bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gαq signaling is required for Rho‐dependent transcriptional activation of the cyclooxygenase‐2 promoter in fibroblasts
Authors: Slice Lee W. , Han Sang‐Kyou , Simon Melvin I. 
Published: December 2002

AbstractPreviously, we demonstrated that the gastrin releasing peptide (GRP) induces cyclooxygenase‐2 (COX‐2) expression through a Rho‐dependent, protein kinase C (PKC)‐independent signaling pathway in fibroblasts (Slice et al., 1999, J Biol Chem 274:27562–27566). However, the specific role of heterotrimeric guanine nucleotide binding regulatory proteins (G‐proteins) that are coupled to the GRP receptor in Rho‐dependent COX‐2 expression has not been elucidated. In this report, we utilize embryonic fibroblasts from transgenic mice containing double gene knock‐outs (DKO) for Gαq/11 and Gα12/13 to demonstrate that COX‐2 promoter activation by GRP requires Gαq. Furthermore, we show that GRP‐dependent COX‐2 gene expression, as assessed by a COX‐2 reporter luciferase assay, was induced in cells lacking Gα12/13 but was blocked in cells that did not express Gαq/11. GRP‐dependent COX‐2 promoter induction in Gαq/11 deficient cells was rescued by expression of wild type Gαq but blocked by inhibition of calcium signaling in calcium‐free media or in cells treated with 2‐aminoethoxydiphenylborate (2‐APB). Co‐stimulation of transfected Gαq/11 deficient cells with GRP and thapsigargin (TG) induced the COX‐2 promoter. Activation of endogenous Rho by expression of Onco‐lbc or expression of Rho A Q63L resulted in COX‐2 promoter activation in Gαq/11 deficient cells. Inhibition of Rho by Clostridium botulinum C3 toxin blocked COX‐2 promoter induction. Expression of Gαq Q209L in the well‐characterized fibroblast cell line, NIH3T3, induced the COX‐2 promoter which was blocked by expression of C3 toxin. These results demonstrate that calcium signaling mediated by Gαq and Rho play critical roles in GRP‐dependent COX‐2 expression in fibroblasts. © 2002 Wiley‐Liss, Inc.
Retinoic acid‐induced AP‐1 transcriptional activity regulates B16 mouse melanoma growth inhibition and differentiation
Authors: Huang Ying , Boskovic Goran , Niles Richard M. 
Published: December 2002

AbstractRetinoic acid (RA) inhibits growth and induces differentiation of B16 mouse melanoma cells. These effects are accompanied by a large increase in PKCα mRNA and protein levels and surprisingly an increase in activating protein‐1 (AP‐1) transcriptional activity. To further investigate the RA‐induced AP‐1 activity we established clones of B16 cells stably expressing an AP‐1‐luciferase reporter gene. Treatment of these clones with phorbol dibutyrate increased AP‐1 activity which peaked at 2–4 h and returned to baseline level by 24 h. In contrast, RA treatment resulted in a slow increase in AP‐1 activity that reached a maximum level at 48 h and was maintained for the duration of the treatment. We tested the importance of the RA‐induced AP‐1 activity by establishing clones which stably express a dominant negative fos gene (A‐fos) and have greatly diminished AP‐1 activity. Growth rates of untreated A‐fos expressing cells were similar to wt B16 and clones not expressing A‐fos. However, clones expressing the dominant‐negative fos had a markedly decreased sensitivity to RA‐induced inhibition of anchorage‐dependent and ‐independent growth. Treatment of wt B16 cells for 48 h with RA increased melanin production by two to fourfold, but this effect was completely lost in the A‐fos clones. The ability of RA to induce RARβ and PKCα expression was retained in A‐fos clones, suggesting that A‐fos was not interfering with RAR transcription activation functions. We tested whether the RA‐induced AP‐1 activity might be mediated by the ERK1/2 MAPK pathway. Inhibition of ERK1/2 phosphorylation stimulated AP‐1 activity, which was not additive to that induced by RA. This finding raises the possibility that this MAPK pathway may be a target of retinoid action. Our observations suggest that AP‐1 transcriptional activity induced by RA likely plays an important role in the biological changes mediated by this retinoid in B16 melanoma cells. © 2002 Wiley‐Liss, Inc.
Differential levels of soluble endoglin (CD105) in myeloid malignancies
Authors: Calabrò Luana , Fonsatti Ester , Bellomo Giacomo , Alonci Andrea , Colizzi Francesca , Sigalotti Luca , Altomonte Maresa , Musolino Caterina , Maio Michele 
Published: December 2002

AbstractAngiogenesis contributes to disease progression in solid and hematopoietic malignancies, and endoglin (CD105), a component of the transforming growth factor (TGF)‐β receptor complex, is a powerful marker of neovascularization. Elevated amounts of soluble CD105 (sCD105) have been recently identified in selected solid tumors but no data are available on sCD105 in hematopoietic malignancies. Therefore, levels of sCD105 were investigated in sera of patients with acute myeloid leukemia (AML) (n = 10) or chronic myeloproliferative disorders (CMD) (n = 28), and correlated with those of soluble TGF‐β1 (sTGF‐β1). Dot blot assay detected higher amounts of sCD105 (P < 0.05) both in AML (4.34 ± 2.62 OD/mm2) and in CMD (3.71 ± 2.09 OD/mm2) patients than in healthy subjects (n = 14, 2.38 ± 1.18 OD/mm2). Instead, enzyme‐linked immunosorbent assay (ELISA) identified (P < 0.05) lower and higher levels of sTGF‐β1 in AML (32,017 ± 1,900 pg/ml) and CMD (60,700 ± 19,200 pg/ml) patients, respectively, compared to healthy individuals (n = 11, 47,173 ± 5,443 pg/ml). In essential thrombocythemia (ET) patients with thrombotic episodes, levels of sCD105 were lower (P < 0.05) compared to patients without thrombotic complications, and inversely correlated with those of sTGF‐β1 (r = 0.94). Conversely, amounts of sCD105 directly correlated with levels of sTGF‐β1 (r = 0.74) in ET patients without thrombotic events. Our results show that high levels of sCD105 are present in myeloid malignancies that are characterized by a high cellular proliferation rate, and suggest that an altered balance between sCD105 and sTGF‐β1 might favor disease progression and clinical complications. © 2002 Wiley‐Liss, Inc.
Role of the IGF‐I receptor in the regulation of cell–cell adhesion: Implications in cancer development and progression
Authors: Mauro Loredana , Salerno Michele , Morelli Catia , Boterberg Tom , Bracke Marc E. , Surmacz Eva 
Published: December 2002

AbstractThe insulin‐like growth factor‐I receptor (IGF‐IR) is a ubiquitous multifunctional tyrosine kinase that has an important role in normal cell growth and development. However, abnormal stimulation of IGF‐IR signaling has been implicated in the development of different types of tumors. The strong antiapoptotic activity of IGF‐IR has been recognized as critical in IGF‐I‐dependent tumorigenesis, however, the impact of other IGF‐IR functions, such as regulation of cell–cell and cell–matrix adhesion are also increasingly acknowledged. Here, on the model of breast cancer cells, we discuss how IGF‐IR‐dependent regulation of intercellular adhesion may affect cell survival, resistance to antiestrogens, and invasion. © 2002 Wiley‐Liss, Inc.
HOX gene network is involved in the transcriptional regulation of in vivo human adipogenesis
Authors: Cantile Monica , Procino Alfredo , D'armiento Maria , Cindolo Luca , Cillo Clemente 
Published: December 2002

AbstractAdipogenesis is regulated by the sequential activation of a series of transcription factors: the C/EBP proteins of type β and δ trigger the process while PPARγ and C/EBPα induce the differentiation from pre‐adipocyte to adipocyte, followed by adipo‐specific gene expression. A number of observations suggest the involvement of genes controlling embryonal development in adipogenesis. In human thyroid follicular carcinoma, it has been recently identified an oncogenetic fusion protein resulting from the interaction between the isoform PPARγ1 of PPARγ and the homeoprotein encoded by the PAX‐8 gene. Recent observations have pointed out that gene expression associated with adipocyte differentiation in vivo and in vitro, although partially overlapping, is actually different. HOX genes make up a network of transcription factors (homeoproteins) controlling embryonal development as well as crucial functions of adult eukaryotic cells. The molecular organization of this network of 39 genes appears to be unique in the genome and probably acts regulating phenotypic cell identity. In the present study we have analyzed the expression of the complete HOX gene network, in vivo, in different deposits of human white adipose tissue and in embryonal brown adipose tissues. Most of the genes in the HOX network are active in white as well as brown adipose tissue. Furthermore HOX genes display a deposit‐specific expression in white adipose tissue. Moreover, expression of the paralogous group 4 genes (HOX A4, HOX B4, HOX C4, and HOX D4), together with that of isolated genes in the network, appears to discriminate between white and brown adipose tissue. This data allows us to postulate the involvement of the HOX network in transcriptional regulation of human adipogenesis and to hypothesize on the molecular mechanisms that could be implicated. © 2002 Wiley‐Liss, Inc.
Fluid shear stress inhibits TNF‐α‐induced apoptosis in osteoblasts: A role for fluid shear stress‐induced activation of PI3‐kinase and inhibition of caspase‐3
Authors: Pavalko Fredrick M. , Gerard Rita L. , Ponik Suzanne M. , Gallagher Patricia J. , Jin Yijun , Norvell Suzanne M. 
Published: December 2002

AbstractIn bone, a large proportion of osteoblasts, the cells responsible for deposition of new bone, normally undergo programmed cell death (apoptosis). Because mechanical loading of bone increases the rate of new bone formation, we hypothesized that mechanical stimulation of osteoblasts might increase their survival. To test this hypothesis, we investigated the effects of fluid shear stress (FSS) on osteoblast apoptosis using three osteoblast cell types: primary rat calvarial osteoblasts (RCOB), MC3T3‐E1 osteoblastic cells, and UMR106 osteosarcoma cells. Cells were treated with TNF‐α in the presence of cyclohexamide (CHX) to rapidly induce apoptosis. Osteoblasts showed significant signs of apoptosis within 4–6 h of exposure to TNF‐α and CHX, and application of FSS (12 dyne/cm2) significantly attenuated this TNF‐α‐induced apoptosis. FSS activated PI3‐kinase signaling, induced phosphorylation of Akt, and inhibited TNF‐α‐induced activation of caspase‐3. Inhibition of PI3‐kinase, using LY294002, blocked the ability of FSS to rescue osteoblasts from TNF‐α‐induced apoptosis and blocked FSS‐induced inhibition of caspase‐3 activation in osteoblasts treated with TNF‐α. LY294002 did not, however, prevent FSS‐induced phosphorylation of Akt suggesting that activation of Akt alone is not sufficient to rescue cells from apoptosis. This result also suggests that FSS can activate Akt via a PI3‐kinase‐independent pathway. These studies demonstrate for the first time that application of FSS to osteoblasts in vitro results in inhibition of TNF‐α‐induced apoptosis through a mechanism involving activation of PI3‐kinase signaling and inhibition of caspases. FSS‐induced activation of PI3‐kinase may promote cell survival through a mechanism that is distinct from the Akt‐mediated survival pathway. © 2002 Wiley‐Liss, Inc.
SNARE protein degradation upon platelet activation: Calpain cleaves SNAP‐23
Authors: Lai Katharine Crane , Flaumenhaft Robert 
Published: December 2002

AbstractIn order to better understand the molecular mechanisms of platelet granule secretion, we evaluated the effect of activation‐induced degranulation on three functional platelet SNARE proteins, SNAP‐23, VAMP‐3, and syntaxin 4. Initial studies showed that SNAP‐23 is lost upon SFLLRN‐induced platelet activation. Experiments with permeabilized platelets demonstrated that proteolysis of SNAP‐23 was Ca2+‐dependent. Ca2+‐dependent proteolysis of SNAP‐23 was inhibited by the cell‐permeable calpain inhibitors, calpeptin and E‐64d, as well as by the naturally occurring calpain inhibitor, calpastatin. In addition, purified calpain cleaved SNAP‐23 in permeabilized platelets in a dose‐dependent manner. In intact platelets, calpeptin prevented SFLLRN‐induced degradation of SNAP‐23. In contrast, calpeptin did not prevent SFLLRN‐induced degradation of VAMP‐3 and syntaxin 4 did not undergo substantial proteolysis following platelet activation. Calpain‐induced cleavage of SNAP‐23 was a late event occurring between 2.5 and 5 min following exposure of permeabilized platelets to Ca2+. Experiments evaluating platelet α‐granule secretion demonstrated that incubation of permeabilized platelets with 10 μM Ca2+ prior to exposure to ATP inhibited ATP‐dependent α‐granule secretion from permeabilized platelets. SNAP‐23 was cleaved under these conditions. Incubation of permeabilized platelets with either calpeptin or calpastatin prevented Ca2+‐mediated degradation of SNAP‐23 and reversed Ca2+‐mediated inhibition of ATP‐dependent α‐granule secretion. Thus, activation of calpain prior to secretion results in loss of SNAP‐23 and inhibits α‐granule secretion. These studies suggest a mechanism whereby calpain activation serves to localize platelet secretion to areas of thrombus formation. © 2002 Wiley‐Liss, Inc.
Quantitative and qualitative adaptation of skeletal muscle mitochondria to increased physical activity
Authors: Zoll Joffrey , Koulmann Nathalie , Bahi Lahoucine , Ventura‐Clapier Renée , Bigard André‐Xavier 
Published: December 2002

AbstractEndurance capacity rely on high muscle oxidative capacity but should also involve a tighter coupling between energy production and utilization within the myocyte. The present study examined the responses of muscle oxidative capacity and the regulation of oxidative phosphorylation by phosphate acceptors in locomotor muscles of voluntary running rats (n = 8), using saponin permeabilized fibers of the deep and superficial parts of plantaris muscle (dPLA and sPLA, respectively). Non‐ADP stimulated respiration of skinned fibers increased by 33% (P < 0.05) and 100% (P < 0.001) in sPLA and dPLA, respectively. The maximal ADP‐stimulated respiration was 57% (P < 0.001) and 32% (P < 0.01) higher in active rats than in sedentary rats (n = 8), in sPLA and dPLA, respectively. This finding was consistent with a 72% increase in the CS activity in plantaris muscle of exercising rats (P < 0.01). Voluntary running induced a 334% increase in the apparent Km for ADP in sPLA (P < 0.001), and a 61% increase in dPLA (P < 0.05), showing a lower affinity for cytosolic ADP of mitochondria present in both, predominantly glycolytic, and oxidative fibers. There was an increase in the creatine kinase efficacy in both sPLA and dPLA (131%, 75%, P < 0.001, respectively), consistent with an increase in the activity of the mitochondrial isoform of creatine kinase (106%, P < 0.01). It is concluded that, in addition to the well‐known increased oxidative capacity, voluntary running is associated with changes in the regulation of oxidative phosphorylation by phosphate acceptors, in both glycolytic and oxidative fibers, in the direction of increased coupling between energy production and energy utilization. © 2002 Wiley‐Liss, Inc.
Current Literature in Journal of Mass Spectrometry
Authors:   John Wiley & Sons, Ltd.
Published: December 2002

AbstractIn order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Books, Reviews & Symposia; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (4 Weeks journals ‐ Search completed at 18th. Sept. 2002)
A new external EI/CI source–ion trap system devoted to the study of ion‐molecule reactions
Authors: Pace Giuseppe , Seraglia Roberta , Cacace Fulvio , Petris Giulia de , Traldi Pietro 
Published: December 2002

AbstractA new instrumental arrangement dedicated to the study of ion‐molecule reactions and consists of by an electron impact/chemical ionization source mounted 420 mm away from an ion trap is described. It has been designed and developed to exclude diffusion into the ion trap of the neutral reactants from the EI/CI source and so to avoid undesired side‐reactions. Its instrumental parameterization is described and some preliminary results are illustrated that show promise for the successful application of the system to the study of ion‐molecule reactions. Copyright © 2002 John Wiley & Sons, Ltd.
Gas‐phase ion chemistry in the ternary SiH4–C3H6–NH3 system
Authors: Calderan Stefania , Carbone Paola , Operti Lorenza , Rabezzana Roberto , Vaglio Gian Angelo 
Published: December 2002

AbstractThe gas‐phase ion chemistry of propene–ammonia and silane–propene–ammonia mixtures was studied by ion trap mass spectrometry. As far as the binary mixture is concerned, the effect of different molar ratios of the reactants on the trend of ion species formed was evaluated, the ion–molecule reaction processes were identified and the rate constants for the main processes were measured. The results were compared with the collisional rate constants to determine the reaction efficiencies. In the ternary silane–propene–ammonia mixture the mechanisms of formation of SimCnNpHq+ clusters were elucidated and the rate constants of the most important steps were measured. For some species, selected by double isolation (MS/MS), the low abundance of the ions allowed us to determine the reaction paths but not the rate constants. Ternary ions are mainly formed by reactions of SimCnHq+ ions with ammonia, whereas a minor contribution comes from reactions of SimNpHq+ ions with propene. On the other hand, the CnNpHq+ ions showed a very low reactivity and no step leading to ternary ion species was identified. The formation of hydrogenated ternary ions with Si, C and N has a basic importance in relation to their possible role as precursors of amorphous silicon carbides doped with nitrogen obtained by deposition from silane–propene–ammonia mixtures properly activated. Copyright © 2002 John Wiley & Sons, Ltd.
Capillary electrophoresis/mass spectrometry: a promising tool for the control of some physiologically hazardous compounds. I—Derivatives of 3‐quinuclidinol
Authors: Bednář Petr , Lemr Karel , Barták Petr , Ševčík Juraj , Hlaváč Jan , Stýskala Jakub , Wiedermannová Iveta , Stránský Zdeněk 
Published: December 2002

AbstractA method based on the coupling of capillary electrophoresis with mass spectrometry (CE/MS) was developed for the monitoring of 3‐quinuclidinol and its four N‐alkyl derivatives (methyl, ethyl, propyl and isopropyl derivatives). A fragmentation study (collision‐induced dissociation of ions in an ion trap) and optimization of the ion optics set‐up for CE/MS experiments using direct infusion of a methanolic solution of the standards into the mass spectrometer were carried out in advance. Molecular ions of all quaternary compounds and the quasi‐molecular ion [M + H]+ of free 3‐quinuclidinol prevail in the mass spectra. In the MS/MS of propyl and isopropyl derivatives, the elimination of the alkyl chain dominates, leading to the ion at m/z 128. The fragmentation of the other compounds is more complex. Previous CE separation of the mixture of isobaric propyl and isopropyl derivatives is necessary for their unambiguous identification. A 10 mM ammonium acetate buffer (pH 4.0) is the optimum running electrolyte, allowing the CE separation of methyl, ethyl, propyl and isopropyl derivatives. A 0.5% (v/v) solution of acetic acid in methanol provides sufficient detection sensitivity when used as the sheath liquid. Limits of detection of 0.1 ppm for 3‐quinuclidinol and 0.05 ppm for quaternary derivatives were achieved under the optimum conditions. The optimized method was applied to the determination of 3‐quinuclidinol and related quaternary derivatives spiked into a sample of pond water. The experimental set‐up for CE/MS/MS was investigated, which strongly increases the identification capability of the technique. Copyright © 2002 John Wiley & Sons, Ltd.
Detoxification of cytotoxic α,β‐unsaturated aldehydes by carnosine: characterization of conjugated adducts by electrospray ionization tandem mass spectrometry and detection by liquid chromatography/mass spectrometry in rat skeletal muscle
Authors: Aldini Giancarlo , Granata Paola , Carini Marina 
Published: December 2002

AbstractOxidation of polyunsaturated fatty acids containing phospholipids in tissue generates lipid hydroperoxides, which are further degraded to several products, among which unsaturated aldehydes such as 4‐hydroxy‐trans‐2‐nonenal (HNE) play an important role in mediating the pathological effects of oxidative stress. While the reaction of HNE with glutathione (GSH) is a well recognized pathway of detoxification in biological systems, no data are available on HNE interactions with carnosine, a dipeptide (β‐alanyl‐L‐histidine) present in high concentration in skeletal muscle. The aim of this work was to study the quenching ability of carnosine towards HNE and to characterize the reaction products by electrospray ionization tandem mass spectrometry (ESI‐MS/MS), using GSH as a model peptide. GSH incubation with HNE in 1 mM phosphate buffer (pH 7.4) results in the complete disappearance of HNE within 1 h owing to the formation of a Michael adduct, S‐(4‐hydroxynonanal‐3‐yl)glutathione. The reaction of HNE with carnosine was studied in different molar ratios and monitored up to 24 h by high‐performance liquid chromatography (HPLC) (HNE consumption), MS/MS (infusion) and liquid chromatography mass spectrometry (LC/MS) experiments. Carnosine, although less reactive than GSH, significantly quenched HNE (48.2 ± 0.9% HNE consumption after 1 h; carnosine:HNE molar ratio 10 : 1). Two reaction products were identified: the Michael adduct, N‐(4‐hydroxynonanal‐3‐yl)carnosine involving the imidazolic nitrogen of histidine, and the imine adduct, involving the amino group of the β‐alanine residue. Definitive structure assignment was achieved by chemical reduction with NaBH4 and multinuclear magnetic resonance experiments. To understand whether carnosine acts as a quencher of unsaturated aldehydes in biological matrices, rat skeletal muscle homogenate was incubated with HNE and the formation of conjugated adducts was determined by LC/MS analysis. Three main products were detected and identified as Michael adducts of HNE with GSH, carnosine and anserine (the N‐methylated derivative of carnosine, present in high concentrations in rat muscle). The results indicate that beside GSH, histidine‐containing dipeptides could be involved in the detoxification pathway of reactive aldehydes from lipid peroxidation generated in skeletal muscle during physical endurance. Copyright © 2002 John Wiley & Sons, Ltd.