Recent studies in our lab have identified a mutant mouse model of obstructive nephropathy designated mgb for megabladder. Homozygotic mgb mice (mgb-/-) develop lower urinary tract obstruction in utero due to a lack of bladder smooth muscle differentiation. This defect is the result of a random transgene insertion into chromosome 16 followed by a translocation of this fragment into chromosome 11. In an effort to identify potential gene targets affected in mgb mice, we performed transcriptional profiling on embryonic day 15 (E15) mgb-/- bladders using both a Chromosome 11/16 Custom GeneChip Array and the Affymetrix Mouse Genome 430 2.0 GeneChip. This analysis identified no definitive mis-expressed gene targets on chromosome 11. In contrast, mgb-/- mice significantly over-expressed a cluster of gene products located on the translocated fragment of chromosome 16 including urotensin II-related peptide (Urp), which was shown to be preferentially over-expressed in developing mgb-/- bladders. Immunohistochemical studies indicated that the spatial distribution of Urp was altered in mgb-/- bladders, while biochemical studies suggested a potential role for Urp in modifying smooth muscle cell phenotype in vitro. Pathway analysis of mgb microarray data showed dysregulation of at least 60 gene products associated with the differentiation of smooth muscle. In conclusion, the results of this study indicate that the molecular pathways controlling normal smooth muscle development are severely altered in mgb-/- bladders, and provide the first evidence that Urp may play a critical role in bladder smooth muscle development.
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View SamplesA deletion in the CMAH gene in humans occurred approximately 3.5 million years ago. This resulted in the inactivation of the CMP-Neu5Ac hydroxylase enzyme, and hence, in the specific deficiency in N-glycolylneuraminic acid (Neu5Gc), a form of sialic acid, in all modern humans. Although there is evidence that this molecular milestone in the origin of humans may have led to the evolution of human-specific pathogens, how deficiency in Neu5Gc might alter progression of non-infectious human diseases remains unanswered. Here, we have investigated cardiac and skeletal muscle gene expression changes in mdx mice, a model of Duchenne muscular dystrophy (DMD), that do or do not carry the human-like inactivating mutation in the mouse Cmah gene. We have evidence that Neu5Gc-deficiency in humans might explain some of the discrepancies in the disease phenotype between mdx mice and DMD patients.
A human-specific deletion in mouse Cmah increases disease severity in the mdx model of Duchenne muscular dystrophy.
Sex, Age, Specimen part
View SamplesTransgenic overexpression of Galgt2 in the skeletal muscles of mdx mice inhibits the development of disease pathology associated with muscular dystrophy. This is the case both in transgenic mice, where Galgt2 overexpression occurs from embryonic timepoints onward and in mdx mice where Galgt2 is overexpressed in the early postnatal period using Adeno-associated virus (AAV). Here, we use gene expression profiling to compare transcriptional changes resulting from embryonic and postnatal Galgt2 overexpression in mdx skeletal muscle. A surprising number of changes were in genes known to ameliorate muscular dystrophy when overexpressed (agrin, integrin alpha 7, ADAM12, Bcl2) or to cause muscular dystrophy when mutated (collagen VI (alpha1,alpha2), plectin 1, dystroglycan, selenoprotein N1, integrin alpha7, biglycan, dysferlin). Several genes involved in calcium homeostasis were also changed. In Galgt2 transgenic mice, where embryonic overexpression of Galgt2 in skeletal muscles alters neuromuscular development and muscle growth, the number of gene expression changes was vastly greater, however, 14% of genes altered in postnatal AAV-Galgt2 infected mdx muscles were also changed with embryonic overexpression. These experiments suggest that postnatal overexpression of Galgt2 inhibits muscular dystrophy in mdx mice via induction of a group of genes that, in aggregate, can govern membrane stability, membrane repair, calcium homeostasis, and apoptosis.
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View SamplesDrug resistance remains a major obstacle to successful cancer treatment. Here we use a novel approach to identify rapamycin as a glucocorticoid resistance reversal agent. A database of drug-associated gene expression profiles was screened for molecules whose profile overlapped with a gene expression signature of glucocorticoid (GC) sensitivity/resistance in Acute Lymphoblastic Leukemia (ALL) cells. The screen indicated the mTOR inhibitor rapamycin profile matched the signature of GC-sensitivity. We thus tested the hypothesis that rapamycin would induce GC sensitivity in lymphoid malignancy cells, and found that it sensitized cells to glucocorticoid induced apoptosis via modulation of antiapoptotic MCL1. These data indicate that MCL1 is an important regulator of GC-induced apoptosis, and that the combination of rapamycin and glucocorticoids has potential utility in ALL. Furthermore this approach represents a novel strategy for identification of promising combination therapies for cancer.
Gene expression-based chemical genomics identifies rapamycin as a modulator of MCL1 and glucocorticoid resistance.
No sample metadata fields
View SamplesHutchinsonGilford progeria syndrome (HGPS) is a rare genetic disease with widespread phenotypic features resembling premature aging. HGPS was recently shown to be caused by dominant mutations in the LMNA gene, resulting in the in-frame deletion of 50 amino acids near the carboxyl terminus of the encoded lamin A protein. Children with this disease typically succumb to myocardial infarction or stroke caused by severe atherosclerosis at an average age of 13 years. To elucidate further the molecular
Genome-scale expression profiling of Hutchinson-Gilford progeria syndrome reveals widespread transcriptional misregulation leading to mesodermal/mesenchymal defects and accelerated atherosclerosis.
Cell line
View SamplesDrug resistance remains a major obstacle to successful cancer treatment. Here we use a novel approach to identify rapamycin as a glucocorticoid resistance reversal agent. A database of drug-associated gene expression profiles was screened for molecules whose profile overlapped with a gene expression signature of glucocorticoid (GC) sensitivity/resistance in Acute Lymphoblastic Leukemia (ALL) cells. The screen indicated the mTOR inhibitor rapamycin profile matched the signature of GC-sensitivity. We thus tested the hypothesis that rapamycin would induce GC sensitivity in lymphoid malignancy cells, and found that it sensitized cells to glucocorticoid induced apoptosis via modulation of antiapoptotic MCL1. These data indicate that MCL1 is an important regulator of GC-induced apoptosis, and that the combination of rapamycin and glucocorticoids has potential utility in ALL. Furthermore this approach represents a novel strategy for identification of promising combination therapies for cancer.
Gene expression-based chemical genomics identifies rapamycin as a modulator of MCL1 and glucocorticoid resistance.
No sample metadata fields
View SamplesLeukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible.
Transformation from committed progenitor to leukaemia stem cell initiated by MLL-AF9.
No sample metadata fields
View SamplesLeukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible.
Transformation from committed progenitor to leukaemia stem cell initiated by MLL-AF9.
No sample metadata fields
View SamplesWe generated MLL-AF9 mediated murine leukemias that originate either from hematopoietic stem or committed progenitors cells. The luekemia stem cell fraction in these two type of leukemias shared exactly the same immunophenotype but their genetic programs differ.
No associated publication
Specimen part
View SamplesHuman iPS cells derived from normal and Fragile-X fibroblasts in order to assess the capability of Fragile-X iPS cells to be used as a model for different aspects of Fragile-X syndrome. Microarry analysis used to compare global gene expression between human ES cells, the normal and the mutant iPS cells and the original fibroblasts, to demonstrate that the overall reprogramming process succeeded, and that the FX-iPS cells are fully reprogrammed cells.
Differential modeling of fragile X syndrome by human embryonic stem cells and induced pluripotent stem cells.
Specimen part, Disease, Cell line
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