Tyrosine phosphorylation is a hallmark for activation of Signal Transducer and Activator of Transcription (STAT) proteins, but their transcriptional activity also depends on other secondary modifications. Type I interferons (IFNs) can activate both the ISGF3 (STAT1:STAT2:IRF9) complex and STAT3, but with cell-specific, selective triggering of only the ISGF3 transcriptional program. Following a genome-wide RNAi screen, we identified the Sin3a complex as an important mediator of this STAT3 transcriptional repression. Sin3a directly interacts with the DNA-binding domain of STAT3 and alters its acetylation status. SIN3A silencing enhances recruitment of STAT3 and enhanceosome components to the SOCS3 promoter, resulting in histone hyperacetylation and enhanced transcription. Conversely, Sin3a is required for ISGF3-dependent gene transcription and for an efficient IFN-mediated antiviral protection against Influenza A and hepatitis C viruses. The Sin3a complex therefore acts as a context-dependent STAT1/3 transcriptional switch.
The Sin3a repressor complex is a master regulator of STAT transcriptional activity.
Cell line, Treatment
View SamplesTo investigate the impact of ablating Bcl9/Bcl9l on tumorigenesis, 6-8- week-old mice were exposed first to a single dose dimethylhydrazine (DMH, 44 mg/kg body weight), which is metabolized in the liver to carcinogenic azoxymethane (AOM), followed by 7 days oral administration of 2 % dextrane sulfate sodium (DSS) in the drinking water. This regimen results in the emergence of dysplastic adenomas, which progress to differentiated adenocarcinomas that are morphologically similar to human colorectal adenocarcinomas and typically harbor -catenin stabilizing mutations of GSK3 phosphorylation sites. Accordingly, these tumors present hallmarks of active Wnt signaling such as accumulation of nuclear -catenin and expression of Wnt target genes.
Bcl9/Bcl9l are critical for Wnt-mediated regulation of stem cell traits in colon epithelium and adenocarcinomas.
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View SamplesHuman breast cancer cell line MCF-7 is usually sensitive to chemotherapy drug BMS-554417, an insulin receptor (IR) and insulin-like growth factor receptor (IGFR) inhibitor. However, through step-wise increase in BMS-554417 doses in culture media, we were able able to screen and select a single MCF-7 clone that is BMS-554417 resistant. It is cross resistant to BMS-536924. This new line of MCF-7 cells was named as MCF-7R4. The transcriptome profiling of both MCF-7 and MCF-7R4 was performed using Affymetrix HG-U133 plus2.0 GeneChip arrays.
Drug efflux by breast cancer resistance protein is a mechanism of resistance to the benzimidazole insulin-like growth factor receptor/insulin receptor inhibitor, BMS-536924.
Specimen part, Cell line
View SamplesWe used microarrays to compare gene expression between shRNA targeting NRL and control replicates in D458Med cell line.
NRL and CRX Define Photoreceptor Identity and Reveal Subgroup-Specific Dependencies in Medulloblastoma.
Cell line
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