammary carcinoma cell line. In addition, all of the cell lines display growth inhibition when plated in media supplemented with charcoal-stripped fetal calf serum (CS FBS). When CS FBS is supplemented with beta estradiol or the progestin MPA, no significant difference in growth rates is observed relative to growth in CS FBS. The development and characterization of a progressive series of new mammary carcinoma cell lines will aid in the study of mammary carcinoma progression both in vitro and in vivo.

Adenocarcinoma↗

Retinal and choroidal neovascularization in a transgenic mouse model of sickle cell disease.

A complication of sickle cell disease is proliferative retinopathy. We investigated the eyes from a transgenic mouse model of sickle cell disease (alpha H beta S[beta MDD] type) to determine if pathological changes occurred in their retinas and choroids. One retina from each animal was processed by flat-embedding adenosine diphosphatase-reacted retinas in glycol methacrylate. The fellow eye from each animal was embedded whole in glycol methacrylate for histopathological analysis of all ocular structures. Retinal vascular occlusions resulted in nonperfused areas of retina and arterio-venous anastomoses. Intra- and extraretinal neovascularization was observed adjacent to nonperfused areas. Retinal pigmented lesions were formed by the migration of retinal pigment epithelial cells into sensory retina, often ensheathing choroidal neovascularization. The incidence of this bilateral chorioretinopathy was 30% in animals older than 15 months of age. The ocular histopathological changes we observed in the mouse model mimicked many aspects of human proliferative sickle cell retinopathy. Furthermore, this is the first genetically derived animal model for chorio-retinal neovascularization.

Anemia, Sickle Cell↗

Therapeutic effects of coenzyme Q10 and remacemide in transgenic mouse models of Huntington's disease.

There is substantial evidence that bioenergetic defects and excitotoxicity may play a role in the pathogenesis of Huntington's disease (HD). Potential therapeutic strategies for neurodegenerative diseases in which there is reduced energy metabolism and NMDA-mediated excitotoxicity are the administration of the mitochondrial cofactor coenzyme Q10 and the NMDA antagonist remacemide. We found that oral administration of either coenzyme Q10 or remacemide significantly extended survival and delayed the development of motor deficits, weight loss, cerebral atrophy, and neuronal intranuclear inclusions in the R6/2 transgenic mouse model of HD. The combined treatment, using coenzyme Q10 and remacemide together, was more efficacious than either compound alone, resulting in an approximately 32 and 17% increase in survival in the R6/2 and N171-82Q mice, respectively. Magnetic resonance imaging showed that combined treatment significantly attenuated ventricular enlargement in vivo. These studies further implicate defective energy metabolism and excitotoxicity in the R6/2 and N171-82Q transgenic mouse models of HD and are of interest in comparison with the outcome of a recent clinical trial examining coenzyme Q10 and remacemide in HD patients.

Acetamides↗

The G gamma / T-15 transgenic mouse model of androgen-independent prostate cancer: target cells of carcinogenesis and the effect of the vitamin D analogue EB 1089.

Transgenic mouse models of prostate cancer provide unique opportunities to understand the molecular events in prostate carcinogenesis and for the preclinical testing of new therapies. We studied the G gamma T-15 transgenic mouse line, which contains the human fetal globin promoter linked to SV40 T antigen (Tag) and which develops androgen-independent prostate cancer. Using the immunohistochemistry of normal mouse prostates before tumor formation, we showed that the target cells of carcinogenesis in G gamma T-15 mice are located in the basal epithelial layer. We tested the efficacy of the 1,25(OH)(2)D(3) analogue, EB 1089, to chemoprevent prostate cancer in these transgenic mice. Compared with treatment with placebo, treatment with EB 1089 at three different time points before the onset of prostate tumors in mice did not prevent or delay tumor onset. However, EB 1089 significantly inhibited prostate tumor growth. At the highest dose, EB 1089 inhibited prostate tumor growth by 60% (P = 0.0003) and the growth in the number of metastases, although this dose also caused significant hypercalcemia and weight loss. We conducted several in vitro experiments to explore why EB 1089 did not prevent the occurrence of the primary tumors. EB 1089 significantly inhibited the growth of a Tag-expressing human prostate epithelial cell line, BPH-1, and an androgen-insensitive subline of LNCaP cells [which was not inhibited by 1,25(OH)(2)D(3)]. Thus, neither Tag expression nor androgen insensitivity explain the absence of chemopreventive effect. Conversely, neither 1,25(OH)(2)D(3) nor EB 1089 inhibited the growth of the normal rat prostate basal epithelial cell line NRP-152. It is likely that EB 1089 was not effective in delaying the growth of the primary tumor in G gamma T-15 transgenic mice because the target cells of carcinogenesis in these mice are located in the basal epithelial layer. We conclude that G gamma T-15 transgenic mice are a useful model for testing vitamin D-based therapies in androgen-insensitive prostate cancer but are not suitable for studies of vitamin D-based chemoprevention. The superiority of EB 1089 over 1,25(OH)(2)D(3) in the growth suppression of androgen-insensitive prostate cancer cells supports the use of EB 1089 in androgen-insensitive prostate cancer.

Androgens↗

Development of transgenic mouse models for the study of human olfactory dysfunction.

BACKGROUND: Olfactory loss is a significant health problem that remains incompletely understood. The development of suitable animal models is essential to the progress of human olfactory loss research. Recent advancements in transgenic technology allow the creation of model systems to address causes of olfactory neuron dysfunction. METHODS: This review describes two transgenic mouse models with potential usefulness in the study of olfactory loss and highlights the molecular techniques that underlie the development of such systems. RESULTS: Genetic constructs generated using standard molecular biological techniques are introduced into mouse germ lines either by homologous recombination or by random integration. One construct (UbI7) places the olfactory receptor I7 under control of the olfactory marker protein promoter. The other two constructs (TI) act together to direct expression of cytokines in the olfactory epithelium, creating a novel approach to the study of inflammatory olfactory loss. CONCLUSIONS: Powerful scientific tools now exist to develop animal models useful to the study of human olfactory disease. Transgenic olfactory neurons from the UbI7 mouse strain will respond to known odorants, facilitating experiments that examine in vitro modulation of olfactory neuron function. The ability to express specific genes in the olfactory mucosa of the TI mouse has great potential in elucidating the role of cytokines in the development of olfactory dysfunction in vivo.

Animals↗

Analysis of primary HLA-specific cytotoxic T cell response in graft-draining lymph nodes--a transgenic mouse model for in vivo recognition of human MHC antigens.

In order to characterize primary anti-HLA cytotoxic T cells and especially those involved in graft rejection, we have utilized a transgenic mouse model. Mice (non-transgenic and HLA-transgenic) were grafted with spleen cells originating from H-2-matched transgenic mice expressing HLA-B27 molecules, and cells from graft-draining lymph nodes were tested in CML assay to investigate the primary in vivo induced CTL responses. The results showed that HLA-B27 molecules were able to raise strong primary xenogeneic CTL responses. Results from split-well analysis indicated that although recognition of HLA-B27 by primary CTL induced in nontransgenic recipients is predominantly unrestricted by H-2, a small fraction (ranging from 2% to 27%) of the primary in vivo induced CTL is able to recognize HLA-B27 in an H-2-restricted manner. HLA-specific H-2-restricted CTL had never so far been demonstrated in the primary T cell response. Thus the protocol used in our study for the generation of a primary CTL response seems to provide not only a more appropriate representation of cytotoxic T cells sensitized by a graft, but also to be a more sensitive approach than the usually used in vitro mixed lymphocyte culture.

Animals↗

Establishment of transgenic mouse model carring the promoter of plunc sequence.

OBJECTIVE: To construct the vector using specific nasopharynx tissue promoter plunc to establish transgeneic mouse model. METHODS: Plunc-EGFP plasmid was digested with XhoI, the purified linearized DNA fragments were recovered by gel extraction and diluted to the final concentration of 4 microg/ml, before introduced into fertilized one-cell mouse eggs by pronuclear microinjection. RESULTS: Thirteen founder mice were obtained, 12 of which were positive for the integrated EGFP gene as detected by PCR, and 3 were positive shown by Southern blotting. CONCLUSION: Specific nasopharynx tissue promoter plunc can effectively induce exogenous gene integration into the mouse genome.

Animals↗

Toxicological aspects of treatment to remove cyanobacterial toxins from drinking water determined using the heterozygous P53 transgenic mouse model.

The presence of toxic cyanobacteria in drinking water reservoirs renders the need to develop treatment methods for the 'safe' removal of their associated toxins. Chlorine has been shown to successfully remove a range of cyanotoxins including microcystins, cylindrospermopsin and saxitoxins. Each cyanotoxin requires specific treatment parameters, particularly solution pH and free chlorine residual. However, currently there has not been any investigation into the toxicological effect of solutions treated for the removal of these cyanotoxins by chlorine. Using the P53(def) transgenic mouse model male and female C57BL/6J hybrid mice were used to investigate potential cancer inducing effects from such oral dosing solutions. Both purified cyanotoxins and toxic cell-free extract cyanobacterial solutions were chlorinated and administered over 90 and 170 days (respectively) in drinking water. No increase in cancer was found in any treatment. The parent cyanotoxins, microcystins, cylindrospermopsin and saxitoxins were readily removed by chlorine. There was no significant increase in the disinfection by-products trihalomethanes or haloacetic acids, levels found were well below guideline values. Histological examination identified no effect of treatment solutions except male mice treated with chlorinated cylindrospermopsin (as a cell free extract). In this instance 40% of males were found to have fatty vacuolation in their livers, cause unknown. It is recommended that further toxicology be undertaken on chlorinated cyanobacterial solutions, particularly for non-genotoxic carcinogenic compounds, for example the Tg. AC transgenic mouse model.

Acetates↗

Transgenic mouse models of Alzheimer's disease.

Recent advances in the understanding of the genetic basis of Alzheimer's disease have enabled the production of transgenic mouse models of the disease. Utilizing both cDNA- and genomic-based approaches, these mouse models for Alzheimer's disease have already provided valuable insights into the pathogenesis of the disease and potential therapeutic interventions.

Alzheimer Disease↗

Construction and evaluation of an independently generated transgenic mouse model carrying mutated human HRAS genes for short-term carcinogenicity assessment.

The study aimed to construct and evaluate an independently generated transgenic mouse model applied to the short-term carcinogenicity assessment. Mutated human HRAS fragment containing an intron point-mutation was inserted into C57BL/6JGpt mice via bacterial artificial chromosome transgenic technology, eventually generating BALB/c;B6J-Tg(hHRAS)16/Gpt mice, abbreviated as HRAS mice. The inserted human HRAS fragment in HRAS mice was characterized, revealing five tandem copies at chromosome 19. Baseline profiles, including biochemical, hematological, immunophenotypic, survival, and carcinogenic data of HRAS mice, were collected. To evaluate the tumor susceptibility in HRAS mice, we applied N-Nitroso-N-methylurea (MNU) to HRAS mice in a short-term carcinogenicity assessment conducted according to Good Laboratory Practice. The genetic characteristics of HRAS mice include five tandem arrays of mutated human HRAS fragments located in genomic coordinate 7,755,606 on chromosome 19 and the duplication of a 9-kilobase genome sequence (genomic coordinate 7,755,606-7,746,509) located on chromosome 19. HRAS mice showed a relatively lower incidence and range of spontaneous tumor formation during long-term observation compared to CByB6F1-Tg(HRAS)2Jic (Tg.rasH2) transgenic mice. The short-term carcinogenicity assessment showed a strong tumor response to MNU, with high incidences of lymphoma (&#x2265;&#x2009;90%) and stomach squamous cell papilloma (&#x2265;&#x2009;90%) in both male and female HRAS mice. The HRAS mice showed susceptibility to MNU and exhibited baseline characteristics distinct from those of Tg.rasH2 mice. The co-expression of HRAS and MKI67 at the cellular localization level was found in neoplasms of HRAS mice. These findings preliminarily evaluated the feasibility of HRAS mice applied to the short-term carcinogenicity assessment.

Animals↗