scholarly journals Metabolic control of G1–S transition: cyclin E degradation by p53-induced activation of the ubiquitin–proteasome system

2010 ◽  
Vol 188 (4) ◽  
pp. 473-479 ◽  
Author(s):  
Sudip Mandal ◽  
William A. Freije ◽  
Preeta Guptan ◽  
Utpal Banerjee
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cyclin E ◽  
Metabolic Stress ◽  
Ubiquitin Proteasome System ◽  
Mitochondrial Activity ◽  
Ubiquitin Proteasome ◽  
Stress Signals ◽  
F Box Protein

Cell cycle progression is precisely regulated by diverse extrinsic and intrinsic cellular factors. Previous genetic analysis in Drosophila melanogaster has shown that disruption of the mitochondrial electron transport chain activates a G1–S checkpoint as a result of a control of cyclin E by p53. This regulation does not involve activation of the p27 homologue dacapo in flies. We demonstrate that regulation of cyclin E is not at the level of transcription or translation. Rather, attenuated mitochondrial activity leads to transcriptional upregulation of the F-box protein archipelago, the Fbxw7 homologue in flies. We establish that archipelago and the proteasomal machinery contribute to degradation of cyclin E in response to mitochondrial dysfunction. Our work provides in vivo genetic evidence for p53-mediated integration of metabolic stress signals, which modulate the activity of the ubiquitin–proteasome system to degrade cyclin E protein and thereby impose cell cycle arrest.

scholarly journals Identification of HiNF-P, a Key Activator of Cell Cycle-Controlled Histone H4 Genes at the Onset of S Phase

2003 ◽  
Vol 23 (22) ◽  
pp. 8110-8123 ◽  
Author(s):  
Partha Mitra ◽  
Rong-Lin Xie ◽  
Ricardo Medina ◽  
Hayk Hovhannisyan ◽  
S. Kaleem Zaidi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cyclin E ◽  
S Phase ◽  
Phase Cell ◽  
Regulatory Sequences ◽  
Histone H4 ◽  
Restriction Point ◽  
Histone H4 Gene

ABSTRACT At the G1/S phase cell cycle transition, multiple histone genes are expressed to ensure that newly synthesized DNA is immediately packaged as chromatin. Here we have purified and functionally characterized the critical transcription factor HiNF-P, which is required for E2F-independent activation of the histone H4 multigene family. Using chromatin immunoprecipitation analysis and ligation-mediated PCR-assisted genomic sequencing, we show that HiNF-P interacts with conserved H4 cell cycle regulatory sequences in vivo. Antisense inhibition of HiNF-P reduces endogenous histone H4 gene expression. Furthermore, we find that HiNF-P utilizes NPAT/p220, a substrate of the cyclin E/cyclin-dependent kinase 2 (CDK2) kinase complex, as a key coactivator to enhance histone H4 gene transcription. The biological role of HiNF-P is reflected by impeded cell cycle progression into S phase upon antisense-mediated reduction of HiNF-P levels. Our results establish that HiNF-P is the ultimate link in a linear signaling pathway that is initiated with the growth factor-dependent induction of cyclin E/CDK2 kinase activity at the restriction point and culminates in the activation of histone H4 genes through HiNF-P at the G1/S phase transition.

scholarly journals Efficient APC/C substrate degradation in cells undergoing mitotic exit depends on K11 ubiquitin linkages

2015 ◽  
Vol 26 (24) ◽  
pp. 4325-4332 ◽  
Author(s):  
Mingwei Min ◽  
Tycho E. T. Mevissen ◽  
Maria De Luca ◽  
David Komander ◽  
Catherine Lindon
Keyword(s):  
Cell Cycle Progression ◽  
Degradation Kinetics ◽  
Ubiquitin Proteasome System ◽  
Mitotic Exit ◽  
Anaphase Promoting Complex ◽  
Polyubiquitin Chains ◽  
Substrate Degradation ◽  
Ubiquitin Proteasome ◽  
In Cells

The ubiquitin proteasome system (UPS) directs programmed destruction of key cellular regulators via posttranslational modification of its targets with polyubiquitin chains. These commonly contain Lys-48 (K48)–directed ubiquitin linkages, but chains containing atypical Lys-11 (K11) linkages also target substrates to the proteasome—for example, to regulate cell cycle progression. The ubiquitin ligase called the anaphase-promoting complex/cyclosome (APC/C) controls mitotic exit. In higher eukaryotes, the APC/C works with the E2 enzyme UBE2S to assemble K11 linkages in cells released from mitotic arrest, and these are proposed to constitute an improved proteolytic signal during exit from mitosis. We tested this idea by correlating quantitative measures of in vivo K11-specific ubiquitination of individual substrates, including Aurora kinases, with their degradation kinetics tracked at the single-cell level. All anaphase substrates tested by this methodology are stabilized by depletion of K11 linkages via UBE2S knockdown, even if the same substrates are significantly modified with K48-linked polyubiquitin. Specific examination of substrates depending on the APC/C coactivator Cdh1 for their degradation revealed Cdh1-dependent enrichment of K11 chains on these substrates, whereas other ubiquitin linkages on the same substrates added during mitotic exit were Cdh1-independent. Therefore we show that K11 linkages provide the APC/C with a means to regulate the rate of substrate degradation in a coactivator-specified manner.

scholarly journals The Drosophila F-box protein dSkp2 regulates cell proliferation by targeting Dacapo for degradation

2013 ◽  
Vol 24 (11) ◽  
pp. 1676-1687 ◽  
Author(s):  
Wen Dui ◽  
Bin Wei ◽  
Feng He ◽  
Wei Lu ◽  
Changqing Li ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Functional Relationship ◽  
Kinase Inhibitors ◽  
Cycle Progression ◽  
Cell Doubling Time ◽  
F Box Protein ◽  
Negative Factors

Cell cycle progression is controlled by a complex regulatory network consisting of interacting positive and negative factors. In humans, the positive regulator Skp2, an F-box protein, has been a subject of intense investigation in part because of its oncogenic activity. By contrast, the molecular and developmental functions of its Drosophila homologue, dSkp2, are poorly understood. Here we investigate the role of dSkp2 by focusing on its functional relationship with Dacapo (Dap), the Drosophila homologue of the cyclin-dependent kinase inhibitors p21cip1/p27kip1/p57kip2. We show that dSkp2 interacts physically with Dap and has a role in targeting Dap for ubiquitination and proteasome-mediated degradation. We present evidence that dSkp2 regulates cell cycle progression by antagonizing Dap in vivo. dSkp2 knockdown reduces cell density in the wing by prolonging the cell doubling time. In addition, the wing phenotype caused by dSkp2 knockdown resembles that caused by dap overexpression and can be partially suppressed by reducing the gene dose of dap. Our study thus documents a conserved functional relationship between dSkp2 and Dap in their control of cell cycle progression, suggesting the possibility of using Drosophila as a model system to study Skp2-mediated tumorigenesis.

scholarly journals Intracellular Dynamics of the Ubiquitin-Proteasome-System

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 367 ◽  
Author(s):  
Maisha Chowdhury ◽  
Cordula Enenkel
Keyword(s):  
Cell Cycle ◽  
Protein Degradation ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Current Knowledge ◽  
Ubiquitin Proteasome System ◽  
Yeast Cells ◽  
Ubiquitin Chain ◽  
Dividing Cells ◽  
Ubiquitin Proteasome

The ubiquitin-proteasome system is the major degradation pathway for short-lived proteins in eukaryotic cells. Targets of the ubiquitin-proteasome-system are proteins regulating a broad range of cellular processes including cell cycle progression, gene expression, the quality control of proteostasis and the response to geno- and proteotoxic stress. Prior to degradation, the proteasomal substrate is marked with a poly-ubiquitin chain. The key protease of the ubiquitin system is the proteasome. In dividing cells, proteasomes exist as holo-enzymes composed of regulatory and core particles. The regulatory complex confers ubiquitin-recognition and ATP dependence on proteasomal protein degradation. The catalytic sites are located in the proteasome core particle. Proteasome holo-enzymes are predominantly nuclear suggesting a major requirement for proteasomal proteolysis in the nucleus. In cell cycle arrested mammalian or quiescent yeast cells, proteasomes deplete from the nucleus and accumulate in granules at the nuclear envelope (NE) / endoplasmic reticulum ( ER) membranes. In prolonged quiescence, proteasome granules drop off the nuclear envelopeNE / ER membranes and migrate as droplet-like entitiesstable organelles  throughout the cytoplasm, as thoroughly investigated in yeast. When quiescence yeast cells are allowed to resume growth, proteasome granules clear and proteasomes are rapidly imported into the nucleus.Here, we summarize our knowledge about the enigmatic structure of proteasome storage granules and the trafficking of proteasomes and their substrates between the cyto- and nucleoplasm.Most of our current knowledge is based on studies in yeast. Their translation to mammalian cells promises to provide keen insight into protein degradation in non-dividing cells, which comprise the majority of our body’s cells.

scholarly journals BRD7 Promotes Cell Proliferation and Tumor Growth Through Stabilization of c-Myc in Colorectal Cancer

2021 ◽  
Vol 9 ◽  
Author(s):  
Ran Zhao ◽  
Yukun Liu ◽  
Chunchun Wu ◽  
Mengna Li ◽  
Yanmei Wei ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cell Cycle ◽  
Cell Proliferation ◽  
Tumor Growth ◽  
Cell Cycle Progression ◽  
Protein Targeting ◽  
Clinical Stage ◽  
Ubiquitin Proteasome

BRD7 functions as a crucial tumor suppressor in numerous malignancies. However, the effects of BRD7 on colorectal cancer (CRC) progression are still unknown. Here, based on the BRD7 knockout (BRD7–/–) and BRD7flox/flox (BRD7+/+) mouse models constructed in our previous work, we established an azoxymethane/dextran sodium sulfate (AOM/DSS)-induced mouse model. BRD7+/+ mice were found to be highly susceptible to AOM/DSS-induced colitis-associated CRC, and BRD7 significantly promoted cell proliferation and cell cycle G1/S transition but showed no significant effect on cell apoptosis. Furthermore, BRD7 interacted with c-Myc and stabilized c-Myc by inhibiting its ubiquitin–proteasome-dependent degradation. Moreover, restoring the expression of c-Myc in BRD7-silenced CRC cells restored cell proliferation, cell cycle progression, and tumor growth in vitro and in vivo. In addition, BRD7 and c-Myc were both significantly upregulated in CRC patients, and high expression of these proteins was associated with clinical stage and poor prognosis in CRC patients. Collectively, BRD7 functions as an oncogene and promotes CRC progression by regulating the ubiquitin–proteasome-dependent stabilization of c-Myc protein. Targeting the BRD7/c-Myc axis could be a potential therapeutic strategy for CRC.

scholarly journals The Control Operated by the Cell Cycle Machinery on MEF2 Stability Contributes to the Downregulation of CDKN1A and Entry into S Phase

2015 ◽  
Vol 35 (9) ◽  
pp. 1633-1647 ◽  
Author(s):  
Eros Di Giorgio ◽  
Enrico Gagliostro ◽  
Andrea Clocchiatti ◽  
Claudio Brancolini
Keyword(s):  
Cell Cycle ◽  
Ubiquitin Proteasome System ◽  
S Phase ◽  
Open Chromatin ◽  
Cyclin Dependent Kinase ◽  
Murine Fibroblasts ◽  
Subsequent Degradation ◽  
Ubiquitin Proteasome ◽  
F Box Protein ◽  
Cdkn1a Gene

MEF2s are pleiotropic transcription factors (TFs) which supervise multiple cellular activities. During the cell cycle, MEF2s are activated at the G0/G1transition to orchestrate the expression of the immediate early genes in response to growth factor stimulation. Here we show that, in human and murine fibroblasts, MEF2 activities are downregulated during late G1. MEF2C and MEF2D interact with the E3 ligase F-box protein SKP2, which mediates their subsequent degradation through the ubiquitin-proteasome system. The cyclin-dependent kinase 4 (CDK4)/cyclin D1 complex phosphorylates MEF2D on serine residues 98 and 110, and phosphorylation of these residues is an important determinant for SKP2 binding. Unscheduled MEF2 transcription during the cell cycle reduces cell proliferation, whereas its containment sustains DNA replication. The CDK inhibitor p21/CDKN1A gene is a MEF2 target gene required to exert this antiproliferative influence. MEF2C and MEF2D bind a region within the first intron ofCDKN1A, presenting epigenetic markers of open chromatin. Importantly, H3K27 acetylation within this regulative region depends on the presence of MEF2D. We propose that following the initial engagement in the G0/G1transition, MEF2C and MEF2D must be polyubiquitylated and degraded during G1progression to diminish the transcription of theCDKN1Agene, thus favoring entry into S phase.

scholarly journals Sirtuin 5 is Regulated by the SCF-Cyclin F Ubiquitin Ligase and is Involved in Cell Cycle Control

2020 ◽  
Author(s):  
Christine A. Mills ◽  
Xianxi Wang ◽  
Dhaval P. Bhatt ◽  
Paul A. Grimsrud ◽  
Jacob Peter Matson ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cell Cycle Control ◽  
Genetically Modify ◽  
Ubiquitin Proteasome System ◽  
Subsequent Increase ◽  
Cycle Progression ◽  
A Cell ◽  
F Box Protein ◽  
Cyclin F

The ubiquitin-proteasome system is essential for cell cycle progression. Cyclin F is a cell cycle regulated substrate adapter F-box protein for the SKP1/CUL1/F-box (SCF) family of E3 ubiquitin ligases. Despite its importance in cell cycle progression, identifying SCFCyclin F substrates has remained challenging. Since Cyclin F overexpression rescues a yeast mutant in the cdc4 gene, we considered the possibility that other genes that genetically modify cdc4 mutant lethality could also encode Cyclin F substrates. We identified the mitochondrial and cytosolic deacylating enzyme Sirtuin 5 (SIRT5) as a novel Cyclin F substrate. SIRT5 has been implicated in metabolic processes, but its connection to the cell cycle is not known. We show that Cyclin F interacts with, and controls the ubiquitination, abundance, and stability of SIRT5. We show SIRT5 knockout results in a diminished G1 population, and subsequent increase in both S and G2/M. Global proteomic analyses reveal CDK signaling changes congruent with the cell cycle changes in SIRT5 knockout cells. Together these data demonstrate that SIRT5 is regulated by Cyclin F and suggest a connection between SIRT5, cell cycle regulation, and metabolism.

scholarly journals Efficient APC/C substrate degradation in cells undergoing mitotic exit depends on K11 ubiquitin linkages

2015 ◽  
Author(s):  
Mingwei Min ◽  
Tycho Mevissen ◽  
Maria De Luca ◽  
David Komander ◽  
Catherine Lindon
Keyword(s):  
Cell Cycle Progression ◽  
Degradation Kinetics ◽  
Ubiquitin Proteasome System ◽  
Mitotic Exit ◽  
Post Translational Modification ◽  
Polyubiquitin Chains ◽  
Substrate Degradation ◽  
Ubiquitin Proteasome ◽  
In Cells

The ubiquitin proteasome system (UPS) directs programmed destruction of key cellular regulators via post-translational modification of its targets with polyubiquitin chains. These commonly contain Lysine 48 (K48)-directed ubiquitin linkages, but chains containing atypical Lysine 11 (K11) linkages also target substrates to the proteasome, for example to regulate cell cycle progression. A single ubiquitin ligase, the Anaphase Promoting Complex/Cyclosome (APC/C), controls mitotic exit. In higher eukaryotes, the APC/C works with the E2 enzyme UBE2S to assemble K11 linkages in cells released from mitotic arrest, and these are proposed to constitute an improved proteolytic signal during exit from mitosis. We have tested this idea by correlating quantitative measures of in vivo K11-specific ubiquitination of individual substrates, including Aurora kinases, with their degradation kinetics tracked at the single cell level. We report that all anaphase substrates tested by this methodology are stabilized by depletion of K11 linkages via UBE2S knockdown, even if the same substrates are significantly modified with K48-linked polyubiquitin. Specific examination of substrates depending on the APC/C coactivator Cdh1 for their degradation revealed Cdh1-dependent enrichment of K11 chains on these substrates, while other ubiquitin linkages on the same substrates added during mitotic exit were Cdh1-independent. Therefore we show that K11 linkages provide the APC/C with a means to regulate the rate of substrate degradation in a co-activator-specified manner.

scholarly journals Intracellular Dynamics of the Ubiquitin-Proteasome-System

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 367 ◽  
Author(s):  
Maisha Chowdhury ◽  
Cordula Enenkel
Keyword(s):  
Cell Cycle ◽  
Protein Degradation ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Current Knowledge ◽  
Ubiquitin Proteasome System ◽  
Yeast Cells ◽  
Ubiquitin Chain ◽  
Dividing Cells ◽  
Ubiquitin Proteasome

The ubiquitin-proteasome system is the major degradation pathway for short-lived proteins in eukaryotic cells. Targets of the ubiquitin-proteasome-system are proteins regulating a broad range of cellular processes including cell cycle progression, gene expression, the quality control of proteostasis and the response to geno- and proteotoxic stress. Prior to degradation, the proteasomal substrate is marked with a poly-ubiquitin chain. The key protease of the ubiquitin system is the proteasome. In dividing cells, proteasomes exist as holo-enzymes composed of regulatory and core particles. The regulatory complex confers ubiquitin-recognition and ATP dependence on proteasomal protein degradation. The catalytic sites are located in the proteasome core particle. Proteasome holo-enzymes are predominantly nuclear suggesting a major requirement for proteasomal proteolysis in the nucleus. In cell cycle arrested mammalian or quiescent yeast cells, proteasomes deplete from the nucleus and accumulate in granules at the nuclear envelope (NE) / endoplasmic reticulum (ER) membranes. In prolonged quiescence, proteasome granules drop off the NE / ER membranes and migrate as stable organelles throughout the cytoplasm, as thoroughly investigated in yeast. When quiescence yeast cells are allowed to resume growth, proteasome granules clear and proteasomes are rapidly imported into the nucleus.Here, we summarize our knowledge about the enigmatic structure of proteasome storage granules and the trafficking of proteasomes and their substrates between the cyto- and nucleoplasm.Most of our current knowledge is based on studies in yeast. Their translation to mammalian cells promises to provide keen insight into protein degradation in non-dividing cells which comprise the majority of our body’s cells.

scholarly journals WD40 domain of Apc1 is critical for the coactivator-induced allosteric transition that stimulates APC/C catalytic activity

2016 ◽  
Vol 113 (38) ◽  
pp. 10547-10552 ◽  
Author(s):  
Qiuhong Li ◽  
Leifu Chang ◽  
Shintaro Aibara ◽  
Jing Yang ◽  
Ziguo Zhang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Catalytic Activity ◽  
Cell Cycle Progression ◽  
Ubiquitin Proteasome System ◽  
Chain Elongation ◽  
Mutant Form ◽  
Anaphase Promoting Complex ◽  
Ubiquitin Chain ◽  
Cell Cycle Regulatory Proteins ◽  
Ubiquitin Proteasome

The anaphase-promoting complex/cyclosome (APC/C) is a large multimeric cullin–RING E3 ubiquitin ligase that orchestrates cell-cycle progression by targeting cell-cycle regulatory proteins for destruction via the ubiquitin proteasome system. The APC/C assembly comprises two scaffolding subcomplexes: the platform and the TPR lobe that together coordinate the juxtaposition of the catalytic and substrate-recognition modules. The platform comprises APC/C subunits Apc1, Apc4, Apc5, and Apc15. Although the role of Apc1 as an APC/C scaffolding subunit has been characterized, its specific functions in contributing toward APC/C catalytic activity are not fully understood. Here, we report the crystal structure of the N-terminal domain of human Apc1 (Apc1N) determined at 2.2-Å resolution and provide an atomic-resolution description of the architecture of its WD40 (WD40 repeat) domain (Apc1WD40). To understand how Apc1WD40 contributes to APC/C activity, a mutant form of the APC/C with Apc1WD40 deleted was generated and evaluated biochemically and structurally. We found that the deletion of Apc1WD40 abolished the UbcH10-dependent ubiquitination of APC/C substrates without impairing the Ube2S-dependent ubiquitin chain elongation activity. A cryo-EM structure of an APC/C–Cdh1 complex with Apc1WD40 deleted showed that the mutant APC/C is locked into an inactive conformation in which the UbcH10-binding site of the catalytic module is inaccessible. Additionally, an EM density for Apc15 is not visible. Our data show that Apc1WD40 is required to mediate the coactivator-induced conformational change of the APC/C that is responsible for stimulating APC/C catalytic activity by promoting UbcH10 binding. In contrast, Ube2S activity toward APC/C substrates is not dependent on the initiation-competent conformation of the APC/C.

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