scholarly journals Increased tumor proliferation and genomic instability without decreased apoptosis in MMTV-ras mice deficient in p53.

1997 ◽  
Vol 17 (2) ◽  
pp. 723-731 ◽  
Author(s):  
J E Hundley ◽  
S K Koester ◽  
D A Troyer ◽  
S G Hilsenbeck ◽  
M A Subler ◽  
...  
Keyword(s):  
Genomic Instability ◽  
Growth Rates ◽  
Cell Cycle Regulation ◽  
Tumor Model ◽  
Tumor Suppressor Protein ◽  
Tumor Proliferation ◽  
Specific Context ◽  
Cycle Regulation ◽  
P53 Tumor Suppressor Protein

We have used an in vivo tumor model to evaluate the consequences of p53 tumor suppressor protein deficiency in a tissue-specific context. By breeding MMTV-ras transgenic mice, which are highly susceptible to the development of mammary and salivary tumors, with p53(-/-) mice, we generated three classes of animals which contained the MMTV-ras transgene but differed in their p53 functional status (ras/p53(+/+), ras/p53(+/-), or ras/p53(-/-)). ras/p53(-/-) mice developed tumors more rapidly than animals of the other two genotypes; however, the distribution of tumors was unexpectedly altered. Whereas the most frequently observed tumors in ras/p53(+/+) and ras/p53(+/-) mice were of mammary origin, ras/p53(-/-) mice developed primarily salivary tumors. In addition, the mammary and salivary tumors from ras/p53(-/-) mice consistently exhibited a number of unfavorable characteristics, including higher histologic grades, increased growth rates, and extensive genomic instability and heterogeneity, relative to tumors from ras/p53(+/+) mice. Interestingly, the increased growth rates of ras/p53(-/-) tumors appear to be due to impaired cell cycle regulation rather than decreased apoptosis, suggesting that p53-mediated tumor suppression can occur independent of its role in apoptosis.

Cell Cycle Regulation of E2F Site Occupation in Vivo

Science ◽  
1996 ◽  
Vol 271 (5255) ◽  
pp. 1595-1597 ◽  
Author(s):  
J. Zwicker ◽  
N. Liu ◽  
K. Engeland ◽  
F. C. Lucibello ◽  
R. Muller
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Regulation ◽  
Site Occupation ◽  
Cycle Regulation

scholarly journals Amyloid-ß promotes neurotoxicity by Cdk5-induced p53 stabilization

2018 ◽  
Author(s):  
Rebeca Lapresa ◽  
Jesús Agulla ◽  
Irene Sánchez-Morán ◽  
Juan P. Bolaños ◽  
Angeles Almeida
Keyword(s):  
Neuronal Apoptosis ◽  
Therapeutic Strategy ◽  
Neuronal Damage ◽  
P53 Protein ◽  
Protein A ◽  
Tumor Suppressor Protein ◽  
Protein Accumulation ◽  
Brain Areas ◽  
P53 Tumor Suppressor Protein

ABSTRACTThe p53 tumor suppressor protein, a key regulator of cell apoptosis, has been described to accumulate in affected brain areas from Alzheimer’s disease (AD) patients. However, whether p53 plays any role in AD pathogenesis remains unknown. Here, we found that exposure of neurons to oligomers of the amyloidogenic fragment 25-35 of the Aß peptide (Aβ25-35) activated Cdk5, which promoted p53 protein phosphorylation and stabilization. Moreover, Aβ25-35-mediated mitochondrial dysfunction and neuronal apoptosis were prevented by both genetic and pharmacological inhibition of either p53 or Cdk5 activities. To confirm this mechanism in vivo, Aβ25-35 was stereotaxically injected in the cerebral right ventricle of mice, a treatment that caused p53 protein accumulation, dendrite disruption and neuronal death. Furthermore, these effects were prevented in p53 knockout mice or by pharmacologically inhibiting p53. Thus, Aβ25-35 triggers Cdk5 activation to induce p53 phosphorylation and stabilization, which leads to neuronal damage. Inhibition of the Cdk5-p53 pathway may therefore represent a novel therapeutic strategy against Aβ-induced neurodegeneration.

190 CELL CYCLE REGULATION IN RHESUS MONKEY OOCYTES AND EMBRYOS OF DIFFERENT DEVELOPMENTAL POTENTIAL

2009 ◽  
Vol 21 (1) ◽  
pp. 194
Author(s):  
N. Mtango ◽  
K. Latham
Keyword(s):  
Cell Cycle ◽  
Rhesus Monkey ◽  
Transcriptional Activation ◽  
Cell Cycle Regulation ◽  
Technical Assistance ◽  
Regulatory Gene ◽  
Developmental Potential ◽  
Cycle Regulation

After fertilization, cell division is required for development during the transition from a zygote to an embryo. Degradation of oocyte transcripts, transcriptional activation of the nucleus, and chromatin remodeling occur during early cleavage divisions. Defects in cell cycle regulation decrease the ability of embryo to grow and can be detrimental. In the rhesus monkey, embryos derived by fertilization of oocytes from prepubertal females or oocytes collected during the non-breeding season undergo cleavage arrest (Schramm and Bavister 1994; Zheng et al. 2001). We employed the Primate Embryo Gene Expression Resource (PREGER; www.Preger.org) to examine the expression pattern of 70 mRNAs involved in cell cycle regulation in rhesus monkey oocytes and embryos derived from different stimulation protocols (non-stimulated, FSH stimulated-in vitro matured, and FSH and hCG stimulated-in vivo matured; Mtango and Latham 2007, 2008; Zheng et al. 2005). The resource encompasses a large, biologically rich set of more than 170 samples with 1 to 4 oocytes or embryos which were constructed using the quantitative amplification and dot blotting method. This method entails the direct lysis of small numbers of oocytes or embryos in a reverse transcription buffer supplemented with nonionic detergent, thereby avoiding RNA losses associated with organic extractions (Brady and Iscove 1993). We find that aberrant regulation of cell cycle regulatory gene mRNAs is a prominent feature of oocytes and embryos of compromised developmental potential (FSH stimulated-moderate reduced potential and NS-severely compromised potential). Of the 56 mRNAs for which expression was detected, there was significant aberrations related to oocyte and embryo quality in the expression of more than half (n = 30), P < 0.05), 26 of 30 display significant differences in metaphase II stage oocytes, 20 being altered in FSH stimulated females and 24 of 30 being altered in NS females. The comparison between monkey and previously reported mouse array expression data (Zeng et al. 2004) revealed striking differences between 2 species. These data provide novel information about disruptions in the expression of genes controlling the cell cycle in oocytes and embryos of compromised developmental potential. We thank Bela Patel, Malgorzata McMenamin, and Ann Marie Paprocki for their technical assistance. We also thank R. Dee Schramm for his contribution to the development of the PREGER resource. This work was supported by National Centers for Research Resources Grant RR-15253.

scholarly journals Androgen-Induced Rhox Homeobox Genes Modulate the Expression of AR-Regulated Genes

2010 ◽  
Vol 24 (1) ◽  
pp. 60-75 ◽  
Author(s):  
Zhiying Hu ◽  
Dineshkumar Dandekar ◽  
Peter J. O'Shaughnessy ◽  
Karel De Gendt ◽  
Guido Verhoeven ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Sertoli Cells ◽  
Cell Cycle Regulation ◽  
Expression Patterns ◽  
Expression Vectors ◽  
Founding Member ◽  
Cell Clones ◽  
Cycle Regulation ◽  
Lines Of Evidence

Abstract Rhox5, the founding member of the reproductive homeobox on the X chromosome (Rhox) gene cluster, encodes a homeodomain-containing transcription factor that is selectively expressed in Sertoli cells, where it promotes the survival of male germ cells. To identify Rhox5-regulated genes, we generated 15P-1 Sertoli cell clones expressing physiological levels of Rhox5 from a stably transfected expression vector. Microarray analysis identified many genes altered in expression in response to Rhox5, including those encoding proteins controlling cell cycle regulation, apoptosis, metabolism, and cell-cell interactions. Fifteen of these Rhox5-regulated genes were chosen for further analysis. Analysis of Rhox5-null male mice indicated that at least nine of these are Rhox5-regulated in the testes in vivo. Many of them have distinct postnatal expression patterns and are regulated by Rhox5 at different postnatal time points. Most of them are expressed in Sertoli cells, indicating that they are candidates to be directly regulated by Rhox5. Transfection analysis with expression vectors encoding different mouse and human Rhox family members revealed that the regulatory response of a subset of these Rhox5-regulated genes is both conserved and redundant. Given that Rhox5 depends on androgen receptor (AR) for expression in Sertoli cells, we examined whether some Rhox5-regulated genes are also regulated by AR. We provide several lines of evidence that this is the case, leading us to propose that RHOX5 serves as a key intermediate transcription factor that directs some of the actions of AR in the testes.

Modulation of Gene Expression Profile and In Vivo Anti-Myeloma Activity Induced by Valproic Acid, a Histone Deacytylase Inhibitor.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4790-4790
Author(s):  
Paola Neri ◽  
Teresa Calimeri ◽  
Mariateresa Di Martino ◽  
Marco Rossi ◽  
Orietta Eramo ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Valproic Acid ◽  
Dna Replication ◽  
Gene Expression Profile ◽  
Cell Cycle Regulation ◽  
Cycle Regulation ◽  
Anti Tumor Activity

Abstract Valproic acid (VPA) is a well-tolerated anticonvulsant drug that has been recently recognized as powerful histone deacetylase (HDCA) inhibitor. VPA induces hyperacetylation of histone H3 and H4 and inhibits both class I and II HDCACs. Recently it has been shown that VPA exerts in vitro and in vivo anti-tumor activity against solid cancers and its in vitro anti-Multiple Myeloma (MM) activity has been previously reported. However, the molecular mechanisms are still unclear. Here we have investigated molecular changes induced by VPA as well as its in vivo activity in murine models of MM. We first studied the in vitro activity of VPA against IL-6 independent as well as IL-6 dependent MM cells. A time- and dose-dependent decrease in proliferation and survival of MM cell lines was observed (IC50 in the range of 1–3 mM). Gene expression profile following treatment with VPA at 2 and 5 mM showed down-regulation of genes involved in cell cycle regulation, DNA replication and transcription as well as up-regulation of genes implicated in apoptosis and chemokine pathways. The signaling pathway analysis performed by Ingenuity Systems Software identified the cell growth, cell cycle, cell death as well as DNA replication and repair as the most important networks modulated by VPA treatment. We next evaluated the in vivo activity of VPA using two xenograft models of human MM. A cohort of SCID mice bearing subcutaneous MM1s or OPM1 were treated i.p. daily with VPA (200 mg/kg, and 300 mg/kg, n=5 mice, respectively), or vehicle alone (n=5 mice) for 16 consecutive days. Tumors were measured every 2 days, and survival was calculated using the Kaplan Mayer method. Following VPA treatment, we found a significant (p=0.006) inhibition of tumor growth in mice bearing subcutaneous MM-1s cells treated with VPA at 200 mg/kg compared to control group, which translated into a significant (p= 0.002) survival advantage in the VPA treated animals. Similar results were obtained in animals bearing subcutaneous OPM1 cells. Flow cytometry analysis performed on retrieved tumor tissues from animals showed reduction of G2-M and S phase in tumor specimens following VPA treatment, versus untreated tumors, strongly suggesting in vivo effects of VPA on cell cycle regulation. Taken together, our data demonstrate the in vitro and in vivo anti-tumor activity of VPA, delineate potential molecular targets triggered by this agent and provide a preclinical rationale for its clinical evaluation, both as a single agent or in combination, to improve patient outcome in MM.

Cell Cycle Regulation and Cell Fate Decisions in Hematopoietic Stem Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1349-1349
Author(s):  
Emmanuelle Passegue ◽  
Amy J. Wagers ◽  
Sylvie Giuriato ◽  
Wade C. Anderson ◽  
Irving L. Weissman
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Cell Fate ◽  
Cell Cycle Regulation ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Cell Fate Decisions ◽  
Cycle Regulation

Abstract The blood is a perpetually renewing tissue seeded by a rare population of adult bone marrow hematopoietic stem cells (HSC). During steady-state hematopoiesis, the HSC population is relatively quiescent but constantly maintains a low numbers of cycling cells that differentiate to produce the various lineage of mature blood cells. However, in response to hematological stress, the entire HSC population can be recruited into cycle to self-renew and regenerate the blood-forming system. HSC proliferation is therefore highly adaptative and requires appropriate regulation of cell cycle progression to drive both differentiation-associated and self-renewal-associated proliferation, without depletion of the stem cell pool. Although the molecular events controlling HSC proliferation are still poorly understood, they are likely determined, at least in part, by regulated expression and/or function of components and regulators of the cell cycle machinery. Here, we demonstrate that the long-term self-renewing HSC (defined as Lin−/c-Kit+/Sca-1+/Thy1.1int/Flk2−) exists in two distinct states that are both equally important for their in vivo functions as stem cells: a numerically dominant quiescent state, which is critical for HSC function in hematopoietic reconstitution; and a proliferative state, which represents almost a fourth of this population and is essential for HSC functions in differentiation and self-renewal. We show that when HSC exit quiescence and enter G1 as a prelude to cell division, at least two critical events occur: first, during the G1 and subsequent S-G2/M phases, they temporarily lose efficient in vivo engraftment activity, while retaining in vitro differentiation potential; and second, they select the particular cell cycle proteins that are associated with specific developmental outcomes (self-renewal vs. differentiation) and developmental fates (myeloid vs. lymphoid). Together, these findings provide a direct link between HSC proliferation, cell cycle regulation and cell fate decisions that have critical implications for both the therapeutic use of HSC and the understanding of leukemic transformation.

Treatment With Hedgehog Inhibitor, PF-04449913, Attenuates Leukemia-Initiation Potential In Acute Myeloid Leukemia Cells

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1649-1649 ◽  
Author(s):  
Nobuaki Fukushima ◽  
Yosuke Minami ◽  
Fumihiko Hayakawa ◽  
Hitoshi Kiyoi ◽  
Anil Sadarangani ◽  
...  
Keyword(s):  
Cell Lines ◽  
Stromal Cells ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Cell Cycle Regulation ◽  
Assay System ◽  
Self Renewal ◽  
Colony Assay ◽  
Cycle Regulation

Abstract Background Aberrant activation of the Hedgehog (Hh) signaling pathway is involved in a variety of cancers, and required for maintenance of the leukemic stem cell (LSC) populations in several experimental systems. Cumulative evidence suggests that dormant self-renewing LSC contribute to acute myeloid leukemia (AML) propagation and relapse by evading conventional chemotherapies that target cycling cells. PF-04449913 (PF) is a novel oral small molecule inhibitor that selectively binds and targets Smoothened (SMO), a membrane protein regulating the Hh pathway. Treatment with PF has shown promising Results regarding safety, tolerability, and early signs of efficacy in a phase 1 dose-escalation study of hematologic malignancies including AML (Jamieson C, et al. ASH, 2011). On the basis of these encouraging Results, phase 1b and phase 2 studies of PF in combination with chemotherapies have been planned in patients with AML. However, the detailed mechanisms and biomarkers remain to be elucidated in AML therapy with Hh pathway inhibitors. Research Aims and Methods We used AML cell lines and patient-derived primary AML cells in order to evaluate the efficacy and elucidate detailed mechanisms and biomarkers in the Hh antagonist, PF treatment. Using the co-culturing system with HS-5 stromal cells, the colony assay system, and the immunodeficient NOD/SCID/IL2rgnull (NOG) mouse model serially xenotransplanted with primary AML cells, we examined the effects of PF on LSC population and AML propagation. Results Using FACS sorting and RQ-PCR assays of AML patient-derived primary cells, the Hh signaling pathway was activated more in CD34-positive cells than CD34-negative cells. Ex vivo-treatment with PF inhibited proliferation and induced minimal cell death in leukemia cell lines and primary AML cells. However, in vivo-treatment with PF attenuated leukemia-initiation potential in AML cells through the serial transplantation system, while limiting reduction of tumor burden in the primary leukemia system. Also in the colony-assay system using primary AML cells, treatment with PF reduced serially colony formation. In MOLM-14 cells, treatment with PF down-regulated mRNA encoding downstream effector GLIs and GLI-targeting molecules in the canonical Hh pathway using RQ-PCR assays, and decreased nuclear expression of GLI-2 using immunofluorescence assays. In addition, treatment with PF remarkably decreased the quiescent (Hoechst-33342low/Pyronin-Ylow) cell population and increased cycling cell population. In the in vivo-NOG mouse system, comprehensive Gene Set Enrichment Analysis (GSEA) revealed that PF treatment modulated cell cycle regulation and self-renewal signaling in primary AML cells. Moreover, combined treatment with PF abrogated resistance to Ara-C in AML cell lines co-cultured with HS-5 stromal cells and sensitized primary AML cells to Ara-C in the colony-assay system. We are also investigating toxicity for normal cord blood cells with PF treatment. Conclusions Our findings imply that selective Hh inhibitor, PF treatment can attenuate the leukemia-initiation potential in AML cells by modulation of cell cycle regulation and self-renewal signaling, and can also improve AML therapy through sensitizing dormant LSC to chemotherapy and overcoming the resistance in the bone marrow microenvironment. Disclosures: Kiyoi: Kyowa Hakko Kirin Co. Ltd.: Research Funding; Novartis Pharma: Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding; Bristol-Myers Squibb: Research Funding.

scholarly journals Antibody microinjection reveals an essential role for human polo-like kinase 1 (Plk1) in the functional maturation of mitotic centrosomes.

1996 ◽  
Vol 135 (6) ◽  
pp. 1701-1713 ◽  
Author(s):  
H A Lane ◽  
E A Nigg
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Regulation ◽  
Fundamental Aspect ◽  
Early Prophase ◽  
Functional Maturation ◽  
A Cell ◽  
Gamma Tubulin ◽  
Cycle Regulation ◽  
Kinetics Of

Mammalian polo-like kinase 1 (Plk1) is structurally related to the polo gene product of Drosophila melanogaster, Cdc5p of Saccharomyces cerevisiae, and plo1+ of Schizosaccharomyces pombe, a newly emerging family of serine-threonine kinases implicated in cell cycle regulation. Based on data obtained for its putative homologues in invertebrates and yeasts, human Plk1 is suspected to regulate some fundamental aspect(s) of mitosis, but no direct experimental evidence in support of this hypothesis has previously been reported. In this study, we have used a cell duplication, microinjection assay to investigate the in vivo function of Plk1 in both immortalized (HeLa) and nonimmortalized (Hs68) human cells. Injection of anti-Plk1 antibodies (Plk1+) at various stages of the cell cycle had no effect on the kinetics of DNA replication but severely impaired the ability of cells to divide. Analysis of Plk1(+)-injected, mitotically arrested HeLa cells by fluorescence microscopy revealed abnormal distributions of condensed chromatin and monoastral microtubule arrays that were nucleated from duplicated but unseparated centrosomes. Most strikingly, centrosomes in Plk1(+)-injected cells were drastically reduced in size, and the accumulation of both gamma-tubulin and MPM-2 immunoreactivity was impaired. These data indicate that Plk1 activity is necessary for the functional maturation of centrosomes in late G2/early prophase and, consequently, for the establishment of a bipolar spindle. Additional roles for Plk1 at later stages of mitosis are not excluded, although injection of Plk1+ after the completion of spindle formation did not interfere with cytokinesis. Injection of Plk1+ into nonimmortalized Hs68 cells produced qualitatively similar phenotypes, but the vast majority of the injected Hs68 cells arrested as single, mononucleated cells in G2. This latter observation hints at the existence, in nonimmortalized cells, of a centrosome-maturation checkpoint sensitive to the impairment of Plk1 function.

scholarly journals Cell cycle-regulated transcription of the CLB2 gene is dependent on Mcm1 and a ternary complex factor.

1995 ◽  
Vol 15 (6) ◽  
pp. 3129-3137 ◽  
Author(s):  
M Maher ◽  
F Cong ◽  
D Kindelberger ◽  
K Nasmyth ◽  
S Dalton
Keyword(s):  
Cell Cycle ◽  
Dna Binding ◽  
Cell Cycle Regulation ◽  
Ternary Complex ◽  
Binding Activity ◽  
Transcriptional Level ◽  
Dna Binding Activity ◽  
Cycle Regulation ◽  
Ternary Complex Factor

Clb2 is the major B-type mitotic cyclin required for entry into mitosis in the budding yeast Saccharomyces cerevisiae. We showed that accumulation of CLB2 transcripts in G2 cells is controlled at the transcriptional level and identified a 55-bp upstream activating sequence (UAS) containing an Mcm1 binding site as being necessary and sufficient for cell cycle regulation. Sequences within the cell cycle-regulated UAS were shown to bind Mcm1 in vitro, and mutation which abolished Mcm1-dependent DNA binding activity eliminated cell cycle-regulated transcription in vivo. A second protein with no autonomous DNA binding activity was also recruited into Mcm1-UAS complexes, generating a ternary complex. A point mutation in the CLB2 UAS which blocked ternary complex formation, but still allowed Mcm1 to bind, resulted in loss of cell cycle regulation in vivo, suggesting that the ternary complex factor is also important in control of CLB2 transcription. We discuss the possibility that the CLB2 gene is coregulated with other genes known to be regulated with the same periodicity and suggest that Mcm1 and the ternary complex factor may coordinately regulate several other G2-regulated transcripts.

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