A commonly inactivated tumor suppressor silences endogenous retroelements in somatic cells [ChIP-Seq]
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE85639 | GEO | 2016/10/31
SECONDARY ACCESSION(S): PRJNA338977
REPOSITORIES: GEO
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Project description:Upon G1-S transition, cyclin-dependent kinases (CDKs) phosphorylate the retinoblastoma tumor suppressor protein (pRB) to release E2F transcription factors, which activate transcriptional programs, required for S-phase entry. Beyond the G1-S transition, pRB activity remains poorly understood. Our lab has discovered that pRB retains exclusive binding to E2F1 through an alternate E2F1-‘specific’ binding site at the pRB c-terminus independent of CDK phosphorylation. We have developed a gene-targeted mouse model that is defective for the E2F1-‘specific’ interaction. We are exploring the function of this complex through genome-wide binding and expression profiling. Overall, this work suggests an alternate pRB-E2F1 complex persists independent of CDK phosphorylation to establish regions of constitutive heterochromatin
2016-10-31 | GSE85638 | GEO
Project description:Upon G1-S transition, cyclin-dependent kinases (CDKs) phosphorylate the retinoblastoma tumor suppressor protein (pRB) to release E2F transcription factors, which activate transcriptional programs, required for S-phase entry. Beyond the G1-S transition, pRB activity remains poorly understood. Our lab has discovered that hyperphosphorylated pRB (ppRB), found beyond G1, retains exclusive binding to E2F1 through an alternate E2F1-‘specific’ binding site at the pRB c-terminus. We have developed a gene-targeted mouse model that is defective for the E2F1-‘specific’ interaction. We are exploring the function of this complex through genome-wide expression profiling. Overall, this work suggests an alternate pRB-E2F1 complex persists beyond the G1-S transition to establish regions of constitutive heterochromatin
2016-10-31 | GSE77993 | GEO
Project description:Upon G1-S transition, cyclin-dependent kinases (CDKs) phosphorylate the retinoblastoma tumor suppressor protein (pRB) to release E2F transcription factors, which activate transcriptional programs, required for S-phase entry. Beyond the G1-S transition, pRB activity remains poorly understood. Our lab has discovered that hyperphosphorylated pRB (ppRB), found beyond G1, retains exclusive binding to E2F1 through an alternate E2F1-‘specific’ binding site at the pRB c-terminus. We have developed a gene-targeted mouse model that is defective for the E2F1-‘specific’ interaction. We are exploring the function of this complex through genome-wide expression profiling. Overall, this work suggests an alternate pRB-E2F1 complex persists beyond the G1-S transition to establish regions of constitutive heterochromatin.
2016-10-31 | GSE62040 | GEO
Project description:The retinoblastoma tumor suppressor protein (Rb) regulates early G1 phase checkpoints, including the DNA damage response, as well as cell cycle exit and differentiation. The widely accepted model of G1 cell cycle progression proposes that cyclin D:Cdk4/6 partially inactivates the Rb tumor suppressor during early G1 phase by progressive multi-phosphorylation, termed hypo-phosphorylation, resulting in release of E2F transcription factors. However, this model remains largely unproven biochemically and the biologically active form(s) of Rb remains unknown. Here we find that Rb is un-phosphorylated in G0 cells and becomes exclusively mono-phosphorylated throughout all of early G1 phase by cyclin D:Cdk4/6. Early G1 phase mono-phosphorylated Rb is composed of 14 independent isoforms that are all targeted by the E1a oncoprotein, but each shows a preferential binding pattern to specific E2F1-4 transcription factors. At the late G1 Restriction Point, cyclin E:Cdk2 inactivates Rb by a quantum hyper-phosphorylation (>12 phosphates/Rb). Cells undergoing a DNA damage response activate cyclin D:Cdk4/6 to generate mono-phosphorylated Rb that regulates global transcription. In contrast, a non-phosphorylatable ?Cdk-Rb allele was non-functional for regulating a DNA damage response, but functional for driving cell cycle exit and differentiation during myogenesis. These observations fundamentally change our understanding of G1 cell cycle progression and show that there is no progressive multi-phosphorylation or hypo-phosphorylation inactivation of Rb during early G1 phase by cyclin D:Cdk4/6. Instead, cyclin D:Cdk4/6 generates functionally active, mono-phosphorylated Rb that is the only Rb isoform present in cells during early G1 phase. Global transcriptional analysis of murine embryonic fibroblasts (MEFs) with conditional deletion of the endogenous RB gene by treatment with cell permeable TAT-Cre. Comparison to unaltered MEFs and MEFs with physiological level of exogenous wildtype or phospho-mutant RB expressed at time of RB gene deletion.
2014-04-03 | E-GEOD-56453 | biostudies-arrayexpress
Project description:The retinoblastoma tumor suppressor protein (Rb) regulates early G1 phase checkpoints, including the DNA damage response, as well as cell cycle exit and differentiation. The widely accepted model of G1 cell cycle progression proposes that cyclin D:Cdk4/6 partially inactivates the Rb tumor suppressor during early G1 phase by progressive multi-phosphorylation, termed hypo-phosphorylation, resulting in release of E2F transcription factors. However, this model remains largely unproven biochemically and the biologically active form(s) of Rb remains unknown. Here we find that Rb is un-phosphorylated in G0 cells and becomes exclusively mono-phosphorylated throughout all of early G1 phase by cyclin D:Cdk4/6. Early G1 phase mono-phosphorylated Rb is composed of 14 independent isoforms that are all targeted by the E1a oncoprotein, but each shows a preferential binding pattern to specific E2F1-4 transcription factors. At the late G1 Restriction Point, cyclin E:Cdk2 inactivates Rb by a quantum hyper-phosphorylation (>12 phosphates/Rb). Cells undergoing a DNA damage response activate cyclin D:Cdk4/6 to generate mono-phosphorylated Rb that regulates global transcription. In contrast, a non-phosphorylatable ?Cdk-Rb allele was non-functional for regulating a DNA damage response, but functional for driving cell cycle exit and differentiation during myogenesis. These observations fundamentally change our understanding of G1 cell cycle progression and show that there is no progressive multi-phosphorylation or hypo-phosphorylation inactivation of Rb during early G1 phase by cyclin D:Cdk4/6. Instead, cyclin D:Cdk4/6 generates functionally active, mono-phosphorylated Rb that is the only Rb isoform present in cells during early G1 phase.
2014-04-03 | GSE56453 | GEO
Project description:While the effect of phosphorylation of the tumor suppressor pRB on cell cycle progression has been analyzed extensively in vitro, little is known about the consequences of blocking the phosphorylation of endogenous pRB on development and homeostasis. Here we show that homozygous RbΔK4 and RbΔK7 knockin mice, with Ser/Thr-to-Ala substitutions in four or all seven CDK sites in the C-terminus of pRb, undergo normal embryogenesis and early development. This is despite inhibition of pRb phosphorylation on additional but not all other upstream sites. Remarkably, adult RbΔK7 but not RbΔK4 mice are smaller than control littermates and exhibit hallmarks of accelerated aging including short telomeres, infertility, kyphosis and diabetes.Diabetes is insulin-sensitive and associated with failure of quiescent pancreatic -cells to re-enter the cell cycle in response to mitogens, leading to induction of DNA damage response (DDR), senescence-associated secretory phenotype, and diminished islet mass. The epigenetic regulator vitamin C decreased pancreatic islet DDR, increased cell cycle re-entry, and attenuated diabetes in RbΔK7 mice. These results have direct implications for cell-cycle regulation, anti-CDK therapy, diabetes and longevity.
2021-12-16 | GSE180507 | GEO
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.
2024-09-02 | BIOMD0000000730 | BioModels
Project description:A mathematical model of regulation of the G1-S transition of the mammalian cell cycle has been formulated to organize available experimental molecular-level information in a systematic quantitative framework and to evaluate the ability of this manifestation of current knowledge to calculate correctly experimentally observed phenotypes. This model includes nine components and includes cyclin-cdk complexes, a pocket protein (pRb), a transcription factor (E2F-1), and a cyclin-cdk complex inhibitor. Simulation of the model equations yields stable oscillatory solutions corresponding to cell proliferation and asymptotically stable solutions corresponding to cell cycle arrest (quiescence). Bifurcation analysis of the system suggests changes in the intracellular concentrations of either E2F or cyclin E can activate cell proliferation and that co-overexpression of these molecules can prevent cell proliferation. Further analysis suggests that the amount of inhibitor necessary to prevent cell proliferation is independent of the concentrations of cyclin E and E2F and depends only on the equilibrium ratio between the bound and unbound forms of the inhibitor to the complex.
2020-05-07 | MODEL2005070001 | BioModels
Project description:Cellular senescence wreaks defects in the aging organism. In this study, we co-treated two chemicals: rho-associated protein kinase (ROCK) inhibitor (Y-27632) and ataxia telangiectasia mutated (ATM) inhibitor (KU-60019) to overcome senescence more efficaciously, these two chemicals are already revealed to have senomorphic effects, suppressing senescent phenotypes. We find out that cocktail treatment synergistically alleviates diverse senescent phenotypes in senescent human dermal fibroblast cells. Through transcriptomic approach, FOXM1 and E2F1 are identified as key transcription factor of synergism to normalize senescent cells, of which activities are attenuated by senescence both in vitro and in vivo, but revitalized by co-treatment. Activation of FOXM1 precedes activation of E2F1 and mediates transcription of numerous genes totally shut off by cellular senescence, including E2F1. After that, E2F1 participates in transcriptomic change. For that, Cyclin-dependent kinase (CDKs), where are the confluences of both ATM-Chk2-CDKs and ROCK-Akt-CDKs signaling axes, are direct regulators of these transcription factors. Surprisingly, canonical aging-related CDK inhibitors have nothing to do with the onset of senomorphism. As the order of activations of FOXM1 and E2F1 that are in charge of G2 and G1 phase transition respectively, chemical combination releases senescent cell arrest in order of G2 then G1. Altogether, our data provide new insight into the way of amelioration of aging via pivotal cell cycle transcription factors, FOXM1 and E2F1, which are synergistically stimulated by inhibiting senescence-associated kinases, ATM and ROCK.
2022-06-22 | GSE178115 | GEO
Project description:In eukaryotes, cyclin/CDK complexes drive cells through DNA replication and mitosis, establising cell cycle temporal order. The fission yeast S. pombe is able to function with a single cyclin/CDK complex, with cell cycle order emerging from differential substrate sensitivities to CDK activity. What influence cyclin specificity has upon the cell cycle in this situation is currently unknown. Here we show that in a system that is reliant on a single cyclin for both the G1/S and G2/M transition, cyclin specificity is not needed for the G1/S transition, but instead is required for the G2/M transition and correct localisation of cyclin/CDK to the yeast centrosome equivalent, the SPB. This loss of centrosome localisation was also seen in human cells expressing mutant Cyclin B1, suggesting conservation of function. In fission yeast, although interphase centrosomal localisation is lost, mitotic SPB localisation remains. This hitherto unknown second localisation method is dependent on Polo kinase, suggesting a finer spatiotemporal control of cyclin/CDK during cell cycle progression than previously known. Thus, cyclin specificity is intrinsically twinned with spatial control of cyclin/CDK, and we suggest that this regulation may be conserved through evolution.
2019-05-27 | PXD011987 | Pride