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Large animal models for Duchenne muscular dystrophy (DMD) are crucial for preclinical evaluation of novel diagnostic procedures and treatment strategies. Pigs cloned from male cells lackingDMDexon 52 (DMDΔ52) resemble molecular, clinical and pathological hallmarks of DMD, but cannot be propagated by breeding due to death before sexual maturity. Therefore, femaleDMD+/-carriers were generated. A single founder animal had 11 litters with 29DMDY/-, 34DMD+/-as well as 36 male and 29 female wild-type (WT) offspring. Breeding with F1 and F2DMD+/-carriers resulted in additional 114DMDY/-piglets. The majority of them survived for 3-4 months, providing large cohorts for experimental studies. Pathological investigations and proteome studies of skeletal muscles and myocardium confirmed the resemblance of human disease mechanisms. Importantly,DMDY/-pigs reveal progressive fibrosis of myocardium and increased expression of connexin-43, associated with significantly reduced left ventricular fractional shortening and ejection fraction already at age 3 months. Furthermore, behavioral tests provided evidence for impaired cognitive ability ofDMDY/-pigs. Our breeding cohort ofDMDΔ52 pigs and standardized tissue repositories fromDMDY/-pigs,DMD+/-carriers, and WT littermate controls provide important resources for studying DMD disease mechanisms and for testing novel diagnostic procedures and treatment strategies.

Objective Human patients with Duchenne muscular dystrophy (DMD) commonly exhibit a short stature, but the pathogenesis of this growth retardation is not completely understood. Due to the suspected involvement of the growth hormone/insulin-like growth factor 1 (GH/IGF1) system, controversial therapeutic approaches have been developed, including both GH- administration, as well as GH-inhibition. In the present study, we examined relevant histomorphological and ultrastructural features of adenohypophyseal GH-producing somatotroph cells in a porcine DMD model. Methods The numbers and volumes of immunohistochemically labelled somatotroph cells were determined in consecutive semi-thin sections of plastic resin embedded adenohypophyseal tissue samples using unbiased state-of-the-art quantitative stereological analysis methods. Results DMD pigs displayed a significant growth retardation, accounting for a 55% reduction of body weight, accompanied by a significant 50% reduction of the number of somatotroph cells, as compared to controls. However, the mean volumes of somatotroph cells and the volume of GH-granules per cell were not altered. Western blot analyses of the adenohypophyseal protein samples showed no differences in the relative adenohypophyseal GH-abundance between DMD pigs and controls. Conclusion The findings of this study do not provide evidence for involvement of somatotroph cells in the pathogenesis of growth retardation of DMD pigs. These results are in contrast with previous findings in other dystrophin-deficient animal models, such as the golden retriever model of Duchenne muscular dystrophy, where increased mean somatotroph cell volumes and elevated volumes of intracellular GH-granules were reported and associated with DMD-related growth retardation. Possible reasons for the differences of somatotroph morphology observed in different DMD models are discussed.

In cattle, infestation with Psoroptes ovis mites may cause severe dermatitis (psoroptic mange) which compromises the health and welfare of the animals and may lead to significant economic losses. To investigate yet undocumented effects of psoroptic mange mite infestations and how successful therapy promotes animal health, the present study examined alterations of the skin, lymph nodes and adrenal glands of P. ovis infested Fleckvieh (Simmental) bulls treated with either ivermectin long-acting injection (IVM LAI; IVOMEC(®) GOLD, Merial; 3.15% ivermectin w/v) or saline (n=16 each). Approximately 8 weeks subsequent to experimental infestation with P. ovis, the bulls had developed mange and were administered either IVM LAI or saline once at 1 mL/50 kg body weight by subcutaneous injection. Mite counts were conducted in weekly intervals for determination of efficacy of treatment, and following humane euthanasia of the animals 8 weeks after treatment, skin samples from affected (mangy or previously mangy) and unaffected areas, prescapular lymph nodes and adrenal glands were collected for gross and pathohistological examination. In addition, four age-matching, uninfested Simmental bulls were sampled as controls for comparison. No P. ovis mites were detected on any IVM LAI-treated bull after 28 days following treatment whereas saline-treated bulls maintained infestation throughout the study. At sampling (approximately 16 weeks after experimental infestation and 8 weeks following saline or IVM LAI treatment), saline-treated bulls displayed a severe, exsudative dermatitis with significantly increased skin thickness and inflammatory cell infiltration, significantly enlarged, hyperplastic prescapular lymph nodes, as well as significantly increased adrenal gland weights and volumes as compared to P. ovis-infested, IVM LAI-treated bulls and uninfested controls. Quantitative stereological analysis revealed that the adrenal gland enlargement in P. ovis-infested, saline-treated bulls was due to a selective increase of the volume of the zona fasciculata in the adrenal cortex. Compared to uninfested controls and P. ovis-infested, IVM LAI-treated bulls, the number of epithelial cells in the zona fasciculata was significantly increased in P. ovis-infested, saline-treated bulls, while the zona fasciculata cell volumes did not differ between the three groups of cattle. While the single point determination of serum cortisol concentrations did not reveal significant differences between the three groups of cattle at tissue sampling, the hyperplastic growth of the adrenal cortex in the P. ovis-infested, saline-treated bulls provides morphologic evidence that a chronic stress reaction is one consequence of mange mite infestations that can be prevented by efficacious acaricidal treatment.

To study insulin-like growth factor 1 (IGF1)-independent effects of permanent growth hormone (GH) excess on body and organ growth and pathology in vivo, hemizygous bovine GH transgenic mice with homozygous disruption of the Igf1 gene (Igf1(-/-)/GH) were generated, and examined in comparison to Igf1(-/-), Igf1(+/-), wild-type (WT), Igf1(+/-)/GH, and GH mice. GH mice and Igf1(+/-)/GH mice showed increased serum IGF1 levels and the well-known giant-phenotype of GH transgenic mice. In contrast, the typical dwarf-phenotype of Igf1(-/-) mice was only slightly ameliorated in Igf1(-/-)/GH mice. Similar to GH mice, Igf1(-/-)/GH mice displayed hepatocellular hypertrophy, glomerulosclerosis, and reduced volumes of acidophilic cells in the pituitary gland. However, GH excess associated skin lesions of male GH mice were not observed in Igf1(-/-)/GH mice. Therefore, development of GH excess induced liver-, kidney-, and pituitary gland-alterations in GH transgenic mice is independent of IGF1 whereas GH stimulated body growth depends on IGF1.

Uromodulin (UMOD)-associated kidney disease (UAKD) belongs to the hereditary progressive ER storage diseases caused by maturation defects of mutant UMOD protein. Current treatments of UAKD patients are symptomatic and cannot prevent disease progression. Two in vitro studies reported a positive effect of the chemical chaperone sodium 4-phenylbutyrate (4-PBA) on mutant UMOD maturation. Thus, 4-PBA was suggested as a potential treatment for UAKD. This study evaluated the effects of 4-PBA in two mouse models of UAKD. In contrast to previous in vitro studies, treatment with 4-PBA did not increase HSP70 expression or improve maturation and trafficking of mutant UMOD in vivo. Kidney function of UAKD mice was actually deteriorated by 4-PBA treatment. In transfected tubular epithelial cells, 4-PBA did not improve maturation but increased the expression level of both mutant and wild-type UMOD protein. Activation of NF-κB pathway in thick ascending limb of Henle's loop cells of UAKD mice was detected by increased abundance of RelB and phospho-IκB kinase α/β, an indirect activator of NF-κB. Furthermore, the abundance of NF-κB1 p105/p50, NF-κB2 p100/p52, and TRAF2 was increased in UAKD. NF-κB activation was identified as a novel disease mechanism of UAKD and might be a target for therapeutic intervention.

Background. Among other mismatches between human and pig incompatibilities in the blood coagulation systems hamper the xenotransplantation of vascularized organs. The provision of the porcine endothelium with human thrombomodulin (hTM) is hypothesized to overcome the impaired activation of protein C by a heterodimer con sisting of human thrombin and porcine TM. Methods. We evaluated regulatory regions of the THBD gene optimized vectors for transgene expression and generated hTM expressing pigs by somatic cell nuclear transfer. Genetically modified pigs were characterized at the molecular cellular histological and physiological levels. Results. A 7.6 kb fragment containing the entire upstream region of the porcine THBD gene was found to drive a high expression in a porcine endothelial cell line and was therefore used to control hTM expression in transgenic pigs. The abundance of hTM was restricted to the endothelium according to the predicted pattern and the trans gene expression of hTM was stably inherited to the offspring. When endothelial cells from pigs carrying the hTM transgeneVeither alone or in combination with an aGalTKO and a transgene encoding the human CD46Vwere tested in a coagulation assay with human whole blood the clotting time was increased three to four fold (PG0.001) compared to wild type and aGalTKO/CD46 transgenic endothelial cells. This for the first time demonstrated the anticoagulant properties of hTM on porcine endothelial cells in a human whole blood assay. Conclusions. The biological efficacy of hTM suggests that the (multi )transgenic donor pigs described here have the potential to overcome coagulation incompatibilities in pig to primate xenotransplantation. Keywords: Xenotransplantation Coagulation incompatibility Thrombomodulin Transgenic donors Human thrombomodulin Transgenic donor pigs.

Moderate low-carbohydrate/high-fat (LC-HF) diets are widely used to induce weight loss in overweight subjects, whereas extreme ketogenic LC-HF diets are used to treat neurological disorders like pediatric epilepsy. Usage of LC-HF diets for improvement of glucose metabolism is highly controversial; some studies suggest that LC-HF diets ameliorate glucose tolerance, whereas other investigations could not identify positive effects of these diets or reported impaired insulin sensitivity. Here, we investigate the effects of LC-HF diets on glucose and insulin metabolism in a well-characterized animal model. Male rats were fed isoenergetic or hypocaloric amounts of standard control diet, a high-protein “Atkins-style” LC-HF diet, or a low-protein, ketogenic, LC-HF diet. Both LC-HF diets induced lower fasting glucose and insulin levels associated with lower pancreatic β-cell volumes. However, dynamic challenge tests (oral and intraperitoneal glucose tolerance tests, insulin-tolerance tests, and hyperinsulinemic euglycemic clamps) revealed that LC-HF pair-fed rats exhibited impaired glucose tolerance and impaired hepatic and peripheral tissue insulin sensitivity, the latter potentially being mediated by elevated intramyocellular lipids. Adjusting visceral fat mass in LC-HF groups to that of controls by reducing the intake of LC-HF diets to 80% of the pair-fed groups did not prevent glucose intolerance. Taken together, these data show that lack of dietary carbohydrates leads to glucose intolerance and insulin resistance in rats despite causing a reduction in fasting glucose and insulin concentrations. Our results argue against a beneficial effect of LC-HF diets on glucose and insulin metabolism, at least under physiological conditions. Therefore, use of LC-HF diets for weight loss or other therapeutic purposes should be balanced against potentially harmful metabolic side effects.

Podocytes are highly specialized epithelial cells with complex actin cytoskeletal architecture crucial for maintenance of the glomerular filtration barrier. The mammalian Rho GTPases Rac1 and Cdc42 are molecular switches that control many cellular processes, but are best known for their roles in the regulation of actin cytoskeleton dynamics. Here, we employed podocyte-specific Cre-lox technology and found that mice with deletion of Rac1 display normal podocyte morphology without glomerular dysfunction well into adulthood. Using the protamine sulfate model of acute podocyte injury, podocyte-specific deletion of Rac1 prevented foot process effacement. In a long-term model of chronic hypertensive glomerular damage, however, loss of Rac1 led to an exacerbation of albuminuria and glomerulosclerosis. In contrast, mice with podocyte-specific deletion of Cdc42 had severe proteinuria, podocyte foot process effacement, and glomerulosclerosis beginning as early as 10 days of age. In addition, slit diaphragm proteins nephrin and podocin were redistributed, and cofilin was dephosphorylated. Cdc42 is necessary for the maintenance of podocyte structure and function, but Rac1 is entirely dispensable in physiological steady state. However, Rac1 has either beneficial or deleterious effects depending on the context of podocyte impairment. Thus, our study highlights the divergent roles of Rac1 and Cdc42 function in podocyte maintenance and injury.

Background Cell damage, tissue and vascular injury are associated with the exposure and release of intracellular components such as RNA , which promote inflammatory reactions and thrombosis. Based on the counteracting anti‐inflammatory and cardioprotective functions of ribonuclease A ( RN ase A) in this context, its role in an experimental model of heart transplantation in rats was studied. Methods and Results Inbred BN /OrlRj rat cardiac allografts were heterotopically transplanted into inbred LEW /OrlRj rats. Recipients were intravenously treated every other day with saline or bovine pancreatic RN ase A (50 μg/kg). Toxic side effects were not found (macroscopically and histologically). Heart tissue flow cytometry and quantitative morphological analyses of explanted hearts at postoperative day 1 or postoperative day 4 showed reduced leukocyte infiltration, edema, and thrombus formation in RN ase A‐treated rats. In allogeneic mixed lymphocyte reactions, RN ase A decreased the proliferation of effector T cells. RN ase A treatment of rats resulted in prolonged median graft survival up to 10.5 days (interquartile range 1.8) compared to 6.5 days (interquartile range 1.0) in saline treatment ( P =0.001). Treatment of rats with a new generated (recombinant) human pancreatic RN ase 1 prolonged median graft survival similarly, unlike treatment with (recombinant) inactive human RN ase 1 (each 50 μg/kg IV every other day, 11.0 days, interquartile range 0.3, versus 8.0 days, interquartile range 0.5, P =0.007). Conclusions Upon heart transplantation, RN ase administration appears to present a promising and safe drug to counteract ischemia/reperfusion injury and graft rejection. Furthermore, RN ase treatment may be considered in situations of critical reperfusion after percutaneous coronary interventions or in cardiac surgery using the heart–lung machine.

In the large-scale Munich N-ethyl-N-nitrosourea (ENU) mouse mutagenesis project murine models recapitulating human diseases were generated. In one strain, a novel missense mutation (D217V) in the glucokinase (Gck) gene was identified, resulting in decreased glucokinase activity. Heterozygous mutants display mild hyperglycaemia, disturbed glucose tolerance, and decreased glucose-induced insulin secretion. In contrast, homozygous mutants exhibit severe but not survival affecting hyperglycaemia, mild growth retardation, diminished oxidative capacity, and increased abundance of CHOP protein in the islets. Furthermore, the total islet and β-cell volumes and the total volume of isolated β-cells are significantly decreased in adult homozygous mutants, whereas in neonatal mice, β-cell mass is not yet significantly decreased and islet neogenesis is unaltered. Therefore, reduced total islet and β-cell volumes of adult homozygous mutants might predominantly emerge from disturbed postnatal islet neogenesis. Thus, we identified a novel Gck mutation in mice, with relevance in humans, leading to glycaemic disease.

The mechanisms underlying detachment of foetal membranes after birth in cows are still unclear. To address this problem in a systematic manner, we performed the first holistic transcriptome study of bovine placentomes antepartum (AP;n=4 cows) and intrapartum (IP;n=4 cows) using Affymetrix GeneChip Bovine Genome Arrays. Three placentomes were extracted from each cow, and tissue samples from the contact zones of the placentomes (foeto-maternal units) were recovered by systematic random sampling and processed for RNA extraction and for stereological quantification of cellular composition. Statistical analysis of microarray data (false discovery rate 1%) revealed 759 mRNAs with at least twofold higher levels in the samples of the AP group, whereas 514 mRNAs showed higher levels in the IP group. The differentially expressed genes were classified according to biological processes and molecular functions using the Functional Annotation Clustering tool of the DAVID Bioinformatics Resources. Genes with higher mRNA levels in the AP group were nearly completely related to mitotic cell cycle and tissue differentiation. During parturition, a complete shift occurred because the genes with higher mRNA levels in IP were nearly all related to three different physiological processes/complexes: i) apoptosis, ii) degradation of extra cellular matrix and iii) innate immune response, which play a fundamental role in placental detachment. These results are an excellent basis for future studies investigating the molecular basis of retained foetal membranes.

Heterozygous male Munich Ins2(C95S) mutant mice, a model for permanent neonatal diabetes mellitus, demonstrate a progressive diabetic phenotype with severe loss of functional beta cell mass. The aim of this study was to investigate the influence of early insulin treatment on glucose homeostasis and beta cell destruction in male Munich Ins2(C95S) mutants.One group of male Ins2(C95S) mutants was treated with subcutaneous insulin pellets, as soon as blood glucose levels began to rise; placebo-treated mutants and wild-type mice served as controls. An additional group of mutant mice received a sodium-dependent glucose transporter 2 (SGLT2) inhibitor (AVE2268) via rodent chow.Insulin treatment normalised blood glucose concentrations, improved oral glucose tolerance, preserved insulin sensitivity and inhibited oxidative stress of Munich Ins2(C95S) mutant mice. Pancreatic C-peptide content, as well as total beta cell and isolated beta cell volumes, of insulin-treated mutant mice were higher than those of placebo-treated mutants. In addition, alpha cell dysfunction and hyperplasia of non-beta cells were completely normalised in insulin-treated mutant mice. Treatment with the SGLT2 inhibitor lowered blood glucose, improved glucose tolerance and normalised insulin sensitivity as well as oxidative stress of Ins2(C95S) mutants. The abundance of the endoplasmic reticulum (ER) stress markers binding Ig protein (BiP) and phosphorylated eukaryotic translation initiation factor 2 alpha (P-eIF2α) was significantly increased in the islets of mutants, before onset of hyperglycaemia, vs wild-type mice.We conclude that early insulin treatment protects Munich Ins2(C95S) mutant mice from insulin resistance, alpha cell hyperfunction, beta cell loss and hyperplasia of non-beta cells, some well-known features of human diabetes mellitus. Therefore, insulin treatment may be considered early for human patients harbouring INS mutations.

Aims Parathyroid hormone (PTH) administration after myocardial infarction (MI) is known to attenuate ischaemic cardiomyopathy. This effect mainly resulted from an increase in mobilization and homing of CD34+/CD45+ cells into the ischaemic myocardium. PTH-related stem cell mobilization was shown to be related to endogenous granulocyte-colony stimulating factor (G-CSF) release. The aim of our study is to determine the role of G-CSF on the cardioprotective effects of PTH. Methods and results G-CSF +/+ (C57BL/6) and G-CSF −/− mice were treated with PTH for 6 days after inducing a MI. The myocardial homing factor stromal cell-derived factor-1 (SDF-1) was analysed on day 2 with enzyme-linked immunosorbent assay. Stem cell populations in peripheral blood and hearts were examined by FACS on days 6 and 2, respectively. Cardiac function and immunohistochemistry were investigated on day 6 and day 30. PTH treatment resulted in a significant increase in CD45+/CD34+ cells in peripheral blood in G-CSF +/+ but not in G-CSF −/− mice. However, a significant increase in SDF-1 and enhanced migration of CD45+/CD34+ cells into the ischaemic myocardium was revealed after PTH administration in both G-CSF +/+ and G-CSF −/− mice. Enhanced stem cell homing was associated with improved cardiac function and post-MI survival after PTH treatment. Furthermore, infarct size, wall thickness, and neovascularization showed a significant improvement in both groups 30 days after MI. Conclusion The cardioprotective effects of PTH were shown to be independent of endogenous G-CSF release and therefore from stem cell mobilization. This puts more emphasis on the role of stem cell homing into ischaemic myocardium.

Members of the epidermal growth factor receptor (EGFR/ERBB) system are essential local regulators of mammary gland development and function. Emerging evidence suggests that EGFR signaling may also influence mammary gland activity indirectly by promoting the release of prolactin from the pituitary gland in a MAPK and estrogen receptor-α (ERα)-dependent manner. Here, we report that overexpression of the EGFR ligand betacellulin (BTC) causes a lactating-like phenotype in the mammary gland of virgin female mice including the major hallmarks of lactogenesis. BTC transgenic (BTC-tg) females showed reduced levels of prolactin in the pituitary gland and increased levels of the hormone in the circulation. Furthermore, treatment of BTC-tg females with bromocriptine, an inhibitor of prolactin secretion, blocked the development of the lactation-like phenotype, suggesting that it is caused by central release of prolactin rather than by local actions of BTC in the mammary gland. Introduction of the antimorphic Egfr allele Wa5 also blocked the appearance of the mammary gland alterations, revealing that the phenotype is EGFR-dependent. We detected an increase in MAPK activity, but unchanged phosphorylation of ERα in the pituitary gland of BTC-tg females as compared with control mice. These results provide the first functional evidence in vivo for a role of the EGFR system in regulating mammary gland activity by modulating prolactin release from the pituitary gland.

Establishment and maintenance of pregnancy in equids is only partially understood. To provide new insights into early events of this process, we performed a systematic analysis of transcriptome changes in the endometrium at Days 8 and 12 of pregnancy. Endometrial biopsy samples from pregnant and nonpregnant stages were taken from the same mares. Composition of the collected biopsy samples was analyzed using quantitative stereological techniques to determine proportions of surface and glandular epithelium and blood vessels. Microarray analysis did not reveal detectable changes in gene expression at Day 8, whereas at Day 12 of pregnancy 374 differentially expressed genes were identified, 332 with higher and 42 with lower transcript levels in pregnant endometrium. Expression of selected genes was validated by quantitative real-time RT-PCR. Gene set enrichment analysis, functional annotation clustering, and cocitation analysis were performed to characterize the genes differentially expressed in Day 12 pregnant endometrium. Many known estrogen-induced genes and genes involved in regulation of estrogen signaling were found, but also genes known to be regulated by progesterone and prostaglandin E2. Additionally, differential expression of a number of genes related to angiogenesis and vascular remodeling suggests an important role of this process. Furthermore, genes that probably have conserved functions across species, such as CRYAB, ERRFI1, FGF9, IGFBP2, NR2F2, STC1, and TNFSF10, were identified. This study revealed the potential target genes and pathways of conceptus-derived estrogens, progesterone, and prostaglandin E2 in the equine endometrium probably involved in the early events of establishment and maintenance of pregnancy in the mare.

Uromodulin-associated kidney disease is a heritable renal disease in humans caused by mutations in the uromodulin ( UMOD) gene. The pathogenesis of the disease is mostly unknown. In this study, we describe a novel chemically induced mutant mouse line termed UmodA227T exhibiting impaired renal function. The A227T amino acid exchange may impair uromodulin trafficking, leading to dysfunction of thick ascending limb cells of Henle's loop of the kidney. As a consequence, homozygous mutant mice display azotemia, impaired urine concentration ability, reduced fractional excretion of uric acid, and a selective defect in concentrating urea. Osteopenia in mutant mice is presumably a result of chronic hypercalciuria. In addition, body composition, lipid, and energy metabolism are indirectly affected in heterozygous and homozygous mutant UmodA227T mice, manifesting in reduced body weight, fat mass, and metabolic rate as well as reduced blood cholesterol, triglycerides, and nonesterified fatty acids. In conclusion, UmodA227T might act as a gain-of-toxic-function mutation. Therefore, the UmodA227T mouse line provides novel insights into consequences of disturbed uromodulin excretion regarding renal dysfunction as well as bone, energy, and lipid metabolism.

Ischemic cardiomyopathy is one of the main causes of death, which may be prevented by stem cell-based therapies. SDF-1alpha is the major chemokine attracting stem cells to the heart. Since SDF-1alpha is cleaved and inactivated by CD26/dipeptidylpeptidase IV (DPP-IV), we established a therapeutic concept--applicable to ischemic disorders in general--by combining genetic and pharmacologic inhibition of DPP-IV with G-CSF-mediated stem cell mobilization after myocardial infarction in mice. This approach leads to (1) decreased myocardial DPP-IV activity, (2) increased myocardial homing of circulating CXCR-4+ stem cells, (3) reduced cardiac remodeling, and (4) improved heart function and survival. Indeed, CD26 depletion promoted posttranslational stabilization of active SDF-1alpha in heart lysates and preserved the cardiac SDF-1-CXCR4 homing axis. Therefore, we propose pharmacological DPP-IV inhibition and G-CSF-based stem cell mobilization as a therapeutic concept for future stem cell trials after myocardial infarction.

Diabetic nephropathy is the leading cause of end-stage renal disease and the largest contributor to the total cost of diabetes care. Rodent models are excellent tools to gain more insight into the pathogenesis of diabetic nephropathy. In the present study, we characterize the age-related sequence of diabetes-associated kidney lesions in GIPRdntransgenic mice, a novel mouse model of early-onset diabetes mellitus. Clinical-chemical analyses as well as qualitative and quantitative morphological analyses of the kidneys of GIPRdntransgenic animals and nontransgenic littermate controls were performed at 3, 8, 20, and 28 wk of age. Early renal changes of transgenic mice consisted of podocyte hypertrophy, reduced numerical volume density of podocytes in glomeruli, and homogenous thickening of the glomerular basement membrane, followed by renal and glomerular hypertrophy as well as mesangial expansion and matrix accumulation. At 28 wk of age, glomerular damage was most prominent, including advanced glomerulosclerosis, tubulointerstitial lesions, and proteinuria. Real-time PCR demonstrated increased glomerular expression of Col4a1, Fn1, and Tgfb1. Immunohistochemistry revealed increased mesangial deposition of collagen type IV, fibronectin, and laminin. The present study shows that GIPRdntransgenic mice exhibit renal changes that closely resemble diabetes-associated kidney alterations in humans. Data particularly from male transgenic mice indicate that podocyte hypertrophy is directly linked to hyperglycemia, without the influence of mechanical stress. GIPRdntransgenic mice are considered an excellent new tool to study the mechanisms involved in onset and progression of diabetic nephropathy.

Betacellulin (BTC), a ligand of the epidermal growth factor receptor, has been shown to promote growth and differentiation of pancreatic beta-cells and to improve glucose metabolism in experimental diabetic rodent models. We employed transgenic mice (BTC-tg) to investigate the effects of long-term BTC overabundance on islet structure and glucose metabolism. Expression of BTC is increased in transgenic islets, which show normal structure and distribution of the different endocrine cell types, without pathological alterations. BTC-tg mice exhibit lower fasted glucose levels and improved glucose tolerance associated with increased glucose-induced insulin secretion. Surprisingly, quantitative stereological analyses revealed that, in spite of increased cell proliferation, the islet and beta-cell volumes were unchanged in BTC-tg mice, suggesting enhanced cell turnover. Insulin secretion in vitro was significantly higher in transgenic islets in medium containing high glucose (11.2 or 16.7mM) as compared to control islets. Our results demonstrate that long-term BTC overabundance does not alter pancreatic islet structure and beta-cell mass, but enhances glucose-induced insulin secretion in vivo as well as in vitro.

Aims An ongoing concept is that stem cells have the potential to regenerate the injured myocardium. In addition to direct vasorelaxing effects on the vasculature, which are mediated by an increased cAMP production leading to a decreased calcium influx in smooth muscle cells, parathyroid hormone (PTH) was recently shown to facilitate stem cell mobilization. Therefore, we analysed in a murine model of experimental myocardial infarction (MI) the influence of PTH treatment on survival, functional parameters, stem cell migration, and expression of vascular endothelial growth factor A (VEGF-A). Methods and results Mice (C57BL/6) were treated with PTH (80 µg/kg/d) for up to 14 days after coronary artery ligation. Functional and immunohistochemical analyses were performed at days 6 and 30 after MI. Stem cells and VEGF expression in the myocardium were analysed by FACS and qRT-PCR at day 2 after MI. PTH-treated animals revealed a significant improvement of post-MI survival and myocardial function that was related to a subsequent reduction of left ventricular wall thinning and scar extension. Infarcted hearts of PTH-treated mice revealed increased numbers of CD45+/CD34+ progenitor cells as well as an upregulation of VEGF-A mRNA associated with increased neovascularization and cell survival. Conclusions PTH application after MI increases migration of angiogenic CD45+/CD34+ progenitor cells to the ischaemic heart, which may attenuate ischaemic cardiomyopathy. As PTH is already used in patients with osteoporosis, our findings may have a direct impact on the initiation of clinical studies in patients with ischaemic heart disease.

Objectives: Proteasome inhibition by bortezomib, a constitutive proteasome inhibitor (PI) approved for the treatment of multiple myeloma, was reported in the field of organ transplantation; despite known role in antigen presentation, the positive effect on graft rejection has not been verified. Since bortezomib is associated with many side effects (pancytopenia, gastrointestinal and transient neurological disorders), specific inhibition of immunoproteasomes might reduce them. The currently unapproved immunospecific PI PR-957 achieved positive results in experimental mice studies in the field of autoimmune diseases. Therefore, we compared the treatment with PR-957 and Bortezomib in a rat model of heterotopic heart transplantation. Methods: Brown Norway rat cardiac allografts were heterotopic abdominal transplanted to Lewis rats using microvascular Langendorff technique. Since postoperative day (POD) 1 recipients were daily treated intravenously with bortezomib (0.1 mg/kg), PR-957 (6 mg/kg) or saline (control, n = 6 in each group). The primary end point of the study was graft survival, determined by daily graft palpation and echocardiography. All explanted hearts were collected for histological analyses. A tolerance study was performed treating Lewis rats daily with bortezomib, PR-957 or saline for 16 days (n = 3 in each group). Blood counts of all treated rats were determined every other day. Results: Mean graft survival was 6.8 ± 0.8d in control group versus 11.5 ± 2.9d (p = 0.002 vs control) in bortezomib, and 11.2 ± 1.3d (p = 0.002 vs control) in PR-957 group. On POD 7 only recipients treated with bortezomib suffered from thrombocytopenia (p = 0.019). No significant differences in red and white blood counts were detected between the treatment groups. The tolerance study showed macroscopic alterations of liver, lymphnodes and thymus in bortezomib treated animals, whereas autopsy of PR-957 or saline treated animals revealed no macroscopic abnormalities. Histological analyses and measurement of cytokines are ongoing. Conclusions: Proteasome inhibitors obviously improved allograft survival. Compared with the constitutive PI bortezomib, the treatment with the immunospecific PI PR-957 suggested being superior in avoidance of side effects. Thus, drug development in the new field of immunoproteasome inhibition could improve the treatment of transplant rejection.

Alterations in glomerular podocyte cell-cell and cell-matrix contacts are key events in progressive glomerular failure. Integrin-linked kinase (ILK) has been implicated in podocyte cell-matrix interaction and is induced in proteinuria. For evaluation of ILK function in vivo, mice with a Cre-mediated podocyte-specific ILK inactivation were generated. These mice seemed normal at birth but developed progressive focal segmental glomerulosclerosis and died in terminal renal failure. The first ultrastructural lesions that are seen at onset of albuminuria are glomerular basement membrane (GBM) alterations with a significant increase in true harmonic mean GBM thickness. Podocyte foot process effacement and loss of slit diaphragm followed with progression to unselective proteinuria. No significant reduction of slit membrane molecules (podocin and nephrin), key GBM components (fibronectin, laminins, and collagen IV isoforms), or podocyte integrins could be observed at onset of proteinuria. However, alpha3-integrins were relocalized into a granular pattern along the GBM, consistent with altered integrin-mediated matrix assembly in ILK-deficient podocytes. As the increased GBM thickness precedes structural podocyte lesions and key components of the GBM were expressed at comparable levels to controls, these data suggest an essential role of ILK for the close interconnection of GBM structure and podocyte function.

Numerous in vitro studies have demonstrated that IGF-binding protein (IGFBP)-4 is a consistent inhibitor of IGF actions. In order to investigate the functions of IGFBP-4 in vivo, transgenic mice were generated by microinjection of a transgene, in which the murine Igfbp4 cDNA is driven by the H-2K(b) promoter, and followed by a splicing cassette and polyadenylation signal of the human beta-globin gene. Transgene mRNA was expressed ubiquitously, and elevated IGFBP-4 protein was detected in the spleen, thymus, kidney and lung of transgenic mice. The activities of serum IGFBPs were not changed in transgenic mice. Immunohistochemical studies revealed transgene expression predominantly in the thymic medulla and red pulp of the spleen. Body weight and the weights of the spleen, kidney and lung of transgenic mice were not different from controls. In contrast, the thymus of transgenic mice showed a significantly reduced weight and cortex volume. In transgenic thymus and spleen, cell proliferation was inhibited and apoptosis was stimulated. Transgenic mice showed normal T- and B-cell development and normal basal plasma immunoglobulin levels. In conclusion, overexpression of IGFBP-4 inhibits growth of the thymus. IGFBP-4 excess inhibits cell proliferation and stimulates apoptosis in lymphoid tissues, but does not affect lymphocyte development. These findings suggest that IGFBP-4 is a potential growth inhibitor of lymphoid tissues.

Granulocyte-colony stimulating factor (G-CSF) has been shown to promote mobilization of bone marrow-derived stem cells (BMCs) into the bloodstream associated with improved survival and cardiac function after myocardial infarction. Therefore, the aim of the present study was to investigate whether G-CSF is able to attenuate cardiac remodelling in a mouse model of pressure-induced LV hypertrophy focusing on mobilization and migration of BMCs. LV hypertrophy was induced by transverse aortic constriction (TAC) in C57BL/6J mice. Four weeks after TAC procedure. Mice were treated with G-CSF (100 μg/kg/day; Amgen Biologicals) for 2 weeks. The number of migrated BMCs in the heart was analysed by flow cytometry. mRNA expression and protein level of different growth factors in the myocardium were investigated by RT-PCR and ELISA. Functional analyses assessed by echocardiography and immunohistochemical analysis were performed 8 weeks after TAC procedure. G-CSF-treated animals revealed enhanced homing of VLA-4(+) and c-kit(+) BMCs associated with increased mRNA expression and protein level of the corresponding homing factors Vascular cell adhesion protein 1 and Stem cell factor in the hypertrophic myocardium. Functionally, G-CSF significantly preserved LV function after TAC procedure, which was associated with a significantly reduced area of fibrosis compared to control animals. Furthermore, G-CSF-treated animals revealed a significant improvement of survival after TAC procedure. In summary, G-CSF treatment preserves cardiac function and is able to diminish cardiac fibrosis after induction of LV hypertrophy associated with increased homing of VLA-4(+) and c-kit(+) BMCs and enhanced expression of their respective homing factors VCAM-1 and SCF.

Uromodulin (UMOD)-associated kidney disease (UAKD) belongs to the hereditary progressive ER storage diseases caused by maturation defects of mutant UMOD protein. Current treatments of UAKD patients are symptomatic and cannot prevent disease progression. Two in vitro studies reported a positive effect of the chemical chaperone sodium-4-phenylbutyrate (4-PBA) on mutant UMOD maturation. Thus, 4-PBA was suggested as potential treatment for UAKD. This study evaluated the effects of 4-PBA in two mouse models of UAKD. In contrast to previous in vitro studies, treatment with 4-PBA did not increase HSP70 expression or improve maturation and trafficking of mutant UMOD in vivo. Kidney function of UAKD mice was actually deteriorated by 4-PBA-treatment. In transfected tubular epithelial cells, 4-PBA did not improve maturation, but increased the expression level of both mutant and wild-type UMOD protein. Activation of NF-κB pathway in thick ascending limb of Henle's loop cells of UAKD mice was detected by increased abundance of RelB and phospho-IKKα/β, an indirect activator of NF-κB. Further, the abundance of NF-κB1 p105/p50, NF-κB2 p100/p52 and TRAF2 was increased in UAKD. NF-κB activation was identified as a novel disease mechanism of UAKD and might be a target for therapeutic intervention.

Mutations in the insulin (INS) gene may cause permanent neonatal diabetes mellitus (PNDM). Ins2 mutant mouse models provided important insights into the disease mechanisms of PNDM but have limitations for translational research. To establish a large animal model of PNDM, we generated INSC94Y transgenic pigs. A line expressing high levels of INSC94Y mRNA (70–86% of wild-type INS transcripts) exhibited elevated blood glucose soon after birth but unaltered β-cell mass at the age of 8 days. At 4.5 months, INSC94Y transgenic pigs exhibited 41% reduced body weight, 72% decreased β-cell mass (−53% relative to body weight), and 60% lower fasting insulin levels compared with littermate controls. β-cells of INSC94Y transgenic pigs showed a marked reduction of insulin secretory granules and severe dilation of the endoplasmic reticulum. Cataract development was already visible in 8-day-old INSC94Y transgenic pigs and became more severe with increasing age. Diabetes-associated pathological alterations of kidney and nervous tissue were not detected during the observation period of 1 year. The stable diabetic phenotype and its rescue by insulin treatment make the INSC94Y transgenic pig an attractive model for insulin supplementation and islet transplantation trials, and for studying developmental consequences of maternal diabetes mellitus.

Uromodulin-associated kidney disease (UAKD) is a dominant heritable renal disease in humans which is caused by mutations in the uromodulin (UMOD) gene and characterized by heterogeneous clinical appearance. To get insights into possible causes of this heterogeneity of UAKD, we describe the new mutant mouse line UmodC93F, leading to disruption of a putative disulfide bond which is also absent in a known human UMOD mutation, and compare the phenotype of this new mouse line with the recently published mouse line UmodA227T. In both mutant mouse lines, which were both bred on the C3H background, the Umod mutations cause a gain-of-toxic function due to a maturation defect of the mutant uromodulin leading to a dysfunction of thick ascending limb of Henle's loop (TALH) cells of the kidney. Umod mutant mice exhibit increased plasma urea and cystatin levels, impaired urinary concentration ability, reduced fractional excretion of uric acid, and nephropathological alterations including uromodulin retention in TALH cells, interstitial fibrosis and inflammatory cell infiltrations, tubular atrophy, and occasional glomerulo- und tubulocystic changes, a phenotype highly similar to UAKD in humans. The maturation defect of mutant uromodulin leads to the accumulation of immature uromodulin in the endoplasmic reticulum (ER) and to ER hyperplasia. Further, this study was able to demonstrate for the first time in vivo that the severity of the uromodulin maturation defect as well as onset and speed of progression of renal dysfunction and morphological alterations are strongly dependent on the particular Umod mutation itself and the zygosity status.

Summary Transgenic mice carrying fusion genes in which the genes coding for human growth hormone (hGH) or bovine growth hormone (bGH) have been put under the transcriptional control of the mouse metallothionein I promoter (MT) or the rat phosphoenolpyruvate carboxykinase promoter (PEPCK) were investigated with respect to transgene expression, phenotypical, clinical and pathomorphological changes. Serum levels of heterologous GH ranged from 1200 to 900 000 ng/ml, from 320 to 3940 ng/ml and from 34 to 1400 ng/ml in transgenic individuals belonging to the MThGH, PEPCKbGH and MTbGH transgenic group, respectively. Transgene expression was detected in a wide variety of tissues in MTGH transgenic mice, and in the hepatocytes and kidney tubular epithelia in PEPCKbGH transgenic mice. GH transgene expression resulted in stimulated growth of the body, skeleton, muscles and internal organs, endocrine and metabolic changes, a shortening of life-span and a variety of pathological changes, with kidney and liver lesions being predominant. Although similar maximum body weights were reached by mice resulting from long-term selection for high body weight, the pattern of their growth was markedly different from that of GH transgenic mice. The pathological findings point to GH transgenic mice as valuable models for studying the pathogenesis of glomerulosclerosis and the mechanisms involved in the progression of chronic renal failure as well as for investigations into the multistep process of hepatocarcinogenesis. Observations in GH transgenic mice further suggest that the benefits and risks of long-term GH administration in individuals that do not exhibit the symptoms of GH deficiency should be carefully evaluated. Zusammenfassung Physiologie und Pathologie des Wachstums–Studien an GH-transgenen Mausen Transgene Mause, die Kopien eines MT (muriner Metallothionein I-Promotor) — hGH (human growth hormone) respektive eines MTbGH (bovine growth hormone) oder eines PEPCK (Phos-phoenolpyruvat Carboxykinase-Promotor der Ratte) — bGH Genkonstruktes im Genom integriert haben, wurden in bezug auf die Transgenexpression sowie phanotypische, klinische und pathomorpho-logische Veranderungen untersucht. Die Konzentrationen der heterologen Wachstumshormone im Serum reichten von 1200 bis 900 000 ng/ml bei den MThGH, von 320 bis 3940 ng/ml bei den PEPCKbGH und von 34 bis 1400 ng/ml bei den MTbGH transgenen Individuen. Bei MTGH transgenen Mausen wurden Expressionsprodukte der Transgene in einer Vielzahl von Geweben detektiert. Eine Expression des PEPCKbGH Transgens war in Hepatozyten und renalen Tubulusepithelzellen nachweisbar. Die Transgenexpression bewirkte eine beschleunigte Entwicklung und Steigerung des Korpergewichts, eine Stimulation des Knochen- und Muskelwachstums sowie eine Viszeromegalie, ging mit Veranderungen von endokrinen und klinisch-chemischen Parametern einher und hatte eine Verkuml;rzung der Lebensdauer sowie regelmasig die Entwicklung einer Reihe von organpathologischen Alterationen zur Folge, wobei renale und hepatische Alterationen vordergrundig waren. Der Vergleich von GH transgenen Mausen mit Mausen einer auf hohes Korpergewicht selektierten Linie ergab keine Differenzen hinsichtlich des maximalen Korpergewichts, jedoch entscheidende Unterschiede in der Art der zugrundeliegenden Wachstumsprozesse. Die organpathologischen Veranderungen GH transgener Mause bieten ein wertvolles Modell fur das Studium der Pathogenese der Glomerulosklerose und der Progredienz der chronischen Niereninsuffizienz sowie zur Untersuchung des Mehrstufenprozesses der Hepatokarzinogenese. Die bei diesen Tieren geraachten Beobachtungen geben ferner Anlas, auf die Notwendigkeit einer sorgfaltigen Abwagung des erwarteten Nutzens und der potentiellen Risiken einer Langzeitbehandlung von normosomatotropen Individuen mit GH hinzuweisen.

The aim of this study was to examine postnatal islet and beta-cell expansion in healthy female control mice and its disturbances in diabetic GIPR(dn) transgenic mice, which exhibit an early reduction of beta-cell mass. Pancreata of female control and GIPR(dn) transgenic mice, aged 10, 45, 90 and 180 days were examined, using state-of-the-art quantitative-stereological methods. Total islet and beta-cell volumes, as well as their absolute numbers increased significantly until 90 days in control mice, and remained stable thereafter. The mean islet volumes of controls also increased slightly but significantly between 10 and 45 days of age, and then remained stable until 180 days. The total volume of isolated beta-cells, an indicator of islet neogenesis, and the number of proliferating (BrdU-positive) islet cells were highest in 10-day-old controls and declined significantly between 10 and 45 days. In GIPR(dn) transgenic mice, the numbers of islets and beta-cells were significantly reduced from 10 days of age onwards vs. controls, and no postnatal expansion of total islet and beta-cell volumes occurred due to a reduction in islet neogenesis whereas early islet-cell proliferation and apoptosis were unchanged as compared to control mice. Insulin secretion in response to pharmacological doses of GIP was preserved in GIPR(dn) transgenic mice, and serum insulin to pancreatic insulin content in response to GLP-1 and arginine was significantly higher in GIPR(dn) transgenic mice vs. controls. We could show that the increase in islet number is mainly responsible for expansion of islet and beta-cell mass in healthy control mice. GIPR(dn) transgenic mice show a disturbed expansion of the endocrine pancreas, due to perturbed islet neogenesis.

Background Cell injury, particularly as consequence of ischemia/reperfusion or acute rejection after (xeno)transplantation, leads to release of intracellular components like RNA. Extracellular RNA, (i) causes edema as a result of increasing permeability of blood vessels [1], (ii) is described as a procoagulation factor by activation of the contact phase system leading to thrombus formation and vessel occlusion [2], and (iii) promotes leukocyte recruitment to the vascular system by mobilising proinflammatory cytokines [3], and thus, triggers immune response. In rodent models of stroke and thrombosis, treatment with counteracting RNase A, a ribonuclease that specifically degrades single-stranded RNA, was shown to result in less edema formation and vessel occlusion [4]. In search of additive drugs to protect (xeno)grafts from dysfunction, we investigated if treatment with RNase A in a rat model of heterotopic heart transplantation results in less edema and less coronary occlusion, and, therefore, in improved graft survival. Methods Brown Norway rat cardiac allografts were transplanted into the abdomen of Lewis rats after perfusion with Bretschneider cardioplegic solution. Microvascular technique for aorto-aortic anastomosis and pulmonary artery to inferior vena cava anastomosis (Langendorff) was used. Recipients were intravenously treated directly before transplantation and every other day with RNase A (50 μg/kg) or vehicle (saline, n = 6 in each group). In addition, in six cases the donor graft was perfused with Bretschneider solution containing RNase A (8 μg in 10 ml), and afterwards transplanted into RNase A treated recipients. The primary end point of the study was graft survival, which was determined by daily examination of the graft function by palpation and in case of inconclusiveness by echocardiography. A tolerance study was performed treating animals daily with 50 μg/kg of RNase A, with 1,000 μg/kg of RNase A, or vehicle, respectively, for 28 days (n = 3 in each group). All explanted hearts were collected for histological evaluation. Results Mean graft survival was 6.5 ± 0.55 day (range 6–7 day) in vehicle treated animals vs. 10.2 ± 1.0 day (range 9–11 day) in RNase A treated animals (P = 0.002). Directly after explantation donor grafts had a mean weight of 0.94 ± 0.03 g (range 0.89–0.98 g). After been rejected, donor graft weight increased to 2.06 ± 0.52 g (range 1.59–2.77 g) in vehicle treated recipients, in contrast to 1.28 ± 0.27 g (1.05–1.61 g) in RNase A treated recipients (P = 0.017). No supplemental benefit was observed by additive using of RNase A in Bretschneider solution (graft survival 9.50 ± 1.52 day, graft weight 1.38 ± 0.15 g) compared to single treatment of the recipient (graft survival P = 0.394, graft weight P = 0.589). Tolerance studies showed neither macroscopic nor histological differences compared to saline treated animals. Outlook: Further histological analyses will help to clarify if RNase A will keep the promise to reduce edema formation even in the field of transplantation, as suggested by the significant less graft weight in RNase A treated recipients. Moreover, we will investigate, if RNase A prevents leukocyte recruitment in the context of rejection reaction. Therefore, grafts of RNase A treated and untreated rats will be explanted on day 4 after transplantation. Conclusions RNase A significantly improved graft survival. On the basis of these sweeping results, however, we suppose that RNase A could be an important adjuvant drug not only in allotransplantation but even in xenotransplantation. References [1] Fischer S, Gerriets T, Wessels C, et al. Extracellular RNA mediates endothelial-cell permeability via vascular endothelial growth factor. Blood 2007; 110(7): 2457–2465. [2] Kannemeier C, Shibamiya A, Nakazawa F, et al. Extracellular RNA constitutes a natural procoagulant cofactor in blood coagulation. Proc Natl Acad Sci U S A 2007; 104(15): 6388–6393. [3] Fischer S, Grantzow T, Pagel JI, et al. Extracellular RNA promotes leukocyte recruitment in the vascular system by mobilising proinflammatory cytokines. Thromb Haemost. 2012; 108(4): 730–741. [4] Walberer M, Tschernatsch M, Fischer S, et al. RNase therapy assessed by magnetic resonance imaging reduces cerebral edema and infarction size in acute stroke. Curr Neurovasc Res. 2009; 6(1): 12–19.

Purpose: Early stages of various entities of progressive kidney diseases are commonly characterized by development of glomerular hypertrophy and albuminuria. The purpose of the present study was to identify protein biomarker candidates for these glomerular alterations. Experimental design: Quantitative differences in the glomerular proteomes of two unrelated murine nephropathy models in the defined stage of glomerular hypertrophy at onset of albuminuria were identified by 2-D DIGE and MALDI-TOF/TOF analysis. Investigated mouse models were (I): transgenic (tg) mice expressing a dominant negative glucose-dependent insulinotropic polypeptide receptor (GIPRdn), a model of diabetes mellitus associated nephropathy and (II): growth hormone (GH)-tg mice, an established model of progressive glomerulosclerosis. Results: In GIPRdn-tg mice, nine differentially abundant glomerular proteins were unambiguously identified, and eight in GH-tg mice (each versus controls). Four proteins (Annexin A4, Dihydropyrimidinase-related protein 2, Myosin regulatory light chain 2, Tropomyosin 1) displayed a congeneric differential glomerular abundance in both models, thus representing a common differential protein expression profile of glomerular hypertrophy at onset of albuminuria. The glomerular presence of these proteins was also detected in specimen of human focal and segmental glomerulosclerosis and diabetic nephropathy. Conclusions and clinical relevance: Our findings suggest a pathogenetic relevance of the identified proteins in early stages of chronic kidney diseases and their potential use as diagnostic markers.

The bumetanide-sensitive Na+-K+-2Cl−cotransporter NKCC2, located in the thick ascending limb of Henle's loop, plays a critical role in the kidney's ability to concentrate urine. In humans, loss-of-function mutations of the solute carrier family 12 member 1 gene ( SLC12A1), coding for NKCC2, cause type I Bartter syndrome, which is characterized by prenatal onset of a severe polyuria, salt-wasting tubulopathy, and hyperreninemia. In this study, we describe a novel chemically induced, recessive mutant mouse line termed Slc12a1I299Fexhibiting late-onset manifestation of type I Bartter syndrome. Homozygous mutant mice are viable and exhibit severe polyuria, metabolic alkalosis, marked increase in plasma urea but close to normal creatininemia, hypermagnesemia, hyperprostaglandinuria, hypotension,, and osteopenia. Fractional excretion of urea is markedly decreased. In addition, calcium and magnesium excretions are more than doubled compared with wild-type mice, while uric acid excretion is twofold lower. In contrast to hyperreninemia present in human disease, plasma renin concentration in homozygotes is not increased. The polyuria observed in homozygotes may be due to the combination of two additive factors, a decrease in activity of mutant NKCC2 and an increase in medullary blood flow, due to prostaglandin-induced vasodilation, that impairs countercurrent exchange of urea in the medulla. In conclusion, this novel viable mouse line with a missense Slc12a1 mutation exhibits most of the features of type I Bartter syndrome and may represent a new model for the study of this human disease.

Several mutant mouse models for human diseases such as diabetes mellitus have been generated in the large-scale Munich ENU ( N-ethyl- N-nitrosourea) mouse mutagenesis project. The aim of this study was to identify the causal mutation of one of these strains and to characterize the resulting diabetic phenotype. Mutants exhibit a T to G transversion mutation at nt 629 in the glucokinase ( Gck) gene, leading to an amino acid exchange from methionine to arginine at position 210. Adult Munich GckM210Rmutant mice demonstrated a significant reduction of hepatic glucokinase enzyme activity but equal glucokinase mRNA and protein abundances. While homozygous mutant mice exhibited growth retardation and died soon after birth in consequence of severe hyperglycemia, heterozygous mutant mice displayed only slightly elevated blood glucose levels, present from birth, with development of disturbed glucose tolerance and glucose-induced insulin secretion. Additionally, insulin sensitivity and fasting serum insulin levels were slightly reduced in male mutant mice from an age of 90 days onward. While β-cell mass was unaltered in neonate heterozygous and homozygous mutant mice, the total islet and β-cell volumes and the total volume of isolated β-cells were significantly decreased in 210-day-old male, but not female heterozygous mutant mice despite undetectable apoptosis. These findings indicate that reduced total islet and β-cell volumes of male mutants might emerge from disturbed postnatal islet neogenesis. Considering the lack of knowledge about the pathomorphology of maturity-onset diabetes of the young type 2 (MODY 2), this glucokinase mutant model of reduced total islet and total β-cell volume provides the opportunity to elucidate the impact of a defective glucokinase on development and maintenance of β-cell mass and its relevance in MODY 2 patients.

Fragestellung: Im Rahmen des Munchener ENU-Mausmutagenese-Projekts wurden diabetische Mauslinien erstellt, die als Modell fur den Diabetes mellitus dienen. Eine dieser Mauslinien wurde in dieser Studie hinsichtlich der zugrundeliegenden Mutation und dem daraus resultierenden Phanotyp untersucht. Methodik: Die Phanotypisierung der diabetischen MunichGckM210R Maus erfolgte an heterozygoten Mutanten und Wildtypwurfgeschwistern auf dem genetischen Hintergrund von C3H-Inzuchtmausen im Alter von 1, 3 und 6 Monaten. Zur chromosomalen Lokalisation der ursachlichen Mutation wurde eine Kopplungsanalyse mit C57BL/6Mausen durchgefuhrt. Ergebnisse: Die SNP-Analyse ergab eine eindeutige Kopplung des diabetischen Phanotyps zu einem polymorphen Marker auf Chromosom 11 im Bereich von 5,8 Mbp. Die Sequenzierung des in dieser Region gelegenen Gck Gens zeigte eine definierte Punktmutation in Exon 6 an der Nukleotidposition 629 von T nach G, die einen Aminosaureaustausch an Position 210 von Met nach Arg zur Folge hat. Heterozygote MunichGckM210R Mausmutanten zeigten im Vergleich zu Wildtyptieren bei ad libitum Futterung und nach 15stundiger Nahrungskarenz in allen untersuchten Altersgruppen signifikant (p

Transgenic mice overexpressing a dominant negative glucose-dependent insulinotropic polypeptide receptor (GIPR(dn)) have recently been shown to develop diabetes mellitus due to disturbed postnatal development of the endocrine pancreas. In this study, the effects of feeding a high fibre/low calorie diet on the diabetic phenotype of GIPR(dn) transgenic mice were examined. Transgenic and control animals received either a conventional breeding diet (BD) or a high fibre diet (HF). Both fasting and postprandial blood glucose levels and HbA1C levels were largely elevated in transgenic mice vs. controls (p0.05), irrespective of the diet fed. Food and water intake and the daily urine volume of GIPR(dn) transgenic mice were higher than that of control mice (p0.05). Transgenic animals receiving the HF diet showed significantly lower blood glucose and HbA1C levels as well as less food and water intake than transgenic mice fed BD. The 365-day survival of transgenic mice was significantly lower than that of control mice. Transgenic animals fed the HF diet lived significantly longer than their counterparts receiving BD. GIPR(dn) transgenic mice develop a severe diabetic phenotype which can be ameliorated by a HF diet, thereby resembling some aspects of the pathophysiology of human type 2 diabetes mellitus.