In T-cell acute lymphoblastic leukemia (T-ALL) NOTCH 1 receptors are frequently mutated. This leads to aberrantly high Notch signaling, but how this translates into deregulated cell cycle control and the transformed cell type is poorly understood. In this report, we analyze downstream responses resulting from the high level of NOTCH 1 signaling in T-ALL. Notch activity, measured immediately downstream of the NOTCH 1 receptor, is high, but expression of the canonical downstream Notch response genes HES 1 and HEY 2 is low both in primary cells from T-ALL patients and in T-ALL cell lines. This suggests that other immediate Notch downstream genes are activated, and we found that Notch signaling controls the levels of expression of the E3 ubiquitin ligase SKP2 and its target protein p27Kip1. We show that in T-ALL cell lines, recruitment of NOTCH 1 ICD to the SKP2 promoter was accompanied by high SKP2 and low p27Kip1 protein levels were low. In contrast, pharmacologically blocking Notch signaling reversed this picture and led to loss of NOTCH 1 ICD occupancy of the SKP2 promoter, decreased SKP2 and increased p27Kip1 expression. T-ALL cells show a rapid G1-S cell cycle transition, while blocked Notch signaling resulted in G0/G1 cell cycle arrest, also observed by transfection of p27Kip1 or, to a smaller extent, a dominant negative SKP2 allele. Collectively, our data suggest that the aberrantly high Notch signaling in T-ALL maintains SKP2 at a high level and reduces p27Kip1, which leads to more rapid cell cycle progression.
Notch signaling induces SKP2 expression and promotes reduction of p27Kip1 in T-cell acute lymphoblastic leukemia cell lines.
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View SamplesIn an attempt to gain insight into the mechanism whereby irradiated cells influence the outcome of DSB repair in their non-irradiated neighbors, we performed whole genome expression profiling.
Co-culturing with High-Charge and Energy Particle Irradiated Cells Increases Mutagenic Joining of Enzymatically Induced DNA Double-Strand Breaks in Nonirradiated Cells.
Cell line
View SamplesPro-inflammation triggered by microbial lipopolysaccharide (LPS) through Toll-like receptor (TLR) 4 in the presence of interferon (IFN)-g induces cytokine secretion in dendritic cells (DCs) tightly regulated by a defined differentiation program. This DC differentiation is characterized by a dynamic immune activating but also tolerance inducing phenotype associated with irreversible down-modulation of cytokines. CD40L on activated T cells further modifies DC differentiation. Using DNA micro arrays we showed down-regulated mRNA levels of TLR signaling molecules while CD40/CD40L signaling molecules were up-regulated at a time when LPS/IFN-g activated DCs have ceased cytokine expression. Accordingly we demonstrated that CD40/CD40L but not TLR4 or TLR3 signaling mediated by LPS or poly (cytidylic-inosinic) acid (poly I:C) and dsRNA re-established the capacity to secret interleukin (IL)-12 in LPS/IFN-g activated DCs, which have exhausted their potential for cytokine secretion. This resulting TH1 polarizing DC phenotype which lacked accompanying secretion of the crucial immune suppressive IL-10 - enhanced activation of cytotoxic T lymphocytes (CTLs). We therefore conclude that immune modulation is restricted to a secondary T-cell mediated stimulus at an exhausted DC state which prevents an immune tolerant DC phenotype. These findings impacts on the rational design of TLR activated DC-based cancer vaccines for the induction of anti-tumoral CTL responses.
CD40 ligation restores type 1 polarizing capacity in TLR4-activated dendritic cells that have ceased interleukin-12 expression.
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View SamplesThe first described feedback loop of the Arabidopsis circadian clock is based on reciprocal regulation between TOC1 and CCA1/LHY. CCA1 and LHY are MYB transcription factors that bind directly to the TOC1 promoter to negatively regulate its expression. Conversely, the activity of TOC1 has remained less well characterized. Genetic data supports that TOC1 is necessary for the reactivation of CCA1/LHY, but there is little description of its biochemical function. Here we show that TOC1 occupies specific genomic regions in the CCA1 and LHY promoters. Purified TOC1 binds directly to DNA through its CCT domain, which is similar to known DNA binding domains. Chemical induction and transient overexpression of TOC1 in Arabidopsis seedlings cause repression of CCA1/LHY expression demonstrating that TOC1 can repress direct targets, and mutation or deletion of the CCT domain prevents this repression showing that DNA binding is necessary for TOC1 action. Furthermore, we use the Gal4/UAS system in Arabidopsis to show that TOC1 acts as a general transcriptional repressor, and that repression activity is in the Pseudoreceiver (PR) domain of the protein. To identify the genes regulated by TOC1 on a genomic scale, we couple TOC1 chemical induction with microarray analysis and identify new potential TOC1 targets and output pathways. Together these results define the biochemical action of the core clock protein TOC1 and refine our perspective on how plant clocks function.
Arabidopsis circadian clock protein, TOC1, is a DNA-binding transcription factor.
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View SamplesContinuous regeneration of digestive enzyme (zymogen) secreting chief cells is a normal aspect of stomach function that is disrupted in pre-cancerous lesions. Regulation of zymogenic cell (ZC) differentiation is poorly understood. Here we profile Parietal, Pit, and Zymogenic cells for comparison and study.
The maturation of mucus-secreting gastric epithelial progenitors into digestive-enzyme secreting zymogenic cells requires Mist1.
Specimen part
View SamplesTranscript profiling analysis of csn3-1, csn4-1 and csn5 (csn5a-2 csn5b) light grown and dark grown mutant seedlings compared to light grown and dark grown wild type using Arabidopsis ATH1 GeneChip array
The Arabidopsis COP9 signalosome is essential for G2 phase progression and genomic stability.
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View SamplesThe phytohormone GA controls multiple important developmental processes in plants such as germination, elongation growth and flowering time. In this experiment, we look for early GA response genes in 7 day-old light-grown Arabidopsis seedlings. To this end we compare four data sets: (1) a GA biosynthesis mutant ga-1 (SALK_109115) mock treated for 1 hr; (2) a GA biosynthesis mutant ga-1 (SALK_109115) treated for 1 hr with 100 M GA3; (3) a gid1a-1 gid1b-1 gid1c-2 GA receptor triple mutant mock treated for 1 hr; (4) a gid1a-1 gid1b-1 gid1c-2 GA receptor triple mutant treated for 1 hr with 100 M GA3. In a comparison of the two ga-1 samples, GA regulated genes can be identified, and the assumption is that bona fide GA regulated genes are not responding in the gid1a-1 gid1b-1 gid1c-2 GA receptor mutant.
The DELLA domain of GA INSENSITIVE mediates the interaction with the GA INSENSITIVE DWARF1A gibberellin receptor of Arabidopsis.
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View SamplesTranscript profiling analysis of csn4-1 light grown mutant seedlings compared to wild type using Arabidopsis ATH1 GeneChip array
Characterization of the VIER F-BOX PROTEINE genes from Arabidopsis reveals their importance for plant growth and development.
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View SamplesAnalysis of genes regulated by STC1 down-regulation in mouse 4T1 derived clone, 4T1ch9. STC1 expression is associated with tumor growth and metastasis. This study looks at genes affected when STC1 expression is down-regulated by STC1 shRNA.
STC1 expression is associated with tumor growth and metastasis in breast cancer.
Cell line
View SamplesNormal primary thyroid cells were incubated with vehicle, 100 IU/ml IFN-gamma, 50 IU/ml IL1-beta, or a combination of both IFN-gamma and IL1-beta for 24 or 72 hours. The experiment was repeated 5 times using thyroid cells from 5 different patients. RNA expression was analyzed using Affymetrix HG_U133A arrays for 3 of the thyroids, and HG_U133A_2.0 (small version of HG_U133A) arrays for 2 of the thyroids.
Microarray analysis of cytokine activation of apoptosis pathways in the thyroid.
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