Project description:Several cyclin-dependent kinases (CDKs) are known to have roles in transcriptional regulation. The datasets presented here are ChIP-seq experiments for different CDKs and RNA polymerase II in murine embryonic stem cells and Jurkat cells. ChIP-Seq of cyclin-dependent kinases in mouse embryonic stem cells and Jurkat human T cell acute lymphoblastic leukemia cell line
Project description:Several cyclin-dependent kinases (CDKs) are known to have roles in transcriptional regulation. The datasets presented here are ChIP-seq experiments for different CDKs and RNA polymerase II in murine embryonic stem cells and Jurkat cells.
Project description:Cyclin dependent kinases (CDKs) lie at the heart of eukaryotic cell division, with different CDK complexes initiating DNA replication (S-CDKs) and mitosis (M-CDKs)1-3. However, the principles on which cyclin-CDKs organise the cell cycle are still contentious, with current theories suggesting that either M-CDKs and S-CDKs are redundant with each other, and simply serve as a source of CDK activity, or that they are functionally specialised and execute distinct tasks. Here we reconcile these two views, showing that although S-CDKs are unable to drive mitosis, global CDK phosphorylation in vivo between S-CDK and M-CDK is surprisingly similar. Remarkably, S-CDK has cryptic mitotic activity which can be exposed by the removal of Protein Phosphatase 1 (PP1). In particular, removal of centrosomal PP1 allows S-CDK to execute mitosis indistinguishably from M-CDK, demonstrating their functional redundancy. Thus, we reconcile the two opposing views of cell cycle control, showing that although there is a minor level of specialisation between S-CDKs and M-CDKs, that the core cell cycle engine is based upon modulation of CDK activity, with cyclins providing refinements to this core system.
Project description:Herpesviruses encode conserved protein kinases to optimize virus infection by targeted phosphorylation. How these kinases bind to cellular factors and how this impacts their regulatory functions is poorly understood. Here, we use quantitative proteomics to determine the interactomes of eight herpesvirus kinases. We identify Cyclin A binding as a distinguishing feature of betaherpesvirus kinases that were previously described as viral mimics of cyclin-dependent kinases (v-CDKs), inert to cellular control. RXL motifs within the non-catalytic regions of roseolo- and muromegalovirus v-CDKs serve as Cyclin A docking sites and closely overlap with nuclear localization signals (NLS). By competing with NLS function, Cyclin A binding redirects NLS-RXL containing v-CDKs to cytoplasmic substrates at late times of infection. Concomitantly, Cyclin A is sequestered to the cytoplasm, which is essential for the viral inhibition of cellular DNA replication. Our data highlight a fine-tuned and physiologically important interplay between a cellular cyclin and viral CDK-like kinases.
Project description:Estrogen Receptor alpha (ERα) is a key driver of most breast cancers, and it is the target of endocrine therapies used in the clinic to treat women with ERα positive (ER+) breast cancer. The two methods ChIP-seq (chromatin immunoprecipitation coupled with deep sequencing) and RIME (Rapid Immunoprecipitation of Endogenous Proteins) have greatly improved our understanding of ERα function during breast cancer progression and in response to anti-estrogens. A critical component of both ChIP-seq and RIME protocols is the antibody that is used to pull down the bait protein. To date, most of the ChIP-seq and RIME experiments for the study of ERα have been performed using the sc-543 antibody from Santa Cruz Biotechnology. However, this antibody has been discontinued, thereby severely impacting the study of ERα in normal physiology as well as diseases such as breast cancer and ovarian cancer. Here, we compare the sc-543 antibody with other commercially available antibodies, and we show that 06-935 (EMD Millipore) and ab3575 (Abcam) antibodies can successfully replace the sc-543 antibody for ChIP-seq and RIME experiments.
Project description:Cell-cycle transitions are generally triggered by variations in the activity of cyclin-dependent kinases (CDKs) bound to cyclins. Malaria-causing parasites have evolved unique cell-cycles with a repertoire of ancestral CDKs and cyclins whose functions and interdependency remain elusive. Here, we show that the divergent Plasmodium berghei CDK-related kinase 5 (CRK5), is a critical cell-cycle regulator of gametogony required for transmission to the mosquito. It phosphorylates canonical CDK motifs on components of the pre-replicative complex and is essential for DNA replication. We also provide evidence for indirect regulation of the concomitant progression through M-phase. Over a replicative cycle, CRK5 stably interacts with a single Plasmodium-specific cyclin (SOC2) with no evidence of SOC2 cycling through transcription, translation nor degradation. Our results present evidence that during Plasmodium gametogony, a unique and divergent cyclin/CDK pair evolved to fulfil the functional space of multiple eukaryotic cell-cycle kinases controlling S-phase entry and progression through M-phase.
Project description:Progesterone receptor (PR) and its co-activators are direct targets of activated cyclin dependent kinases (CDKs) in response to peptide growth factors, progesterone, and deregulation of cell cycle inhibitors. Herein, using the T47D breast cancer model, we probed mechanisms of cell cycle-dependent PR action. In the absence of exogenous progestin, PR is specifically phosphorylated during the G2/M phase. Accordingly, numerous PR target genes are cell cycle regulated, including HSPB8, a heat-shock protein whose high expression is associated with tamoxifen-resistance. Progestin-induced HSPB8 expression required cyclin D1 and was insensitive to anti-estrogens, but blocked by anti-progestins or inhibition of specificity factor 1 (SP1). HSPB8 expression increased with or without ligand when cells were G2/M synchronized or contained high levels of cyclin D1. Knock-down of PR abrogated ligand-independent HSPB8 expression in synchronized cells. Notably, PR and cyclin D1 co-purified in whole cell lysates of transiently transfected COS-1 cells and in PR-positive T47D breast cancer cells expressing endogenous cyclin D1. PR, cyclin D1, and SP1 were recruited to the HSPB8 promoter in progestin-treated T47D breast cancer cells. Mutation of PR Ser345 to Ala (S345A) or inhibition of CDK2 activity using roscovitine disrupted PR/cyclin D1 interactions with DNA and blocked HSPB8 mRNA expression. Interaction of phosphorylated PRs with SP1 and cyclin D1 provides a mechanism for targeting transcriptionally active PRs to selected gene promoters relevant to breast cancer progression. Understanding the functional linkage between PR and cell cycle regulatory proteins will provide keys to targeting novel PR/cyclin D1 cross-talk in both hormone-responsive and HSPB8-high refractory disease. The study contains 4 different sample groups measured in triplicate, for a total of 12 individual samples (12 arrays). In T47D human breast cancer cell lines stably expressing PR-B, cells were synchronized (or not synchronized) before G2/M phase using nocodazole. These cell lines (synchronized or not synchronized) were treated with either (1) vehicle control (ethanol) or (2) PR ligand R5020 10e-8 M for 6 hours before total RNA harvest. Thus, the experiment contains two cell lines, and two treatments (4 sample groups) treated and analyzed in triplicate (12 microarrays). Standard Illumina HT-12v4 chip controls were used during hybridization.
Project description:H9 human pluripotent stem cells were grown in chemically defined media with Activin A and FGF2. Four 10cm plates with 70% confluency were used per sample. Cells were cross-linked by adding a final concentration of 1% PFA into culture media and incubated for 10 min at RT for Cyclin D1 ChIP. ChIP-seq experiment was performed in duplicate.
Project description:Cyclin C was cloned as a growth-promoting G1 cyclin, and several studies postulated a role for cyclin C in driving cell proliferation. Moreover, cyclin C, together with its kinase partner, the cyclin-dependent kinase CDK8, is believed to represent an essential component of basal transcriptional machinery where it globally represses gene expression. However, the function of cyclin C in vivo has never been addressed. Here we show that in the living organism cyclin C acts as a haploinsufficient tumor suppressor, through its function of controlling Notch1 oncogene levels. Cyclin C activates an M-bM-^@M-^\orphanM-bM-^@M-^] CDK19 kinase, as well as CDK8 and CDK3. These cyclin C-CDK complexes phosphorylate Notch1 intracellular domain (ICN1), which allows binding of ICN1 to Fbw7 and triggers ICN1 polyubiquitination. Genetic ablation of cyclin C blocks ICN1 phosphorylation, disrupts Fbw7 binding, and decreases ICN1 ubiquitination in vivo, thereby strongly elevating ICN1 levels in several compartments of cyclin C knockout mice. Ablation of cyclin C, or cyclin C heterozygosity collaborate with other oncogenic lesions and accelerate development of T-cell acute lymphoblastic leukemia (T-ALL) in cyclin Cdeficient mice. Furthermore, the locus encoding cyclin C is heterozygously deleted in a significant fraction of human T-ALL, and these tumors express reduced cyclin C levels. In addition, we describe point mutations in human T-ALL tumors that render cyclin C-CDK unable to phosphorylate ICN1. These studies reveal that in sharp contrast to all other cyclin proteins, cyclin C functions as a growth-suppressor in vivo, and suggest that human tumor cells develop different strategies to evade cyclin C inhibitory function. Comparison of wild-type mouse embryonic fibroblasts (n=3 biological replicates) versus cyclin C knockout MEFs (n=3), wild-type mouse embryonic stem cells (n=3) versus cyclin C knockout ESC (n=3), wild-type mouse embryonic brain (n=3) versus cyclin C knockout embryonic brain (n=3)
Project description:Cell-cycle transitions are generally triggered by variations in the activity of cyclin-dependent kinases (CDKs) bound to cyclins. Malaria parasites express ancestral CDKs and cyclins, whose functions and interdependency remain elusive. Here, we show that the unique Plasmodium berghei CDK-related kinase 5 (CRK5), is a critical cell-cycle regulator of gametogony required for transmission to the mosquito. It is essential for DNA replication and phosphorylates canonical S/TPxK CDK motifs on components of the pre-replicative complex otherwise regulated by distinct kinases in other eukaryotes. Over a replicative cycle, CRK5 stably interacts with a single Haemosporidia-specific cyclin (SOC2) with no evidence of SOC2 degradation. Regulation of CRK5 activity relies instead on dynamic phosphorylation of a C-terminus extension that mediates its interaction with SOC2. Our results present evidence that during the atypical cell cycles of Plasmodium gametogony, a unique and divergent cyclin/CDK pair fulfils the functional space of multiple eukaryotic cell-cycle kinases to initiate DNA replication.