Project description:DNA damage results in the activation of checkpoint kinases, which phosphorylate downstream effectors that inhibit the cell cycle, activate DNA repair, and cause widespread changes in transcription. However, the specific connections between the checkpoint kinases and downstream transcription factors (TFs) are not well understood. Here, we introduce a strategy for mapping regulatory networks between kinases and TFs involving integration of kinase mutant expression profiles, transcriptional regulatory interactions, and phosphoproteomics. We use this approach to investigate the role of the Saccharomyces cerevisiae checkpoint kinases (Mec1, Tel1, Chk1, Rad53, and Dun1) in the transcriptional response to DNA damage caused by methyl methanesulfonate (MMS). The result is a global kinase-TF regulatory network in which Mec1 and Tel1 signal through Rad53 to synergistically regulate the expression of more than 600 genes. This network implicates at least nine TFs, including Msn4, Gcn4, SBF (Swi4/Swi6), MBF (Swi6/Mbp1), and Fkh2/Ndd1/Mcm1, nearly all of which have sites of Rad53-dependent phosphorylation, as downstream regulators of checkpoint kinase-dependent genes. We also identify a major DNA damage-induced transcriptional network acting independently of Rad53 and other checkpoint kinases to regulate expression of genes involved in general and oxidative stress responses. Expression was profiled with and without MMS treatment in several genetic backgrounds (gene deletion strains).
Project description:Yeast cell cycle transcription dynamics in two S. cerevisae strains: BF264-15DU (MATa ade1 his2 leu2-3, 112 trp1-1 ura3Dns, bar1) [referred to as wild type] and a mutant of the wild type strain, clb1,2,3,4,5,6 GAL1-CLB1, [referred to as cyclin mutant] that does not express S-phase and mitotic cyclins. Both strains were synchronized by elutriation and released into YEP 2% dextrose/1M sorbitol at 30c. 15 samples were taken at 16 min intervals covering ~2 cycles in wild-type and ~1.5 cycles for the mutants. A significant fraction of the Saccharomyces cerevisiae genome is transcribed periodically during the cell division cycle, suggesting that properly timed gene expression is important for regulating cell cycle events. Genomic analyses of transcription factor localization and expression dynamics suggest that a network of sequentially expressed transcription factors could control the temporal program of transcription during the cell cycle. However, directed studies interrogating small numbers of genes indicate that their periodic transcription is governed by the activity of cyclin-dependent kinases (CDKs). To determine the extent to which the global cell cycle transcription program is controlled by cyclin/CDK complexes, we compared genome-wide transcription dynamics in wild type budding yeast to mutants that do not express S-phase and mitotic cyclins. Experiment Overall Design: Cell cycle synchrony/time series experiments. G1 cells collected by elutriation was examined over time for 2 cell cycles. Strains compared: wild type vs cyclin mutants. 15 samples per time course at 16 min resolution. 2 biological replicates per strain.
Project description:We previously proposed a detailed, 39-variable model for the network of cyclin-dependent kinases (Cdks) that controls progression along the successive phases of the mammalian cell cycle. Here, we propose a skeleton, 5-variable model for the Cdk network that can be seen as the backbone of the more detailed model for the mammalian cell cycle. In the presence of sufficient amounts of growth factor, the skeleton model also passes from a stable steady state to sustained oscillations of the various cyclin/Cdk complexes. This transition corresponds to the switch from quiescence to cell proliferation. Sequential activation of the cyclin/Cdk complexes allows the ordered progression along the G1, S, G2 and M phases of the cell cycle. The 5-variable model can also account for the existence of a restriction point in G1, and for endoreplication. Like the detailed model, it contains multiple oscillatory circuits and can display complex oscillatory behaviour such as quasi-periodic oscillations and chaos. We compare the dynamical properties of the skeleton model with those of the more detailed model for the mammalian cell cycle.
Project description:We propose an integrated computational model for the network of cyclin-dependent kinases (Cdks) that controls the dynamics of the mammalian cell cycle. The model contains four Cdk modules regulated by reversible phosphorylation, Cdk inhibitors, and protein synthesis or degradation. Growth factors (GFs) trigger the transition from a quiescent, stable steady state to self-sustained oscillations in the Cdk network. These oscillations correspond to the repetitive, transient activation of cyclin D/Cdk4-6 in G(1), cyclin E/Cdk2 at the G(1)/S transition, cyclin A/Cdk2 in S and at the S/G(2) transition, and cyclin B/Cdk1 at the G(2)/M transition. The model accounts for the following major properties of the mammalian cell cycle: (i) repetitive cell cycling in the presence of suprathreshold amounts of GF; (ii) control of cell-cycle progression by the balance between antagonistic effects of the tumor suppressor retinoblastoma protein (pRB) and the transcription factor E2F; and (iii) existence of a restriction point in G(1), beyond which completion of the cell cycle becomes independent of GF. The model also accounts for endoreplication. Incorporating the DNA replication checkpoint mediated by kinases ATR and Chk1 slows down the dynamics of the cell cycle without altering its oscillatory nature and leads to better separation of the S and M phases. The model for the mammalian cell cycle shows how the regulatory structure of the Cdk network results in its temporal self-organization, leading to the repetitive, sequential activation of the four Cdk modules that brings about the orderly progression along cell-cycle phases.
Project description:DNA damage results in the activation of checkpoint kinases, which phosphorylate downstream effectors that inhibit the cell cycle, activate DNA repair, and cause widespread changes in transcription. However, the specific connections between the checkpoint kinases and downstream transcription factors (TFs) are not well understood. Here, we introduce a strategy for mapping regulatory networks between kinases and TFs involving integration of kinase mutant expression profiles, transcriptional regulatory interactions, and phosphoproteomics. We use this approach to investigate the role of the Saccharomyces cerevisiae checkpoint kinases (Mec1, Tel1, Chk1, Rad53, and Dun1) in the transcriptional response to DNA damage caused by methyl methanesulfonate (MMS). The result is a global kinase-TF regulatory network in which Mec1 and Tel1 signal through Rad53 to synergistically regulate the expression of more than 600 genes. This network implicates at least nine TFs, including Msn4, Gcn4, SBF (Swi4/Swi6), MBF (Swi6/Mbp1), and Fkh2/Ndd1/Mcm1, nearly all of which have sites of Rad53-dependent phosphorylation, as downstream regulators of checkpoint kinase-dependent genes. We also identify a major DNA damage-induced transcriptional network acting independently of Rad53 and other checkpoint kinases to regulate expression of genes involved in general and oxidative stress responses.
Project description:Progression through the cell cycle is driven by cyclin dependent kinases that control gene expression, orchestration of the mitotic spindle and cell division. Here we used a Fluorescent Ubiquitination-based Cell Cycle Indicator (FUCCI) and performed transcriptomic analysis of human non-transformed cells. Cell sorting allowed efficient isolation of G1, S and G2 cells from asynchronously growing cell cultures. Altogether, we identified 701 differentially expressed genes in G1 and G2 cells.
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:Cyclin D1 is a regulatory subunit of cyclin-Dependent Kinases 4 and 6 (CDK4/6) and regulates progression from G1 to S phase of the cell cycle. Dysregulated cyclin D1-CDK4/6 contributes to tumor development. Enforced expression of non-phosphorylatable cyclin D1T286A mutant, frequently observed in human cancers, drives tumorigenesis. However, physiological functions of cyclin D1T286A is unclear. We have generated a conditional knock-in mouse model where cyclin D1T286A is expressed under the control of its endogenous promoter, permitting us to study the precise functions of cyclin D1T286A in tumorigenesis. The expression of cyclin D1T286A from its endogenous promoter induces inflammation-mediated lymphocyte disorder and mesenteric tumor formation. Uterine-specific expression of cyclin D1T286A accelerates Pten loss driven endometrial hyperplasia to promote uterine cancer.
Project description:CDK11 is an emerging druggable target for cancer therapy due to its prevalent roles in phosphorylating critical transcription and splicing factors and in facilitating cell cycle progression in cancer cells. Like other cyclin-dependent kinases, CDK11 requires its cognate cyclin, cyclin L1 or cyclin L2, for activation. However, little is known about how CDK11 activities might be modulated by other regulators. In this study, we show that CDK11 forms a tight complex with cyclins L1/L2 and SAP30BP, the latter of which is a poorly characterized factor. Acute degradation of SAP30BP mirrors that of CDK11 in causing widespread and strong defects in pre-mRNA splicing. Furthermore, we demonstrate that SAP30BP facilitates CDK11 kinase activities in vitro and in vivo, through ensuring the stabilities and the assembly of cyclins L1/L2 with CDK11. Together, these findings uncover SAP30BP as a critical CDK11 activator that regulates global pre-mRNA splicing.