Center for Modeling Human Disease

Toronto, Canada

Center for Modeling Human Disease

Toronto, Canada

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Kelsey L.,Samuel Lunenfeld Research Institute | Kelsey L.,Center for Modeling Human Disease | Flenniken A.M.,Samuel Lunenfeld Research Institute | Flenniken A.M.,Center for Modeling Human Disease | And 40 more authors.
PLoS Genetics | Year: 2013

KLF3 is a Krüppel family zinc finger transcription factor with widespread tissue expression and no previously known role in heart development. In a screen for dominant mutations affecting cardiovascular function in N-ethyl-N-nitrosourea (ENU) mutagenized mice, we identified a missense mutation in the Klf3 gene that caused aortic valvular stenosis and partially penetrant perinatal lethality in heterozygotes. All homozygotes died as embryos. In the first of three zinc fingers, a point mutation changed a highly conserved histidine at amino acid 275 to arginine (Klf3H275R). This change impaired binding of the mutant protein to KLF3's canonical DNA binding sequence. Heterozygous Klf3H275R mutants that died as neonates had marked biventricular cardiac hypertrophy with diminished cardiac chambers. Adult survivors exhibited hypotension, cardiac hypertrophy with enlarged cardiac chambers, and aortic valvular stenosis. A dominant negative effect on protein function was inferred by the similarity in phenotype between heterozygous Klf3H275R mutants and homozygous Klf3 null mice. However, the existence of divergent traits suggested the involvement of additional interactions. We conclude that KLF3 plays diverse and important roles in cardiovascular development and function in mice, and that amino acid 275 is critical for normal KLF3 protein function. Future exploration of the KLF3 pathway provides a new avenue for investigating causative factors contributing to cardiovascular disorders in humans. © 2013 Kelsey et al.


Adissu H.A.,Center for Modeling Human Disease | Adissu H.A.,University of Toronto | Estabel J.,Wellcome Trust Sanger Institute | Sunter D.,Wellcome Trust Sanger Institute | And 13 more authors.
DMM Disease Models and Mechanisms | Year: 2014

The Mouse Genetics Project (MGP) at the Wellcome Trust Sanger Institute aims to generate and phenotype over 800 genetically modified mouse lines over the next 5 years to gain a better understanding of mammalian gene function and provide an invaluable resource to the scientific community for follow-up studies. Phenotyping includes the generation of a standardized biobank of paraffin-embedded tissues for each mouse line, but histopathology is not routinely performed. In collaboration with the Pathology Core of the Centre for Modeling Human Disease (CMHD) we report the utility of histopathology in a high-throughput primary phenotyping screen. Histopathology was assessed in an unbiased selection of 50 mouse lines with (n=30) or without (n=20) clinical phenotypes detected by the standard MGP primary phenotyping screen. Our findings revealed that histopathology added correlating morphological data in 19 of 30 lines (63.3%) in which the primary screen detected a phenotype. In addition, seven of the 50 lines (14%) presented significant histopathology findings that were not associated with or predicted by the standard primary screen. Three of these seven lines had no clinical phenotype detected by the standard primary screen. Incidental and strain-associated background lesions were present in all mutant lines with good concordance to wild-type controls. These findings demonstrate the complementary and unique contribution of histopathology to high-throughput primary phenotyping of mutant mice. © 2014. Published by The Company of Biologists Ltd.


PubMed | Wellcome Trust Sanger Institute and Center for Modeling Human Disease
Type: Journal Article | Journal: Disease models & mechanisms | Year: 2015

Knowledge of the expression profile of a gene is a critical piece of information required to build an understanding of the normal and essential functions of that gene and any role it may play in the development or progression of disease. High-throughput, large-scale efforts are on-going internationally to characterise reporter-tagged knockout mouse lines. As part of that effort, we report an open access adult mouse expression resource, in which the expression profile of 424 genes has been assessed in up to 47 different organs, tissues and sub-structures using a lacZ reporter gene. Many specific and informative expression patterns were noted. Expression was most commonly observed in the testis and brain and was most restricted in white adipose tissue and mammary gland. Over half of the assessed genes presented with an absent or localised expression pattern (categorised as 0-10 positive structures). A link between complexity of expression profile and viability of homozygous null animals was observed; inactivation of genes expressed in 21 structures was more likely to result in reduced viability by postnatal day 14 compared with more restricted expression profiles. For validation purposes, this mouse expression resource was compared with Bgee, a federated composite of RNA-based expression data sets. Strong agreement was observed, indicating a high degree of specificity in our data. Furthermore, there were 1207 observations of expression of a particular gene in an anatomical structure where Bgee had no data, indicating a large amount of novelty in our data set. Examples of expression data corroborating and extending genotype-phenotype associations and supporting disease gene candidacy are presented to demonstrate the potential of this powerful resource.


Ly J.P.,Samuel Lunenfeld Research Institute | Onay T.,Samuel Lunenfeld Research Institute | Sison K.,Samuel Lunenfeld Research Institute | Sivaskandarajah G.,Samuel Lunenfeld Research Institute | And 16 more authors.
Journal of the American Society of Nephrology | Year: 2011

Inhibiting renal glucose transport is a potential pharmacologic approach to treat diabetes. The renal tubular sodium-glucose transporter 2 (SGLT2) reabsorbs approximately 90% of the filtered glucose load. An animal model with sglt2 dysfunction could provide information regarding the potential long-term safety and efficacy of SGLT2 inhibitors, which are currently under clinical investigation. Here, we describe Sweet Pee, a mouse model that carries a nonsense mutation in the Slc5a2 gene, which results in the loss of sglt2 protein function. The phenotype of Sweet Pee mutants was remarkably similar to patients with mutations in the Scl5a2 gene. The Sweet Pee mutants had improved glucose tolerance, higher urinary excretion of calcium and magnesium, and growth retardation. Renal physiologic studies demonstrated a prominent distal osmotic diuresis without enhanced natriuresis. Sweet Pee mutants did not exhibit increased KIM-1 or NGAL, markers of acute tubular injury. After induction of diabetes, Sweet Pee mice had better overall glycemic control than wild-type control mice, but had a higher risk for infection and an increased mortality rate (70% in homozygous mutants versus 10% in controls at 20 weeks). In summary, the Sweet Pee model allows study of the long-term benefits and risks associated with inhibition of SGLT2 for the management of diabetes. Our model suggests that inhibiting SGLT2 may improve glucose control but may confer increased risks for infection, malnutrition, volume contraction, and mortality. Copyright © 2011 by the American Society of Nephrology.


Chen F.,King's College | Guo R.,King's College | Itoh S.,King's College | Moreno L.,Samuel Lunenfeld Research Institute | And 18 more authors.
Journal of Bone and Mineral Research | Year: 2014

By using a genome-wide N-ethyl-N-nitrosourea (ENU)-induced dominant mutagenesis screen in mice, a founder with low bone mineral density (BMD) was identified. Mapping and sequencing revealed a T to C transition in a splice donor of the collagen alpha1 type I (Col1a1) gene, resulting in the skipping of exon 9 and a predicted 18-amino acid deletion within the N-terminal region of the triple helical domain of Col1a1. Col1a1Jrt/+ mice were smaller in size, had lower BMD associated with decreased bone volume/tissue volume (BV/TV) and reduced trabecular number, and furthermore exhibited mechanically weak, brittle, fracture-prone bones, a hallmark of osteogenesis imperfecta (OI). Several markers of osteoblast differentiation were upregulated in mutant bone, and histomorphometry showed that the proportion of trabecular bone surfaces covered by activated osteoblasts (Ob.S/BS and N.Ob/BS) was elevated, but bone surfaces undergoing resorption (Oc.S/BS and N.Oc/BS) were not. The number of bone marrow stromal osteoprogenitors (CFU-ALP) was unaffected, but mineralization was decreased in cultures from young Col1a1Jrt/+ versus +/+ mice. Total collagen and type I collagen content of matrices deposited by Col1a1Jrt/+ dermal fibroblasts in culture was ∼40% and 30%, respectively, that of +/+ cells, suggesting that mutant collagen chains exerted a dominant negative effect on type I collagen biosynthesis. Mutant collagen fibrils were also markedly smaller in diameter than +/+ fibrils in bone, tendon, and extracellular matrices deposited by dermal fibroblasts in vitro. Col1a1Jrt/+ mice also exhibited traits associated with Ehlers-Danlos syndrome (EDS): Their skin had reduced tensile properties, tail tendon appeared more frayed, and a third of the young adult mice had noticeable curvature of the spine. Col1a1Jrt/+ is the first reported model of combined OI/EDS and will be useful for exploring aspects of OI and EDS pathophysiology and treatment. © 2014 American Society for Bone and Mineral Research. © 2014 American Society for Bone and Mineral Research.


Siu A.G.,University of Toronto | Siu A.G.,Sunnybrook Research Institute | Ramadeen A.,Li Ka Shing Knowledge Institute | Hu X.,Li Ka Shing Knowledge Institute | And 17 more authors.
NMR in Biomedicine | Year: 2015

Although current cardiovascular MR (CMR) techniques for the detection of myocardial fibrosis have shown promise, they nevertheless depend on gadolinium-based contrast agents and are not specific to collagen. In particular, the diagnosis of diffuse myocardial fibrosis, a precursor of heart failure, would benefit from a non-invasive imaging technique that can detect collagen directly. Such a method could potentially replace the need for endomyocardial biopsy, the gold standard for the diagnosis of the disease. The objective of this study was to measure the MR properties of collagen using ultrashort TE (UTE), a technique that can detect short T2* species. Experiments were performed in collagen solutions. Via a model of bi-exponential T2* with oscillation, a linear relationship (slope=0.40±0.01, R2=0.99696) was determined between the UTE collagen signal fraction associated with these properties and the measured collagen concentration in solution. The UTE signal of protons in the collagen molecule was characterized as having a mean T2* of 0.75±0.05ms and a mean chemical shift of -3.56±0.01ppm relative to water at 7T. The results indicated that collagen can be detected and quantified using UTE. A knowledge of the collagen signal properties could potentially be beneficial for the endogenous detection of myocardial fibrosis. © 2015 John Wiley & Sons, Ltd.


Adissu H.A.,Center for Modeling Human Disease | Adissu H.A.,University of Toronto | Adissu H.A.,King's College | Adissu H.A.,University of Guelph | And 9 more authors.
Prostate | Year: 2015

BACKGROUND Altered expression and activity of proteases is implicated in inflammation and cancer progression. An important negative regulator of protease activity is TIMP3 (tissue inhibitor of metalloproteinase 3). TIMP3 expression is lacking in many cancers including advanced prostate cancer, and this may facilitate invasion and metastasis by allowing unrestrained protease activity. METHODS To investigate the role of TIMP3 in prostate cancer progression, we crossed TIMP3-deficient mice (Timp3-/-) to mice with prostate-specific deletion of the tumor suppressor Pten (Pten-/-), a well-established mouse model of prostate cancer. Tumor growth and progression were compared between Pten-/-, Timp3-/- and control (Pten-/-, Timp3+/+) mice at 16 weeks of age by histopathology and markers of proliferation, vascularity, and tumor invasion. Metalloproteinase activity within the tumors was assessed by gelatin zymography. Inflammatory infiltrates were assessed by immunohistochemistry for macrophages and lymphocytes whereas expression of cytokines and other inflammatory mediators was assessed by quantitative real time PCR and multiplex ELISA. RESULTS Increased tumor growth, proliferation index, increased microvascular density, and invasion was observed in Pten-/-, Timp3-/- prostate tumors compared to Pten-/-, Timp3+/+ tumors. Tumor cell invasion in Pten-/-, Timp3-/- mice was associated with increased expression of matrix metalloprotease (MMP)-9 and activation of MMP-2. There was markedly increased inflammatory cell infiltration into the TIMP3-deficient prostate tumors along with increased expression of monocyte chemoattractant protein-1, cyclooxygenase-2, TNF-α, and interleukin-1β; all of which are implicated in inflammation and cancer. CONCLUSIONS This study provides important insights into the role of altered protease activity in promoting prostate cancer invasion and implicates prostate inflammation as an important promoting factor in prostate cancer progression. Prostate 75:1831-1843, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.


PubMed | University of Toronto, Li Ka Shing Knowledge Institute and Center for Modeling Human Disease
Type: Journal Article | Journal: NMR in biomedicine | Year: 2015

Although current cardiovascular MR (CMR) techniques for the detection of myocardial fibrosis have shown promise, they nevertheless depend on gadolinium-based contrast agents and are not specific to collagen. In particular, the diagnosis of diffuse myocardial fibrosis, a precursor of heart failure, would benefit from a non-invasive imaging technique that can detect collagen directly. Such a method could potentially replace the need for endomyocardial biopsy, the gold standard for the diagnosis of the disease. The objective of this study was to measure the MR properties of collagen using ultrashort TE (UTE), a technique that can detect short T2* species. Experiments were performed in collagen solutions. Via a model of bi-exponential T2* with oscillation, a linear relationship (slope=0.400.01, R(2)=0.99696) was determined between the UTE collagen signal fraction associated with these properties and the measured collagen concentration in solution. The UTE signal of protons in the collagen molecule was characterized as having a mean T2* of 0.750.05ms and a mean chemical shift of -3.560.01ppm relative to water at 7T. The results indicated that collagen can be detected and quantified using UTE. A knowledge of the collagen signal properties could potentially be beneficial for the endogenous detection of myocardial fibrosis.

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