scholarly journals Cdc34 C-terminal tail phosphorylation regulates Skp1/cullin/F-box (SCF)-mediated ubiquitination and cell cycle progression

2007 ◽  
Vol 405 (3) ◽  
pp. 569-581 ◽  
Author(s):  
Martin Sadowski ◽  
Amanda Mawson ◽  
Rohan Baker ◽  
Boris Sarcevic
Keyword(s):  
Cell Cycle ◽  
Catalytic Activity ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Phosphorylation Sites ◽  
Tail Domain ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cycle Progression

The ubiquitin-conjugating enzyme Cdc34 (cell division cycle 34) plays an essential role in promoting the G1–S-phase transition of the eukaryotic cell cycle and is phosphorylated in vivo. In the present study, we investigated if phosphorylation regulates Cdc34 function. We mapped the in vivo phosphorylation sites on budding yeast Cdc34 (yCdc34; Ser207 and Ser216) and human Cdc34 (hCdc34 Ser203, Ser222 and Ser231) to serine residues in the acidic tail domain, a region that is critical for Cdc34's cell cycle function. CK2 (protein kinase CK2) phosphorylates both yCdc34 and hCdc34 on these sites in vitro. CK2-mediated phosphorylation increased yCdc34 ubiquitination activity towards the yeast Saccharomyces cerevisiae Sic1 in vitro, when assayed in the presence of its cognate SCFCdc4 E3 ligase [where SCF is Skp1 (S-phase kinase-associated protein 1)/cullin/F-box]. Similarly, mutation of the yCdc34 phosphorylation sites to alanine, aspartate or glutamate residues altered Cdc34–SCFCdc4-mediated Sic1 ubiquitination activity. Similar results were obtained when yCdc34's ubiquitination activity was assayed in the absence of SCFCdc4, indicating that phosphorylation regulates the intrinsic catalytic activity of Cdc34. To evaluate the in vivo consequences of altered Cdc34 activity, wild-type yCdc34 and the phosphosite mutants were introduced into an S. cerevisiae cdc34 deletion strain and, following synchronization in G1-phase, progression through the cell cycle was monitored. Consistent with the increased ubiquitination activity in vitro, cells expressing the phosphosite mutants with higher catalytic activity exhibited accelerated cell cycle progression and Sic1 degradation. These studies demonstrate that CK2-mediated phosphorylation of Cdc34 on the acidic tail domain stimulates Cdc34–SCFCdc4 ubiquitination activity and cell cycle progression.

scholarly journals Regulation of Focal Adhesion Kinase by a Novel Protein Inhibitor FIP200

2002 ◽  
Vol 13 (9) ◽  
pp. 3178-3191 ◽  
Author(s):  
Smita Abbi ◽  
Hiroki Ueda ◽  
Chuanhai Zheng ◽  
Lee Ann Cooper ◽  
Jihe Zhao ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Cell Cycle Progression ◽  
Protein Inhibitor ◽  
Cellular Functions ◽  
Cycle Progression ◽  
Novel Protein

Focal adhesion kinase (FAK) is a major mediator of integrin signaling pathways. The mechanisms of regulation of FAK activity and its associated cellular functions are not very well understood. Here, we present data suggesting that a novel protein FIP200 functions as an inhibitor for FAK. We show the association of endogenous FIP200 with FAK, which is decreased upon integrin-mediated cell adhesion concomitant with FAK activation. In vitro- and in vivo-binding studies indicate that FIP200 interacts with FAK through multiple domains directly. FIP200 bound to the kinase domain of FAK inhibited its kinase activity in vitro and its autophosphorylation in vivo. Overexpression of FIP200 or its segments inhibited cell spreading, cell migration, and cell cycle progression, which correlated with their inhibition of FAK activity in vivo. The inhibition of these cellular functions by FIP200 could be rescued by coexpression of FAK. Last, we show that disruption of the functional interaction between endogenous FIP200 with FAK leads to increased FAK phosphorylation and partial restoration of cell cycle progression in cells plated on poly-l-lysine, providing further support for FIP200 as a negative regulator of FAK. Together, these results identify FIP200 as a novel protein inhibitor for FAK.

scholarly journals Anticancer Activity of Cynomorium coccineum

Cancers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 354 ◽  
Author(s):  
Mouna Sdiri ◽  
Xiangmin Li ◽  
William Du ◽  
Safia El-Bok ◽  
Yi-Zhen Xie ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Anticancer Activity ◽  
Cancer Cells ◽  
Cell Lines ◽  
Cancer Cell ◽  
Cell Cycle Progression ◽  
Cycle Progression

The extensive applications of Cynomorium species and their rich bioactive secondary metabolites have inspired many pharmacological investigations. Previous research has been conducted to examine the biological activities and numerous interesting pharmaceutical activities have been reported. However, the antitumor activities of these species are unclear. To understand the potential anticancer activity, we screened Cynomorium coccineum and Cynomorium songaricum using three different extracts of each species. In this study, the selected extracts were evaluated for their ability to decrease survival rates of five different cancer cell lines. We compared the cytotoxicity of the three different extracts to the anticancer drug vinblastine and one of the most well-known medicinal mushrooms Amaurederma rude. We found that the water and alcohol extracts of C. coccineum at the very low concentrations possessed very high capacity in decreasing the cancer cells viability with a potential inhibition of tumorigenesis. Based on these primitive data, we subsequently tested the ethanol and the water extracts of C. coccineum, respectively in in vitro and in vivo assays. Cell cycle progression and induction of programmed cell death were investigated at both biological and molecular levels to understand the mechanism of the antitumor inhibitory action of the C. coccineum. The in vitro experiments showed that the treated cancer cells formed fewer and smaller colonies than the untreated cells. Cell cycle progression was inhibited, and the ethanol extract of C. coccineum at a low concentration induced accumulation of cells in the G1 phase. We also found that the C. coccineum’s extracts suppressed viability of two murine cancer cell lines. In the in vivo experiments, we injected mice with murine cancer cell line B16, followed by peritoneal injection of the water extract. The treatment prolonged mouse survival significantly. The tumors grew at a slower rate than the control. Down-regulation of c-myc expression appeared to be associated with these effects. Further investigation showed that treatment with C. coccineum induced the overexpression of the tumor suppressor Foxo3 and other molecules involved in inducing autophagy. These results showed that the C. coccineum extract exerts its antiproliferative activity through the induction of cell death pathway. Thus, the Cynomorium plants appear to be a promising source of new antineoplastic compounds.

scholarly journals (S)-10-Hydroxycamptothecin Inhibits Esophageal Squamous Cell Carcinoma Growth In Vitro and In Vivo Via Decreasing Topoisomerase I Enzyme Activity

Cancers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1964 ◽  
Author(s):  
Mengqiu Song ◽  
Shuying Yin ◽  
Ran Zhao ◽  
Kangdong Liu ◽  
Joydeb Kumar Kundu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Enzymatic Activity ◽  
Topoisomerase I ◽  
Cell Cycle Progression ◽  
Caspase 3 ◽  
Cyclin B1 ◽  
Phase Cell ◽  
Cycle Progression

Topoisomerase (TOP) I plays a major role in the process of supercoiled DNA relaxation, thereby facilitating DNA replication and cell cycle progression. The expression and enzymatic activity of TOP I is positively correlated with tumor progression. Although the anticancer activity of (S)-10-Hydroxycamptothecin (HCPT), a TOP I specific inhibitor, has been reported in various cancers, the effect of HCPT on esophageal cancer is yet to be examined. In this study, we investigate the potential of HCPT to inhibit the growth of ESCC cells in vitro and verify its anti-tumor activity in vivo by using a patient-derived xenograft (PDX) tumor model in mice. Our study revealed the overexpression of TOP I in ESCC cells and treatment with HCPT inhibited TOP I enzymatic activity at 24 h and decreased expression at 48 h and 72 h. HCPT also induced DNA damage by increasing the expression of H2A.XS139. HCPT significantly decreased the proliferation and anchorage-independent growth of ESCC cells (KYSE410, KYSE510, KYSE30, and KYSE450). Mechanistically, HCPT inhibited the G2/M phase cell cycle transition, decreased the expression of cyclin B1, and elevated p21 expression. In addition, HCPT stimulated ESCC cells apoptosis, which was associated with elevated expression of cleaved PARP, cleaved caspase-3, cleaved caspase-7, Bax, Bim, and inhibition of Bcl-2 expression. HCPT dramatically suppressed PDX tumor growth and decreased the expression of Ki-67 and TOP I and increased the level of cleaved caspase-3 and H2A.XS139 expression. Taken together, our data suggested that HCPT inhibited ESCC growth, arrested cell cycle progression, and induced apoptosis both in vitro and in vivo via decreasing the expression and activity of TOP I enzyme.

scholarly journals Identification of DHX9 as a cell cycle regulated nucleolar recruitment factor for CIZ1

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Urvi Thacker ◽  
Tekle Pauzaite ◽  
James Tollitt ◽  
Maria Twardowska ◽  
Charlotte Harrison ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Zinc Finger Protein ◽  
S Phase ◽  
Cycle Progression ◽  
Inactive X Chromosome ◽  
Functional Characterisation ◽  
Interaction Partners

Abstract CIP1-interacting zinc finger protein 1 (CIZ1) is a nuclear matrix associated protein that facilitates a number of nuclear functions including initiation of DNA replication, epigenetic maintenance and associates with the inactive X-chromosome. Here, to gain more insight into the protein networks that underpin this diverse functionality, molecular panning and mass spectrometry are used to identify protein interaction partners of CIZ1, and CIZ1 replication domain (CIZ1-RD). STRING analysis of CIZ1 interaction partners identified 2 functional clusters: ribosomal subunits and nucleolar proteins including the DEAD box helicases, DHX9, DDX5 and DDX17. DHX9 shares common functions with CIZ1, including interaction with XIST long-non-coding RNA, epigenetic maintenance and regulation of DNA replication. Functional characterisation of the CIZ1-DHX9 complex showed that CIZ1-DHX9 interact in vitro and dynamically colocalise within the nucleolus from early to mid S-phase. CIZ1-DHX9 nucleolar colocalisation is dependent upon RNA polymerase I activity and is abolished by depletion of DHX9. In addition, depletion of DHX9 reduced cell cycle progression from G1 to S-phase in mouse fibroblasts. The data suggest that DHX9-CIZ1 are required for efficient cell cycle progression at the G1/S transition and that nucleolar recruitment is integral to their mechanism of action.

The Cold-Shock Domain Protein YB-1 Is Important for Cellular Proliferation and the Prevention of Premature Senescence.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2571-2571
Author(s):  
Zhi Hong Lu ◽  
Jason T. Books ◽  
Timothy James Ley
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Cycle Progression ◽  
Binding Proteins ◽  
Cellular Proliferation ◽  
Cold Shock ◽  
Premature Senescence ◽  
Cycle Progression

Abstract Mammalian proteins containing “cold-shock” domains belong to the most evolutionarily conserved family of nucleic acid-binding proteins known in bacteria, plants, and animals. One of these proteins, YB-1, has been implicated in basic cellular functions such as cell proliferation and responses to environmental stresses. In mammalian cells, YB-1 has been shown to shuttle between the nuclear and cytoplasmic compartments. Within the nucleus, YB-1 interacts with several DNA-and pre-mRNA-binding proteins, and has been implicated in nuclear activities, including transcriptional regulation, chromatin remodeling, and pre-mRNA splicing. YB-1 is also abundant in the cytoplasm, where it binds nonspecifically to mRNA, and may act as a general regulator of mRNA stability, cytoplasmic localization, and translation. Thus, YB-1 has been proposed to function as a multifunctional regulator for the control of gene expression in both the nucleus and cytoplasm. YB-1 overexpression has been frequently detected in a variety of human cancers, often associated with unfavorable clinical outcomes. However, it remains unclear whether YB-1 overexpression contributes directly to the malignant phenotype, or whether it is simply a non-causal “marker” associated with rapid cell growth (and poor prognostic outcomes). To further assess the role of this protein in health and disease, we created mice deficient for YB-1. Complete loss of function of this gene results in fully-penetrant late embryonic and perinatal lethality. Morphological and histological analyses revealed that YB-1−/− embryos displayed major developmental and functional defects, including neurological abnormalities, hemorrhage, and respiratory failure, which probably contributed to lethality. Growth retardation occurred in all late-stage embryos, and was the result of hypoplasia in multiple organ systems. Consistent with these in vivo results, fibroblasts isolated from YB-1−/− embryos (MEFs) grew slowly and entered senescence prematurely in vitro; these defects were rescued by ectopic expression of a GFP-tagged human YB-1 cDNA. This data suggests that YB-1 plays an important cell-autonomous role in cell proliferation and prevention of premature senescence. We further showed that loss of YB-1 in early passage MEFs resulted a delay in G0/G1 to S-phase progression, and a defect in a transcriptional mechanism that normally represses the expression of the G1-specific CDK inhibitor gene p16Ink4a, and the p53 target genes p21Cip1 and Mdm2. However, YB-1 does not cause “global” changes in the transcriptome, the proteome, or protein synthesis efficiency. As predicted, p16Ink4a and p21Cip1 double knockdown by siRNA treatment led to an increase in the rate of cell proliferation, and an extension of proliferative capacity during late passages in YB-1−/− cells. Furthermore, YB-1 deficiency reduced the ability of MEFs to proliferate normally in response to c-Myc overexpression. In conclusion, our data has revealed that YB-1 is required for normal mouse development and survival, and that it plays an important role in supporting rapid cellular proliferation both in vivo and in vitro. Our data further suggests that YB-1 is a cell cycle progression regulator that is important for preventing the early onset of senescence in cultured MEF cells. This data raises the possibility that disregulated expression of YB-1 may contribute to malignant phenotypes by supporting rapid cell cycle progression, and by protecting cells from cytotoxic stresses.

PI3K/Akt/FOXO3a Pathway Contributes to Thrombopoietin-Induced Proliferation of Primary Megakaryocytes In Vitro and In Vivo Via Modulation of p27Kip1.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 202-202
Author(s):  
Takafumi Nakao ◽  
Amy E Geddis ◽  
Norma E. Fox ◽  
Kenneth Kaushansky
Keyword(s):  
Cell Cycle ◽  
Cell Line ◽  
Cell Cycle Progression ◽  
Wild Type ◽  
Cycle Progression ◽  
P27kip1 Expression ◽  
Cell Counts ◽  
Deficient Mice

Abstract Thrombopoietin (TPO), the primary regulator of megakaryocyte (MK) and platelet formation, modulates the activity of multiple signal transduction molecules, including those in the Jak/STAT, p42/p44 MAPK, and phosphatidylinositol 3-kinase (PI3K)/Akt pathways. In the previous study, we reported that PI3K and Akt are necessary for TPO-induced cell cycle progression of primary MK progenitors. The absence of PI3K activity results in a block of transition from G1 to S phase in these cells (Geddis AE et al. JBC2001276:34473–34479). However, the molecular events secondary to the activation of PI3K/Akt responsible for MK proliferation remain unclear. In this study we show that FOXO3a and its downstream target p27Kip1 play an important role in TPO-induced proliferation of MK progenitors. TPO induces phosphorylation of Akt and FOXO3a in both UT-7/TPO, a megakaryocytic cell line, and primary murine MKs in a PI3K dependent fashion. Cell cycle progression of UT-7/TPO cells is blocked in G1 phase by inhibition of PI3K. We found that TPO down-modulates p27Kip1 expression at both the mRNA and protein levels in UT-7/TPO cells and primary MKs in a PI3K dependent fashion. UT-7/TPO stably expressing constitutively active Akt or a dominant-negative form of FOXO3a failed to induce p27Kip1 expression after TPO withdrawal. Induced expression of an active form of FOXO3a resulted in increased p27Kip1 expression in this cell line. In an attempt to assess whether FOXO3a has an effect of MK proliferation in vivo, we compared the number of MKs in Foxo3a-deficient mice and in wild type controls. Although peripheral blood cell counts of erythrocytes, neutrophils, monocytes and platelets were normal in the Foxo3a-deficient mice, total nucleated marrow cell count of Foxo3a-deficient mice were 60% increased compared with wild type controls. In addition, the increase of MKs was more profound than that of total nucleated marrow cells; CD41+ MKs from Foxo3a-deficient mice increased 2.1-fold, and mature MKs with 8N and greater ploidy increased 2.5-fold, compared with wild type controls. Taken together with the previous observation that p27Kip1-deficient mice also display increased numbers of MK progenitors, our findings strongly suggest that the effect of TPO on MK proliferation is mediated by PI3K/Akt-induced FOXO3a inactivation and subsequent p27Kip1 down-regulation in vitro and in vivo.

scholarly journals Cdc53p acts in concert with Cdc4p and Cdc34p to control the G1-to-S-phase transition and identifies a conserved family of proteins.

1996 ◽  
Vol 16 (12) ◽  
pp. 6634-6643 ◽  
Author(s):  
N Mathias ◽  
S L Johnson ◽  
M Winey ◽  
A E Adams ◽  
L Goetsch ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Large Family ◽  
S Phase ◽  
Genetic Interactions ◽  
Cycle Progression ◽  
Cyclin Dependent Kinases ◽  
Ubiquitin Conjugating Enzyme ◽  
Regulation Of Cell Cycle

Regulation of cell cycle progression occurs in part through the targeted degradation of both activating and inhibitory subunits of the cyclin-dependent kinases. During G1, CDC4, encoding a WD-40 repeat protein, and CDC34, encoding a ubiquitin-conjugating enzyme, are involved in the destruction of these regulators. Here we describe evidence indicating that CDC53 also is involved in this process. Mutations in CDC53 cause a phenotype indistinguishable from those of cdc4 and cdc34 mutations, numerous genetic interactions are seen between these genes, and the encoded proteins are found physically associated in vivo. Cdc53p defines a large family of proteins found in yeasts, nematodes, and humans whose molecular functions are uncharacterized. These results suggest a role for this family of proteins in regulating cell cycle proliferation through protein degradation.

scholarly journals Multifaceted Regulation of Cell Cycle Progression by Estrogen: Regulation of Cdk Inhibitors and Cdc25A Independent of Cyclin D1-Cdk4 Function

2001 ◽  
Vol 21 (3) ◽  
pp. 794-810 ◽  
Author(s):  
James S. Foster ◽  
Donald C. Henley ◽  
Antonin Bukovsky ◽  
Prem Seth ◽  
Jay Wimalasena
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Inhibitory Activity ◽  
Cell Cycle Progression ◽  
Estrogen Action ◽  
Cycle Progression ◽  
Cdk2 Activity ◽  
Mcf 7

ABSTRACT Estrogens induce proliferation of estrogen receptor (ER)-positive MCF-7 breast cancer cells by stimulating G1/S transition associated with increased cyclin D1 expression, activation of cyclin-dependent kinases (Cdks), and phosphorylation of the retinoblastoma protein (pRb). We have utilized blockade of cyclin D1-Cdk4 complex formation through adenovirus-mediated expression of p16INK4a to demonstrate that estrogen regulates Cdk inhibitor expression and expression of the Cdk-activating phosphatase Cdc25A independent of cyclin D1-Cdk4 function and cell cycle progression. Expression of p16INK4a inhibited G1/S transition induced in MCF-7 cells by 17-β-estradiol (E2) with associated inhibition of both Cdk4- and Cdk2-associated kinase activities. Inhibition of Cdk2 activity was associated with delayed removal of Cdk-inhibitory activity in early G1 and decreased cyclin A expression. Cdk-inhibitory activity and expression of both p21Cip1 and p27Kip1 was decreased, however, in both control and p16INK4a-expressing cells 20 h after estrogen treatment. Expression of Cdc25A mRNA and protein was induced by E2 in control and p16INK4a-expressing MCF-7 cells; however, functional activity of Cdc25A was inhibited in cells expressing p16INK4a. Inhibition of Cdc25A activity in p16INK4a-expressing cells was associated with depressed Cdk2 activity and was reversed in vivo and in vitro by active Cdk2. Transfection of MCF-7 cells with a dominant-negative Cdk2 construct inhibited the E2-dependent activation of ectopic Cdc25A. Supporting a role for Cdc25A in estrogen action, antisenseCDC25A oligonucleotides inhibited estrogen-induced Cdk2 activation and DNA synthesis. In addition, inactive cyclin E-Cdk2 complexes from p16INK4a-expressing, estrogen-treated cells were activated in vitro by treatment with recombinant Cdc25A and in vivo in cells overexpressing Cdc25A. The results demonstrate that functional association of cyclin D1-Cdk4 complexes is required for Cdk2 activation in MCF-7 cells and that Cdk2 activity is, in turn, required for the in vivo activation of Cdc25A. These studies establish Cdc25A as a growth-promoting target of estrogen action and further indicate that estrogens independently regulate multiple components of the cell cycle machinery, including expression of p21Cip1 and p27Kip1.

scholarly journals A Mammalian Bromodomain Protein, Brd4, Interacts with Replication Factor C and Inhibits Progression to S Phase

2002 ◽  
Vol 22 (18) ◽  
pp. 6509-6520 ◽  
Author(s):  
Tetsuo Maruyama ◽  
Andrea Farina ◽  
Anup Dey ◽  
JaeHun Cheong ◽  
Vladimir P. Bermudez ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Cell Cycle Progression ◽  
S Phase ◽  
Replication Factor C ◽  
Cycle Progression ◽  
Vitro Analysis ◽  
Factor C ◽  
In Vitro Analysis

ABSTRACT Brd4 belongs to the BET family of nuclear proteins that carry two bromodomains implicated in the interaction with chromatin. Expression of Brd4 correlates with cell growth and is induced during early G1 upon mitogenic stimuli. In the present study, we investigated the role of Brd4 in cell growth regulation. We found that ectopic expression of Brd4 in NIH 3T3 and HeLa cells inhibits cell cycle progression from G1 to S. Coimmunoprecipitation experiments showed that endogenous and transfected Brd4 interacts with replication factor C (RFC), the conserved five-subunit complex essential for DNA replication. In vitro analysis showed that Brd4 binds directly to the largest subunit, RFC-140, thereby interacting with the entire RFC. In line with the inhibitory activity seen in vivo, recombinant Brd4 inhibited RFC-dependent DNA elongation reactions in vitro. Analysis of Brd4 deletion mutants indicated that both the interaction with RFC-140 and the inhibition of entry into S phase are dependent on the second bromodomain of Brd4. Lastly, supporting the functional importance of this interaction, it was found that cotransfection with RFC-140 reduced the growth-inhibitory effect of Brd4. Taken as a whole, the present study suggests that Brd4 regulates cell cycle progression in part by interacting with RFC.

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