We have recently shown a remarkable regenerative capacity of the prenatal heart using a genetic model of mosaic mitochondrial dysfunction in mice. This model is based on inactivation of the X-linked gene encoding holocytochrome c synthase (Hccs) specifically in the developing heart. Loss of HCCS activity results in respiratory chain dysfunction, disturbed cardiomyocyte differentiation and reduced cell cycle activity. The Hccs gene is subjected to X chromosome inactivation, such that in females heterozygous for the heart conditional Hccs knockout approximately 50% of cardiac cells keep the defective X chromosome active and develop mitochondrial dysfunction while the other 50% remain healthy. During heart development, however, the contribution of HCCS deficient cells to the cardiac tissue decreases from 50% at midgestation to 10% at birth. This regeneration of the prenatal heart is mediated by increased proliferation of the healthy cardiac cell population, which compensate for the defective cells and allow the formation of a fully functional heart at birth. Here we performed microarray expression ananlyses on 13.5 dpc control and heterozygous Hccs knockout hearts to identify molecular mechanisms that drive embryonic heart regeneration.
Embryonic cardiomyocytes can orchestrate various cell protective mechanisms to survive mitochondrial stress.
Sex, Specimen part
View SamplesToxin A (TcdA) and Toxin B (TcdB), of the pathogen Clostridium difficile, are virulence factors that cause gross pathologic changes (e.g. inflammation, secretion, and diarrhea) in the infected host, yet the molecular and cellular pathways leading to observed host responses are poorly understood. To address this gap, TcdA and/or TcdB were injected into the ceca of mice and the genome-wide transcriptional response of epithelial layer cells was examined. Bioinformatic analysis of gene expression identified sets of cooperatively expressed genes. Further analysis of inflammation associated genes revealed dynamic chemokine responses.
In vivo physiological and transcriptional profiling reveals host responses to Clostridium difficile toxin A and toxin B.
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View SamplesLevels of C/EBP are low in myeloid blast crisis (BC) of chronic myelogenous leukemia (CML) and its expression in p210BCR/ABL-expressing hematopoietic cells induces granulocytic differentiation, inhibits proliferation and suppresses leukemogenesis. To assess the mechanisms involved in these effects, C/EBP targets were identified by microarray analyses. Upon C/EBP activation, expression of c-Myb and GATA-2 was repressed in 32D-BCR/ABL, K562 and CML-BC primary cells but only c-Myb levels decreased slightly in CD34+ normal progenitors. The role of these two genes for the biological effects of C/EBP was assessed by perturbing their expression in K562 cells. Expression of c-Myb blocked the proliferation inhibition and differentiation-inducing effects of C/EBP while c-Myb siRNA treatment enhanced C/EBP-mediated proliferation inhibition and induced changes in gene expression indicative of monocytic differentiation. GATA-2 expression suppressed the proliferation inhibitory effect of C/EBP but blocked in part the effect on differentiation; GATA-2 siRNA treatment had no effects on C/EBP induction of differentiation but inhibited proliferation of K562 cells, alone or upon C/EBP activation. In summary, the effects of C/EBP in p210BCR/ABL -expressing cells depend, in part, on transcriptional repression of c-Myb and GATA-2. Since perturbation of c-Myb and GATA-2 expression has non identical consequences for proliferation and differentiation of K562 cells, the effects of C/EBP appear to involve different transcription-regulated targets.
Transcriptional repression of c-Myb and GATA-2 is involved in the biologic effects of C/EBPalpha in p210BCR/ABL-expressing cells.
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View SamplesThe immune system can both promote and suppress cancer. Chronic inflammation and proinflammatory cytokines such as interleukin (IL)-1 and IL-6 are considered tumor-promoting. In contrast, the exact nature of protective antitumor immunity remains obscure. In this study, we have quantified locally secreted cytokines during primary immune responses against myeloma and B-cell lymphoma in mice. Strikingly, successful cancer immunosurveillance mediated by tumor-specific CD4+ T cells was consistently associated with elevated local levels of both proinflammatory (IL-1aplha, IL-1beta, and IL-6) and T helper 1 (Th1)-associated cytokines (interferon-alpha, IL-2, IL-12). Cancer eradication was achieved by a collaboration between tumor-specific Th1 cells and tumor-infiltrating, antigen-presenting macrophages. Th1 cells induced secretion of IL-1? and IL-6 by macrophages. Th1-derived interferon-? was shown to render macrophages directly cytotoxic to cancer cells, and to induce macrophages to secrete the angiostatic chemokines CXCL9/MIG and CXCL10/IP-10. Thus, inflammation, when driven by tumor-specific Th1 cells, may prevent rather than promote cancer.
Inflammation driven by tumour-specific Th1 cells protects against B-cell cancer.
Specimen part
View SamplesThe insulin-like growth factor (IGF) axis is an important signaling pathway in the growth and survival of many cell types and has been implicated in multiple aspects of cancer progression from tumorigenesis to metastasis. The multiple roles of IGF signaling in cancer suggest that selective inhibition of the pathway might yield clinically effective therapeutics. Here we describe A-928605, a novel small molecule inhibitor of the receptor tyrosine kinase responsible for IGF signal transduction. This small molecule is able to abrogate activation of the pathway as shown by effects on the target and downstream effectors and is shown to be effective at inhibiting the proliferation of an oncogene addicted tumor model cell line (CD8-IGF1R 3T3) both in vitro and in vivo.
Reversal of oncogene transformation and suppression of tumor growth by the novel IGF1R kinase inhibitor A-928605.
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View SamplesThe role of Tfr1 in non-erythroid tissues remains elusive due to the embryonic lethality of the Tfr1 global knockout mouse model. To bypass this problem, we generated a mouse model in which Tfr1 was conditionally deleted in intestinal epithelial cells (IECs). These mice developed severe IEC disruption, characterized by blunted villi, edema, loss of proliferative intervillus IECs, accumulation of lipids, and early neonatal lethality. Strikingly, a wide range of genes associated with epithelial-to-mesenchymal transition were highly upregulated in IEC lacking Tfr1. Additionally, candidate vesicular transport and sorting genes implicated in lipid absorption and trafficking were downregulated. Surprisingly, the presence of a mutant allele of Tfr1, which is unable to bind to iron-loaded transferrin, was capable of rescuing the lethality, intestinal epithelial homeostasis, and proliferation in a majority of the Tfr1 conditional knockout mice.
Noncanonical role of transferrin receptor 1 is essential for intestinal homeostasis.
Specimen part
View SamplesIn the early zebrafish embryo, the developing genome profile can be interfered with by exposure to pentachlorophenol, and some specific sets of genes are up-regulated or down-regulated. We used microarrays to detail the global program of gene expression underlying cellularisation and identified distinct classes of up-regulated genes during this process.
Pentachlorophenol exposure causes Warburg-like effects in zebrafish embryos at gastrulation stage.
Specimen part, Treatment
View SamplesWe performed miRNA and mRNA profiling in BASC cells and c-Myc depleted BASC cells. We built potential miRNA-mRNA interaction networks specific to c-Myc regulation in BASCs
c-Myc regulates self-renewal in bronchoalveolar stem cells.
Specimen part
View SamplesSHS exposure during pregnancy has adverse effects on offspring.
In utero exposure to second-hand smoke aggravates the response to ovalbumin in adult mice.
Sex, Specimen part
View SamplesSymptomatic glycerol kinase deficiency (GKD) is associated with episodic metabolic and central nervous system deterioration. We report here the first application of Weighted Gene Co-Expression Network Analysis (WGCNA) to investigate a knockout (KO) murine model of a human genetic disease. WGCNA identified networks and key hub transcripts from liver mRNA of glycerol kinase (Gyk) KO and wild type (WT) mice. Day of life 1 (dol1) samples from KO mice contained a network module enriched for organic acid metabolism before Gyk KO mice develop organic acidemia and die on dol3-4 and the module containing Gyk was enriched with apoptotic genes. Roles for the highly connected Acot, Psat and Plk3 transcripts were confirmed in cell cultures and subsequently validated by causality testing. We provide evidence that GK may have an apoptotic moonlighting role that is lost in GKD. This systems biology strategy has improved our understanding of GKD pathogenesis and suggests possible treatments.
Weighted gene co-expression network analysis identifies biomarkers in glycerol kinase deficient mice.
Sex, Specimen part
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