bluuebunny/crossref_metadata_2025 huggingface dataset:
The Heterotrimeric Protein Go Is Required for the Formation of Heart Epithelium in Drosophila
Authors: Frémion F. , Astier M. , Zaffran S. , Guillèn A. , Homburger V. , Sémériva M.
Published: July 2002

The gene encoding the α subunit of the Drosophila Go protein is expressed early in embryogenesis in the precursor cells of the heart tube, of the visceral muscles, and of the nervous system. This early expression coincides with the onset of the mesenchymal-epithelial transition to which are subjected the cardial cells and the precursor cells of the visceral musculature. This gene constitutes an appropriate marker to follow this transition. In addition, a detailed analysis of its expression suggests that the cardioblasts originate from two subpopulations of cells in each parasegment of the dorsal mesoderm that might depend on the wingless and hedgehog signaling pathways for both their determination and specification.

In the nervous system, the expression of Goα shortly precedes the beginning of axonogenesis.

Mutants produced in the Goα gene harbor abnormalities in the three tissues in which the gene is expressed. In particular, the heart does not form properly and interruptions in the heart epithelium are repeatedly observed, henceforth the brokenheart (bkh) name. Furthermore, in the bkh mutant embryos, the epithelial polarity of cardial cells was not acquired (or maintained) in various places of the cardiac tube. We predict that bkh might be involved in vesicular traffic of membrane proteins that is responsible for the acquisition of polarity.
Yeast Bim1p Promotes the G1-specific Dynamics of Microtubules
Authors: Tirnauer Jennifer S. , O'Toole Eileen , Berrueta Lisbeth , Bierer Barbara E. , Pellman David
Published: July 2002

Microtubule dynamics vary during the cell cycle, and microtubules appear to be more dynamic in vivo than in vitro. Proteins that promote dynamic instability are therefore central to microtubule behavior in living cells. Here, we report that a yeast protein of the highly conserved EB1 family, Bim1p, promotes cytoplasmic microtubule dynamics specifically during G1. During G1, microtubules in cells lacking BIM1 showed reduced dynamicity due to a slower shrinkage rate, fewer rescues and catastrophes, and more time spent in an attenuated/paused state. Human EB1 was identified as an interacting partner for the adenomatous polyposis coli (APC) tumor suppressor protein. Like human EB1, Bim1p localizes to dots at the distal ends of cytoplasmic microtubules. This localization, together with data from electron microscopy and a synthetic interaction with the gene encoding the kinesin Kar3p, suggests that Bim1p acts at the microtubule plus end. Our in vivo data provide evidence of a cell cycle–specific microtubule-binding protein that promotes microtubule dynamicity.
Roles for α2p24 and COPI in Endoplasmic Reticulum Cargo Exit Site Formation
Authors: Lavoie C. , Paiement J. , Dominguez M. , Roy L. , Dahan S. , Gushue J.N. , Bergeron J.J.M.
Published: July 2002

A two-step reconstitution system for the generation of ER cargo exit sites from starting ER-derived low density microsomes (LDMs; 1.17 g/cc) is described. The first step is mediated by the hydrolysis of Mg2+ATP and Mg2+GTP, leading to the formation of a transitional ER (tER) with the soluble cargo albumin, transferrin, and the ER-to-Golgi recycling membrane proteins α2p24 and p58 (ERGIC-53, ER-Golgi intermediate compartment protein) enriched therein. Upon further incubation (step two) with cytosol and mixed nucleotides, interconnecting smooth ER tubules within tER transforms into vesicular tubular clusters (VTCs). The cytosolic domain of α2p24 and cytosolic COPI coatomer affect VTC formation. This is deduced from the effect of antibodies to the COOH-terminal tail of α2p24, but not of antibodies to the COOH-terminal tail of calnexin on this reconstitution, as well as the demonstrated recruitment of COPI coatomer to VTCs, its augmentation by GTPγS, inhibition by Brefeldin A (BFA), or depletion of β-COP from cytosol. Therefore, the p24 family member, α2p24, and its cytosolic coat ligand, COPI coatomer, play a role in the de novo formation of VTCs and the eneration of ER cargo exit sites.
Human Cyclin a Is Required for Mitosis until Mid Prophase
Authors: Furuno Nobuaki , den Elzen Nicole , Pines Jonathon
Published: July 2002

We have used microinjection and time-lapse video microscopy to study the role of cyclin A in mitosis. We have injected purified, active cyclin A/cyclin-dependent kinase 2 (CDK2) into synchronized cells at specific points in the cell cycle and assayed its effect on cell division. We find that cyclin A/CDK2 will drive G2 phase cells into mitosis within 30 min of microinjection, up to 4 h before control cells enter mitosis. Often this premature mitosis is abnormal; the chromosomes do not completely condense and daughter cells fuse. Remarkably, microinjecting cyclin A/CDK2 into S phase cells has no effect on progress through the following G2 phase or mitosis. In complementary experiments we have microinjected the amino terminus of p21Cip1/Waf1/Sdi1 (p21N) into cells to inhibit cyclin A/CDK2 activity. We find that p21N will prevent S phase or G2 phase cells from entering mitosis, and will cause early prophase cells to return to interphase. These results suggest that cyclin A/CDK2 is a rate-limiting component required for entry into mitosis, and for progress through mitosis until late prophase. They also suggest that cyclin A/CDK2 may be the target of the recently described prophase checkpoint.
Regulation of Hmg-Coa Reductase Degradation Requires the P-Type Atpase Cod1p/Spf1p
Authors: Cronin Stephen R. , Khoury Afif , Ferry Dana K. , Hampton Randolph Y.
Published: July 2002

The integral ER membrane protein HMG-CoA reductase (HMGR) is a key enzyme of the mevalonate pathway from which sterols and other essential molecules are produced. HMGR degradation occurs in the ER and is regulated by mevalonate-derived signals. Little is known about the mechanisms responsible for regulating HMGR degradation. The yeast Hmg2p isozyme of HMGR undergoes regulated degradation in a manner very similar to mammalian HMGR, allowing us to isolate mutants deficient in regulating Hmg2p stability. We call these mutants cod mutants for the control of HMG-CoA reductase degradation. With this screen, we have identified the first gene of this class, COD1, which encodes a P-type ATPase and is identical to SPF1. Our data suggested that Cod1p is a calcium transporter required for regulating Hmg2p degradation. This role for Cod1p is distinctly different from that of the well-characterized Ca2+ P-type ATPase Pmr1p which is neither required for Hmg2p degradation nor its control. The identification of Cod1p is especially intriguing in light of the role Ca2+ plays in the regulated degradation of mammalian HMGR.
Phosphorylation of Tyrosine Residues 31 and 118 on Paxillin Regulates Cell Migration through an Association with Crk in Nbt-II Cells
Authors: Petit Valérie , Boyer Brigitte , Lentz Delphine , Turner Christopher E. , Thiery Jean Paul , Vallés Ana M.
Published: July 2002

Identification of signaling molecules that regulate cell migration is important for understanding fundamental processes in development and the origin of various pathological conditions. The migration of Nara Bladder Tumor II (NBT-II) cells was used to determine which signaling molecules are specifically involved in the collagen-mediated locomotion. We show here that paxillin is tyrosine phosphorylated after induction of motility on collagen. Overexpression of paxillin mutants in which tyrosine 31 and/or tyrosine 118 were replaced by phenylalanine effectively impaired cell motility. Moreover, stimulation of motility by collagen preferentially enhanced the association of paxillin with the SH2 domain of the adaptor protein CrkII. Mutations in both tyrosine 31 and 118 diminished the phosphotyrosine content of paxillin and prevented the formation of the paxillin–Crk complex, suggesting that this association is necessary for collagen-mediated NBT-II cell migration. Other responses to collagen, such as cell adhesion and spreading, were not affected by these mutations. Overexpression of wild-type paxillin or Crk could bypass the migration-deficient phenotype. Both the SH2 and the SH3 domains of CrkII are shown to play a critical role in this collagen-mediated migration. These results demonstrate the important role of the paxillin–Crk complex in the collagen-induced cell motility.
Indications for a Novel Muscular Dystrophy Pathway
Authors: van der Ven Peter F.M. , Wiesner Sebastian , Salmikangas Paula , Auerbach Daniel , Himmel Mirko , Kempa Stefan , Hayeß Katrin , Pacholsky Dirk , Taivainen Anu , Schröder Rolf , Carpén Olli , Fürst Dieter O.
Published: July 2002

γ-Filamin, also called ABP-L, is a filamin isoform that is specifically expressed in striated muscles, where it is predominantly localized in myofibrillar Z-discs. A minor fraction of the protein shows subsarcolemmal localization. Although γ-filamin has the same overall structure as the two other known isoforms, it is the only isoform that carries a unique insertion in its immunoglobulin (Ig)-like domain 20. Sequencing of the genomic region encoding this part of the molecule shows that this insert is encoded by an extra exon. Transient transfections of the insert-bearing domain in skeletal muscle cells and cardiomyocytes show that this single domain is sufficient for targeting to developing and mature Z-discs. The yeast two-hybrid method was used to identify possible binding partners for the insert-bearing Ig-like domain 20 of γ-filamin. The two Ig-like domains of the recently described α-actinin–binding Z-disc protein myotilin were found to interact directly with this filamin domain, indicating that the amino-terminal end of γ-filamin may be indirectly anchored to α-actinin in the Z-disc via myotilin. Since defects in the myotilin gene were recently reported to cause a form of autosomal dominant limb-girdle muscular dystrophy, our findings provide a further contribution to the molecular understanding of this disease.
Hcp-4, a Cenp-C–Like Protein inCaenorhabditis elegans, Is Required for Resolution of Sister Centromeres
Authors: Moore Landon L. , Roth Mark B.
Published: July 2002

The centromere plays a critical role in the segregation of chromosomes during mitosis. In mammals, sister centromeres are resolved from one another in the G2 phase of the cell cycle. During prophase, chromosomes condense with sister centromeres oriented in a back to back configuration enabling only one chromatid to be captured by each half spindle. To study this process, we identified a centromere protein (CENP)-C–like protein, holocentric protein (HCP)-4, in Caenorhabditis elegans based on sequence identity, loss of function phenotype, and centromeric localization. HCP-4 is found in the cytoplasm during interphase, but is nuclear localized in mitosis, where it localizes specifically to the centromere. The localization of HCP-4 to the centromere is dependent on the centromeric histone HCP-3; in addition, HCP-3 and HCP-4 are both required for localization of a CENP-F–like protein, HCP-1, indicating an ordered assembly pathway. Loss of HCP-4 expression by RNA-mediated interference resulted in a failure to generate resolution of sister centromeres on chromosomes, suggesting that HCP-4 is required for sister centromere resolution. These chromosomes also failed to form a functional kinetochore. Thus, the CENP-C–like protein HCP-4 is essential for both resolution sister centromeres and attachment to the mitotic spindle.
Keratin attenuates tumor necrosis factor–induced cytotoxicity through association with TRADD
Authors: Inada Hiroyasu , Izawa Ichiro , Nishizawa Miwako , Fujita Eriko , Kiyono Tohru , Takahashi Toshitada , Momoi Takashi , Inagaki Masaki
Published: July 2002

Keratin 8 and 18 (K8/18) are the major components of intermediate filament (IF) proteins of simple or single-layered epithelia. Recent data show that normal and malignant epithelial cells deficient in K8/18 are nearly 100 times more sensitive to tumor necrosis factor (TNF)–induced cell death. We have now identified human TNF receptor type 1 (TNFR1)–associated death domain protein (TRADD) to be the K18-interacting protein. Among IF proteins tested in two-hybrid systems, TRADD specifically bound K18 and K14, type I (acidic) keratins. The COOH-terminal region of TRADD interacted with the coil Ia of the rod domain of K18. Endogenous TRADD coimmunoprecipitated with K18, and colocalized with K8/18 filaments in human mammary epithelial cells. Overexpression of the NH2 terminus (amino acids 1–270) of K18 containing the TRADD-binding domain as well as overexpression of K8/18 in SW13 cells, which are devoid of keratins, rendered the cells more resistant to killing by TNF. We also showed that overexpressed NH2 termini of K18 and K8/18 were associated with endogenous TRADD in SW13 cells, resulting in the inhibition of caspase-8 activation. These results indicate that K18 may sequester TRADD to attenuate interactions between TRADD and activated TNFR1 and moderate TNF-induced apoptosis in simple epithelial cells.
Modulation of substrate adhesion dynamics via microtubule targeting requires kinesin-1
Authors: Krylyshkina Olga , Kaverina Irina , Kranewitter Wolfgang , Steffen Walter , Alonso Maria C. , Cross Robert A. , Small J. Victor
Published: July 2002

Recent studies have shown that the targeting of substrate adhesions by microtubules promotes adhesion site disassembly (Kaverina, I., O. Krylyshkina, and J.V. Small. 1999. J. Cell Biol. 146:1033–1043). It was accordingly suggested that microtubules serve to convey a signal to adhesion sites to modulate their turnover. Because microtubule motors would be the most likely candidates for effecting signal transmission, we have investigated the consequence of blocking microtubule motor activity on adhesion site dynamics. Using a function-blocking antibody as well as dynamitin overexpression, we found that a block in dynein–cargo interaction induced no change in adhesion site dynamics in Xenopus fibroblasts. In comparison, a block of kinesin-1 activity, either via microinjection of the SUK-4 antibody or of a kinesin-1 heavy chain construct mutated in the motor domain, induced a dramatic increase in the size and reduction in number of substrate adhesions, mimicking the effect observed after microtubule disruption by nocodazole. Blockage of kinesin activity had no influence on either the ability of microtubules to target substrate adhesions or on microtubule polymerisation dynamics. We conclude that conventional kinesin is not required for the guidance of microtubules into substrate adhesions, but is required for the focal delivery of a component(s) that retards their growth or promotes their disassembly.
Golgi matrix proteins interact with p24 cargo receptors and aid their efficient retention in the Golgi apparatus
Authors: Barr Francis A. , Preisinger Christian , Kopajtich Robert , Körner Roman
Published: July 2002

The Golgi apparatus is a highly complex organelle comprised of a stack of cisternal membranes on the secretory pathway from the ER to the cell surface. This structure is maintained by an exoskeleton or Golgi matrix constructed from a family of coiled-coil proteins, the golgins, and other peripheral membrane components such as GRASP55 and GRASP65. Here we find that TMP21, p24a, and gp25L, members of the p24 cargo receptor family, are present in complexes with GRASP55 and GRASP65 in vivo. GRASPs interact directly with the cytoplasmic domains of specific p24 cargo receptors depending on their oligomeric state, and mutation of the GRASP binding site in the cytoplasmic tail of one of these, p24a, results in it being transported to the cell surface. These results suggest that one function of the Golgi matrix is to aid efficient retention or sequestration of p24 cargo receptors and other membrane proteins in the Golgi apparatus.
Tolerance to p53 by A2.1-restricted Cytotoxic T Lymphocytes
Authors: Theobald Matthias , Biggs Judith , Hernández Javier , Lustgarten Joseph , Labadie Colleen , Sherman Linda A.
Published: July 2002

Elevated levels of the p53 protein occur in ∼50% of human malignancies, which makes it an excellent target for a broad-spectrum T cell immunotherapy of cancer. A major barrier to the design of p53-specific immunotherapeutics and vaccines, however, is the possibility that T cells may be tolerant of antigens derived from wild-type p53 due to its low level of expression in normal thymus and lymphohemopoetic cells. The combination of p53 deficient (p53−/−) and p53+/+ HLA-A2.1/Kb transgenic mice was used as a model to explore the possibility that A2.1restricted cytotoxic T lymphocytes (CTL) are functionally tolerant of self peptides derived from the wild-type p53 tumor suppressor protein. A2.1-restricted CTL specific for a naturally processed p53 self-epitope spanning residues 187-197 were completely aborted in p53+/+ as opposed to p53−/− transgenic mice. In contrast, CTL specific for a second self-epitope spanning residues 261-269 of the murine p53 sequence were detected in both p53−/− and p53+/+ A2.1/Kb transgenic mice. However, the avidity of the CTL effectors obtained from p53+/+ mice was 10-fold lower than that obtained from p53−/− mice, again suggesting elimination of CTL with high avidity for the A2.1-peptide complex. The circumvention of functional tolerance of high avidity CTL may therefore be a necessary prerequisite for optimizing immunotherapy against A2.1-restricted wild-type p53 epitopes in humans.
Permanent CD8+ T Cell Depletion Prevents Proteinuria in Active Heymann Nephritis
Authors: Penny Mark J. , Boyd Rochelle A. , Hall Bruce M.
Published: July 2002

Active Heymann nephritis (HN) is a rat model of human idiopathic membranous nephropathy in which injury is thought to be mediated by membrane attack complex of complement (MAC) activated by antibody (Ab) to glomerular epithelial cells. Recent work has shown that HN develops in C6-deficient rats which cannot assemble MAC, and that infiltration of activated cytotoxic CD8+ T cells and macrophages into glomeruli coincides with proteinuria. This study examined the role of CD8+ T cells in mediating glomerular injury in HN by permanent CD8+ cytotoxic T cell depletion via adult thymectomy (ATx) and anti-CD8 mAb. Groups of rats were depleted of CD8+ T cells either before immunization for HN or 6 wk after immunization when Ab responses and glomerular IgG deposition were well established. These were compared with groups of HN, ATx/HN, and complete Freund's adjuvant (CFA) controls. Neither group of CD8+ T cell–depleted rats developed proteinuria, although there was normal development and deposition of Ab. CD8+ T cell–depleted rats developed neither T cell or macrophage infiltrates nor their effector cytokines, which are present in glomeruli of rats with HN. Examination of lymph node (LN) draining sites of immunization showed these findings were not explained by altered immune events within these LNs. It was concluded that CD8+ cytotoxic T cells are essential to the mediation of glomerular injury in HN and may be relevant to the pathogenesis and treatment of membranous nephropathy.
Multidrug Resistance Protein 1 Protects the Oropharyngeal Mucosal Layer and the Testicular Tubules against Drug-induced Damage
Authors: Wijnholds Jan , Scheffer George L. , van der  Valk Martin , van der  Valk Paul , Beijnen Jos H. , Scheper Rik J. , Borst Piet
Published: July 2002

The multidrug resistance protein 1 (MRP1) gene encodes a transporter protein that helps to protect cells against xenobiotics. Elevated levels of MRP1 in tumor cells can result in active extrusion of a wide range of (anticancer) drugs with different cellular targets, a phenomenon called multidrug resistance (MDR). To explore the protective function of the mouse mrp1 protein during drug treatment, we investigated the toxicity caused by the anticancer drug etoposide-phosphate (ETOPOPHOS) in mice lacking the mrp1 gene (mrp1−/− mice). We show here that the lack of mrp1 protein results in increased etoposide-induced damage to the mucosa of the oropharyngeal cavity and to the seminiferous tubules of the testis. The high concentrations of mrp1 that we find in the basal layers of the oropharyngeal mucosa and in the basal membrane of the Sertoli cells in the testis apparently protect wild-type mice against this tissue damage. We also find drug-induced polyuria in mrp1−/− mice, which correlates with the presence of mrp1 protein in the urinary collecting tubules, the major site of kidney water reabsorption. Our results indicate that specific inhibitors of MRP1 used to reverse MDR, in combination with carcinostatic drugs transported by MRP1, might lead to drug-induced mucositis, (temporary) infertility, and diabetes insipidus.
Highly Restricted T Cell Repertoire Shaped by a Single Major Histocompatibility Complex–Peptide Ligand in the Presence of a Single Rearranged T Cell Receptor β Chain
Authors: Fukui Yoshinori , Hashimoto Osamu , Inayoshi Ayumi , Gyotoku Takahiro , Sano Tetsuro , Koga Takahiro , Gushima Toshifumi , Sasazuki Takehiko
Published: July 2002

The T cell repertoire is shaped by positive and negative selection of thymocytes through the interaction of α/β-T cell receptors (TCR) with self-peptides bound to self-major histocompatibility complex (MHC) molecules. However, the involvement of specific TCR-peptide contacts in positive selection remains unclear. By fixing TCR-β chains with a single rearranged TCR-β irrelevant to the selecting ligand, we show here that T cells selected to mature on a single MHC–peptide complex express highly restricted TCR-α chains in terms of Vα usage and amino acid residue of their CDR3 loops, whereas such restriction was not observed with those selected by the same MHC with diverse sets of self-peptides including this peptide. Thus, we visualized the TCR structure required to survive positive selection directed by this single ligand. Our findings provide definitive evidence that specific recognition of self-peptides by TCR could be involved in positive selection of thymocytes.
Translation of a Retained Intron in Tyrosinase-related Protein (TRP) 2 mRNA Generates a New Cytotoxic T Lymphocyte (CTL)-defined and Shared Human Melanoma Antigen Not Expressed in Normal Cells of the Melanocytic Lineage
Authors: Lupetti Raffaella , Pisarra Patrizia , Verrecchia Alessandro , Farina Cinthia , Nicolini Gabriella , Anichini Andrea , Bordignon Claudio , Sensi Marialuisa , Parmiani Giorgio , Traversari Catia
Published: July 2002

We report here the identification of a new shared human melanoma antigen recognized by a human leukocyte antigen (HLA)-A*68011–restricted cytotoxic T lymphocyte clone (CTL 128). The cDNA encoding this antigen is composed of a partially spliced form of the melanocyte differentiation antigen tyrosinase-related protein (TRP)-2, containing exons 1–4 with retention of intron 2 and part of intron 4 (TRP-2–INT2). The sequence coding for the antigenic epitope is located at the 5′ end of intron 2 and is available for translation in the same open reading frame of the fully spliced TRP-2 mRNA. This peptide is also recognized by CTL 128 when presented by the HLA-A*3301, a member of the HLA-A3–like supertype that includes the HLA-A*68011. Quantitative reverse transcription PCR analysis carried out on total and/or cytoplasmic mRNA demonstrated that, in contrast to the fully spliced TRP-2 mRNA expressed in melanomas, normal skin melanocytes, and retina, the TRP-2–INT2 mRNA could be detected at significant levels in melanomas but not in normal cells of the melanocytic lineage. Instead, in these normal samples, both the spliced and the unspliced transcript of gp100 were expressed at high levels. Absence of endogenous TRP-2–INT2 expression in melanocytes was also confirmed by lack of recognition of HLA-A*68011–transduced, TRP-2+ melanocyte lines by CTL 128. These results indicate that a partially spliced form of a differentiation antigen mRNA, present in the cytoplasmic compartment of neoplastic but not normal cells of the melanocytic lineage, can be the source of a melanoma-restricted T cell epitope.
The Action of Bax and Bcl-2 on T Cell Selection
Authors: Williams Owen , Norton Trisha , Halligey Mark , Kioussis Dimitris , Brady Hugh J.M.
Published: July 2002

T cell development and selection in the thymus are shaped by the induction of apoptosis. However, a direct role in T cell development and selection for any of the molecules known to regulate apoptosis has remained controversial. We have studied the effect of bax and bcl-2 transgenes in recombination activation gene 1–deficient (RAG-1−/−) mice transgenic for the major histocompatibility complex class I–restricted F5 T cell receptor. Overexpression of a bax transgene in the thymus seriously impairs the production of mature T cells, whereas bcl-2 overexpression greatly promotes it. The effect of bax and bcl-2 overexpression on antigen-induced negative selection was studied using fetal thymic organ cultures. This analysis showed that Bcl-2 strongly inhibits negative selection, whereas Bax does not affect it. Our data directly show that Bcl-2 family members have specific roles in T cell selection and also lend support to the hypothesis that Bax and Bcl-2 can antagonize each other's action in a certain apoptosis pathway while in another they can be functionally nonreciprocal.
Type I Interferon Induces Inhibitory 16-kD CCAAT/ Enhancer Binding Protein (C/EBP)β, Repressing the HIV-1 Long Terminal Repeat in Macrophages: Pulmonary Tuberculosis Alters C/EBP Expression, Enhancing HIV-1 Replication
Authors: Honda Yoshihiro , Rogers Linda , Nakata Koh , Zhao Ben-Yang , Pine Richard , Nakai Yushi , Kurosu Katsushi , Rom William N. , Weiden Michael
Published: July 2002

We have previously observed that HIV-1 replication is suppressed in uninflamed lung and increased during tuberculosis. In vitro THP-1 cell–derived macrophages inhibited HIV-1 replication after infection with Mycobacterium tuberculosis. Suppression of HIV-1 replication was associated with inhibition of the HIV-1 long terminal repeat (LTR) and induction of ISGF-3, a type I interferon (IFN)–specific transcription factor. Repression of the HIV-1 LTR required intact CCAAT/enhancer binding protein (C/EBP) sites. THP-1 cell–derived macrophages infected with M. tuberculosis, lipopolysaccharide, or IFN-β induced the 16-kD inhibitory C/EBPβ isoform and coincidentally repressed HIV-1 LTR transcription. C/EBPβ was the predominant C/EBP family member produced in THP-1 macrophages during HIV-1 LTR repression. In vivo, alveolar macrophages from uninflamed lung strongly expressed inhibitory 16-kD C/EBPβ, but pulmonary tuberculosis abolished inhibitory C/EBPβ expression and induced a novel C/EBP DNA binding protein. Therefore, in vitro, proinflammatory stimulation produces an IFN response inhibiting viral replication by induction of a C/EBPβ transcriptional repressor. THP-1 cell–derived macrophages stimulated with type I IFN are similar to alveolar macrophages in the uninflamed lung in vivo. In contrast, the cellular immune response in active pulmonary tuberculosis disrupts this innate immunity, switching C/EBP expression and allowing high level viral replication.
Grf40, A Novel Grb2 Family Member, Is Involved in T Cell Signaling through Interaction with SLP-76 and LAT
Authors: Asada Hiroshi , Ishii Naoto , Sasaki Yoshiteru , Endo Kazuhiro , Kasai Hirotake , Tanaka Nobuyuki , Takeshita Toshikazu , Tsuchiya Shigeru , Konno Tasuke , Sugamura Kazuo
Published: July 2002

We molecularly cloned a new Grb2 family member, named Grf40, containing the common SH3-SH2-SH3 motif. Expression of Grf40 is predominant in hematopoietic cells, particularly T cells. Grf40 binds to the SH2 domain–containing leukocyte protein of 76 kD (SLP-76) via its SH3 domain more tightly than Grb2. Incidentally, Grf40 binds to linker for activation of T cells (LAT) possibly via its SH2 domain. Overexpression of wild-type Grf40 in Jurkat cells induced a significant increase of SLP-76–dependent interleukin (IL)-2 promoter and nuclear factor of activated T cell (NF-AT) activation upon T cell receptor (TCR) stimulation, whereas the COOH-terminal SH3-deleted Grf40 mutant lacked any recognizable increase in IL-2 promoter activity. Furthermore, the SH2-deleted Grf40 mutant led to a marked inhibition of these regulatory activities, the effect of which is apparently stronger than that of the SH2-deleted Grb2 mutant. Our data suggest that Grf40 is an adaptor molecule involved in TCR-mediated signaling through a more efficient interaction than Grb2 with SLP-76 and LAT.
The Dynamics of Human Cytomegalovirus Replication in Vivo
Authors: Emery Vincent C. , Cope Alethea V. , Bowen E. Frances , Gor Dehila , Griffiths Paul D.
Published: July 2002

Cytomegalovirus (CMV) is generally described as a slowly replicating virus. During studies of immunocompromised patients, we observed rapid changes in the quantity of CMV DNA present in serial blood samples by quantitative-competitive polymerase chain reaction commensurate with a doubling time of <2 d. To further investigate the dynamics of replication in vivo, patients in three distinct situations were studied in detail: (a) those receiving intravenous ganciclovir; (b) those in whom ganciclovir-resistant strains appeared during long-term therapy; and (c) those in whom ganciclovir-resistant strains disappeared with alternative drug therapy. In all cases, it was possible to provide accurate estimates of the doubling time of CMV and its half-life of disappearance after antiviral chemotherapy. The results from all three approaches demonstrated that the doubling time/half-life of CMV in blood is ∼1 d when frequent samples are collected. These results show that CMV DNA replication in vivo is a highly dynamic process. We conclude that the reputation of CMV as a slowly replicating virus based on the time taken to produce cytopathic effects in vitro is unwarranted. These findings have implications for the potency, dose, and duration of antiviral chemotherapy needed for the effective treatment of this important human pathogen.
Identical T Cell Clones Are Located within the Mouse Gut Epithelium and Lamina Propria and Circulate in the Thoracic Duct Lymph
Authors: Arstila Tuula , Arstila T. Petteri , Calbo Sébastien , Selz Françoise , Malassis-Seris Michèle , Vassalli Pierre , Kourilsky Philippe , Guy-Grand Delphine
Published: July 2002

Murine gut intraepithelial (IEL) T cell receptor (TCR)-α/β1 lymphocytes bearing CD8α/β or CD8α/α coreceptors have been shown previously to express different oligoclonal TCR β chain repertoires in the same mouse, in agreement with other evidence indicating that these two populations belong to different ontogenic lineages, with only CD8α/β1 IELs being fully thymus dependent. CD8α/β1, but not CD8α/α1, T lymphocytes are also present in the lamina propria. Here, we show that CD8α/β+ lymphocytes from the lamina propria and the epithelium are both oligoclonal, and that they share the same TCR-β clonotypes in the same mouse, as is also the case for CD4+ T cells. Furthermore, identical T cell clones were detected among CD8α/β1 IELs and CD8α/β1 blasts circulating into the thoracic duct (TD) lymph of the same mouse, whereas TD small lymphocytes are polyclonal. These findings must be considered in light of previous observations showing that T blasts, but not small T lymphocytes, circulating in the TD lymph have the capacity of homing into the gut epithelium and lamina propria. These combined observations have interesting implications for our understanding of the recirculation of gut thymus-dependent lymphocytes and their precursors, and of the events leading up to the selection of their restricted TCR repertoire.
Reversal of Spontaneous Autoimmune Insulitis in Nonobese Diabetic Mice by Soluble Lymphotoxin Receptor
Authors: Wu Qiang , Salomon Benoît , Chen Min , Wang Yang , Hoffman Lisa M. , Bluestone Jeffrey A. , Fu Yang-Xin
Published: July 2002

One striking feature of spontaneous autoimmune diabetes is the prototypic formation of lymphoid follicular structures within the pancreas. Lymphotoxin (LT) has been shown to play an important role in the formation of lymphoid follicles in the spleen. To explore the potential role of LT-mediated microenvironment in the pathogenesis of insulin-dependent diabetes mellitus (IDDM), an LTβ receptor–immunoglobulin fusion protein (LTβR–Ig) was administered to nonobese diabetic mice. Early treatment with LTβR–Ig prevented insulitis and IDDM, suggesting that LT plays a critical role in the insulitis development. LTβR–Ig treatment at a late stage of the disease also dramatically reversed insulitis and prevented diabetes. Moreover, LTβR–Ig treatment prevented the development of IDDM by diabetogenic T cells in an adoptive transfer model. Thus, LTβR–Ig can disassemble the well established lymphoid microenvironment in the islets, which is required for the development and progression of IDDM.
Mannose Receptor Is a Novel Ligand for L-Selectin and Mediates Lymphocyte Binding to Lymphatic Endothelium
Authors: Irjala Heikki , Johansson Eva-Liz , Grenman Reidar , Alanen Kalle , Salmi Marko , Jalkanen Sirpa
Published: July 2002

Continuous lymphocyte recirculation between blood and lymphoid tissues forms a basis for the function of the immune system. Lymphocyte entrance from the blood into the tissues has been thoroughly characterized, but mechanisms controlling lymphocyte exit from the lymphoid tissues via efferent lymphatics have remained virtually unknown. In this work we have identified mannose receptor (MR) on human lymphatic endothelium and demonstrate its involvement in binding of lymphocytes to lymphatic vessels. We also show that the binding requires L-selectin, and L-selectin and MR form a receptor–ligand pair. On the other hand, L-selectin binds to peripheral lymph node addressins (PNAds) on high endothelial venules (HEVs) that are sites where lymphocytes enter the lymphatic organs. Interestingly, MR is absent from HEVs and PNAds from lymphatic endothelium. Thus, lymphocyte L-selectin uses distinct ligand molecules to mediate binding at sites of lymphocyte entrance and exit within lymph nodes. Taken together, interaction between L-selectin and MR is the first molecularly defined mechanism mediating lymphocyte binding to lymphatic endothelium.
Tumor Necrosis Factor–dependent Segmental Control of MIG Expression by High Endothelial Venules in Inflamed Lymph Nodes Regulates Monocyte Recruitment
Authors: Janatpour Mary J. , Hudak Susan , Sathe Manjiri , Sedgwick Jonathon D. , McEvoy Leslie M.
Published: July 2002

Monocytes recruited from the blood are key contributors to the nature of an immune response. While monocyte recruitment in a subset of immunopathologies has been well studied and largely attributed to the chemokine monocyte chemoattractant protein (MCP)-1, mechanisms mediating such recruitment to other sites of inflammation remain elusive. Here, we showed that localized inflammation resulted in an increased binding of monocytes to perifollicular high endothelial venules (HEVs) of lymph nodes draining a local inflammatory site. Quantitative PCR analyses revealed the upregulation of many chemokines in the inflamed lymph node, including MCP-1 and MIG. HEVs did not express detectable levels of MCP-1; however, a subset of HEVs in inflamed lymph nodes in wild-type (but not tumor necrosis factor [TNF] null mice) expressed MIG and this subset of HEVs preferentially supported monocyte binding. Expression of CXCR3, the receptor for MIG, was detected on a small subset of peripheral blood monocytes and on a significant percentage of recruited monocytes. Most importantly, in both ex vivo and in vivo assays, neutralizing anti-MIG antibodies blocked monocyte binding to inflamed lymph node HEVs. Together, these results suggest that the lymph node microenvironment can dictate the nature of molecules expressed on HEV subsets in a TNF-dependent fashion and that inflammation-induced MIG expression by HEVs can mediate monocyte recruitment.
Plasmodium falciparum Phospholipase C Hydrolyzing Sphingomyelin and Lysocholinephospholipids Is a Possible Target for Malaria Chemotherapy
Authors: Hanada Kentaro , Palacpac Nirianne Marie Q. , Magistrado Pamela A. , Kurokawa Ken , Rai Ganesh , Sakata Daiji , Hara Tomoko , Horii Toshihiro , Nishijima Masahiro , Mitamura Toshihide
Published: July 2002

Sphingomyelinase (SMase) is one of the principal enzymes in sphingomyelin (SM) metabolism. Here, we identified a Plasmodium falciparum gene (PfNSM) encoding a 46-kD protein, the amino acid sequence of which is ∼25% identical to that of bacteria SMases. Biochemical analyses of the recombinant protein GST-PfNSM, a fusion protein of the PfNSM product with glutathione-S-transferase, reveal that this enzyme retained similar characteristics in various aspects to SMase detected in P. falciparum–infected erythrocytes and isolated parasites. In addition, the recombinant protein retains hydrolyzing activity not only of SM but also of lysocholinephospholipids (LCPL) including lysophosphatidylcholine and lysoplatelet-activating factor, indicating that PfNSM encodes SM/LCPL-phospholipase C (PLC). Scyphostatin inhibited SM/LCPL-PLC activities of the PfNSM product as well as the intraerythrocytic proliferation of P. falciparum in a dose-dependent manner with ID50 values for SM/LCPL-PLC activities and the parasite growth at 3–5 μM and ∼7 μM, respectively. Morphological analysis demonstrated most severe impairment in the intraerythrocytic development with the addition of scyphostatin at trophozoite stage than at ring or schizont stages, suggesting its effect specifically on the stage progression from trophozoite to schizont, coinciding with the active transcription of PfNSM gene.
A Unique Subset of Self-specific Intraintestinal T Cells Maintains Gut Integrity
Authors: Poussier Philippe , Ning Terri , Banerjee Diponkar , Julius Michael
Published: July 2002

Lymphocytes residing in the intestinal epithelium are exclusively T cells and account for one of the largest collection of T cells in the organism. However, their function remains obscure. We and others have shown that the development of intestinal intraepithelial T cells is compromised in mutant mice prone to chronic intestinal inflammation. These results led us to directly assess their role in regulating the development of colitis secondary to transfer of primary splenic TCRαβ+CD4+CD45RBhi T cells into severe combined immunodeficiency (SCID) mice. Here we demonstrate that prior reconstitution of SCID recipients with intraintestinal TCRαβ+CD4−CD8α+β− T cells prevents disease, and does so in an interleukin (IL)-10–dependent fashion. In contrast, reconstitution with either TCRγδ+ or TCRαβ+CD4− CD8α+β+ intestinal T cells did not prevent colitis. TCRαβ+CD4−8α+β− T cells are unique to the intestinal epithelium of both rodents and humans. Previous repertoire analyses of TCRαβ+CD4−CD8α+β− T cells revealed a high proportion of cells expressing high affinity, self-specific TCR within this subset. We demonstrate that monoclonal, self specific TCRαβ+CD4−CD8α+β− cells derived from TCR transgenic mice also prevent the onset of colitis. Thus, intestinal TCRαβ+CD4−CD8α+β− T cells, selected based on their self-reactivity, maintain gut integrity in a IL-10–dependent fashion.
Plasma Membrane Water Permeability of Cultured Cells and Epithelia Measured by Light Microscopy with Spatial Filtering
Authors: Farinas Javier , Kneen Malea , Moore Megan , Verkman A.S.
Published: July 2002

A method was developed to measure the osmotic water permeability (Pf) of plasma membranes in cell layers and applied to cells and epithelia expressing molecular water channels. It was found that the integrated intensity of monochromatic light in a phase contrast or dark field microscope was dependent on relative cell volume. For cells of different size and shape (Sf9, MDCK, CHO, A549, tracheal epithelia, BHK), increased cell volume was associated with decreased signal intensity; generally the signal decreased 10–20% for a twofold increase in cell volume. A theory relating signal intensity to relative cell volume was developed based on spatial filtering and changes in optical path length associated with cell volume changes. Theory predictions were confirmed by signal measurements of cell layers bathed in solutions of various osmolarities and refractive indices. The excellent signal-to-noise ratio of the transmitted light detection permitted measurement of cell volume changes of <1%. The method was applied to characterize transfected cells and tissues that natively express water channels. Pf in control Chinese hamster ovary cells was low (0.0012 cm/s at 23°C) and increased more than fourfold upon stable transfection with aquaporins 1, 2, 4, or 5. Pf in apical and basolateral membranes in polarized epithelial cells grown on porous supports was measured. Pfbl and Pfap were 0.0011 and 0.0024 cm/s (MDCK cells), and 0.0039 and 0.0052 cm/s (human tracheal cells) at 23°C. In intact toad urinary bladder, basolateral Pf was 0.036 cm/s and apical membrane Pf after vasopressin stimulation was 0.025 cm/s at 23°C. The results establish light microscopy with spatial filtering as a technically simple and quantitative method to measure water permeability in cell layers and provide the first measurement of the apical and basolateral membrane permeabilities of several important epithelial cell types.
Electronic scholarly monographs: issues and challenges for the UK
Authors: Lonsdale R. E. , Armstrong C. J.
Published: July 2002

The literature on electronic publishing reveals that scant attention has been paid to the area of scholarly monographs. This paper reports on a recent and rare investigation into the nature and provision of electronic scholarly monographs and textbooks in the UK. Publishing structures are delineated; the physical characteristics of electronic scholarly monographs are reviewed; and issues associated with their nature and content are discussed. Problems of bibliographical control and of quality are also explored.
Publishing a well‐established international environmental journal in Chinese
Authors: Kessler Elisabeth , Keyu Zhang
Published: July 2002

A Chinese‐language version of Ambio – A Journal of the Human Environment – published by the Royal Swedish Academy of Science – has been published in China since 1994. We describe the background to the project and the processes and problems involved in its successful development.
The electronic alternative: Sociological Research Online
Authors: Peters Stuart , Gilbert Nigel
Published: July 2002

Examines how the electronic journal Sociological Research Online has rapidly established itself as a leading journal and how it has gained credibility; discusses possible future sources of revenue.
Steering clear of libel
Authors: Mathieson Keith
Published: July 2002

Libel claims are a less frequent occurrence for learned publishers than for many other kinds of publisher but whenever they do arise, they are an expensive nuisance. This article explains the nasty consequences of libel claims and the circumstances that give rise to them. It also offers some hints to publishers on how best to avoid libel claims.
Journey to the future
Authors: Scott Elspeth J.
Published: July 2002

The Library view on development and initiatives in the electronic publishing environment: a paper presented at the STM Innovations Seminar, London, December 1996
An analogue of Hardy’s theorem for semi-simple Lie groups
Authors: Sengupta J.
Published: July 2002

A well known theorem of Hardy on Fourier transform pairs says that a function

f
f

on

R

n

{\mathbf R}^n

and its Fourier transform

f

∧

\stackrel {\wedge }{f}

cannot both be “very rapidly decreasing”. We prove here an analogue of this result in the case of semi-simple Lie groups.
The homotopy type of hyperbolic monopole orbit spaces
Authors: Gritsch Ursula
Published: July 2002

We prove that the spaceBU(1)0{\mathcal {B}}_{U(1)}^{0}of equivalence classes ofU(1)U(1)-invariant connections on someSU(2)SU(2)-principle bundles overS4S^{4}is weakly homotopy equivalent to a component of the second loop spaceΩ2(S2)\Omega ^{2} (S^{2}).
Groups acting on quasiconvex spaces and translation numbers
Authors: Poleksić Aleksandar
Published: July 2002

We prove that groups acting geometrically on

δ
\delta

-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero.
Desynchronization of large scale delayed neural networks
Authors: Chen Yuming , Huang Ying , Wu Jianhong
Published: July 2002

We consider a ring of identical neurons with delayed nearest neighborhood inhibitory interaction. Under general conditions, such a network has a slowly oscillatory synchronous periodic solution which is completely characterized by a scalar delay differential equation with negative feedback. Despite the fact that the slowly oscillatory periodic solution of the scalar equation is stable, we show that the associated synchronous solution is unstable if the size of the network is large.
Finsler metrics and action potentials
Authors: Iturriaga Renato , Sánchez-Morgado Héctor
Published: July 2002

We study the behavior of Mañé’s action potential

Φ
k

\Phi _k

associated to a convex superlinear Lagrangian, for

k
k

bigger than the critical value

c
(
L
)

c(L)

. We obtain growth estimates for the action potential as a function of

k
k

. We also prove that the action potential can be written as
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Phi Subscript k Baseline left-parenthesis x comma y right-parenthesis equals upper D Subscript upper F Baseline left-parenthesis x comma y right-parenthesis plus f left-parenthesis y right-parenthesis minus f left-parenthesis x right-parenthesis">

Φ
k

(
x
,
y
)
=

D
F

(
x
,
y
)
+
f
(
y
)
−
f
(
x
)

\Phi _k(x,y)=D_F(x,y)+f(y)-f(x)

where

f
f

is a smooth function and

D
F

D_F

is the distance function associated to a Finsler metric.
Relative boundedness and relative compactness for linear operators in Banach spaces
Authors: Binding P. , Hryniv R.
Published: July 2002

If

A
A

and

B
B

are linear operators acting between Banach spaces, we show that compactness of

B
B

relative to

A
A

does not in general imply that

B
B

has

A
A

-bound zero. We do, however, give conditions under which the above implication is valid.
Almost positive curvature on the Gromoll-Meyer 7-sphere
Authors: Eschenburg J.-H.
Published: July 2002

D. Gromoll and W. Meyer have represented a certain exotic 7-sphere

M
M

as a biquotient of the compact Lie group

S
p
(
2
)

Sp(2)

. Thus any invariant normal homogeneous metric on

S
p
(
2
)

Sp(2)

induces a metric of nonnegative sectional curvature on

M
M

. We show that the simplest such metrics (except the bi-invariant one) induce metrics which have in fact strictly positive curvature outside a subset of

M
M

with measure zero.
On Legendrian knots and polynomial invariants
Authors: Ferrand Emmanuel
Published: July 2002

It is proved in this note that the analogues of the Bennequin inequality which provide an upper bound for the Bennequin invariant of a Legendrian knot in the standard contact three dimensional space in terms of the least degree in the framing variable of the HOMFLY and the Kauffman polynomials are not sharp. Furthermore, the relationships between these restrictions on the range of the Bennequin invariant are investigated, which leads to a new simple proof of the inequality involving the Kauffman polynomial.
On the horocyclic coordinate for the Teichmüller space of once punctured tori
Authors: Miyachi Hideki
Published: July 2002

This paper deals with analytic and geometric properties of the Maskit embedding of the Teichmüller space of once punctured tori. We show that the image of this embedding has an inward-pointing cusp and study the boundary behavior of conformal automorphisms. These results are proved using Y.N. Minsky’s Pivot Theorem.
Immersions of surfaces in almost–complex 4–manifolds
Authors: Bohr Christian
Published: July 2002

In this paper, we investigate the relation between double points and complex points of immersed surfaces in almost–complex 4–manifolds and show how estimates for the minimal genus of embedded surfaces lead to inequalities between the number of double points and the number of complex points of an immersion.