Very little is known about how animals discriminate pathogens from innocuous microbes. To address this question, we examined infection-response gene induction in the nematode Caenorhabditis elegans. We focused on genes that are induced in C. elegans by infection with the bacterial pathogen Pseudomonas aeruginosa, but are not induced by an isogenic attenuated gacA mutant. Most of these genes are induced independently of known immunity pathways. We generated a GFP reporter for one of these genes, infection response gene 1 (irg-1), which is induced strongly by wild-type P. aeruginosa strain PA14, but not by other C. elegans pathogens or by other wild-type P. aeruginosa strains that are weakly pathogenic to C. elegans. To identify components of the pathway that induces irg-1 in response to infection, we performed an RNA interference screen of C. elegans transcription factors. This screen identified zip-2, a bZIP transcription factor that is required for inducing irg-1, as well as several other genes, and is important for defense against infection by P. aeruginosa. These data indicate that zip-2 is part of a specialized pathogen response pathway that is induced by virulent strains of P. aeruginosa and provides defense against this pathogen.
bZIP transcription factor zip-2 mediates an early response to Pseudomonas aeruginosa infection in Caenorhabditis elegans.
Time
View SamplesMaternal obesity is linked with increased adverse outcomes for mother and fetus. However, the metabolic impact of excessive fat accumulation within the altered hormonal context of pregnancy is not well understood. We used a murine model of obesity, the high fat diet-fed C57BL/6J mouse to determine adipose tissue-mediated molecular mechanisms driving metabolic dysfunction throughout pregnancy. Remarkably, obese mice exhibited a normalization of visceral fat accumulation at late-stage pregnancy (-53%, P<0.001 E18.5) to achieve levels comparable in mass (per gram of body weight) to that of non pregnant, control diet fed mice. Moreover, whilst obese pregnant mice showed a marked glucose intolerance and apparent insulin resistance at mid-stage pregnancy (E14.5), glucose homeostasis converged with that of lean pregnant mice at late-stage pregnancy, suggesting an unexpected amelioration of the worsening metabolic dysfunction in obese pregnant mice.
Pregnancy in obese mice protects selectively against visceral adiposity and is associated with increased adipocyte estrogen signalling.
Specimen part
View SamplesMice deficient in the glucocorticoid-regenerating enzyme 11-HSD1 resist age-related spatial memory impairment. To investigate the mechanisms/pathways involved, we used microarrays to identify differentially expressed hippocampal genes that associate with cognitive ageing and 11-HSD1. Aged wild-type mice were separated into memory-impaired and unimpaired relative to young controls according to their performance in the Y-maze. All individual aged 11-HSD1-deficient mice showed intact spatial memory. The majority of differentially expressed hippocampal genes were increased with ageing (e.g. immune/inflammatory response genes) with no genotype differences. However, the neuronal-specific transcription factor, Npas4 and immediate early gene, Arc were reduced (relative to young) in the hippocampus of memory-impaired but not unimpaired aged wild-type or aged 11-HSD1-deficient mice. Quantitative RT-PCR and in situ hybridization confirmed reduced Npas4 and Arc mRNA expression in memory-impaired aged wild-type mice. These findings suggest that 11-HSD1 may contribute to the decline in Npas4 and Arc mRNA levels associated with memory impairment during ageing, and that decreased activity of synaptic plasticity pathways involving Npas4 and Arc may, in part, underlie the memory deficits seen in cognitively-impaired aged wild-type mice.
Decreased Npas4 and Arc mRNA Levels in the Hippocampus of Aged Memory-Impaired Wild-Type But Not Memory Preserved 11β-HSD1 Deficient Mice.
Age
View Samples5,6-Dimethylxanthenone-4-acetic acid (DMXAA), a tumor vascular disrupting agent, is shown here to have substantial activity as a single agent against human A375 melanoma xenografts in nude mice (94 % hemorrhagic necrosis after 24 h, and 26 days growth delay following single dose at 25 mg/kg). CD45+ cells in tumor tissue increased 5-fold over the first 3 days after treatment, which was due largely to an influx of CD11b+ Ly6G+ neutrophils. Using murine and human multiplex cytokine assays to dissect the cytokines produced by host stromal cells or by the melanoma cells, it was shown that both the stromal cells and the A375 melanoma cells produced cytokines capable of attracting neutrophils into the tumor. The same xenografts were also analyzed using human and mouse Affymetrix microarrays to separately identify tumor cell-specific (human) and stromal cell-specific (mouse) gene expression changes. DMXAA induced numerous stromal cytokine mRNAs, including IP-10, IL-6, MIP-1/, MIP-2, KC, RANTES, MIG, MCP-1 and IL-1, many of which were also elevated at the protein level. Numerous human cytokine mRNAs were also induced including MCP-1, IL-8, GRO, VEGF, GM-CSF and IL-6, which again was in line with our protein data. Pathway analysis indicated that significant numbers of the stromal mRNAs induced by DMXAA are regulated downstream of TNF-, interferon- and NFB. Our results suggest that DMXAA may have utility in combination therapy for human melanoma through the activation of pro-inflammatory signalling pathways and cytokine expression from both stromal and tumor cells, leading to haemorrhagic necrosis, neutrophil influx and growth inhibition.
Dissection of stromal and cancer cell-derived signals in melanoma xenografts before and after treatment with DMXAA.
Specimen part, Cell line
View SamplesCritically short telomeres activate p53-mediated apoptosis, resulting in organ failure and causing malignant transformation. Mutations in genes responsible for telomere maintenance are linked to a number of specific human diseases. We derived induced pluripotent stem cells (iPSCs) from patients with mutations in the TERT and TERC telomerase genes. Telomerase-mutant iPSCs elongated telomeres, but at a lower rate than healthy iPSCs, and the magnitude of the elongation deficit correlated with the specific mutations impact on telomerase activity. However, elongation significantly varied among iPSC clones harboring the same mutation, and was affected by genetic and environmental factors. iPSCs cultured in hypoxia showed increased telomere length. Potential influence of residual expression of reprogramming factors on telomerase regulation and telomere length was ruled out by excising the transgenes after successful reprogramming. Evidence for telomerase-independent telomere elongation was not observed in these cells. We demonstrate that telomerase is required for telomere elongation in iPSCs and uncover heterogeneity in telomere maintenance even between clones derived from individual patients or siblings with the same mutation, indicating that telomere phenotype may be influenced by acquired and environmental agents. Our data underscore the necessity of studying multiple clones when using iPSCs to model disease. The exon array were done to validate the pluripotent phenotype of the derived normal and telomerase mutant iPSC and to potentially identify differentially expressed genes in mutant iPSC.
Defective telomere elongation and hematopoiesis from telomerase-mutant aplastic anemia iPSCs.
Specimen part, Cell line
View SamplesMetastasis of human tumours to LNs is a universally negative prognostic factor. LN stromal cells (SCs) play a crucial role in enabling T cell responses, and since tumour metastases modulate their structure and function, this interaction may suppress immune responses to tumour antigens. However the SC subpopulations that respond to infiltration of malignant cells into human LNs have not been defined. Using microarray, we sought to assess gene expression profiles of two distinct SC subpopulations isolated from melanoma-infiltrated LNs.
Distinctive Subpopulations of Stromal Cells Are Present in Human Lymph Nodes Infiltrated with Melanoma.
Specimen part
View SamplesThe occurrence of clonal perturbations and leukemia in patients transplanted with retrovirally-transduced autologous hematopoietic stem and progenitor cells (HSPCs) has stimulated extensive investigation, demonstrating that proviral insertions perturb adjacent proto-oncogene expression. Although enhancer-deleted lentiviruses are less likely to result in insertional oncogenesis, there is evidence that they may perturb transcript splicing, and one patient with a benign clonal expansion of lentivirally-transduced HPSC has been reported. The rhesus macaque model provides an opportunity for informative long-term analysis to ask whether transduction impacts on long-term HSPC properties. We utilized two techniques to examine whether lentivirally-transduced HSPCs from eight rhesus macaques transplanted 1-13.5 years previously are perturbed at a population level, comparing telomere length as a measure of replicative history and gene expression profile of vector positive versus vector negative cells. There were no differences in telomere lengths between sorted GFP+ and GFP- blood cells, suggesting that lentiviral transduction did not globally disrupt replicative patterns. Bone marrow GFP+ and GFP- CD34+ cells showed no differences in gene expression using unsupervised and principal component analysis. These studies did not uncover any global long-term perturbation of proliferation, differentiation, or other important functional parameters of transduced HSPCs in the rhesus macaque model.
No impact of lentiviral transduction on hematopoietic stem/progenitor cell telomere length or gene expression in the rhesus macaque model.
Specimen part
View SamplesDyskeratosis congenita (DC) is an inherited multi-system disorder, characterized by oral leukoplakia, nail dystrophy, and abnormal skin pigmentation, as well as high rates of bone marrow failure, solid tumors, and other medical problems such as osteopenia. DC and telomere biology disorders (collectively referred to as TBD here) are caused by germline mutations in telomere biology genes leading to very short telomeres and limited proliferative potential of hematopoietic stem cells. We found that skeletal stem cells (SSCs) within the bone marrow stromal cell population (BMSCs, also known as bone marrow-derived mesenchymal stem cells), may contribute to the hematological phenotype.
Bone marrow skeletal stem/progenitor cell defects in dyskeratosis congenita and telomere biology disorders.
Cell line
View SamplesCells undergoing apoptosis are known to modulate their tissue microenvironments. By acting on phagocytes, notably macrophages, apoptotic cells inhibit immunological and inflammatory responses and promote trophic signaling pathways. Paradoxically because of their potential to cause death of tumor cells and thereby militate against malignant disease progression, both apoptosis and tumor-associated macrophages (TAM) are often associated with poor prognosis in cancer. In order to better understand the influence of tumor cell apoptosis and in particular its effect on TAM, we investigated global gene expression signatures of undisturbed TAM engaged in engulfment of apoptotic tumor cells. We studied a xenograft model of an aggressive starry-sky non-Hodgkins lymphoma, Burkitts lymphoma (BL), in which apoptotic tumor cells are common and frequently observed in association with the starry-sky TAM (SS-TAM, so called because they appear histologically as stars in a sky of tumor cells) that accumulate in these tumors. We used a BL cell line (BL2) whose cells phenotypically resemble the tumor biopsy cells from which the line was derived including the capacity to undergo apoptosis constitutively. BL xenografts in SCID mice closely recapitulated the starry-sky histological picture of the human lymphoma. Due to the high sensitivity of macrophages to their environments, we adopted laser-capture microdissection of individual SS-TAM in BL xenografts in order to obtain unbiased in situ transcriptional profiles of these cells, which we compared specifically with those of similarly-captured macrophages, the tingible-body macrophages from normal germinal centers (GCM). The rationale for this comparison was based upon BL being a germinal center malignancy and tingible-body macrophages being regarded as normal equivalents of SS-TAM.
Oncogenic properties of apoptotic tumor cells in aggressive B cell lymphoma.
Sex, Specimen part
View SamplesGene expression profile of in vitro differentiated control and CD33 KO CD34+ cells (with 70-85% CD33 KO) were analyzed by RNA-seq to exclude any major impact of CD33 loss on downstream gene expression Overall design: Primary CD34+ cells were treated with CRISPR/Cas9 to disrupt the CD33 gene and grown in culture for 5-7 days prior to analysis; mRNA profile was compared to control cells from the same donor that were also treated with Cas9 and a control gRNA; 5 different donors were evaluated (CD33 KO/control for each = total 10 samples)
Genetic Inactivation of CD33 in Hematopoietic Stem Cells to Enable CAR T Cell Immunotherapy for Acute Myeloid Leukemia.
Subject
View Samples