Table of Contents

Volume 3, Issue 1

  January 2004

  Pages 1 - 88

View covers archive

PORTRAIT OF AN EDITORIAL BOARD MEMBER

Open Access Article

Our Unforgettable Experience in the Reed Laboratory

Juliane M. Jürgensmeier, Shigemi Matsuyama, Toshiyuki Miyashita, Mikihiko Naito, Ryosuke Takahashi and Hong-Gang Wang
Pages 1 - 2
http://dx.doi.org/10.4161/cc.3.1.587
Abstract | PDF

No abstract available.




EXTRA VIEWS

Open Access Article

A Role for JNK-Paxillin Signaling in Cell Migration

Cai Huang, Ken Jacobson and Michael D. Schaller
Pages 3 - 5
http://dx.doi.org/10.4161/cc.3.1.601
Abstract | PDF

Recently, we and others demonstrated that JNK is essential for cell migration in a number of cell types. We also showed that JNK phosphorylates serine 178 on paxillin, a focal adhesion adaptor, both in vitro and in vivo. Moreover, phosphorylation of Ser 178 on paxillin is essential for cell migration and involved in modulating cell adhesions. A model is proposed to depict the role of JNK-paxillin signaling in cell migration.

Open Access Article

Bcl-2 in Cell Cycle Regulation

Leonie M. Quinn and Helena Richardson
Pages 6 - 8
http://dx.doi.org/10.4161/cc.3.1.602
Abstract | PDF

No abstract yet available.

Open Access Article

Early Growth Response-1: Blocking Angiogenesis by Shooting the Messenger

Levon M. Khachigian
Pages 9 - 10
http://dx.doi.org/10.4161/cc.3.1.604
Abstract | PDF

Early growth response-1 (Egr-1) is an immediate early gene, which encodes a zinc finger transcription factor. Recent evidence indicates that Egr-1 plays a crucial role in angiogenesis, the formation of new blood vessels from the pre-existing vasculature. DNAzymes (catalytic single-stranded DNA) targeting the Egr-1 mRNA inhibit Egr-1 and FGF-2 expression, block endothelial cell growth, and suppress neovascularization and tumor angiogenesis in various animal models.

Open Access Article

Lkb1 and GSK3b: Kinases at the Center (and the poles) of the Action

Jeremy B.A. Green
Pages 11 - 13
http://dx.doi.org/10.4161/cc.3.1.619
Abstract | PDF

No abstract available.

Open Access Article

How to Activate a Damage-Tolerant Polymerase

Helle D. Ulrich
Pages 14 - 17
http://dx.doi.org/10.4161/cc.3.1.623
Abstract | PDF

No abstract yet available.

Open Access Article

Replication Initiation In Mammalian Cells: Changing Preferences

MIchelle Debatisse, Franck Toledo and Mauro Anglana
Pages 18 - 20
http://dx.doi.org/10.4161/cc.3.1.628
Abstract | PDF

No abstract yet available.

Open Access Article

Functional Link Between Myc and the Werner Gene in Tumorigenesis

Carla Grandori, Kristin L. Robinson, Denise A. Galloway and Karen Swisshelm
Pages 21 - 24
http://dx.doi.org/10.4161/cc.3.1.630
Abstract | PDF

We have recently reported a connection between the expression of the Werner syndrome gene (WRN), whose loss of function has been implicated in a human progeroid syndrome (WS), and the Myc oncoprotein. Myc overexpression directly elevates trancription of the WRN gene, whose presence is required to avoid senescence during Myc proliferative stimuli. Here we discuss several hypotheses to explain why WRN might be required to support oncogenic proliferation in light of the known function of WRN protein and Myc in genomic instability and transcriptional modulation. In addition, we address the apparent paradox of why patients with WS, lacking WRN function, have increased incidence of certain cancers.

Open Access Article

Chromosome Shaping by Two Condensins

Tatsuya Hirano
Pages 25 - 27
http://dx.doi.org/10.4161/cc.3.1.633
Abstract | PDF

It remains a big challenge in modern cell biology to determine the mechanism by which a discrete set of rod-shaped chromosomes is assembled from an amorphous mass of interphase chromatin. Recent studies start to shed new lights on how this process is actively supported by a class of multiprotein complexes called condensins. In vertebrate cells, two different condensin complexes make distinct mechanistic contributions to determining the shape and integrity of mitotic chromosomes.

Open Access Article

Gene Expression Signatures, Cancer Cell Evolution and Metastatic Progression

Christoph A. Klein
Pages 28 - 30
http://dx.doi.org/10.4161/cc.3.1.634
Abstract | PDF

Global gene expression profiling and molecular cytogenetics for single cells provide new opportunities to resolve important questions, such as the mechanisms of tumor cell selection during cancer progression. While gene expression analyses show that metastatic progression correlates with the deregulation of certain gene sets in the primary tumor, the direct analysis of disseminated cancer cells, the putative precursors of metachronous metastases, suggests that dissemination is a very early event in the genetic development of human cancers.




PERSPECTIVES

Open Access Article

Cycling without Cyclins

Frank Traganos
Pages 31 - 33
http://dx.doi.org/10.4161/cc.3.1.608
Abstract | PDF

Complex oscillations in the activation and inactivation of cyclin-dependent kinase complexes propel mammalian cells through the cycle. A recent spate of studies seems to indicate that many, if not most, of these seemingly essential molecules may, in some senses, be dispensable. If true, that would mean the essential components of the mammalian cell cycle are not much different from those found in prokaryotes. That, in turn, would imply a fair amount redundancy exists in the system which may call into question current cancer treatment strategies designed to target some of these "dispensable" cell cycle control molecules.

Key Words: cyclin-dependent kinases, cyclin E, knockout, S phase, cell cycle

Open Access Article

Cdk2 as a Master of S phase Entry: Fact or Fake?

Eiman Aleem, Cyril Berthet and Philipp Kaldis
Pages 34 - 36
http://dx.doi.org/10.4161/cc.3.1.632
Abstract | PDF

It has long been believed that Cdk2 and its activator cyclin E play essential roles in the progression of the mitotic cell cycle. However, recent studies using knockout mouse models revealed that neither Cdk2 nor cyclin E are essential in vivo. The purpose of this mini-review is to compare both Cdk2 and cyclin E knockout mice models and to discuss potential mechanisms driving the cell cycle in the absence of Cdk2 or cyclin E. Particular emphasis is placed on possible non-catalytic roles of cyclin E, the expression and activity of the second cyclin binding partner of Cdk2, cyclin A, as well as on the expression and degradation of the Cdk2 inhibitor p27Kip1 in the absence of Cdk2.

Open Access Article

Drosophila Invasive Tumors: A Model for Understanding Metastasis

Elisa C. Woodhouse and Lance A. Liotta
Pages 37 - 39
http://dx.doi.org/10.4161/cc.3.1.636
Abstract | PDF

Inactivation of Drosophila tumor suppressor genes can cause excessive proliferation and, in some cases, neoplastic growth. Neoplastic growth in Drosophila tissues can also be followed by metastasis upon transplantation into hosts or in vivo. Recently, we have shown that metastatic tumors of Drosophila can provide a model in which to identify genes that are involved in the metastatic process.




REVIEWS

Open Access Article

Many Fingers on the Mitotic Trigger: Post-Translational Regulation of the Cdc25C Phosphatase

James R.A. Hutchins and Paul R. Clarke
Pages 40 - 44
http://dx.doi.org/10.4161/cc.3.1.595
Abstract | PDF

Abstract The mitotic inducer Cdc25 phosphatase controls the activation of Cdc2/cyclin B protein kinase and entry into mitosis in eukaryotic cells. Cdc25C is highly regulated by multiple post-translational modifications within its N-terminal regulatory domain and site-specific protein interactions. Phosphorylation of one inhibitory site targeted by multiple kinases determines the timing of Cdc25C activation and arrests cells in G2 in response to checkpoint, stress, developmental and extracellular signals. In mitosis, phosphorylation of several Ser/Thr residues and Pin1-catalysed peptidyl-proline isomerisation produces activation. Phosphorylation of one activating site is antagonistic to the proximal inhibitory site and maintains Cdc25C activity during mitosis. Phosphorylation and interacting proteins also modulate the nuclear import and export signals on Cdc25C, inducing dramatic changes in its localisation within the cell. Thus, the regulation of Cdc25C activity and localisation integrates multiple signals that govern the decision to enter mitosis.

Open Access Article

Cell Cycle Checkpoint Proteins and Cellular Response to Treatment by Anticancer Agents

Giovanna Damia and Massimo Broggini
Pages 45 - 49
http://dx.doi.org/10.4161/cc.3.1.631
Abstract | PDF

The response of cancer cells to treatment with anticancer agents is mediated in part by proteins controlling both the cell cycle progression and the genomic integrity, including p53, p73 and checkpoint proteins chk1 and chk2. We here summarized the cellular functions of these proteins, their alterations in human tumors and the impact of their mutations/alterations on cellular response to treatment, Particular attention has been paid for those studies performed in isogenic cell systems, to minimize as much as possible interference by other alterations invariably present when different cell types are considered. Focus has also be given to the approaches taken to exploit the differential expression of these proteins between normal and tumor cells to improve the selectivity of treatment with anticancer agents.




SPOTLIGHT ON HSP

Open Access Article

The Achilles Heel of ErbB-2/HER2: Regulation by the Hsp90 Chaperone Machine and Potential for Pharmacological Intervention

Ami Citri, Bose S. Kochupurakkal and Yosef Yarden
Pages 50 - 59
http://dx.doi.org/10.4161/cc.3.1.607
Abstract | PDF

Signal transduction mediated by ErbB/HER receptor tyrosine kinases is crucial for the development and maintenance of epithelial tissues, and aberrant signaling is frequently associated with malignancies of epithelial origin. This review focuses on the roles played by the Hsp90 chaperone machinery in the regulation of signaling through the ErbB/HER network, and discusses potential therapeutic strategies that disrupt chaperone functions. Hsp90 and its associated co-chaperones regulate ErbB signal transduction through multiple mechanisms. The chaperone system controls the stability of the nascent forms of both ErbB-1 (EGF-receptor) and ErbB-2/HER2, while regulation of the mature form is restricted to ErbB-2. Regulation by the Hsp90 complex extends to downstream effectors of ErbB signaling, namely Raf-1, Pdk-1 and Akt/PKB. Disrupting the function of Hsp90 results in the degradation of both the receptors and their effectors, thereby inhibiting tumor cell growth. The importance of an Hsp90-recognition motif located within the kinase domain of ErbB-2 is discussed, as well as a direct role for Hsp90 in regulating tyrosine kinase activity. In light of recent observations, we emphasize the ability of specific tyrosine kinase inhibitors to selectively target ErbB-2 to the chaperone-mediated degradation pathway. ErbB-specific drugs are already used to treat cancers, and clinical trials are underway for additional compounds that intercept ErbB signaling, including drugs that target Hsp90. Hence, the dependence of ErbB-2 upon Hsp90 reveals an Achilles heel, which opens a window of opportunity for combating cancers driven by the ErbB/HER signaling network.

Open Access Article

Why Do Cells Require Heat Shock Proteins to Survive Heat Stress?

Howard Riezman
Pages 60 - 62
http://dx.doi.org/10.4161/cc.3.1.625
Abstract | PDF

The cellular response to heat stress includes the induction of a group of proteins called the Heat Shock Proteins, whose functions include the synthesis of the thermoprotectant trehalose, refolding of denatured proteins, and ubiquitin- and proteasome-dependent degradation. Recent studies show that simply increasing the activity of ubiquitin- and proteasome-dependent degradation can replace the essential functions played by the induction of heat shock proteins during a heat stress. These results suggest that accumulation of denatured or aggregated proteins is the reason for the loss of cell viability due to heat stress.




VIEWS AND COMMENTARIES

Open Access Article

Apoptosis, Necrosis and Between

Boris Zhivotovsky
Pages 63 - 65
http://dx.doi.org/10.4161/cc.3.1.606
Abstract | PDF

No abstract available.




REPORTS

Open Access Article

Inhibition of Phosphatidylinositol 3-Kinase Causes Apoptosis in Retinoic Acid-Differentiated HL-60 Leukemia Cells

Jin Ma, Qiang Liu and Yi-Xin Zeng
Pages 66 - 69
http://dx.doi.org/10.4161/cc.3.1.592
Abstract | PDF

Phosphatidylinositol 3-kinase (PI3-K) signaling may inhibit apoptosis in neoplastic cells. The PI-3K inhibitor wortmannin renders cells apoptosis-prone. Inducers of differentiation may also cause apoptosis. To detect the effect of wortmannin on the survival of differentiated human acute promyeloid leukemia cells, HL-60 cells were induced to differentiation with treatment of all trans-retinoic acid (ATRA) followed by treatment with wortmannin. Results showed that apoptosis occurred in cells that underwent differentiation, but not in undifferentiated HL-60 cells. The pro-apoptotic molecule, Bad, played a role in this apoptotic mechanism. Thus, the survival of differentiated HL-60 cells induced by ATRA depends on the ability of the PI3-K pathway to transduce survival signals; the PI3-K inhibitor, wortmannin, can induce apoptosis of differentiated HL-60 cells. These results may indicate a novel method for treating cancer with differentiation induction and signal pathway regulation.

Open Access Article

PAK Is Essential for RAS-Induced Upregulation of Cyclin D1 During the G1 to S Transition

Thao Nheu, Hong He, Yumiko Hirokawa, Francesca Walker, John Wood and Hiroshi Maruta
Pages 70 - 73
http://dx.doi.org/10.4161/cc.3.1.593
Abstract | PDF

Oncogenic RAS mutants such as v-Ha-RAS induce cell cycling, in particular the G1 to S transition, by up-regulating cyclin D1 and down-regulating p27, an inhibitor for cyclin-dependent kinases (CDKs). PI-3 kinase appears to be involved in the regulation of both cyclin D1 and p27. In this report, using two distinct inhibitors specific for PAK1-3 (CEP-1347 and WR-PAK18), we present the first evidence indicating that the PIX/Rac/CDC42-dependent Ser/Thr kinases PAK1-3, acting downstream of PI-3 kinase and up-stream of the Raf/MEK/ERKs kinase cascade, is essential for RAS-induced up-regulation of cyclin D1, but not down-regulation of p27. Since these PAK-inhibitors block selectively the malignant growth of RAS transformants, in which PAK1 is constitutively activated, but not normal cell growth, it is suggested that RAS transformants are addicted to the high levels of PAK1 for their malignant entry to S phase.

Open Access Article

Codon-Optimized Cloning, Expression and Characterization of the C-Terminal Region of Human Apoptotic Protein GADD34 in Escherichia coli

Ping Yu, Nouri Neamati, Sergey Tarasov, Qin He, M. Saeed Sheikh and Yun-Xing Wang
Pages 74 - 78
http://dx.doi.org/10.4161/cc.3.1.594
Abstract | PDF

The human GADD34 (Growth Arrest and DNA Damage-inducible 34) is the product of an apoptosis- and DNA-damage-inducible gene. The C-terminus domain of GADD34 is highly homologous to HSV-1 g1 34.5, HSV-2 and the African swine fever virus virulence-associated factor NL-S. Among these viral proteins, HSV-1 g 34.5 protein is known to prevent apoptosis of viral-infected cells. Because of the difficulty in expressing GADD34 protein or any of its fragments, including the C-terminus (amino acids 533-632) in E. coli, partially due to sub-optimal expression of eukaryotic codons in prokaryotic E. coli, we used a codon-optimized cloning scheme to construct the eukaryotic gene that codes for GADD34533-632. We derived a novel PCR protocol to assemble 20 oligonucleotides into the synthetic GADD34533-632 gene. The clear advantage of using this protocol is that the assembled gene is without the mutation and deletion that are usually of major problem in constructing synthetic genes. The synthetic GADD34533-632 gene was cloned, expressed, and purified in large quantity. We obtained approximately 50 mg of GADD34533-632 protein per liter minimum-medium culture. To our knowledge, this is the first report of a large-scale production of the C-terminus of GADD34. The production and purification of GADD34533-632 in large quantity are essential for structure determination as well as for understanding its interactions with other proteins such as phosphatase 1-a using NMR spectroscopy and other biophysical methods.

Open Access Article

The Development of a CDK2-Docking Site Peptide that Inhibits p53 and Sensitizes Cells to Death

Michelle Ferguson, M.Gloria Luciani, Lee Finlan, Sally Ibbotson, Alan Fersht and Ted R. Hupp
Pages 79 - 88
http://dx.doi.org/10.4161/cc.3.1.603
Abstract | PDF

Cyclin-dependent protein kinases play important roles in cell cycle progression and are attractive targets for the design of anti-proliferative drugs. Two distinct synthetic CDK1/2 inhibitors, Roscovitine and NU2058, are pharmacologically distinct in their ability to modify p53-dependent transcription and perturb cell cycle progression. Although such active-site CDK1/2 inhibitors comprise the most standard type of enzyme inhibitor, many protein kinases are proving to harbour high affinity docking sites that may provide a potentially novel interface for the design of kinase-inhibitors. We examined whether CDK2 has a docking site for its oligomeric substrate p53, whether small-peptide leads can be developed that inhibit CDK2 function, and whether such peptide-inhibitors are pharmacologically distinct from Roscovitine or NU2058. A docking site for CDK2 was identified in the tetramerization domain of p53 at a site that is distinct from the phospho-acceptor site. Peptides derived from the tetramerization domain of p53 block CDK2 phosphorylation and identification of critical CDK2 contacts in the tetramerization domain of p53 suggest that kinase docking does not require tetramerization of the substrate. Transient transfection assays were developed to show that the GFP-CDK2 docking site fusion protein (GFP-CIP) attenuates p53 activity in vivo and suppresses p21WAF1 induction which is similar to NU2058 but distinct from Roscovitine. A stable cell line with an inducible GFP-CIP gene attenuates p53 activity and induces significant cell death in a drug-resistant melanoma cell line, sensitizes cells to death induced by Doxorubicin, and suppresses cell growth in a colony formation assay. These data indicate that CDK2, in addition to cyclin A, can have a high affinity docking site for a substrate and highlights the possibility that CDK2 docking sites may represent effective targets for inhibitor design.