The Mediator complex allows communication between transcription factors and RNA polymerase II (RNAPII). CDK8, the kinase found in some variants of Mediator, has been characterized mostly as a transcriptional repressor. Recently, CDK8 was demonstrated to be a potent oncoprotein. Here we show that CDK8 is predominantly a positive regulator of gene expression within the serum response network, as it is required for expression of several members of the AP-1 and EGR family of oncogenic transcription factors (e.g. FOS, JUN, EGR1-3). Mechanistic studies demonstrate that CDK8 is not required for recruitment of RNAPII and promoter escape at these loci. Instead, CDK8 depletion leads to the appearance of slower elongation complexes carrying hypophosphorylated RNAPII. We show that CDK8-Mediator regulates precise steps in the assembly of a functional elongation complex, including the recruitment of P-TEFb and BRD4, but is dispensable for recruitment of SPT5 and FACT. Furthermore, CDK8-Mediator specifically interacts with P-TEFb. Thus, we uncovered a novel role for CDK8 in transcriptional regulation that may contribute to its oncogenic effects.
CDK8 is a positive regulator of transcriptional elongation within the serum response network.
Cell lineView Samples
Notch activation is instrumental in the development of most T-cell acute lymphoblastic leukemia (T-ALL) cases, yet Notch mutations alone are not sufficient to recapitulate the full human disease in animal models. We here found that Notch1 activation at the fetal liver (FL) stage expanded the hematopoietic progenitor population and conferred it transplantable leukemic-initiating capacity. However, leukemogenesis and leukemic-initiating cell capacity induced by Notch1 was critically dependent on the levels of ß-Catenin in both FL and adult bone marrow contexts. In addition, inhibition of ß-Catenin compromised survival and proliferation of human T-ALL cell lines carrying activated Notch1. By transcriptome analyses, we identified the MYC pathway as a crucial element downstream of ß-Catenin in these T-ALL cells and demonstrate that the MYC 3'' enhancer required ß-Catenin and Notch1 recruitment to induce transcription. Finally, PKF115-584 treatment prevented and partially reverted leukemogenesis induced by active Notch1. Overall design: Four T-ALL cell lines (RPMI8402, HPB-ALL, Jurkat, CCRF-CEM) were treated with DMSO (control) or PKF115-584 (310nM) for 3hrs. Gene expression changes were measured with Cufflinks comparing the 4 control with the 4 treated samples.
β-Catenin is required for T-cell leukemia initiation and MYC transcription downstream of Notch1.
No sample metadata fieldsView Samples
We have generated a mouse model for tumor initiation carrying a mutation in APC and lacking IKKa in intestinal epithelial cells. IKKa-deficient intestinal cells primarily failed to generate adenomas, and the few adenomas arising in this background displayed a significant reduction in cell proliferation. Using an in vitro model for intestinal tumoroids (derived from adenoma initiating cells), we have performed RNA sequencing of wild type and IKKa-deficient intestinal tumoroids. This has demonstrated that epithelial IKKa controls transcription of stem cell-related genes and genes associated with proliferation and apoptosis. Overall design: RNA sequencing of IKKa WT and KO tumoroids, done in triplicates
IKKα is required in the intestinal epithelial cells for tumour stemness.
Specimen part, Cell line, SubjectView Samples
Hematopoietic Stem Cells (HSC) are originated during embryonic development from endothelial-like cells located in the ventral side of the dorsal aorta around day E10-12 of murine development. This region is called AGM for Aorta/Gonad/Mesonephros and refers to the tissues around the hemogenic aorta. Cells that emerge from the endothelium and show hematopoietic traits can be distinguished by the expression of the c-kit receptor and finally acquire the CD45 marker.
Hematopoietic stem cell development requires transient Wnt/β-catenin activity.
Specimen partView Samples
Sjgren's syndrome is an autoimmune disease manifesting primarily as dryness of eyes and mouth. In this study, we compared gene expression in PBMCs between age- and gender-matched patients with Sjgren's syndrome (diagnosed by ACR criteria) and healthy controls. Cells were collected in heparinized tubes and PBMCs were prepared using Ficoll.
Expression of the immune regulator tripartite-motif 21 is controlled by IFN regulatory factors.
Specimen part, DiseaseView Samples
To determine the impact of ?Np63a knockdown on steady-state mRNA levels, we performed poly(A)-enriched RNA-seq analysis of lung squamous cell carcinoma line H226 (inducible shControl and shp63) in the presence of 1µg/mL doxycycline to induce shRNA expression. Overall design: Poly(A)+ RNA for two independent biological replicates was purified from H226 cells (inducible shControl and shp63) incubated treated for six days with 1 µg/mL doxycycline. a TruSeq Stranded mRNA Library Prep Kit (Illumina). Libraries were sequenced on an Illumina HiSeq 2000 system at the University of Colorado Cancer Center Genomics and Microarray Core facility. Reads were aligned (TopHat2) to the Human reference genome (GRCh37/hg19) and gene-level counts (HTseq-count) were used for differential expression analysis (DESeq2).
ΔNp63α Suppresses TGFB2 Expression and RHOA Activity to Drive Cell Proliferation in Squamous Cell Carcinomas.
Specimen part, Cell line, Treatment, SubjectView Samples
To determine effects of p53 activation on levels of RNA associated with polysomes, we performed RNA-seq analysis of colorectal carcinoma cell line HCT116, breast carcinoma line MCF7, and osteosarcoma line SJSA treated with MDM2 inhibitor Nutlin. Overall design: Polysomal RNA was extracted from HCT116, MCF7 and SJSA cells treated with Nutlin, polyA enriched and subjected to RNA-seq protocol.
Identification of a core TP53 transcriptional program with highly distributed tumor suppressive activity.
Cell line, Treatment, SubjectView Samples
Robles-Valero et al. report a tumor suppression role for the otherwise oncogenic Vav1 Rho GEF. This paradoxical action is mediated by the catalysis-independent buffering of Notch1 signaling in immature T cells.
A Paradoxical Tumor-Suppressor Role for the Rac1 Exchange Factor Vav1 in T Cell Acute Lymphoblastic Leukemia.
Specimen part, TreatmentView Samples
A subset of our SLNs would be upregulated by Nutlin-3 and down-regulated by 5-FU and that this differential regulation could potentially explain how cell fate choice is determined
ATM and MET kinases are synthetic lethal with nongenotoxic activation of p53.
Cell line, TreatmentView Samples
To define the contribution of CDK8 versus CDK19 to gene expression control, we performed a series of microarray assays for cells where each kinase was stably knocked down.
HIF1A employs CDK8-mediator to stimulate RNAPII elongation in response to hypoxia.
Cell line, TreatmentView Samples