bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature Dependence of MinD Oscillation in
Escherichia coli
: Running Hot and Fast
Authors: Touhami Ahmed , Jericho Manfred , Rutenberg Andrew D. 
Published: October 2006

ABSTRACT

We observed that the oscillation period of MinD within rod-like and filamentous cells of
Escherichia coli
varied by a factor of 4 in the temperature range from 20°C to 40°C. The detailed dependence was Arrhenius, with a slope similar to the overall temperature-dependent growth curve of
E. coli
. The detailed pattern of oscillation, including the characteristic wavelength in filamentous cells, remained independent of temperature. A quantitative model of MinDE oscillation exhibited similar behavior, with an activated temperature dependence of the MinE-stimulated MinD-ATPase rate.
Posttranslational Modification of the 20S Proteasomal Proteins of the Archaeon
Haloferax volcanii
Authors: Humbard Matthew A. , Stevens Stanley M. , Maupin-Furlow Julie A. 
Published: October 2006

ABSTRACT

20S proteasomes are large, multicatalytic proteases that play an important role in intracellular protein degradation. The barrel-like architecture of 20S proteasomes, formed by the stacking of four heptameric protein rings, is highly conserved from archaea to eukaryotes. The outer two rings are composed of α-type subunits, and the inner two rings are composed of β-type subunits. The halophilic archaeon
Haloferax volcanii
synthesizes two different α-type proteins, α1 and α2, and one β-type protein that assemble into at least two 20S proteasome subtypes. In this study, we demonstrate that all three of these 20S proteasomal proteins (α1, α2, and β) are modified either post- or cotranslationally. Using electrospray ionization quadrupole time-of-flight mass spectrometry, a phosphorylation site of the β subunit was identified at Ser129 of the deduced protein sequence. In addition, α1 and α2 contained N-terminal acetyl groups. These findings represent the first evidence of acetylation and phosphorylation of archaeal proteasomes and are one of the limited examples of post- and/or cotranslational modification of proteins in this unusual group of organisms.
Knockout and Overexpression of Pyrroloquinoline Quinone Biosynthetic Genes in
Gluconobacter oxydans
621H
Authors: Hölscher Tina , Görisch Helmut 
Published: October 2006

ABSTRACT

In
Gluconobacter oxydans
, pyrroloquinoline quinone (PQQ) serves as the cofactor for various membrane-bound dehydrogenases that oxidize sugars and alcohols in the periplasm. Proteins for the biosynthesis of PQQ are encoded by the
pqqABCDE
gene cluster. Our reverse transcription-PCR and promoter analysis data indicated that the
pqqA
promoter represents the only promoter within the
pqqABCDE
cluster of
G. oxydans
621H. PQQ overproduction in
G. oxydans
was achieved by transformation with the plasmid-carried
pqqA
gene or the complete
pqqABCDE
cluster. A
G. oxydans
mutant unable to produce PQQ was obtained by site-directed disruption of the
pqqA
gene. In contrast to the wild-type strain, the
pqqA
mutant did not grow with
d
-mannitol,
d
-glucose, or glycerol as the sole energy source, showing that in
G. oxydans
621H, PQQ is essential for growth with these substrates. Growth of the
pqqA
mutant, however, was found with
d
-gluconate as the energy source. The growth behavior of the
pqqA
mutant correlated with the presence or absence of the respective PQQ-dependent membrane-bound dehydrogenase activities, demonstrating the vital role of these enzymes in
G. oxydans
metabolism. A different PQQ-deficient mutant was generated by Tn
5
transposon mutagenesis. This mutant showed a defect in a gene with high homology to the
Escherichia coli tldD
gene, which encodes a peptidase. Our results indicate that the
tldD
gene in
G. oxydans
621H is involved in PQQ biosynthesis, possibly with a similar function to that of the
pqqF
genes found in other PQQ-synthesizing bacteria.
INTEGRATION TESTING OF CONTEXT-SENSITIVE MIDDLEWARE-BASED APPLICATIONS: A METAMORPHIC APPROACH
Authors: CHAN W. K. , CHEN T. Y. , LU HENG , TSE T. H. , YAU STEPHEN S. 
Published: October 2006

During the testing of context-sensitive middleware-based software, the middleware checks the current situation to invoke the appropriate functions of the applications. Since the middleware remains active and the situation may continue to evolve, however, the conclusion of some test cases may not easily be identified. Moreover, failures appearing in one situation may be superseded by subsequent correct outcomes and, therefore, be hidden. We alleviate the above problems by making use of a special kind of situation, which we call checkpoints, such that the middleware will not activate the functions under test. We recommend testers to generate test cases that start at a checkpoint and end at another. Testers may identify relations that associate different execution sequences of a test case. They then check the results of each test case to detect any contravention of such relations. We illustrate our technique with an example that shows how hidden failures can be detected. We also report the experimentation carried out on an RFID-based location-sensing application on top of a context-sensitive middleware.
c-Jun NH2-Terminal Kinase 2α2 Promotes the Tumorigenicity of Human Glioblastoma Cells
Authors: Cui Jian , Han Shuang-Yin , Wang Congli , Su Wanwen , Harshyne Larry , Holgado-Madruga Marina , Wong Albert J. 
Published: October 2006

Abstract
c-Jun NH2-terminal kinases (JNK) are members of the mitogen-activated protein kinase family and have been implicated in the formation of several human tumors, especially gliomas. We have previously shown that a 55 kDa JNK isoform is constitutively active in 86% of human brain tumors and then showed that it is specifically a JNK2 isoform and likely to be either JNK2α2 or JNK2β2. Notably, we found that only JNK2 isoforms possess intrinsic autophosphorylation activity and that JNK2α2 has the strongest activity. In the present study, we have further explored the contribution of JNK2 isoforms to brain tumor formation. Analysis of mRNA expression by reverse transcription-PCR revealed that JNK2α2 is expressed in 91% (10 of 11) of glioblastoma tumors, whereas JNK2β2 is found in only 27% (3 of 11) of tumors. Both JNK2α2 and JNK2β2 mRNAs are expressed in normal brain (3 of 3). Using an antibody specific for JNK2α isoforms, we verified that JNK2α2 protein is expressed in 88.2% (15 of 17) of glioblastomas, but, interestingly, no JNK2α2 protein was found in six normal brain samples. To evaluate biological function, we transfected U87MG cells with green fluorescent protein–tagged versions of JNK1α1, JNK2α2, and JNK2α2APF (a dominant-negative mutant), and derived cell lines with stable expression. Each cell line was evaluated for various tumorigenic variables including cellular growth, soft agar colony formation, and tumor formation in athymic nude mice. In each assay, JNK2α2 was found to be the most effective in promoting that phenotype. To identify effectors specifically affected by JNK2α2, we analyzed gene expression. Gene profiling showed several genes whose expression was specifically up-regulated by JNK2α2 but down-regulated by JNK2α2APF, among which eukaryotic translation initiation factor 4E (eIF4E) shows the greatest change. Because AKT acts on eIF4E, we also examined AKT activation. Unexpectedly, we found that JNK2α2 could specifically activate AKT. Our data provides evidence that JNK2α2 is the major active JNK isoform and is involved in the promotion of proliferation and growth of human glioblastoma tumors through specific activation of AKT and overexpression of eIF4E. (Cancer Res 2006; 66(20): 10024-31)
Probing the Intracellular Redox Status of Tumors with Magnetic Resonance Imaging and Redox-Sensitive Contrast Agents
Authors: Hyodo Fuminori , Matsumoto Ken-ichiro , Matsumoto Atsuko , Mitchell James B. , Krishna Murali C. 
Published: October 2006

Abstract
Nitroxide radicals are paramagnetic contrast agents, used in magnetic resonance imaging (MRI), that also exert antioxidant effects. Participating in cellular redox reactions, they lose their ability to provide contrast as a function of time after administration. In this study, the rate of contrast loss was correlated to the reducing power of the tissue or the “redox status.” The preferential reduction of nitroxides in tumors compared with normal tissue was observed by MRI. The influence of the structure of the nitroxide on the reduction rate was investigated by MRI using two cell-permeable nitroxides, 4-hydroxy-2,2,6,6,-tetramethyl-1-piperidynyloxyl (Tempol) and 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (3CP), and one cell-impermeable nitroxide, 3-carboxy-2,2,5,5,5-tetramethylpyrrolidine-1-oxyl (3CxP). Pharmacokinetic images of these nitroxides in normal tissue, tumor, kidney, and artery regions in mice were simultaneously obtained using MRI. The decay of Tempol and 3CP in tumor tissue was significantly faster than in normal tissue. No significant change in the total nitroxide (oxidized + reduced forms) was noted from tissue extracts, suggesting that the loss in contrast as a function of time is a result of intracellular bioreduction. However, in the case of 3CxP (membrane impermeable), there was no difference in the reduction rates between normal and tumor tissue. The time course of T1 enhancement by 3CxP and the total amount of 3CxP (oxidized + reduced) in the femoral region showed similar pharmacokinetics. These results show that the differential bioreduction of cell-permeable nitroxides in tumor and normal tissue is supported by intracellular processes and the reduction rates are a means by which the intracellular redox status can be assessed noninvasively. (Cancer Res 2006; 66(20): 9921-8)
Characterizing Vascular Parameters in Hypoxic Regions: A Combined Magnetic Resonance and Optical Imaging Study of a Human Prostate Cancer Model
Authors: Raman Venu , Artemov Dmitri , Pathak Arvind P. , Winnard Paul T. , McNutt Stephen , Yudina Anna , Bogdanov Alexei , Bhujwalla Zaver M. 
Published: October 2006

Abstract
The integration of imaging technologies with the capabilities of genetic engineering has created novel opportunities for understanding and imaging cancer. Here, we have combined vascular magnetic resonance imaging (MRI) and optical imaging to understand the relationship between hypoxia and vascularization in a human prostate cancer model engineered to express enhanced green fluorescent protein (EGFP) under hypoxia. Characterization and validation of EGFP expression under hypoxic conditions was done in culture and in solid tumors in vivo. MRI measurements showed that vascular volume was significantly lower in fluorescing regions. These regions also frequently exhibited high permeability. These data were further supported by the detection of low vessel density in EGFP-positive regions, as determined by the distribution of intravascularly administered, fluorescence-labeled Lycopersicon esculentum lectin in frozen tumor sections. These observations are consistent with the possibility that regions of low vascular volumes are hypoxic, which induces increased expression of functionally active vascular endothelial growth factor, a potent vascular permeability factor. (Cancer Res 2006; 12(20): 9929-36)
Signal Transducers and Activators of Transcription 5b Activation Enhances Hepatocellular Carcinoma Aggressiveness through Induction of Epithelial-Mesenchymal Transition
Authors: Lee Terence K. , Man Kwan , Poon Ronnie T.P. , Lo Chung Mau , Yuen Anthony P. , Ng Irene O. , Ng Kevin T. , Leonard Warren , Fan Sheung Tat 
Published: October 2006

Abstract
Poor prognosis of hepatocellular carcinoma (HCC) is associated with a high potential of vascular invasion and metastasis. Epithelial-mesenchymal transition (EMT) is a key event in the tumor invasion process. Recently, signal transducers and activators of transcription 5 (STAT5) has been linked to tumor progression by EMT induction. However, the precise roles of STAT5 genes (STAT5a and STAT5b) in human epithelial cancers have not been elucidated clearly. The aim of this study is to analyze the roles of STAT5 isoforms in HCC progression using HCC clinical samples. We showed that activation of STAT5b, but not STAT5a, was found in HCC clinical samples and its expression was significantly associated with younger age (P = 0.037), advanced tumor stages (P = 0.003), venous infiltration (P = 0.016), microsatellite formation (P = 0.024), multiple tumor nodules (P = 0.02), and poor patient survival. To specifically investigate the mechanism underlying constitutive activation of STAT5b in HCC, EGFP-HBX was introduced into Huh-7 cells. STAT5b activation in HCC is at least partially mediated by HBX activation. Ectopic STAT5b transfection conferred increased HCC cell motility and invasiveness by induction of EMT changes. In conclusion, STAT5b activation enhanced HCC aggressiveness by induction of EMT, which was possibly mediated by HBX activation. STAT5b could serve as a novel molecular target for HCC treatment. (Cancer Res 2006; 66(20): 9948-56)
Role of SPA-1 in Phenotypes of Chronic Myelogenous Leukemia Induced by BCR-ABL–Expressing Hematopoietic Progenitors in a Mouse Model
Authors: Kometani Kohei , Aoki Misayo , Kawamata Shin , Shinozuka Yoriko , Era Takumi , Taniwaki Masafumi , Hattori Masakazu , Minato Nagahiro 
Published: October 2006

Abstract
SPA-1 is a negative regulator of Rap1 signal in hematopoietic cells, and SPA-1-deficient mice develop myeloproliferative disorders (MPD) of long latency. In the present study, we showed that the MPDs in SPA-1−/− mice were associated with the increased hematopoietic stem cells expressing LFA-1 in bone marrow and their premature mobilization to spleen with extensive extramedullary hematopoiesis, resembling human chronic myelogenous leukemia (CML). We further showed that human BCR-ABL oncogene caused a partial down-regulation of endogenous SPA-1 gene expression in mouse hematopoietic progenitor cells (HPC) and immature hematopoietic cell lines. Although both BCR-ABL-transduced wild-type (wt) and SPA-1−/− HPC rapidly developed CML-like MPD when transferred to severe combined immunodeficient mice, the latter recipients showed significantly increased proportions of BCR-ABL+ Lin− c-Kit+ cells compared with the former ones. Serial transfer experiments revealed that spleen cells of secondary recipients of BCR-ABL+ wt HPC failed to transfer MPD to tertiary recipients due to a progressive reduction of BCR-ABL+ Lin− c-Kit+ cells. In contrast, SPA-1−/− BCR-ABL+ Lin− c-Kit+ cells were sustained at high level in secondary recipients, and their spleen cells could transfer MPD to tertiary recipients, a part of which rapidly developed blast crisis. Present results suggest that endogenous SPA-1 plays a significant role in regulating expansion and/or survival of BCR-ABL+ leukemic progenitors albeit partial repression by BCR-ABL and that Rap1 signal may represent a new molecular target for controlling leukemic progenitors in CML. (Cancer Res 2006; 66(20): 9967-76)
EBV Latent Membrane Protein 1 Up-regulates Hypoxia-Inducible Factor 1α through Siah1-Mediated Down-regulation of Prolyl Hydroxylases 1 and 3 in Nasopharyngeal Epithelial Cells
Authors: Kondo Satoru , Seo So Young , Yoshizaki Tomokazu , Wakisaka Naohiro , Furukawa Mitsuru , Joab Irene , Jang Kyung Lib , Pagano Joseph S. 
Published: October 2006

Abstract
Hypoxia-inducible factor 1 (HIF1) is up-regulated in most malignant tumors usually via interruption of ubiquitination and proteasomal degradation of its subunit α. Recently, we have shown that the principal EBV oncoprotein, latent membrane protein 1 (LMP1), activates HIF1α and subsequently expression of HIF1-responsive genes in epithelial cells. Here, we explore the mechanism for HIF1α activation by LMP1 in nasopharyngeal epithelial cells: LMP1 up-regulates the level of Siah1 E3 ubiquitin ligase by enhancing its stability, which subsequently induces proteasomal degradation of prolyl HIF-hydroxylases 1 and 3 that normally mark HIF1α for degradation. As a result, LMP1 prevents formation of von Hippel-Lindau/HIF1α complex, as shown by coimmunoprecipitation analyses. Thus, Siah1 is implicated in the regulation of HIF1α and is involved in a recently appreciated aspect of EBV-mediated tumorigenesis, namely, the angiogenesis process triggered by LMP1. (Cancer Res 2006; 66(20): 9870-7)
Characterization of the Nuclear Import Pathways of Galectin-3
Authors: Nakahara Susumu , Oka Natsuo , Wang Yi , Hogan Victor , Inohara Hidenori , Raz Avraham 
Published: October 2006

Abstract
Galectin-3 (Gal-3), a pleiotropic β-galactoside–binding protein, was shown to be involved in several nuclear-dependent functions, including up-regulation of transcriptional factors, RNA processing, and cell cycle regulation. Gal-3 compartmentalization in the nucleus versus the cytoplasm affects, in part, the malignant phenotype of various cancers. However, to date, the mechanism by which Gal-3 translocates into the nucleus remains debatable. Thus, we have constructed and expressed a variety of fusion proteins containing deletion mutants of Gal-3 fused with monomers, dimers, and trimers of enhanced green fluorescent protein and searched for the Gal-3 sequence motifs essential for its nuclear localization in vivo. In addition, a digitonin-permeabilized, cell-free transport in vitro assay was used to directly examine the mechanism of Gal-3 nuclear import. Partial deletions of the COOH-terminal region (114-250) of the human Gal-3 significantly decreases its nuclear translocation, whereas a peptide (1-115) was transported to the nuclei. The in vitro nuclear import assay revealed that there are at least two independent nuclear pathways for shuttling Gal-3 into the nucleus: a passive diffusion and an active transport. This is the first article providing direct evidence for the nuclear import mechanisms of Gal-3 and suggests that Gal-3 nuclear translocation is governed by dual pathways, whereas the cytoplasmic/nuclear distribution may be regulated by multiple processes, including cytoplasmic anchorage, nuclear retention, and or nuclear export. These results may lead to the development of a therapeutic modality aiming at abrogating Gal-3 translocation into the nucleus and thus hampering its activity during cancer progression and metastasis. (Cancer Res 2006; 66(20): 9995-10006)
Common Variants in RB1 Gene and Risk of Invasive Ovarian Cancer
Authors: Song Honglin , Ramus Susan J. , Shadforth Danielle , Quaye Lydia , Kjaer Susanne Kruger , DiCioccio Richard A. , Dunning Alison M. , Hogdall Estrid , Hogdall Claus , Whittemore Alice S. , McGuire Valerie , Lesueur Fabienne , Easton Douglas F. , Jacobs Ian J. , Ponder Bruce A.J. , Gayther Simon A. , Pharoah Paul D.P. 
Published: October 2006

Abstract
Somatic alteration of the RB1 gene is common in several types of cancer, and germ-line variants are implicated in others. We have used a single nucleotide polymorphism (SNP) tagging approach to evaluate the association between common variants (SNP) in RB1 and risks of invasive ovarian cancer. We genotyped 11 tagging SNPs in three ovarian case-control studies from the United Kingdom, United States, and Denmark, comprising &gt;1500 cases and 4,800 controls. Two SNPs showed significant association with ovarian cancer risk: carriers of the minor allele of rs2854344 were at reduced risk compared with the common homozygotes [odds ratio (OR), 0.73; 95% confidence interval (95% CI), 0.61-0.89; P = 0.0009 dominant model]. Similarly, the minor allele of rs4151620 was found to be associated with reduced risk (rare versus common homozygote; OR, 0.19; 95% CI, 0.07-0.53; P = 0.00005 recessive model). After adjusting for multiple testing, the most significant association (rs4151620) was P = 0.001. A global test comparing common haplotype frequencies in cases and controls was of borderline significance (P8df = 0.04). There are no common coding SNPs in the RB1 gene. However, intron 17 of RB1 contains the open reading frame for the P2RY5 gene, and rs4151620 is perfectly correlated with rs2227311, which is located in the 5′-untranslated region of P2RY5 and is predicted to affect P2RY5 transcription. rs2854344 has been reported previously to be associated with breast cancer risk. The possible associations of rs2854344 and rs4151620 with ovarian cancer risk warrant confirmation in independent case-control studies before studies on their biological mode of action. (Cancer Res 2006; 66(20): 10220-6)
Phosphorylation of the Menin Tumor Suppressor Protein on Serine 543 and Serine 583
Authors: MacConaill Laura E. , Hughes Christina M. , Rozenblatt-Rosen Orit , Nannepaga Suraj , Meyerson Matthew 
Published: October 2006

Abstract
Multiple endocrine neoplasia type 1 (MEN-1) is a heritable syndrome typified by tumors in multiple endocrine organs, including the pituitary, parathyroids, and pancreatic islets. MEN-1 is attributable to mutations in the MEN1 tumor-suppressor gene that encodes the menin protein. Recent studies have implicated menin in transcriptional regulation and in covalent histone modification; however, little is known about modifications of the menin protein. Here, we report that menin is subject to phosphorylation on serine residues, including Ser543 and Ser583. Phosphorylation-defective mutants of either or both of these residues retain the associated histone methyltransferase activity of menin, as well as binding to the trithorax complex members Ash2L, Rbbp5, and MLL2 and to RNA polymerase II. Chromatin immunoprecipitation experiments reveal that binding of menin to the Hoxc8 locus is not affected by phosphorylation on Ser543 or Ser583. (Mol Cancer Res 2006;4(10):793–801)
PIK3CA Gene Mutations in Pediatric and Adult Glioblastoma Multiforme
Authors: Gallia Gary L. , Rand Vikki , Siu I-Mei , Eberhart Charles G. , James C. David , Marie Suely K.N. , Oba-Shinjo Sueli M. , Carlotti Carlos G. , Caballero Otavia L. , Simpson Andrew J.G. , Brock Malcolm V. , Massion Pierre P. , Carson Benjamin S. , Riggins Gregory J. 
Published: October 2006

Abstract
The phosphatidylinositol 3-kinases (PI3K) are a family of enzymes that relay important cellular growth control signals. Recently, a large-scale mutational analysis of eight PI3K and eight PI3K-like genes revealed somatic mutations in PIK3CA, which encodes the p110α catalytic subunit of class IA PI3K, in several types of cancer, including glioblastoma multiforme. In that report, 4 of 15 (27%) glioblastomas contained potentially oncogenic PIK3CA mutations. Subsequent studies, however, showed a significantly lower mutation rate ranging from 0% to 7%. Given this disparity and to address the relation of patient age to mutation frequency, we examined 10 exons of PIK3CA in 73 glioblastoma samples by PCR amplification followed by direct DNA sequencing. Overall, PIK3CA mutations were found in 11 (15%) samples, including several novel mutations. PIK3CA mutations were distributed in all sample types, with 18%, 9%, and 13% of primary tumors, xenografts, and cell lines containing mutations, respectively. Of the primary tumors, PIK3CA mutations were identified in 21% and 17% of pediatric and adult samples, respectively. No evidence of PIK3CA gene amplification was detected by quantitative real-time PCR in any of the samples. This study confirms that PIK3CA mutations occur in a significant number of human glioblastomas, further indicating that therapeutic targeting of this pathway in glioblastomas is of value. Moreover, this is the first study showing PIK3CA mutations in pediatric glioblastomas, thus providing a molecular target in this important pediatric malignancy. (Mol Cancer Res 2006;4(10):709–14)