The Oak Ridge Polycystic Kidney mouse: Modeling ciliopathies of mice and men

The Oak Ridge Polycystic Kidney (ORPK) mouse was described nearly 14 years ago as a model for human recessive polycystic kidney disease. The ORPK mouse arose through integration of a transgene into an intron of the Ift88 gene resulting in a hypomorphic allele (Ift88(Tg737Rpw)). The Ift88(Tg737Rp omega) mutation impairs intraflagellar transport (IFT), a process required for assembly of motile and immotile cilia. Historically, the primary immotile cilium was thought to have minimal importance for human health; however, a rapidly expanding number of human disorders have now been attributed to ciliary defects. Importantly, many of these phenotypes are present and can be analyzed using the ORPK mouse. In this review, we highlight the research conducted using the OPRK mouse and the phenotypes shared with human cilia disorders. Furthermore, we describe an additional follicular dysplasia phenotype in the ORPK mouse, which alongside the ectodermal dysplasias seen in human Ellis-van Creveld and Sensenbrenner's syndromes, suggests an unappreciated role for primary cilia in the skin and hair follicle

The Cowpox Virus SPI-3 and Myxoma Virus SERP1 Serpins Are Not Functionally Interchangeable despite Their Similar Proteinase Inhibition Profiles in Vitro

AbstractThe myxoma virus (MYX) serpin SERP1 is a secreted glycoprotein with anti-inflammatory activity that is required for full MYX virulence in vivo. The cowpox virus (CPV) serpin SPI-3 (vaccinia virus ORF K2L) is a nonsecreted glycoprotein that blocks cell–cell fusion, independent of serpin activity, and is not required for virulence of vaccinia virus or CPV in mice. Although SPI-3 has only 29% overall identity to SERP1, both serpins have arginine at the P1 position in the reactive center loop, and SPI-3 has a proteinase inhibitory profile strikingly similar to that of SERP1 [Turner, P. C., Baquero, M. T., Yuan, S., Thoennes, S. R., and Moyer, R. W. (2000) Virology 272, 267–280]. To determine whether SPI-3 and SERP1 were functionally equivalent, a CPV variant was constructed where the SPI-3 gene was deleted and replaced with the SERP1 gene regulated by the SPI-3 promoter. Cells infected with CPVΔSPI-3::SERP1 secrete SERP1 and show extensive fusion, suggesting that SERP1 is unable to functionally substitute for SPI-3 in fusion inhibition. In the reciprocal experiment, both copies of SERP1 were deleted from MYX and replaced with SPI-3 under the control of the SERP1 promoter. Cells infected with the MYXΔSERP1::SPI-3 recombinant unexpectedly secreted SPI-3, suggesting either that the cellular secretory pathway is enhanced by MYX or that CPV encodes a protein that prevents SPI-3 secretion. MYXΔSERP1::SPI-3 was as attenuated in rabbits as MYXΔSERP1::lacZ, indicating that SPI-3 cannot substitute for SERP1 in MYX pathogenesis

Medium-chain acyl-CoA dehydrogenase deficiency in gene-targeted mice

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is the most common inherited disorder of mitochondrial fatty acid β-oxidation in humans. To better understand the pathogenesis of this disease, we developed a mouse model for MCAD deficiency (MCAD-/-) by gene targeting in embryonic stem (ES) cells. The MCAD-/- mice developed an organic aciduria and fatty liver, and showed profound cold intolerance at 4 °C with prior fasting. The sporadic cardiac lesions seen in MCAD-/- mice have not been reported in human MCAD patients. There was significant neonatal mortality of MCAD -/- pups demonstrating similarities to patterns of clinical episodes and mortality in MCAD-deficient patients. The MCAD-deficient mouse reproduced important aspects of human MCAD deficiency and is a valuable model for further analysis of the roles of fatty acid oxidation and pathogenesis of human diseases involving fatty acid oxidation. © 2005 Tolwani et al

Genetic and Informatic Analyses Implicate Kif12 as a Candidate Gene within the Mpkd2 Locus That Modulates Renal Cystic Disease Severity in the Cys1cpk Mouse.

We have previously mapped the interval on Chromosome 4 for a major polycystic kidney disease modifier (Mpkd) of the B6(Cg)-Cys1cpk/J mouse model of recessive polycystic kidney disease (PKD). Informatic analyses predicted that this interval contains at least three individual renal cystic disease severity-modulating loci (Mpkd1-3). In the current study, we provide further validation of these predicted effects using a congenic mouse line carrying the entire CAST/EiJ (CAST)-derived Mpkd1-3 interval on the C57BL/6J background. We have also generated a derivative congenic line with a refined CAST-derived Mpkd1-2 interval and demonstrated its dominantly-acting disease-modulating effects (e.g., 4.2-fold increase in total cyst area;

Magnetic resonance microscopy of renal and biliary abnormalities in excised tissues from a mouse model of autosomal recessive polycystic kidney disease.

Polycystic kidney disease (PKD) is transmitted as either an autosomal dominant or recessive trait and is a major cause of renal failure and liver fibrosis. The cpk mouse model of autosomal recessive PKD (ARPKD) has been extensively characterized using standard histopathological techniques after euthanasia. In the current study, we sought to validate magnetic resonance microscopy (MRM) as a robust tool for assessing the ARPKD phenotype. We used MRM to evaluate the liver and kidney of wild-type and cpk animals at resolutions \u3c100 \u3eμm and generated three-dimensional (3D) renderings for pathological evaluation. Our study demonstrates that MRM is an excellent method for evaluating the complex, 3D structural defects in this ARPKD mouse model. We found that MRM was equivalent to water displacement in assessing kidney volume. Additionally, using MRM we demonstrated for the first time that the cpk liver exhibits less extensive ductal arborization, that it was reduced in volume, and that the ductal volume was disproportionately smaller. Histopathology indicates that this is a consequence of bile duct malformation. With its reduced processing time, volumetric information, and 3D capabilities, MRM will be a useful tool for future in vivo and longitudinal studies of disease progression in ARPKD. In addition, MRM will provide a unique tool to determine whether the human disease shares the newly appreciated features of the murine biliary phenotype

TH17 cells require ongoing classic IL-6 receptor signaling to retain transcriptional and functional identity

Acting in concert with TGF-b, IL-6 signaling induces Th17 cell development by programming Th17-related genes via STAT3. A role for IL-6 signaling beyond the inductive phase of Th17 cell development has not been defined, as IL-23 signaling downstream of Th17 cell induction also activates STAT3 and is thought responsible for Th17 cell maintenance. Here, we find that IL-6 signaling is required for both induction and maintenance of Th17 cells; IL-6Ra–deficient Th17 cells rapidly lost their Th17 phenotype and did not cause disease in two models of colitis. Cotransfer of WT Th17 cells with IL-6Ra–deficient Th17 cells induced colitis but was unable to rescue phenotype loss of the latter. High IL-6 in the colon promoted classic, or cis, rather than trans receptor signaling that was required for maintenance of Th17 cells. Thus, ongoing classic IL6 signaling underpins the Th17 program and is required for Th17 cell maintenance and function

Cardiomyopathy and Response to Enzyme Replacement Therapy in a Male Mouse Model for Fabry Disease

Fabry disease is an X-linked disorder of glycosphingolipid metabolism that results in progressive accumulation of neutral glycosphingolipids, (predominately globotriaosylceramide; GL-3) in lysosomes, as well as other cellular compartments and the extracellular space. Our aim was to characterize the cardiac phenotype of male knock-out mice that are deficient in alpha-galactosidase A activity, as a model for Fabry disease and test the efficacy of Enzyme Replacement Therapy with agalsidase-beta. Male mice (3–4 months of age) were characterized with awake blood pressure and heart rate measurements, cardiac echocardiography and electrocardiography measurements under light anesthesia, histological studies and molecular studies with real-time polymerase chain reaction. The Fabry knock-out mouse has bradycardia and lower blood pressure than control wild type (CB7BL/6J) mice. In Fabry knock-out mice, the cardiomyopathy associated mild hypertrophy at echography with normal systolic LV function and mild diastolic dysfunction. Premature atrial contractions were more frequent in without conduction defect. Heart weight normalized to tibial length was increased in Fabry knock-out mice. Ascending aorta dilatation was observed. Molecular studies were consistent with early stages of cardiac remodeling. A single dose of agalsidase-beta (3 mg/kg) did not affect the LV hypertrophy, function or heart rate, but did improve the mRNA signals of early cardiac remodeling. In conclusion, the alpha-galactosidase A deficient mice at 3 to 4 months of age have cardiac and vascular alterations similar to that described in early clinical stage of Fabry disease in children and adolescents. Enzyme replacement therapy affects cardiac molecular remodeling after a single dose

Vesicular Stomatitis Viruses with Rearranged Genomes Have Altered Invasiveness and Neuropathogenesis in Mice

Transcription of vesicular stomatitis virus is controlled by the position of a gene relative to the single 3′ genomic promoter: promoter-proximal genes are transcribed at higher levels than those in more 5′ distal positions. In previous work, we generated viruses having rearranged gene orders. These viruses had the promoter-proximal gene that encodes the nucleocapsid protein, N, moved to the second or fourth position in the genome in combination with the glycoprotein gene, G, moved from its usual promoter-distal fourth position to the first or third position. This resulted in three new viruses identified by the positions of the N and G genes in the gene order: G3N4, G1N4, and G1N2. The viruses G3N4 and G1N4 were attenuated for lethality in mice. In the present study, we addressed the basis of this attenuation by measuring the ability of each of the rearranged viruses to travel to and replicate in the olfactory bulb and brain following intranasal inoculation. In addition, the neuropathogenicity, serum cytokine levels, and immunoglobulin G isotype profiles in infected mice were determined. All the viruses reached the olfactory bulb and brain, but the outcomes of these infections were dramatically different. Viruses N1G4(wt) and G1N2 caused lethal encephalitis in 100% of animals within 7 days postinoculation; however, viruses G3N4 and G1N4 were cleared from the brain by 7 days postinoculation and all animals survived without apparent distress. The viruses differed in the distribution and intensity of lesions produced and the type and levels of cytokines induced. Animals inoculated with N1G4(wt) or G1N2 displayed extensive encephalitis and meningitis and had elevated levels of serum gamma interferon compared to what was seen with G3N4- or G1N4-infected mice. In contrast to what occurred with intranasal inoculation, all four viruses caused lethal encephalitis when administered by direct inoculation to the brain, a route that circumvents the majority of the host immune response, demonstrating that G3N4 and G1N4 were not deficient in their abilities to cause disease in the brain. These findings indicate that gene rearrangement and its consequent alteration of gene expression can, without any other changes, alter the viral spread and cytokine response following intranasal infection