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Functional, structural, and neuronal alterations in urinary bladder during diabetes: investigations of a mouse model.

Urinary bladder dysfunction is a common complication in diabetes, but the mechanisms involved are undefined and treatment options are limited. Murine models provide opportunities to utilize transgenic technologies for bladder research and here we investigate the functional, structural and neuronal aspects of the bladder in a mouse model of type-1 diabetes. Mice were injected with streptozotocin (150 mg/kg) or vehicle and studied at 5 weeks. Increases in blood glucose and total urine output were observed. In vitro cystometry showed a 2-fold increase in bladder capacity and compliance and decreased intravesical plateau pressure in diabetics versus controls. Bladder structure and composition were evaluated by digital imaging; region-specific changes included increased smooth muscle and urothelium and no change in collagen content. Alterations in cholinergic, adrenergic and nitric oxide-related functional responsiveness were also observed. The prevalence of cholinergic and adrenergic neuronal tracts was determined by immunohistochemistry: decreased vesicular acetylcholine transferase was observed in smooth muscle, whereas tyrosine hydroxylase was increased in the lamina propria, demonstrating a 'neuronal remodeling' shift toward pro-relaxant neuronal pathways. These studies demonstrate that this mouse model of diabetes exhibits important features of urinary bladder remodeling that are similar to the findings in humans and other animal models and will therefore be useful for further mechanistic investigations.

Afferent Pathways↗

Behavioral phenotypes and pharmacology in genetic mouse models of Parkinsonism.

Prior to the discovery of genes associated with familial forms of Parkinson's disease, animal models of Parkinson's disease mainly consisted of toxin models based exclusively on the degeneration of nigrostriatal dopamine neurons. These traditional models have provided valuable insight into symptomatic treatments for Parkinson's disease; however, they lack the broad extra-nigral pathology and the progression that is observed in the disease. The novel genetic mouse models recently generated are advantageous because they have mutations that are known to cause familial Parkinson's disease and thus they have good construct validity. To maximize the utility of these models, a thoughtful phenotypical characterization is important. Our laboratory has assembled a battery of behavioral tests to assess sensorimotor function in genetic mouse models of Parkinsonism. This review discusses the sensitivity of these tests in different genetic mice in addition to their behavioral response to dopamine agonists.

Animals↗

Mouse model to study the replication of primate foamy viruses.

A mouse model was developed to study the virus-host interaction of molecularly cloned human foamy virus (HFV) in vivo. The infectious process was analysed in two mouse strains, CBA/Ca and C57BL/6J, over a period of 24 weeks by PCR on DNAs from various animal tissues; virus serology was examined by immunoblotting. The infection persisted in both mouse strains and did not induce clinical symptoms. Upon infection of adult CBA/Ca mice HFV became detectable by PCR in an increasing number of organs over time. In contrast, in C57BL/6J mice, after an initial phase of dissemination, viral DNA sequences were found only in a few organs. Interestingly, the different course of infection was accompanied by differences in the antiviral immune response. In particular, C57BL/6J mice were high responders with respect to antibodies to the viral Bet protein, while CBA/Ca mice were low responders.

Animals↗

Cardiac manifestations in the mouse model of mucopolysaccharidosis I.

Mucopolysaccharidosis I (MPS I, alpha-l-iduronidase deficiency disease) is a heritable lysosomal storage disorder involving multiple organs, including the heart. Malfunction of the heart is also a major manifestation in the mouse model of MPS I, progressing in severity from 6 to 10 months (of a 1 year life span). In comparisons of MPS I with wild-type mice, the heart was found enlarged, with thickened septal and posterior walls, primarily because of infiltration of the muscle by storage-laden cells. Heart valves were enlarged and misshapen, and contained large numbers of highly vacuolated interstitial cells. The thickened aortic wall contained vacuolated smooth muscle cells and interrupted elastic fibers. Hemodynamic measurements and echocardiography revealed reduced left ventricular function as well as mitral and aortic regurgitation. But despite these abnormalities, free-roaming MPS I mice implanted with radio telemetry devices showed surprisingly normal heart rate and blood pressure, though their electrocardiograms were abnormal. An incidental finding of the telemetry studies was a disturbed circadian rhythm in the MPS I mice. Restoration of enzyme activity in the heart of one mouse, by transplantation of retrovirally modified bone marrow, resulted in normalization of left ventricular function as well as loss of storage vacuoles in myocytes and endothelial cells, though not in valvular interstitial cells. This study demonstrates the usefulness of the mouse model for in-depth studies of the cardiovascular component of MPS I.

Animals↗

Neutrophils and their Fc gamma receptors are essential in a mouse model of transfusion-related acute lung injury.

Transfusion-related acute lung injury (TRALI) is the most common cause of transfusion-related mortality. To explore the pathogenesis of TRALI, we developed an in vivo mouse model based on the passive transfusion of an MHC class I (MHC I) mAb (H2Kd) to mice with the cognate antigen. Transfusion of the MHC I mAb to BALB/c mice produced acute lung injury with increased excess lung water, increased lung vascular and lung epithelial permeability to protein, and decreased alveolar fluid clearance. There was 50% mortality at a 2-hour time point after Ab administration. Pulmonary histology and immunohistochemistry revealed prominent neutrophil sequestration in the lung microvasculature that occurred concomitantly with acute peripheral blood neutropenia, all within 2 hours of administration of the mAb. Depletion of neutrophils by injection of anti-granulocyte mAb Gr-1 protected mice from lung injury following MHC I mAb challenge. FcRgamma-/- mice were resistant to MHC I mAb-induced lung injury, while adoptive transfer of wild-type neutrophils into the FcRgamma-/- animals restored lung injury following MHC I mAb challenge. In conclusion, in a clinically relevant in vivo mouse model of TRALI using an MHC I mAb, the mechanism of lung injury was dependent on neutrophils and their Fc gamma receptors.

Adoptive Transfer↗

Mouse models for human familial adenomatous polyposis.

Colorectal cancer (CRC) is the second most frequent type of cancer in the Western hemisphere. In the United States alone, it is estimated that 150 000 new cases are detected every year and more than 65 000 patients die from complications associated with this cancer. Identification of genes implicated in the initiation and progression of colorectal cancer in humans has prompted the generation of mouse models for this cancer. We will provide a brief overview of these mouse models for CRC and what they have contributed to our understanding of the events involved in the initiation and progression of this cancer.

Adenomatous Polyposis Coli↗

Decreased thrombotic tendency in mouse models of the Bernard-Soulier syndrome.

OBJECTIVE: The platelet glycoprotein (GP)Ib-V-IX complex is a receptor required for normal hemostasis deficient in the Bernard-Soulier bleeding disorder. To evaluate the consequences of GPIb-V-IX deficiency in thrombosis we generated mouse models of the disease by targeting the GPIb beta subunit. METHODS AND RESULTS: Complete deletion (GPIb beta-/-) or an intracellular truncation (GPIb beta deltaIC-/-) reproduced typical and variant forms of Bernard-Soulier, with absent and partial (20%) expression of the complex on the platelet surface. Both strains exhibited thrombocytopenia and enlarged platelets with abnormal microtubular structures but normal granule composition. They exhibited prolonged tail bleeding times, which were less pronounced in GPIb beta deltaIC-/-. Decreased thrombus formation was observed after blood perfusion over a collagen coated surface at high shear. Resistance to vascular occlusion and an abnormal thrombus composition were observed in a model of FeCl3-induced lesion of carotid arteries. In a model of laser-induced lesion of mesenteric arterioles, thrombosis was strongly reduced in GPIb beta-/- mice, while a more modest effect was observed in GPIb beta deltaIC-/- animals. Finally, the two strains were protected against death in a model of systemic thromboembolism. CONCLUSIONS: This study provides in vivo evidence of a decreased thrombotic tendency linked to defective platelet GPIb-V-IX in mouse models of Bernard-Soulier syndrome.

Animals↗

Suppression of renal disease and mortality in the female NZB x NZW F1 mouse model of systemic lupus erythematosus (SLE) by chenodeoxycholic acid.

The objective of this study was to examine the effects of ursodeoxycholic (UDCA) and chenodeoxycholic acid (CDCA) on autoimmune disease in the NZB x NZW F1 (B/W) mouse model of systemic lupus erythematosus (SLE). The development of murine lupus was assessed in female B/W mice given UDCA or CDCA. At 6 week intervals mice were examined for weight change, albuminuria, anti-DNA antibody and total IgG levels. Morbidity and mortality were assessed daily. UDCA- and CDCA-treated mice were examined at 24 weeks of age for serum cytokines, lymphocyte phenotype, and in vitro cytokine production after immunization with DNP-KLH. Liver and kidneys were examined histopathologically. The administration of UDCA and CDCA was tolerated without side effects. Weight gain in UDCA- or CDCA-treated and control mice was identical through 24 weeks of age. CDCA, but not UDCA, suppressed the development of renal disease. CDCA-treated B/W mice also had improved survival compared to UDCA-treated or control B/W mice. There were no significant effects of CDCA on anti-DNA antibodies, serum total IgG, or other immunologic parameters. CDCA-treated mice had lower serum IFN-gamma concentrations compared to control and UDCA-treated mice. The bile acid, CDCA, significantly inhibited the development of renal disease and modestly prolonged lifespan in the female B/W mouse model of SLE. Suppression of glomerulonephritis was associated with lower serum IFNgamma concentrations. Further investigation is needed to verify potential mechanisms of action, but these findings suggest that bile acids may alter the development or progression of autoimmunity.

Albuminuria↗

Prolonged neutropenia in a novel mouse granulocyte colony-stimulating factor neutralizing auto-immunoglobulin G mouse model.

Therapeutic use of recombinant human cytokines in humans can result in the generation of drug-specific antibodies. To predetermine the maximum potential effects of a granulocyte colony-stimulating factor (G-CSF) neutralizing auto-immunoglobulin G (auto-IgG) response during recombinant human G-CSF therapy, we developed a mouse model of mouse G-CSF (mG-CSF) neutralizing auto-IgG response. Mice were immunized and boosted with mG-CSF chemically conjugated to either keyhole limpet hemocyanin or ovalbumin on an alternating schedule. Sera were analyzed for mG-CSF-specific titers and full blood counts were performed on a Technicon H-1E. On day 252, tissues were collected for histology. IgG was protein A affinity purified from pooled mG-CSF autoimmune sera. Mice immunized with mG-CSF conjugates produced mG-CSF-specific auto-IgG responses that lasted for the length of the study. Significant neutropenia (p(max) < 0.004) was concurrent with the rise in mG-CSF-specific IgG titers. However, neutrophil counts remained at approximately 20% of preimmunization levels through day 252. Endogenous mG-CSF neutralizing auto-IgG had no significant effect on hemoglobin, erythrocyte, lymphocyte, eosinophil, basophil, and platelet counts, and had minor, transient, or no effects on monocyte counts. Bone marrow colony assays from mG-CSF autoimmune mice demonstrated no significant effect of G-CSF neutralization on the numbers or proliferative capacity of preneutrophil lineage progenitors. Purified IgG from mG-CSF autoimmune mice neutralized mG-CSF in vitro. High-titer G-CSF neutralizing auto-IgG in adult mice partially inhibited steady-state granulopoiesis and had little or no effect on steady-state levels of other hematopoietic cells.

Animals↗

A chimeric mouse model of Gaucher disease.

BACKGROUND: There is a major need for a mouse model of Gaucher disease, but the glucocerebrosidase knockout mouse is not viable; it dies shortly before or immediately after birth, apparently because of involvement of the central nervous system and/or skin. The most common form of Gaucher disease, type I, has a phenotype that is limited to the monocyte-macrophage system. MATERIALS AND METHODS: We have created a chimeric mouse by infusing hematopoietic stem cells from fetuses that are homozygous for the glucocerebrosidase knockout into irradiated mice. RESULTS: The chimeric mice manifested a severe deficiency of glucocerebrosidase activity in peripheral blood cells and spleen indicating a lack of cell-cell correction. Levels of glucocerebroside in spleen and liver are increased, and infusing the mice with exogenous glucocerebroside/albumin particles produced a marked increase in the amount of glucocerebroside stored in liver and spleen. Morphologically identifiable Gaucher cells were not present. CONCLUSIONS: The chimeric model reflects the increased glycolipid storage in the reticuloendothelial system that is characteristic of Gaucher disease, and could be useful as a model for studying treatment of Gaucher disease.

Animals↗

Genetic mapping of putative Chrna7 and Luzp2 neuronal transcriptional enhancers due to impact of a transgene-insertion and 6.8 Mb deletion in a mouse model of Prader-Willi and Angelman syndromes.

BACKGROUND: Prader-Willi and Angelman syndrome (PWS and AS) patients typically have an approximately 5 Mb deletion of human chromosome 15q11-q13, of opposite parental origin. A mouse model of PWS and AS has a transgenic insertion-deletion (TgPWS/TgAS) of chromosome 7B/C subsequent to paternal or maternal inheritance, respectively. In this study, we define the deletion endpoints and examine the impact on expression of flanking genes. RESULTS: Using molecular and cytological methods we demonstrate that 13 imprinted and 11 non-imprinted genes are included in the TgPWS/TgAS deletion. Normal expression levels were found in TgPWS brain for genes extending 9.1- or 5.6-Mb centromeric or telomeric of the deletion, respectively. Our molecular cytological studies map the proximal deletion breakpoint between the Luzp2 and Siglec-H loci, and we show that overall mRNA levels of Luzp2 in TgPWS and TgAS brain are significantly reduced by 17%. Intriguingly, 5' Chrna7 shows 1.7-fold decreased levels in TgPWS and TgAS brain whereas there is a > or =15-fold increase in expression in neonatal liver and spleen of these mouse models. By isolating a Chrna7-Tg fusion transcript from TgAS mice, we mapped the telomeric deletion breakpoint in Chrna7 intron 4. CONCLUSION: Based on the extent of the deletion, TgPWS/TgAS mice are models for PWS/AS class I deletions. Other than for the first gene promoters immediately outside the deletion, since genes extending 5.6-9.1 Mb away from each end of the deletion show normal expression levels in TgPWS brain, this indicates that the transgene array does not induce silencing and there are no additional linked rearrangements. Using gene expression, non-coding conserved sequence (NCCS) and synteny data, we have genetically mapped a putative Luzp2 neuronal enhancer responsible for approximately 33% of allelic transcriptional activity. The Chrna7 results are explained by hypothesizing loss of an essential neuronal transcriptional enhancer required for approximately 80% of allelic Chrna7 promoter activity, while the Chrna7 promoter is upregulated in B lymphocytes by the transgene immunoglobulin enhancer. The mapping of a putative Chrna7 neuronal enhancer inside the deletion has significant implications for understanding the transcriptional regulation of this schizophrenia-susceptibility candidate gene.

Alleles↗

Mouse models created to study the pathophysiology of Type 2 diabetes.

Obesity and Type 2 diabetes have become epidemics in the Western world. Understanding the pathophysiology of the disease should help in prevention and treatment of these disorders. A common theme is the presence of insulin resistance that eventually results in Type 2 diabetes. To understand the underlying mechanisms in the progression of the disease states, investigators have created mouse models by transgenic overexpression of a candidate gene or produced gene-deletion mouse models. This review will summarize many of the more appropriate models that study insulin resistance and Type 2 diabetes.

Adolescent↗

Deficiency of nitric oxide synthase 2 results in increased neointima formation in a mouse model of vascular injury.

Restenosis frequently occurs after arterial interventions. The inducible form of nitric oxide synthase (NOS2) may both promote and inhibit neointima formation. This study investigated the role of NOS2 for neointima formation in a mouse model of carotid artery injury. The common carotid artery was ligated in anesthetized mice. Homozygous NOS2 knockout mice were compared with wild-type B6/129 mice or wild-type mice treated with the pharmacologic NOS2 inhibitor aminoguanidine given orally daily after ligation (n = 6-8 in each group). Vessels were harvested for quantification of lesion size 4 weeks later, or serially after ligation for tissue analysis. mRNA for NOS2 increased 1-4 days after ligation of the carotid artery. Cell proliferation could be visualized with an antibody against proliferating cell nuclear antigen. An intimal smooth muscle cell layer, confirmed by an alpha-actin antibody, was observed in the lumen 4 weeks after injury. Inhibition of NOS2 by either pharmacologic or genetic approaches tended to increase the area of intima formation (P = 0.13 or P < 0.05, respectively) and increased the intima/media ratio (P = 0.14 and P < 0.01, respectively). Inhibition of NOS2 by two different approaches increased neointima formation in a mouse model of mechanical vessel injury, indicating that the NOS2 expressed in the injured vessel wall is beneficial.

Animals↗

Mouse models of brain tumors and their applications in preclinical trials.

Primary brain tumors, including gliomas and medulloblastomas, often represent the most devastating and difficult-to-treat tumors, and are thought to arise from glial cells and/or their precursors or the external granule cell layer, respectively. The majority of genetic alterations characteristic of the human brain tumors are thought to occur in genes encoding proteins involved in signal transduction or cell cycle regulation. Accurate recapitulation of these genetic alterations using genetically engineered mouse models allows for in vivo modeling of brain tumors with similar histopathology, etiology, and biology. These mouse models, in turn, increase our understanding of brain tumor initiation, formation, progression, and metastasis, providing an experimental system to discover novel therapeutic targets and test various therapeutic agents.

Animals↗

IL-8 is a key chemokine regulating neutrophil recruitment in a new mouse model of Shigella-induced colitis.

The lack of a mouse model of acute rectocolitis mimicking human bacillary dysentery in the presence of invasive Shigella is a major handicap to study the pathogenesis of the disease and to develop a Shigella vaccine. The inability of the mouse intestinal mucosa to elicit an inflammatory infiltrate composed primarily of polymorphonuclear leukocytes (PMN) may be due to a defect in epithelial invasion, in the sensing of invading bacteria, or in the effector mechanisms that recruit the PMN infiltrate. We demonstrate that the BALB/cJ mouse colonic epithelium not only can be invaded by Shigella, but also elicits an inflammatory infiltrate that, however, lacks PMN. This observation points to a major defect of mice in effector mechanisms, particularly the lack of expression of the CXC chemokine, IL-8. Indeed, this work demonstrates that the delivery of recombinant human IL-8, together with Shigella infection of the colonic epithelial surface, causes an acute colitis characterized by a strong PMN infiltrate that, by all criteria, including transcription profiles of key mediators of the innate/inflammatory response and histopathological lesions, mimics bacillary dysentery. This is a major step forward in the development of a murine model of bacillary dysentery.

Animals↗

Mouse models of human cancer as tools in drug development.

Histologically accurate mouse models of human cancers generated by somatic or germline genetic modification strategies recapitulate the genetic alterations found in human tumors. In this issue of Cancer Cell, test a novel signaling inhibitor in a genetically defined mouse medulloblastoma and show the utility of these models in drug development. They demonstrate that targeting signaling components downstream of tumor initiating mutations can be an effective therapeutic strategy for solid tumors.

Animals↗

Long-lasting impairment in hippocampal neurogenesis associated with amyloid deposition in a knock-in mouse model of familial Alzheimer's disease.

Neurogenesis in the adult hippocampus has been implicated in regulating long-term memory and mood, but its integrity in Alzheimer's disease (AD) is uncertain. Studies of neurogenesis in transgenic mouse models of familial AD are complicated by ectopic overexpression restricted to terminally differentiated neurons, while AD cases have been studied only at the pre-senile or end-stage of disease. To investigate further the fidelity of adult neurogenesis, we examined mice carrying targeted mutations in amyloid precursor protein (APP), presenilin-1 (PS-1), or both APP and PS-1, in which FAD-causing mutations have been inserted into their endogenous genes. The latter "double knock-in" mice developed aging- and region-dependent amyloid deposition starting around 6 months, and by 9 months exhibited microglial activation associated with the amyloid. In the 9-month-old dentate gyrus, the double knock-in mutations reduced the numbers of MCM2-positive neural stem and progenitor cells by 3-fold and doublecortin-positive neuroblasts by 2-fold. The reduction in dentate neuroblasts persisted at 18 months of age. The impairment in neurogenesis was confirmed by quantitative Western blot analysis of doublecortin content and was restricted to the hippocampal but not the olfactory bulb neurogenic system. In contrast, neither mutant PS-1 nor APP alone led to amyloid deposition or significant alterations in the two markers. These results demonstrate long-lasting and selective impairment in adult hippocampal neurogenesis in a knock-in mutant mouse model of FAD and suggest a novel mechanism by which amyloid and its attendant microglia-mediated neuroinflammation could contribute to the cognitive and behavioral abnormalities of AD.

Alzheimer Disease↗

A novel transgenic mouse model reveals humanlike regulation of an 8-kbp human TERT gene promoter fragment in normal and tumor tissues.

Telomerase activity is repressed in most human somatic tissues during differentiation processes but strongly up-regulated in most human tumors. Regulation of human telomerase activity primarily occurs at the level of transcriptional initiation of the TERT gene, which encodes the catalytic subunit of telomerase. We have generated a novel transgenic mouse model to study the regulation of the human TERT gene promoter in an in vivo system. For this purpose, we have cloned an 8.0-kbp human TERT promoter fragment in front of the bacterial lacZ reporter gene (hTERTp-lacZ), which encodes the beta-galactosidase enzyme. Expression of the reporter gene was monitored by reverse transcription-PCR analysis, 5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside staining of whole mount preparations, and histologic sections. We find that the activity of the human TERT promoter in most normal mouse tissues recapitulates the expression of the hTERT gene in normal human tissues and is under tighter control when compared with the endogenous mouse TERT gene expression. In testis, where highest lacZ expression was observed, the expression of the reporter gene was restricted to the spermatogonial stem cells and the spermatocytes. Intriguingly, we find increased levels of lacZ expression in mammary tumors of hTERTp-lacZ x p53(+/-) bitransgenic mouse mammary tumor model. Thus, this transgenic mouse model provides a suitable in vivo system to analyze the expression of the human TERT gene under physiologic conditions and during tumorigenesis.

Animals↗