STAT3 is a transcription factor playing a crucial role in inflammation, immunity and oncogenesis, able to induce distinct subsets of target genes in different cell types or under different conditions. Identification of direct transcriptional targets however has only defined a relatively limited set of genes, not sufficient to explain its variegated functions. In order to improve our understanding of the STAT3 transcriptional network we decided to develop a computational approach for the discovery of STAT3 functional binding sites. Upon generating a Positional Weight Matrix to define STAT3 binding sites, we applied a loglikelihood ratio scoring function and were able to assign affinity scores with very high specificity (93.5%) as measured by EMSA. STAT3 binding sites scoring above a stringent threshold have been identified genome-wide in Homo sapiens and Mus musculus and selected for phylogenetic conservation by genomic sequence alignment using eight vertebrate species. Validation was carried out on a subset of predicted
Genome-wide discovery of functional transcription factor binding sites by comparative genomics: the case of Stat3.
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View SamplesEpithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) facilitate breast cancer (BC) metastasis, however stable molecular changes that result as a consequence of these processes remain poorly defined. Therefore, we sought to identify molecular markers that could distinguish tumor cells that had completed the EMT:MET cycle in the hopes of identifying and targeting unique aspects of metastatic tumor outgrowth.Therefore, normal murine mammary gland (NMumG) cells transformed by overexpression of EGFR (NME) cells were cultured in the presence of TGF-beta1 (5 ng/ml) for 4 weeks, at which point TGF-beta1 supplementation was discontinued and the cells were allowed to recover for an additional 4 weeks (Post-TGF-Rec). Total RNA was prepared from unstimulated cells (Pre-TGF) of similar passage and compared by microarray analysis.
Fibroblast growth factor receptor splice variants are stable markers of oncogenic transforming growth factor β1 signaling in metastatic breast cancers.
Specimen part
View SamplesThe protease activity of the paracaspase MALT1 plays an important role in antigen receptor-mediated lymphocyte activation by controlling the activity of the transcription factor NF-kB and is thus essential for the expression of inflammatory target genes.
MALT1 Protease Activity Controls the Expression of Inflammatory Genes in Keratinocytes upon Zymosan Stimulation.
Treatment
View SamplesCurrent models imply that the FERM domain protein Merlin, encoded by the tumor suppressor NF2, inhibits mitogenic signaling at or near the plasma membrane. Here, we show that the closed, growth inhibitory form of Merlin accumulates in the nucleus, binds to the E3 ubiquitin ligase CRL4DCAF1, and suppresses its activity. Depletion of DCAF1 blocks the promitogenic effect of inactivation of Merlin. Conversely, enforced expression of a Merlin-insensitive mutant of DCAF1 counteracts the antimitogenic effect of Merlin. Re-expression of Merlin and silencing of DCAF1 induce a similar, tumor-suppressive program of gene expression. Tumor-derived mutations invariably disrupt Merlins ability to interact with or inhibit CRL4DCAF1. Finally, depletion of DCAF1 inhibits the hyperproliferation of Schwannoma cells from NF2 patients and suppresses the oncogenic potential of Merlin-deficient tumor cell lines. We propose that Merlin suppresses tumorigenesis by translocating to the nucleus to inhibit CRL4DCAF1.
Merlin/NF2 suppresses tumorigenesis by inhibiting the E3 ubiquitin ligase CRL4(DCAF1) in the nucleus.
Specimen part
View SamplesAstrocyte responses to neuronal injury may be beneficial or detrimental to neuronal recovery, but the mechanism that determines these different responses are poorly understood. Transcriptional analysis showed that EphB1 induces a protective inflammatory signature in astrocytes, which is distinct from the response evoked by interleukin (IL)-6, which is known to have both pro- and anti-inflammatory properties. We demonstrate that this beneficial EphB1 induced signaling pathway is disrupted in astrocytes derived from human induced pluripotent stem cells (iPSC) of amyotrophic lateral sclerosis (ALS) patients. Overall design: Examination of transcriptome-wide gene expression profiles of purified murine wildtype astrocyte cultures (untreated and treated with IL-6 or EphB1).
A neuroprotective astrocyte state is induced by neuronal signal EphB1 but fails in ALS models.
Specimen part, Cell line, Subject
View SamplesAstrocyte responses to neuronal injury may be beneficial or detrimental to neuronal recovery, but the mechanism that determines these different responses are poorly understood. Transcriptional analysis showed that EphB1 induces a protective inflammatory signature in astrocytes, which is distinct from the response evoked by interleukin (IL)-6, which is known to have both pro- and anti-inflammatory properties. We demonstrate that this beneficial EphB1 induced signaling pathway is disrupted in astrocytes derived from human induced pluripotent stem cells (iPSC) of amyotrophic lateral sclerosis (ALS) patients. Overall design: Examination of transcriptome-wide gene expression profiles of terminally differentiated and enriched iPSC-derived astrocytes harboring the SOD1 D90A mutation
A neuroprotective astrocyte state is induced by neuronal signal EphB1 but fails in ALS models.
Specimen part, Subject
View SamplesThe pesticide rotenone, a neurotoxin that inhibits the mitochondrial complex I, and destabilizes microtubules (MT) has been linked to Parkinson disease (PD) etiology and is often used to model this neurodegenerative disease (ND). Many of the mechanisms of action of rotenone are posited mechanisms of neurodegeneration; however, they are not fully understood. Therefore, the study of rotenone-affected functional pathways is pertinent to the understanding of NDs pathogenesis. This report describes the transcriptome analysis of a neuroblastoma (NB) cell line chronically exposed to marginally toxic and moderately toxic doses of rotenone. The results revealed a complex pleiotropic response to rotenone that impacts a variety of cellular events, including cell cycle, DNA damage response, proliferation, differentiation, senescence and cell death, which could lead to survival or neurodegeneration depending on the dose and time of exposure and cell phenotype. The response encompasses an array of physiological pathways, modulated by transcriptional and epigenetic regulatory networks, likely activated by homeostatic alterations. Pathways that incorporate the contribution of MT destabilization to rotenone toxicity are suggested to explain complex I-independent rotenone-induced alterations of metabolism and redox homeostasis. The postulated mechanisms involve the blockage of mitochondrial voltage-dependent anions channels (VDACs) by tubulin, which coupled with other rotenone-induced organelle dysfunctions may underlie many presumed neurodegeneration mechanisms associated with pathophysiological aspects of various NDs including PD, AD and their variant forms. Thus, further investigation of such pathways may help identify novel therapeutic paths for these NDs.
Transcriptome analysis of a rotenone model of parkinsonism reveals complex I-tied and -untied toxicity mechanisms common to neurodegenerative diseases.
Cell line, Treatment, Time
View SamplesWNT-induced secreted protein 1 (WISP1/CCN4), a member of the CCN protein family, acts as a downstream factor of the canonical WNT-signaling pathway. A dysregulated expression of WISP1 often reflects its oncogenic potential by inhibition of apoptosis, a necessary form of cell death that protect cell populations for transformation into malignant phenotypes. WISP1-signaling is also known to affect proliferation and differentiation of human mesenchymal stem cells (hMSCs), which are fundamental for the constitution and maintenance of the musculoskeletal system. Our study emphasizes the importance of WISP1-signaling for cell survival of primary human cells. Therefore, we established a successful down-regulation of endogenous WISP1 transcripts through gene silencing in hMSCs. We were able to demonstrate the consequence of cell death immediately after WISP1 down-regulation took place. Bioinformatical analyses of subsequent performed microarrays from WISP1 down-regulated vs. control samples confirmed this observation. We uncovered several clusters of differential expressed genes important for cellular apoptosis induction and immuno-regulatory processes, thereby indicating TRAIL-induced and p53-mediated apoptosis as well as IFNbeta-signaling. Since all of them act as potent inhibitors for malignant cell growth, in vitro knowledge about the connection with WISP1-signaling could help to find new therapeutic approaches concerning cancerogenesis and tumor growth in musculoskeletal tissues.
WISP 1 is an important survival factor in human mesenchymal stromal cells.
Specimen part, Treatment
View SamplesHairy cell leukemia (HCL) shows unique clinico-pathological and biological features. HCL responds well to purine analogues but relapses are frequent and novel therapies are required. BRAF-V600E is the key driver mutation in HCL and distinguishes it from other B-cell lymphomas, including HCL-like leukemias/lymphomas (HCL-variant and splenic marginal zone lymphoma). The kinase-activating BRAF-V600E mutation also represents an ideal therapeutic target in HCL. Here, we investigated the biological and therapeutic importance of the activated BRAF-MEK-ERK pathway in HCL by exposing in vitro primary leukemic cells purified from 26 patients to clinically available BRAF (Vemurafenib; Dabrafenib) or MEK (Trametinib) inhibitors. Results were validated in vivo in samples from Vemurafenib-treated HCL patients within a phase-2 clinical trial. BRAF and MEK inhibitors caused, specifically in HCL (but not HCL-like) cells, marked MEK/ERK dephosphorylation, silencing of the BRAF-MEK-ERK pathway transcriptional output, loss of the HCL-specific gene expression signature, downregulation of the HCL markers CD25, TRAP and cyclin-D1, smoothening of leukemic cells' hairy surface, and, eventually, apoptosis. Apoptosis was partially blunted by co-culture with bone marrow stromal cells antagonizing MEK-ERK dephosphorylation. This protective effect could be counteracted by combined BRAF and MEK inhibition. Our results strongly support and inform the clinical use of BRAF and MEK inhibitors in HCL.
BRAF inhibitors reverse the unique molecular signature and phenotype of hairy cell leukemia and exert potent antileukemic activity.
Specimen part, Treatment, Subject
View SamplesRepro9 in an allele of Mybl1 (A-Myb) transcription factor obtained in ENU screen to identify alleles causing mouse infertility. Repro9/repro9 mutant males are infertile due to meiotic arrest at pachytene stage. Mutants show wide range of abnormalities including inefficient chromosome synapsis, sex body formation and progression through meiotic cycle. Females are unaffected. To determine genes transcriptionally regulated by MYBL1 we analyzed gene expression profiles of wild type and repro9/repro9 mutant testis at 14 and 17 days postpartum. Analysis revealed many misregulated genes, in majority downregulated, at day 14 pp and even more at day 17 pp, probably due to secondary effects of meiotic arrest. Significantly misregulated genes were characterized by Gene Ontology. Comparative gene expression analysis uncovered potential targets of MYBL1 regulation that play roles in regulation of transcription, cell cycle, apoptosis, protein phosphorylation and ubiquitination, chromosome organization and others.
A-MYB (MYBL1) transcription factor is a master regulator of male meiosis.
Specimen part
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