Despite its key role in Alzheimer pathogenesis, the physiological function(s) of the amyloid precursor protein (APP) and of its proteolytic fragments are still poorly understood. The secreted APPs ectodomain has been shown to be involved in neuroprotection and synaptic plasticity. The -secretase generated APP intracellular domain, AICD, functions as a transcriptional regulator in heterologous reporter assays although its role for endogenous gene regulation has remained controversial. Previously, we have generated APPs knockin (KI) mice expressing solely the secreted ectodomain APPs. Here, we generated double mutants (APPs-DM) by crossing APPs-KI mice onto an APLP2-deficient background and show that APPs rescues the postnatal lethality of the majority of APP/APLP2 double knockout mice. Despite normal CNS morphology and unaltered basal synaptic transmission, young APPs-DM mice already showed pronounced hippocampal dysfunction, impaired spatial learning and a deficit in LTP. To gain further mechanistic insight into which domains/proteolytic fragments are crucial for hippocampal APP/APLP2 mediated functions, we performed a DNA microarray transcriptome profiling of prefrontal cortex and hippocampus of adult APLP2-KO (APLP2-/-) and APPs-DM mice (APP/APLP2-/- mice).Interestingly, this analysis failed to reveal major genotype-related transcriptional differences. Expression differences between cortex and hippocampus were, however, readily detectable.
APP and APLP2 are essential at PNS and CNS synapses for transmission, spatial learning and LTP.
Sex, Specimen part
View SamplesNeuroprotective therapies for retinal degeneration may be used to rescue retinal cells and preserve vision. Hypoxic preconditioning stabilizes the transcription factor HIF-1 in the retina and strongly protects photoreceptors in an animal model of light-induced retinal degeneration.
Analysis of the retinal gene expression profile after hypoxic preconditioning identifies candidate genes for neuroprotection.
No sample metadata fields
View SamplesWe used microarrays to detail the global programme of gene expression dependent upon Stat3 in regulatory T cells
CD4+ regulatory T cells control TH17 responses in a Stat3-dependent manner.
Sex, Specimen part
View SamplesWe are investigating the transcriptional response of mice infected with Helicobacter hepaticus and links to liver cancer
Genetic susceptibility to chronic hepatitis is inherited codominantly in Helicobacter hepaticus-infected AB6F1 and B6AF1 hybrid male mice, and progression to hepatocellular carcinoma is linked to hepatic expression of lipogenic genes and immune function-associated networks.
No sample metadata fields
View SamplesMethylazoxymethanol (MAM), the genotoxic metabolite of the cycad azoxyglucoside cycasin, induces genetic alterations in bacteria, yeast, plants, insects and mammalian cells, but adult nerve cells are thought to be unaffected. We show that the brains of young adult mice treated with a single systemic dose of MAM display DNA damage (O6-methylguanine lesions) that peaks at 48 hours and decline to near-normal levels at 7 days post-treatment. By contrast, at this time, MAM-treated mice lacking the gene encoding the DNA repair enzyme O6-methylguanine DNA methyltransferase (MGMT), showed persistent O6-methylguanine DNA damage. The DNA damage was linked to cell-signaling pathways that are perturbed in cancer and neurodegenerative disease. These data are consistent with the established carcinogenic and developmental neurotoxic properties of MAM in rodents, and they support the proposal that cancer and neurodegeneration share common signal transduction pathways. They also strengthen the hypothesis that early life exposure to the MAM glucoside cycasin has an etiological association with a declining, prototypical neurodegenerative disease seen in Guam, Japan, and New Guinea populations that formerly used the neurotoxic cycad plant for medicine and/or food. Exposure to environmental genotoxins may have relevance to the etiology of related tauopathies, notably, Alzheimers disease, as well as cancer.
The cycad genotoxin MAM modulates brain cellular pathways involved in neurodegenerative disease and cancer in a DNA damage-linked manner.
Sex, Specimen part, Time
View SamplesBreast cancer metastasis to bone is a critical determinant of long-term survival after treatment of primary tumors. We used a mouse model of spontaneous bone metastasis to determine new molecular mechanisms. Differential transcriptome comparisons of primary and metastatic tumor cells revealed that a substantial set of genes suppressed in bone metastases were highly enriched for promoter elements for the type I interferon (IFN) regulatory factor, Irf7, itself suppressed in mouse and human metastases. The critical function of the Irf7 pathway was demonstrated by restoration of exogenous Irf7 or systemic interferon administration, which significantly reduced bone metastases and prolonged metastasis-free survival. Using mice deficient in the type I receptor (Ifnar1-/-) or mature B, T and NK cell responses (NOD Scid IL-2r-/- mice), we demonstrated that Irf7-driven suppression of metastasis was reliant on IFN signaling to host immune cells. Metastasis suppression correlated with decreased accumulation of myeloid-derived suppressor cells and increased CD4++, CD8 T cells and NK cells in the peripheral blood and was reversed by depletion of CD8+ cells and NK cells. Clinical importance of our findings was demonstrated as increased primary tumor Irf7 expression predicted prolonged bone and lung metastasis-free survival. Thus we report for the first time, a novel innate immune pathway, intrinsic to breast cancer cells, whose suppression in turn restricts systemic immunosurveillance to enable metastasis. This pathway may constitute a novel therapeutic target for restricting breast cancer metastases.
Silencing of Irf7 pathways in breast cancer cells promotes bone metastasis through immune escape.
Specimen part
View SamplesThe pathways by which oncogenes, such as MLL-AF9, initiate transformation and leukemia in humans and mice are incompletely defined. In a study of target cells and oncogene dosage, we found that Mll-AF9, when under endogenous regulatory control, efficiently transformed LSK (Lin- Sca1+ c-kit+) stem cells while committed granulocyte-monocyte progenitors (GMPs) were transformation-resistant and did not cause leukemia. Mll-AF9 was expressed at higher levels in hematopoietic stem (HSC) than GMP cells. Mll- AF9 gene dosage effects were directly shown in experiments where GMPs were efficiently transformed by the high dosage of Mll-AF9 resulting from retroviral transduction. Mll-AF9 up-regulated expression of 196 genes in both LSK and progenitor cells, but to higher levels in LSKs than in committed myeloid progenitors.
Malignant transformation initiated by Mll-AF9: gene dosage and critical target cells.
No sample metadata fields
View SamplesGoal of the experiment: Analysis of gene expression changes in the cortex, striatum, hippocampus, hypothalamus, Drd2-MSNs and Drd1-MSNs of mice with a postnatal, neuron-specific ablation of GLP or G9a as compared to control mice.
Control of cognition and adaptive behavior by the GLP/G9a epigenetic suppressor complex.
Specimen part
View SamplesLeukemias with MLL-rearrangements are characterized by high expression of the homeo box gene MEIS1. In these studies, we knocked down Meis1 expression by shRNA lentivirus transduction in murine Mll-AF9 leukemia cells. Meis1 knockdown resulted in decreased proliferation and survival of murine Mll-AF9 leukemia cells. We also observed reduced clonogenic capacity and increased monocytic differentiation. The establishment of leukemia in transplant recipients was significantly delayed by Meis1 knockdown. Gene expression profiling of cells transduced with Meis1 shRNA showed reduced expression of genes associated with cell cycle entry and progression. shRNA mediated knockdown of MEIS1 in human MLL-fusion gene leukemia cell lines resulted in reduced cell growth. These results show that MEIS1 expression is important for MLL-rearranged leukemias and suggest that MEIS1 promotes cell cycle entry. Targeting MEIS1 may have therapeutic potential for treating leukemias expressing this transcription factor.
A role for MEIS1 in MLL-fusion gene leukemia.
No sample metadata fields
View SamplesWnt-4 signaling is critical for embryonic female sexual development. When Wnt-4 gene is deleted during embryonic development, the knock-out females present a partial sex reversal.
Identification of the genes regulated by Wnt-4, a critical signal for commitment of the ovary.
Specimen part
View Samples