scholarly journals Heat shock protein 27 promotes cell cycle progression by down-regulating E2F transcription factor 4 and retinoblastoma family protein p130

2018 ◽  
Vol 293 (41) ◽  
pp. 15815-15826 ◽  
Author(s):  
Ah-Mee Park ◽  
Ikuo Tsunoda ◽  
Osamu Yoshie
Keyword(s):  
Cell Cycle ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Cellular Senescence ◽  
Cell Cycle Progression ◽  
Heat Shock Protein 27 ◽  
Serum Starvation ◽  
Cell Cycle Gene ◽  
Cycle Progression ◽  
Human Lung Fibroblast

Heat shock protein 27 (HSP27) protects cells under stress. Here, we demonstrate that HSP27 also promotes cell cycle progression of MRC-5 human lung fibroblast cells. Serum starvation for 24 h induced G1 arrest in these cells, and upon serum refeeding, the cells initiated cell cycle progression accompanied by an increase in HSP27 protein levels. HSP27 levels peaked at 12 h, and transcriptional up-regulation of six G2/M-related genes (CCNA2, CCNB1, CCNB2, CDC25C, CDCA3, and CDK1) peaked at 24–48 h. siRNA-mediated HSP27 silencing in proliferating MRC-5 cells induced G2 arrest coinciding with down-regulation of these six genes. Of note, the promoters of all of these genes have the cell cycle–dependent element and/or the cell cycle gene-homology region. These promoter regions are known to be bound by the E2F family proteins (E2F-1 to E2F-8) and retinoblastoma (RB) family proteins (RB1, p107, and p130), among which E2F-4 and p130 were strongly up-regulated in HSP27-knockdown cells. E2F-4 or p130 knockdown concomitant with the HSP27 knockdown rescued MRC-5 cells from G2 arrest and up-regulated the six cell cycle genes. Moreover, we observed cellular senescence in MRC-5 cells on day 3 after the HSP27 knockdown, as evidenced by increased senescence-associated β-gal activity and up-regulated inflammatory cytokines. The cellular senescence was also suppressed by the concomitant knockdown of E2F-4/HSP27 or p130/HSP27. Our findings indicate that HSP27 promotes cell cycle progression of MRC-5 cells by suppressing expression of the transcriptional repressors E2F-4 and p130.

scholarly journals Babam2 Regulates Cell Cycle Progression and Pluripotency in Mouse Embryonic Stem Cells as Revealed by Induced DNA Damage

Biomedicines ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 397
Author(s):  
Cheuk Yiu Tenny Chung ◽  
Paulisally Hau Yi Lo ◽  
Kenneth Ka Ho Lee
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Dna Damage ◽  
Gamma Irradiation ◽  
Cellular Senescence ◽  
Cell Cycle Regulation ◽  
Cell Cycle Progression ◽  
Embryonic Stem ◽  
Cycle Progression ◽  
Cycle Regulation

BRISC and BRCA1-A complex member 2 (Babam2) plays an essential role in promoting cell cycle progression and preventing cellular senescence. Babam2-deficient fibroblasts show proliferation defect and premature senescence compared with their wild-type (WT) counterpart. Pluripotent mouse embryonic stem cells (mESCs) are known to have unlimited cell proliferation and self-renewal capability without entering cellular senescence. Therefore, studying the role of Babam2 in ESCs would enable us to understand the mechanism of Babam2 in cellular aging, cell cycle regulation, and pluripotency in ESCs. For this study, we generated Babam2 knockout (Babam2−/−) mESCs to investigate the function of Babam2 in mESCs. We demonstrated that the loss of Babam2 in mESCs leads to abnormal G1 phase retention in response to DNA damage induced by gamma irradiation or doxorubicin treatments. Key cell cycle regulators, CDC25A and CDK2, were found to be degraded in Babam2−/− mESCs following gamma irradiation. In addition, Babam2−/− mESCs expressed p53 strongly and significantly longer than in control mESCs, where p53 inhibited Nanog expression and G1/S cell cycle progression. The combined effects significantly reduced developmental pluripotency in Babam2−/− mESCs. In summary, Babam2 maintains cell cycle regulation and pluripotency in mESCs in response to induced DNA damage.

Comparative genomics identifies genes mediating cardiotoxicity in the embryonic zebrafish heart

2008 ◽  
Vol 33 (2) ◽  
pp. 148-158 ◽  
Author(s):  
Jing Chen ◽  
Sara A. Carney ◽  
Richard E. Peterson ◽  
Warren Heideman
Keyword(s):  
Heart Failure ◽  
Cell Cycle ◽  
Heart Development ◽  
Cell Cycle Progression ◽  
Transcriptional Response ◽  
Cell Cycle Gene ◽  
Zebrafish Embryos ◽  
Transcriptional Responses ◽  
Cycle Progression ◽  
Necessary And Sufficient

Retinoic acid (RA) and 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) activate distinct ligand-dependent transcription factors, and both cause cardiac malformation and heart failure in zebrafish embryos. We hypothesized that they cause this response by hyperactivating a common set of genes critical for heart development. To test this, we used microarrays to measure transcript changes in hearts isolated from zebrafish embryos 1, 2, 4, and 12 h after exposure to 1 μM RA. We used hierarchical clustering to compare the transcriptional responses produced in the embryonic heart by RA and TCDD. We could identify no early responses in common between the two agents. However, at 12 h both treatments produced a dramatic downregulation of a common cluster of cell cycle progression genes, which we term the cell cycle gene cluster. This was associated with a halt in heart growth. These results suggest that RA and TCDD ultimately trigger a common transcriptional response associated with heart failure, but not through the direct activation of a common set of genes. Among the genes rapidly induced by RA was Nr2F5, a member of the COUP-TF family of transcriptional repressors. We found that induction of Nr2F5 was both necessary and sufficient for the cardiotoxic response to RA.

Truncation in CCND1 mRNA 3′ UTR Is Associated with An Aggressive Phenotype and Chemoresistance

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5287-5287
Author(s):  
Robert W Chen ◽  
Myo Htut ◽  
Britta Hoehn ◽  
Eamon Berge ◽  
William Robinson ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Protein Expression ◽  
Cyclin D1 ◽  
Cell Lines ◽  
Cell Cycle Progression ◽  
Serum Starvation ◽  
Cycle Progression ◽  
Serum Free ◽  
Aggressive Phenotype ◽  
Free Media

Abstract Mantle Cell Lymphoma (MCL) represents 5–10% of all non-Hodgkins lymphomas, making it an uncommon but difficult form of lymphoma to treat. It has the worst prognosis among the B cell lymphomas with median survival of three years. The genetic hallmark of MCL is the t(11,14)(q13;32) translocation causing amplification of cyclin D1 (CCND1). It is a well known cell cycle regulator. Multiple reports have shown a truncation in the cyclin D1 mRNA 3′ untranslated region. This truncation increases CCND1 protein expression by not only enhancing the half-life of CCND1 mRNA, but also evades microRNA regulation of mRNA translation. The dramatic overexpression of CCND1 mRNA and protein has been associated to poor clinical outcome in patients. We hypothesize that this truncation leads to a more aggressive phenotype and induces chemoresistance in MCL. We have identified 4 MCL cell lines (Granta-519, JVM-2, Jeko-1, and Z138) with different levels of the truncated CCND1 mRNA. We were able to show that Z138 and Jeko-1 have a much higher ratio of truncated CCND1 mRNA to the full length CCND1 mRNA as compared to Granta-519 and JVM-2. We were also able to show that this truncated mRNA leads to an increase in CCND1 protein expression. By using flow cytometry, we correlated the increase in CCND1 protein expression to faster cell cycle progression. We proposed that cell lines with increased CCND1 expression are phenotypically more aggressive, and would be able to continue cell cycle progression without serum support. We were able to arrest JVM-2 in G1 phase after 48 hours of serum starvation. However, we were not able to arrest cell cycle progression in Jeko-1 even after 96 hours of serum starvation. Western blot analysis shows that CCND1 protein expression is decreased in JVM-2 but remains unchanged in Jeko-1 with serum starvation. The same phenomenon was observed in Granta-519 and Z138. The MCL cell lines (Jeko-1 and Z-138) with more CCND1 protein expression were able to continue cell cycle progression in serum free media. The MCL cell lines (JVM-2 and Granta-519) with less CCND1 protein expression were not able to continue cell cycle progression in serum free media. This shows that CCND1 overexpression is associated with a more aggressive phenotype. We then treated the 4 MCL cell lines with varying concentrations of doxorubicin, a standard anthracycline chemotherapy used in the treatment of MCL patients. We used MTS assay to assess cell proliferation after treatment with doxorubicin. We found the IC 50 (inhibitory concentration 50%) of doxorubicin in these cell lines varied from 6nM to 600nM. The cell lines (Jeko-1 and Z-138) with more CCND1 protein expression have a much higher IC 50 as compared to the cell lines (JVM-2 and Granta-519) with less CCND1 protein expression. This demonstrates that CCND1 overexpression is associated with chemoresistance. We conclude truncation in CCND1 mRNA leads to increased CCND1 protein expression and faster cell cycle progression CCND1 overexpression is associated with an aggressive phenotype CCND1 overexpression is associated with chemoresistance.

scholarly journals Lamina-associated polypeptide 2α regulates cell cycle progression and differentiation via the retinoblastoma–E2F pathway

2006 ◽  
Vol 173 (1) ◽  
pp. 83-93 ◽  
Author(s):  
Daniela Dorner ◽  
Sylvia Vlcek ◽  
Nicole Foeger ◽  
Andreas Gajewski ◽  
Christian Makolm ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Target Genes ◽  
Serum Starvation ◽  
Dependent Manner ◽  
Cycle Progression ◽  
Promoter Sequences ◽  
Delayed Entry ◽  
Accelerated Proliferation

Lamina-associated polypeptide (LAP) 2α is a nonmembrane-bound LAP2 isoform that forms complexes with nucleoplasmic A-type lamins. In this study, we show that the overexpression of LAP2α in fibroblasts reduced proliferation and delayed entry into the cell cycle from a G0 arrest. In contrast, stable down-regulation of LAP2α by RNA interference accelerated proliferation and interfered with cell cycle exit upon serum starvation. The LAP2α-linked cell cycle phenotype is mediated by the retinoblastoma (Rb) protein because the LAP2α COOH terminus directly bound Rb, and overexpressed LAP2α inhibited E2F/Rb-dependent reporter gene activity in G1 phase in an Rb-dependent manner. Furthermore, LAP2α associated with promoter sequences in endogenous E2F/Rb-dependent target genes in vivo and negatively affected their expression. In addition, the expression of LAP2α in proliferating preadipocytes caused the accumulation of hypophosphorylated Rb, which is reminiscent of noncycling cells, and initiated partial differentiation into adipocytes. The effects of LAP2α on cell cycle progression and differentiation may be highly relevant for the cell- and tissue-specific phenotypes observed in laminopathic diseases.

scholarly journals Increased Expression of Cyclin D2 during Multiple States of Growth Arrest in Primary and Established Cells

1998 ◽  
Vol 18 (6) ◽  
pp. 3163-3172 ◽  
Author(s):  
Muthupalaniappan Meyyappan ◽  
Howard Wong ◽  
Christopher Hull ◽  
Karl T. Riabowol
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Growth Arrest ◽  
Growth Conditions ◽  
Cellular Growth ◽  
Serum Starvation ◽  
Cyclin D2 ◽  
Cycle Progression ◽  
Quiescent Cells ◽  
D2 Protein

ABSTRACT Cyclin D2 is a member of the family of D-type cyclins that is implicated in cell cycle regulation, differentiation, and oncogenic transformation. To better understand the role of this cyclin in the control of cell proliferation, cyclin D2 expression was monitored under various growth conditions in primary human and established murine fibroblasts. In different states of cellular growth arrest initiated by contact inhibition, serum starvation, or cellular senescence, marked increases (5- to 20-fold) were seen in the expression levels of cyclin D2 mRNA and protein. Indirect immunofluorescence studies showed that cyclin D2 protein localized to the nucleus in G0, suggesting a nuclear function for cyclin D2 in quiescent cells. Cyclin D2 was also found to be associated with the cyclin-dependent kinases CDK2 and CDK4 but not CDK6 during growth arrest. Cyclin D2-CDK2 complexes increased in amounts but were inactive as histone H1 kinases in quiescent cells. Transient transfection and needle microinjection of cyclin D2 expression constructs demonstrated that overexpression of cyclin D2 protein efficiently inhibited cell cycle progression and DNA synthesis. These data suggest that in addition to a role in promoting cell cycle progression through phosphorylation of retinoblastoma family proteins in some cell systems, cyclin D2 may contribute to the induction and/or maintenance of a nonproliferative state, possibly through sequestration of the CDK2 catalytic subunit.

scholarly journals RB, p130 and p107 differentially repress G1/S and G2/M genes after p53 activation

2019 ◽  
Vol 47 (21) ◽  
pp. 11197-11208 ◽  
Author(s):  
Amy E Schade ◽  
Martin Fischer ◽  
James A DeCaprio
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Dna Damage ◽  
Cell Cycle Progression ◽  
Human Fibroblasts ◽  
Cell Cycle Gene ◽  
Cycle Progression ◽  
Cell Cycle Genes ◽  
P53 Activation ◽  
S Genes

Abstract Cell cycle gene expression occurs in two waves. The G1/S genes encode factors required for DNA synthesis and the G2/M genes contribute to mitosis. The Retinoblastoma protein (RB) and DREAM complex (DP, RB-like, E2F4 and MuvB) cooperate to repress all cell cycle genes during G1 and inhibit entry into the cell cycle. DNA damage activates p53 leading to increased levels of p21 and inhibition of cell cycle progression. Whether the G1/S and G2/M genes are differentially repressed by RB and the RB-like proteins p130 and p107 in response to DNA damage is not known. We performed gene expression profiling of primary human fibroblasts upon DNA damage and assessed the effects on G1/S and G2/M genes. Upon p53 activation, p130 and RB cooperated to repress the G1/S genes. In addition, in the absence of RB and p130, p107 contributed to repression of G1/S genes. In contrast, G2/M genes were repressed by p130 and p107 after p53 activation. Furthermore, repression of G2/M genes by p107 and p130 led to reduced entry into mitosis. Our data demonstrates specific roles for RB, p130-DREAM, and p107-DREAM in p53 and p21 mediated repression of cell cycle genes.

scholarly journals Characterization of a novel CDC gene (ORC1) partly homologous to CDC6 of Saccharomyces cerevisiae.

1996 ◽  
Vol 7 (3) ◽  
pp. 409-418 ◽  
Author(s):  
Y Hori ◽  
K Shirahige ◽  
C Obuse ◽  
T Tsurimoto ◽  
H Yoshikawa
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Sequence Data ◽  
Cell Cycle Gene ◽  
Computer Search ◽  
Cycle Progression ◽  
Nucleotide Sequence Data ◽  
Haploid Strain ◽  
Cloned Gene

A novel cell cycle gene was identified by a computer search for genes partly homologous to known CDC genes, CDC6 of Saccharomyces cerevisiae and CDC18 of Schizosaccharomyces pombe, using the nucleotide sequence data base for S. cerevisiae produced by the Yeast Sequencing Project. The protein sequence coded by the cloned gene was found to be identical to that of purified ORC1 protein. Disruption of the gene and subsequent tetrad analysis revealed that the gene was essential for growth. The function of the gene product was analyzed by depleting the protein from the cell using a mutant haploid strain containing the disrupted ORC1 gene on the chromosome and a galactose-inducible gene coding for HA-tagged ORC1 protein on a single copy plasmid. The HA-tagged protein was expressed during growth in the presence of galactose but began to decrease rapidly upon depletion of galactose. Analysis of the cell cycle progression of the mutant cells by FACS after the removal of galactose from the medium, and microscope observations of cells and their nuclei revealed that the normal progression of 2N cells was immediately impeded as the ORC1 protein started to decrease. This was blocked completely in the cells that had progressed to the S phase under conditions deficient in ORC1 protein followed by cell death. Two-dimensional gel analysis of the replication intermediates after the galactose removal revealed that the depletion of ORC1 protein caused a decrease in the frequency of initiation of chromosomal replication, eventually resulting in the inhibition of replication as a whole. The function of the ORC1 protein in the cell cycle progression of S. cerevisiae is discussed in light of current information on ORC.

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