The glomerular filtration barrier prevents large serum proteins from being lost into the urine. It is not known, however, why the filter does not routinely clog with large proteins that enter the glomerular basement membrane (GBM). Here we provide evidence that an active transport mechanism exists to remove immunoglobulins that accumulate at the filtration barrier. We found that FcRn, an IgG and albumin transport receptor, is expressed in podocytes and functions to internalize IgG from the GBM. Mice lacking FcRn accumulated IgG in the GBM as they aged and tracer studies showed delayed clearance of IgG from the kidneys of FcRn deficient mice. Supporting a role for this pathway in disease, saturating the clearance mechanism potentiated the pathogenicity of nephrotoxic sera. These studies support the idea that podocytes play an active role in removing proteins from the GBM and suggest that genetic or acquired impairment of the clearance machinery is likely to be a common mechanism promoting glomerular diseases.
Podocytes use FcRn to clear IgG from the glomerular basement membrane.
Specimen part
View SamplesThe specialized glomerular epithelial cell (podocyte) of the kidney is a complex cell that is often damaged in glomerular diseases. Study of this cell type is facilitated by an in vitro system of propagation of conditionally immortalized podocytes. Here, genes that are differentially expressed in this in vitro model of podocyte differentiation are evaluated.
No associated publication
Specimen part
View SamplesWe performed gene expression profile of different B cell populations found in old (18 months old) C57BL/6 female mouse (B1 cells were recovered from both young and old C57BL/6 mice). Mice were nave and healthy (no autoimmunity was detected at the time of the experiment).
Toll-like receptor 7 (TLR7)-driven accumulation of a novel CD11c⁺ B-cell population is important for the development of autoimmunity.
Sex, Age, Specimen part
View SamplesInterferon is effective at inducing complete remissions in patients with Chronic Myelogenous Leukemia (CML), and evidence supports an immune mechanism. Here we show that the Type I Interferons (alpha and beta) regulate expression of the Interferon consensus sequence binding protein (ICSBP) in bcr-abl transformed cells and as shown previously for ICSBP, induce a vaccine-like immunoprotective effect in a murine model of bcr-abl induced leukemia. We identify the chemokines CCL6 and CCL9 as genes prominently induced by the Type I Interferons and ICSBP, and demonstrate that these immunomodulators are required for the immunoprotective effect of ICSBP expression. Insights into the role of these chemokines in the anti-leukemic response of interferons suggest new strategies for immunotherapy of CML.
ICSBP-mediated immune protection against BCR-ABL-induced leukemia requires the CCL6 and CCL9 chemokines.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Developmental stage-specific interplay of GATA1 and IGF signaling in fetal megakaryopoiesis and leukemogenesis.
Specimen part, Disease, Cell line, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
ETV1 directs androgen metabolism and confers aggressive prostate cancer in targeted mice and patients.
Specimen part, Cell line, Treatment
View SamplesRecent 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.
No associated publication
No sample metadata fields
View SamplesOrigins of the brain tumor, medulloblastoma, from stem cells or restricted pro-genitor cells are unclear. To investigate this, we activated oncogenic Hedgehog signaling in multipotent and lineage-restricted CNS progenitors. We observed that normal unipo-tent cerebellar granule neuron precursors (CGNP) derive from hGFAP+ and Olig2+ rhombic lip progenitors. Hedgehog activation in a spectrum of early and late stage CNS progenitors generated similar medulloblastomas, but not other brain cancers, indicating that acquisition of CGNP identity is essential for tumorigenesis. We show in human and mouse medulloblastoma that cells expressing the glia-associated markers Gfap and Olig2 are neoplastic and that they retain features of embryonic-type granule lineage progenitors. Thus, oncogenic Hedgehog signaling promotes medulloblastoma from lineage-restricted granule cell progenitors.
Acquisition of granule neuron precursor identity is a critical determinant of progenitor cell competence to form Shh-induced medulloblastoma.
No sample metadata fields
View SamplesHuntington's disease (HD) features a unique disease-initiating mechanism hypothesized to entail an impact of the CAG repeat encoded polyglutamine region on the full-length huntingtin protein, with dominant effects that are continuous with CAG size, in a simple gain of function. To evaluate these predictions, we generated a series of heterozygous Hdh CAG knock-in mouse embryonic stem (ES) cell lines, with 18, 48, 89, 109 CAGs, and found that a continuous analytic strategy efficiently identified, from genome-wide datasets, 73 genes and 172 pathways whose expression varied continuously with CAG length. The CAG-correlated genes were distinct from the set of 754 genes that distinguished huntingtin null ES cells from wild-type controls, and CAG-correlated pathways did not display a one-to-one correspondence with the 238 pathways altered in huntingtin null ES cells. Rather, the genes that varied with CAG size were either members of the same pathways as altered genes in huntingtin null cells or were members of unique pathways related to these pathways. These findings falsified a gain of function/loss of function proposal but were consistent with the simple gain of novel function mechanism hypothesis. The dominant CAG correlated gene expression changes conformed to the genetic features of the HD initiating mechanism and were system-wide and inter-related with pathways perturbed by lack of full-length huntingtin function, urging system-wide approaches for the discovery and validation of potential modulating factors, in the search for effective HD therapeutics.
HD CAG-correlated gene expression changes support a simple dominant gain of function.
Cell line
View SamplesHuntingtons disease (HD) involves marked early neurodegeneration in the striatum whereas the cerebellum is relatively spared despite the ubiquitous expression of full-length mutant huntingtin, implying that inherent tissue-specific differences determine susceptibility to the HD CAG mutation. To understand this tissue specificity, we compared early mutant huntingtin-induced gene expression changes in striatum to those in cerebellum in young Hdh CAG knock-in mice, prior to onset of evident pathological alterations. Endogenous levels of full-length mutant huntingtin caused qualitatively similar, but quantitatively different gene expression changes in the two brain regions. Importantly, the quantitatively different responses in striatum and cerebellum in mutant mice were well accounted for by the intrinsic molecular differences in gene expression between striatum and cerebellum in wild-type animals. Tissue-specific gene expression changes in response to the HD mutation, therefore, appear to reflect the different inherent capacities of these tissues to buffer qualitatively similar effects of mutant huntingtin. These findings highlight a role for intrinsic quantitative tissue differences in contributing to HD pathogenesis, and likely to other neurodegenerative disorders exhibiting tissue-specificity, thereby guiding the search for effective therapeutic interventions.
Differential effects of the Huntington's disease CAG mutation in striatum and cerebellum are quantitative not qualitative.
Specimen part
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