bluuebunny/crossref_metadata_2025 huggingface dataset:
Gastric Hyperplasia and Increased Proliferative Responses of Lymphocytes in Mice Lacking the COOH-terminal Ankyrin Domain of NF-κB2
Authors: Ishikawa Hideaki , Carrasco Daniel , Claudio Estefania , Ryseck Rolf-Peter , Bravo Rodrigo
Published: July 2002

The nfkb2 gene encodes the p100 precursor which produces the p52 protein after proteolytic cleavage of its COOH-terminal domain. Although the p52 product can act as an alternative subunit of NF-κB, the p100 precursor is believed to function as an inhibitor of Rel/NF-κB activity by cytoplasmic retention of Rel/NF-κB complexes, like other members of the IκB family. However, the physiological relevance of the p100 precursor as an IκB molecule has not been understood. To assess the role of the precursor in vivo, we generated, by gene targeting, mice lacking p100 but still containing a functional p52 protein. Mice with a homozygous deletion of the COOH-terminal ankyrin repeats of NF-κB2 (p100−/−) had marked gastric hyperplasia, resulting in early postnatal death. p100−/− animals also presented histopathological alterations of hematopoietic tissues, enlarged lymph nodes, increased lymphocyte proliferation in response to several stimuli, and enhanced cytokine production in activated T cells. Dramatic induction of nuclear κB–binding activity composed of p52-containing complexes was found in all tissues examined and also in stimulated lymphocytes. Thus, the p100 precursor is essential for the proper regulation of p52-containing Rel/NF-κB complexes in various cell types and its absence cannot be efficiently compensated for by other IκB proteins.
Dendritic Cells Retrovirally Transduced with a Model Antigen Gene Are Therapeutically Effective against Established Pulmonary Metastases
Authors: Specht Jennifer M. , Wang Gang , Do My T. , Lam John S. , Royal Richard E. , Reeves Mark E. , Rosenberg Steven A. , Hwu Patrick
Published: July 2002

Dendritic cells (DCs) are bone marrow–derived leukocytes that function as potent antigen presenting cells capable of initiating T cell–dependent responses from quiescent lymphocytes. DC pulsed with tumor-associated antigen (TAA) peptide or protein have recently been demonstrated to elicit antigen-specific protective antitumor immunity in a number of murine models. Transduction of DCs with TAA genes may allow stable, prolonged antigen expression as well as the potential for presentation of multiple, or unidentified, epitopes in association with major histocompatibility complex class I and/or class II molecules. To evaluate the potential efficacy of retrovirally transduced DCs, bone marrow cells harvested from BALB/c mice were transduced with either a model antigen gene encoding β-galactosidase (β-gal) or a control gene encoding rat HER-2/neu (Neu) by coculture with irradiated ecotropic retroviral producer lines. Bone marrow cells were differentiated into DC in vitro using granulocyte/macrophage colony-stimulating factor and interleukin-4. After 7 d in culture, cells were 45–78% double positive for DC phenotypic cell surface markers by FACS® analysis, and DC transduced with β-gal were 41–72% positive for β-gal expression by X-gal staining. In addition, coculture of β-gal transduced DC with a β-gal–specific T cell line (CTLx) resulted in the production of large amounts of interferon-γ, demonstrating that transduced DCs could process and present endogenously expressed β-gal. DC transduced with β-gal and control rat HER-2/neu were then used to treat 3-d lung metastases in mice bearing an experimental murine tumor CT26.CL25, expressing the model antigen, β-gal. Treatment with β-gal–transduced DC significantly reduced the number of pulmonary metastatic nodules compared with treatment with Hank's balanced salt solution or DCs transduced with rat HER-2/neu. In addition, immunization with β-gal–transduced DCs resulted in the generation of antigen-specific cytotoxic T lymphocytes (CTLs), which were significantly more reactive against relevant tumor targets than CTLs generated from mice immunized with DCs pulsed with the Ld-restricted β-gal peptide. The results observed in this rapidly lethal tumor model suggest that DCs transduced with TAA may be a useful treatment modality in tumor immunotherapy.
CD4+ T Cell Tolerance to Parenchymal Self-Antigens Requires Presentation by Bone Marrow–derived Antigen-presenting Cells
Authors: Adler Adam J. , Marsh David W. , Yochum Gregory S. , Guzzo James L. , Nigam Ankesh , Nelson William G. , Pardoll Drew M.
Published: July 2002

T cell tolerance to parenchymal self-antigens is thought to be induced by encounter of the T cell with its cognate peptide–major histocompatibility complex (MHC) ligand expressed on the parenchymal cell, which lacks appropriate costimulatory function. We have used a model system in which naive T cell receptor (TCR) transgenic hemagglutinin (HA)-specific CD4+ T cells are adoptively transferred into mice expressing HA as a self-antigen on parenchymal cells. After transfer, HA-specific T cells develop a phenotype indicative of TCR engagement and are rendered functionally tolerant. However, T cell tolerance is not induced by peptide–MHC complexes expressed on parenchymal cells. Rather, tolerance induction requires that HA is presented by bone marrow (BM)–derived cells. These results indicate that tolerance induction to parenchymal self-antigens requires transfer to a BM-derived antigen-presenting cell that presents it to T cells in a tolerogenic fashion.
The Serine Proteinase Inhibitor (Serpin) Plasminogen Activation Inhibitor Type 2 Protects against Viral Cytopathic Effects by Constitutive Interferon α/β Priming
Authors: Antalis Toni M. , La Linn May , Donnan Karen , Mateo Luis , Gardner Joy , Dickinson Joanne L. , Buttigieg Kathy , Suhrbier Andreas
Published: July 2002

The serine proteinase inhibitor (serpin) plasminogen activator inhibitor type 2 (PAI-2) is well characterized as an inhibitor of extracellular urokinase-type plasminogen activator. Here we show that intracellular, but not extracellular, PAI-2 protected cells from the rapid cytopathic effects of alphavirus infection. This protection did not appear to be related to an effect on apoptosis but was associated with a PAI-2–mediated induction of constitutive low-level interferon (IFN)-α/β production and IFN-stimulated gene factor 3 (ISGF3) activation, which primed the cells for rapid induction of antiviral genes. This primed phenotype was associated with a rapid development of resistance to infection by the PAI-2 transfected cells and the establishment of a persistent productive infection. PAI-2 was also induced in macrophages in response to viral RNA suggesting that PAI-2 is a virus response gene. These observations, together with the recently demonstrated PAI-2–mediated inhibition of tumor necrosis factor-α induced apoptosis, (a) illustrate that PAI-2 has an additional and distinct function as an intracellular regulator of signal transduction pathway(s) and (b) demonstrate a novel activity for a eukaryotic serpin.
Transforming Growth Factor β1, in the Presence of Granulocyte/Macrophage Colony-stimulating Factor and Interleukin 4, Induces Differentiation of Human Peripheral Blood Monocytes into Dendritic Langerhans Cells
Authors: Geissmann Frederic , Prost Catherine , Monnet Jean-Paul , Dy Michel , Brousse Nicole , Hermine Olivier
Published: July 2002

Langerhans cells (LCs) are dendritic cells (DCs) that are present in the epidermis, bronchi, and mucosae. Although LCs originate in bone marrow, little is known about their lineage of origin. In this study, we demonstrate that in vitro LCs may originate from monocytes. Adult peripheral blood CD14+ monocytes differentiate into LCs (CD1a+, E-cadherin+, cutaneous lymphocyte-associated antigen+, Birbeck granules+, Lag+) in the presence of granulocyte/macrophage colony-stimulating factor, interleukin 4, and transforming growth factor β1 (TGF-β1). This process occurs with virtually no cell proliferation and is not impaired by 30 Gy irradiation. Selection of monocyte subpopulations is ruled out since monocyte-derived DCs can further differentiate into LCs. Our data suggest that in vivo LC differentiation may be induced peripherally, from a nonproliferating myeloid precursor, i.e., the monocyte, in response to a TGF-β1–rich microenvironment, as found in the skin and epithelia. Therefore, the monocyte may represent a circulating precursor critical to the immune response in vivo.
Involvement of Guanosine Triphosphatases and Phospholipase C-γ2 in Extracellular Signal–regulated Kinase, c-Jun NH2-terminal Kinase, and p38 Mitogen-activated Protein Kinase Activation by the B Cell Antigen Receptor
Authors: Hashimoto Ari , Okada Hidetaka , Jiang Aimin , Kurosaki Mari , Greenberg Steven , Clark Edward A. , Kurosaki Tomohiro
Published: July 2002

Mitogen-activated protein (MAP) kinase family members, including extracellular signal–regulated kinase (ERK), c-Jun NH2-terminal kinase (  JNK), and p38 MAP kinase, have been implicated in coupling the B cell antigen receptor (BCR) to transcriptional responses. However, the mechanisms that lead to the activation of these MAP kinase family members have been poorly elucidated. Here we demonstrate that the BCR-induced ERK activation is reduced by loss of Grb2 or expression of a dominant-negative form of Ras, RasN17, whereas this response is not affected by loss of Shc. The inhibition of the ERK response was also observed in phospholipase C (PLC)-γ2–deficient DT40 B cells, and expression of RasN17 in the PLC-γ2–deficient cells completely abrogated the ERK activation. The PLC-γ2 dependency of ERK activation was most likely due to protein kinase C (PKC) activation rather than calcium mobilization, since loss of inositol 1,4,5-trisphosphate receptors did not affect ERK activation. Similar to cooperation of Ras with PKC activation in ERK response, both PLC-γ2–dependent signal and GTPase are required for BCR-induced JNK and p38 responses. JNK response is dependent on Rac1 and calcium mobilization, whereas p38 response requires Rac1 and PKC activation.
CD1d-restricted Recognition of Synthetic Glycolipid Antigens by Human Natural Killer T Cells
Authors: Spada Franca M. , Koezuka Yasuhiko , Porcelli Steven A.
Published: July 2002

A conserved subset of mature circulating T cells in humans expresses an invariant Vα24-JαQ T cell receptor (TCR)-α chain rearrangement and several natural killer (NK) locus–encoded C-type lectins. These human T cells appear to be precise homologues of the subset of NK1.1+ TCR-α/β+ T cells, often referred to as NK T cells, which was initially identified in mice. Here we show that human NK T cell clones are strongly and specifically activated by the same synthetic glycolipid antigens as have been shown recently to stimulate murine NK T cells. Responses of human NK T cells to these synthetic glycolipids, consisting of certain α-anomeric sugars conjugated to an acylated phytosphingosine base, required presentation by antigen-presenting cells expressing the major histocompatibility complex class I–like CD1d protein. Presentation of synthetic glycolipid antigens to human NK T cells required internalization of the glycolipids by the antigen-presenting cell and normal endosomal targeting of CD1d. Recognition of these compounds by human NK T cells triggered proliferation, cytokine release, and cytotoxic activity. These results demonstrate a striking parallel in the specificity of NK T cells in humans and mice, thus providing further insight into the potential mechanisms of immune recognition by NK T cells and the immunological function of this unique T cell subset.
Potent T Cell Activation with Dimeric Peptide–Major Histocompatibility Complex Class II Ligand: The Role of CD4 Coreceptor
Authors: Hamad Abdel Rahim A. , O'Herrin Sean M. , Lebowitz Michael S. , Srikrishnan Ananth , Bieler Joan , Schneck Jonathan , Pardoll Drew
Published: July 2002

The interaction of the T cell receptor (TCR) with its cognate peptide–major histocompatibility complex (MHC) on the surface of antigen presenting cells (APCs) is a primary event during T cell activation. Here we used a dimeric IEk-MCC molecule to study its capacity to activate antigen-specific T cells and to directly analyze the role of CD4 in physically stabilizing the TCR–MHC interaction. Dimeric IEk-MCC stably binds to specific T cells. In addition, immobilized dimeric IEk-MCC can induce TCR downregulation and activate antigen-specific T cells more efficiently than anti-CD3. The potency of the dimeric IEk-MCC is significantly enhanced in the presence of CD4. However, CD4 does not play any significant role in stabilizing peptide-MHC–TCR interactions as it fails to enhance binding of IEk-MCC to specific T cells or influence peptide-MHC–TCR dissociation rate or TCR downregulation. Moreover, these results indicate that dimerization of peptide-MHC class II using an IgG molecular scaffold significantly increases its binding avidity leading to an enhancement of its stimulatory capacity while maintaining the physiological properties of cognate peptide–MHC complex. These peptide-MHC–IgG chimeras may, therefore, provide a novel approach to modulate antigen-specific T cell responses both in vitro and in vivo.
Essential Role of Nuclear Factor κB in the Induction of Eosinophilia in Allergic Airway Inflammation
Authors: Yang Liyan , Cohn Lauren , Zhang Dong-Hong , Homer Robert , Ray Anuradha , Ray Prabir
Published: July 2002

The molecular mechanisms that contribute to an eosinophil-rich airway inflammation in asthma are unclear. A predominantly T helper 2 (Th2)-type cell response has been documented in allergic asthma. Here we show that mice deficient in the p50 subunit of nuclear factor (NF)- κB are incapable of mounting eosinophilic airway inflammation compared with wild-type mice. This deficiency was not due to a block in T cell priming or proliferation in the p50−/− mice, nor was it due to a defect in the expression of the cell adhesion molecules VCAM-1 and ICAM-1 that are required for the extravasation of eosinophils into the airways. The major defects in the p50−/− mice were the lack of production of the Th2 cytokine interleukin 5 and the chemokine eotaxin, which are crucial for proliferation and for differentiation and recruitment, respectively, of eosinophils into the asthmatic airway. Additionally, the p50−/− mice were deficient in the production of the chemokines macrophage inflammatory protein (MIP)-1α and MIP-1β that have been implicated in T cell recruitment to sites of inflammation. These results demonstrate a crucial role for NF-κB in vivo in the expression of important molecules that have been implicated in the pathogenesis of asthma.
The HIV-1 Virion-associated Protein Vpr Is a Coactivator of the Human Glucocorticoid Receptor
Authors: Kino Tomoshige , Gragerov Alexander , Kopp Jeffrey B. , Stauber Roland H. , Pavlakis George N. , Chrousos George P.
Published: July 2002

The HIV-1 virion-associated accessory protein Vpr affects both viral replication and cellular transcription, proliferation, and differentiation. We report that Vpr enhances the activity of glucocorticoids in lymphoid and muscle-derived cell lines by interacting directly with the glucocorticoid receptor and general transcription factors, acting as a coactivator. Vpr contains the signature motif LXXLL also present in cellular nuclear receptor coactivators, such as steroid receptor coactivator 1 and p300/CREB-binding protein, which mediates their interaction with the glucocorticoid and other nuclear hormone receptors. A mutant Vpr molecule with disruption of this coactivator signature motif lost its ability to influence transcription of glucocorticoid-responsive genes and became a dominant-negative inhibitor of Vpr, possibly by retaining its general transcription factor–binding activities. The glucocorticoid coactivator activity of Vpr may contribute to increased tissue glucocorticoid sensitivity in the absence of hypercortisolism and to the pathogenesis of AIDS.
Interleukin 12 Protects from a T Helper Type 1–mediated Autoimmune Disease, Experimental Autoimmune Uveitis, through a Mechanism Involving Interferon γ, Nitric Oxide, and Apoptosis
Authors: Tarrant Teresa K. , Silver Phyllis B. , Wahlsten Jennifer L. , Rizzo Luiz V. , Chan Chi-Chao , Wiggert Barbara , Caspi Rachel R.
Published: July 2002

Pathogenic effector T cells in experimental autoimmune uveitis (EAU) are T helper type 1–like, and interleukin (IL)-12 is required for their generation and function. Therefore, we expected that IL-12 administration would have disease-enhancing effects. Mice were immunized with a uveitogenic regimen of the retinal antigen interphotoreceptor retinoid-binding protein, treated with IL-12 (100 ng/d for 5 d), and EAU was assessed by histopathology. Unexpectedly, IL-12 treatment failed to enhance EAU in resistant strains and downregulated disease in susceptible strains. Only treatment during the first, but not during the second, week after immunization was consistently protective. High levels of interferon γ (IFN-γ) were present in the serum during IL-12 treatment, but subsequent antigen-specific IFN-γ production in protected mice was diminished, as were IL-5 production, lymph node cell proliferation, and serum antibody levels. Treated mice had fewer cells and evidence of enhanced apoptosis in the draining lymph nodes. Unlike wild-type mice, IFN-γ–deficient, inducible nitric oxide synthase (iNOS)-deficient, and Bcl-2lck transgenic mice were poorly protected by IL-12, whereas IL-10–deficient mice were protected. We conclude that administration of IL-12 aborts disease by curtailing development of uveitogenic effector T cells. The data are compatible with the interpretation that IL-12 induces systemic hyperinduction of IFN-γ, causing activation of iNOS and production of NO, which mediates protection at least in part by triggering Bcl-2 regulated apoptotic deletion of the antigen-specific T cells as they are being primed.
T Cell Receptor (TCR) Antagonism without a Negative Signal: Evidence from T Cell Hybridomas Expressing Two Independent TCRs
Authors: Stotz Sabine H. , Bolliger Luca , Carbone Francis R. , Palmer Ed
Published: July 2002

Antagonist peptides inhibit T cell responses by an unknown mechanism. By coexpressing two independent T cell receptors (TCRs) on a single T cell hybridoma, we addressed the question of whether antagonist ligands induce a dominant-negative signal that inhibits the function of a second, independent TCR. The two receptors, Vα2Vβ5 and Vα2Vβ10, restricted by H-2Kb and specific for the octameric peptides SIINFEKL and SSIEFARL, respectively, were coexpressed on the same cell. Agonist stimulation demonstrated that the two receptors behaved independently with regard to antigen-induced TCR downregulation and intracellular biochemical signaling. The exposure of one TCR (Vα2Vβ5) to antagonist peptides could not inhibit a second independent TCR (Vα2Vβ10) from responding to its antigen. Thus, our data clearly demonstrate that these antagonist ligands do not generate a dominant-negative signal which affects the responsiveness of the entire cell. In addition, a kinetic analysis showed that even 12 h after engagement with their cognate antigen and 10 h after reaching a steady-state of TCR internalization, T cells were fully inhibited by the addition of antagonist peptides. The window of susceptibility to antagonist ligands correlated exactly with the time required for the responding T cells to commit to interleukin 2 production. The data support a model where antagonist ligands can competitively inhibit antigenic peptides from productively engaging the TCR. This competitive inhibition is effective during the entire commitment period, where sustained TCR engagement is essential for full T cell activation.
A Seven-transmembrane, G Protein–coupled Receptor, FPRL1, Mediates the Chemotactic Activity of Serum Amyloid A for Human Phagocytic Cells
Authors: Su Shao Bo , Gong Wanghua , Gao Ji-Liang , Shen Weiping , Murphy Philip M. , Oppenheim Joost J. , Wang Ji Ming
Published: July 2002

We have previously reported (Badolato, R., J.M. Wang, W.J. Murphy, A.R. Lloyd, D.F. Michiel, L.L. Bausserman, D.J. Kelvin, and J.J. Oppenheim. 1994. J. Exp. Med. 180:203; Xu, L., R. Badolato, W.J. Murphy, D.L. Longo, M. Anver, S. Hale, J.J. Oppenheim, and J.M. Wang. 1995. J. Immunol. 155:1184.) that the acute phase protein serum amyloid A (SAA) is a potent chemoattractant for human leukocytes in vitro and mouse phagocytes in vivo. To identify the signaling mechanisms, we evaluated patterns of cross-desensitization between SAA and other leukocyte chemoattrctants. We found that the chemotactic bacterial peptide, N-formyl- methionyl-leucyl-phenylalanine (fMLP), was able to specifically attenuate Ca2+ mobilization in human phagocytes induced by SAA, but only at very high concentrations, suggesting that SAA uses a low affinity fMLP receptor. Here we demonstrate that SAA selectively induced Ca2+ mobilization and migration of HEK cells expressing FPRL1, a human seven-transmembrane domain phagocyte receptor with low affinity for fMLP, and high affinity for lipoxin A4. Furthermore, radiolabeled SAA specifically bound to human phagocytes and FPRL1-transfected 293 cells. In contrast, SAA was not a ligand or agonist for FPR, the high affinity fMLP receptor. Thus, SAA is the first chemotactic ligand identified for FPRL1. Our results suggest that FPRL1 mediates phagocyte migration in response to SAA.
The Common Cytokine Receptor γ Chain and the Pre-T Cell Receptor Provide Independent but Critically Overlapping Signals in Early α/β T Cell Development
Authors: Di Santo James P. , Aifantis Iannis , Rosmaraki Eleftheria , Garcia Corinne , Feinberg Jacqueline , Fehling Hans Jörg , Fischer Alain , von Boehmer Harald , Rocha Benedita
Published: July 2002

Intracellular signals emanating from cytokine and antigen receptors are integrated during the process of intrathymic development. Still, the relative contributions of cytokine receptor signaling to pre-T cell receptor (TCR) and TCR-mediated differentiation remain undefined. Interleukin (IL)-7 interactions with its cognate receptor complex (IL-7Rα coupled to the common cytokine receptor γ chain, γc) play a dominant role in early thymopoiesis. However, α/β T cell development in IL-7–, IL-7Rα–, and γc-deficient mice is only partially compromised, suggesting that additional pathways can rescue α/β T lineage cells in these mice. We have investigated the potential interdependence of γc- and pre-TCR–dependent pathways during intrathymic α/β T cell differentiation. We demonstrate that γc-dependent cytokines do not appear to be required for normal pre-TCR function, and that the rate-limiting step in α/β T cell development in γc− mice does not involve TCR-β chain rearrangements, but rather results from poor maintenance of early thymocytes. Moreover, mice double mutant for both γc and pre-Tα show vastly reduced thymic cellularity and a complete arrest of thymocyte differentiation at the CD44+CD25+ cell stage. These observations demonstrate that the pre-TCR provides the γc-independent signal which allows α/β T cell development in γc− mice. Thus, a series of overlapping signals derived from cytokine and T cell receptors guide the process of α/β thymocyte development.
In Autoimmune Diabetes the Transition from Benign to Pernicious Insulitis Requires an Islet Cell Response to Tumor Necrosis Factor α
Authors: Pakala Syamasundar V. , Chivetta Marylee , Kelly Colleen B. , Katz Jonathan D.
Published: July 2002

The islet-infiltrating and disease-causing leukocytes that are a hallmark of insulin-dependent diabetes mellitus produce and respond to a set of cytokine molecules. Of these, interleukin 1β, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ are perhaps the most important. However, as pleiotropic molecules, they can impact the path leading to β cell apoptosis and diabetes at multiple points. To understand how these cytokines influence both the formative and effector phases of insulitis, it is critical to determine their effects on the assorted cell types comprising the lesion: the effector T cells, antigen-presenting cells, vascular endothelium, and target islet tissue. Here, we report using nonobese diabetic chimeric mice harboring islets deficient in specific cytokine receptors or cytokine-induced effector molecules to assess how these compartmentalized loss-of-function mutations alter the events leading to diabetes. We found that islets deficient in Fas, IFN-γ receptor, or inducible nitric oxide synthase had normal diabetes development; however, the specific lack of TNF- α receptor 1 (p55) afforded islets a profound protection from disease by altering the ability of islet-reactive, CD4+ T cells to establish insulitis and subsequently destroy islet β cells. These results argue that islet cells play a TNF-α–dependent role in their own demise.
Partially Phosphorylated T Cell Receptor ζ Molecules Can Inhibit T Cell Activation
Authors: Kersh Ellen N. , Kersh Gilbert J. , Allen Paul M.
Published: July 2002

The T cell receptor complex (TCR) ζ chain is constitutively tyrosine phosphorylated specifically at two of the six ζ immunoreceptor tyrosine-based activation motif (ITAM) tyrosine residues in resting peripheral T cells. Further phosphorylation of ζ is induced by both agonist and antagonist ligands of the TCR, with agonists inducing complete phosphorylation of the ζ ITAM tyrosines. After antagonist stimulation, ζ phosphorylation is incomplete and generates discrete forms of partially phosphorylated ITAMs. Here, we mutate specific tyrosines in chimeric human CD8-ζ molecules to reflect phosphorylation in resting T cells as well as phosphorylation induced by agonist and antagonist ligands. We demonstrate that such partially phosphorylated TCR-ζ species can inhibit IL-2 production in T cell hybridomas and proliferation in T cell clones. This reveals a previously unrecognized, inhibitory function of partially phosphorylated ITAMs. These findings support the concept that TCR antagonism can arise through the generation of an inhibitory signal within the TCR complex and that constitutive ζ phosphorylation in resting T cells is an inhibitory signaling environment.
Augmentation of Vα14 Nkt Cell–Mediated Cytotoxicity by Interleukin 4 in an Autocrine Mechanism Resulting in the Development of Concanavalin a–Induced Hepatitis
Authors: Kaneko Yoshikatsu , Harada Michishige , Kawano Tetsu , Yamashita Masakatsu , Shibata Youichi , Gejyo Fumitake , Nakayama Toshinori , Taniguchi Masaru
Published: July 2002

The administration of concanavalin A (Con A) induces a rapid severe injury of hepatocytes in mice. Although the Con A–induced hepatitis is considered to be an experimental model of human autoimmune hepatitis, the precise cellular and molecular mechanisms that induce hepatocyte injury remain unclear. Here, we demonstrate that Vα14 NKT cells are required and sufficient for induction of this hepatitis. Moreover, interleukin (IL)-4 produced by Con A–activated Vα14 NKT cells is found to play a crucial role in disease development by augmenting the cytotoxic activity of Vα14 NKT cells in an autocrine fashion. Indeed, short-term treatment with IL-4 induces an increase in the expression of granzyme B and Fas ligand (L) in Vα14 NKT cells. Moreover, Vα14 NKT cells from either perforin knock-out mice or FasL-mutant gld/gld mice fail to induce hepatitis, and hence perforin–granzyme B and FasL appear to be effector molecules in Con A–induced Vα14 NKT cell–mediated hepatocyte injury.
Ionizing Radiation and Chemotherapeutic Drugs Induce Apoptosis in Lymphocytes in the Absence of FAS or Fadd/Mort1 Signaling
Authors: Newton Kim , Strasser Andreas
Published: July 2002

Ionizing radiation and cytotoxic drugs used in the treatment of cancer induce apoptosis in many cell types, including tumor cells. It has been reported that tumor cells treated with anticancer drugs increase surface expression of Fas ligand (FasL) and are killed by autocrine or paracrine apoptosis signaling through Fas (Friesen, C., I. Herr, P.H. Krammer, and K.-M. Debatin. 1996. Nat. Med. 2:574–577). We show that lymphocytes that cannot be killed by FasL, such as those from Fas-deficient lpr mice or transgenic mice expressing a dominant negative mutant of Fas-associated death domain protein (FADD/MORT1), are as sensitive as normal lymphocytes to killing by gamma radiation or the cytotoxic drugs cis-platin, doxorubicin, and etoposide. In contrast, p53 deficiency or constitutive expression of Bcl-2 markedly increased the resistance of lymphocytes to gamma radiation or anticancer drugs but had no effect on killing by FasL. Consistent with these observations, lpr and wild-type T cells both had a reduced capacity for mitogen-induced proliferation after drug treatment, whereas bcl-2 transgenic or p53-deficient T cells retained significant clonogenic potential. These results demonstrate that apoptosis induced by ionizing radiation or anticancer drugs requires p53 and is regulated by the Bcl-2 protein family but does not require signals transduced by Fas and FADD/MORT1.
Transgenic Expression of the Chemokine Receptor Encoded by Human Herpesvirus 8 Induces an Angioproliferative Disease Resembling Kaposi's Sarcoma
Authors: Yang Tong-Yuan , Chen Shu-Cheng , Leach Michael W. , Manfra Denise , Homey Bernhard , Wiekowski Maria , Sullivan Lee , Jenh Chung-Her , Narula Satwant K. , Chensue Stephen W. , Lira Sergio A.
Published: July 2002

Human herpesvirus 8 (HHV8, also known as Kaposi's sarcoma [KS]-associated herpesvirus) has been implicated as an etiologic agent for KS, an angiogenic tumor composed of endothelial, inflammatory, and spindle cells. Here, we report that transgenic mice expressing the HHV8-encoded chemokine receptor (viral G protein–coupled receptor) within hematopoietic cells develop angioproliferative lesions in multiple organs that morphologically resemble KS lesions. These lesions are characterized by a spectrum of changes ranging from erythematous maculae to vascular tumors, by the presence of spindle and inflammatory cells, and by expression of vGPCR, CD34, and vascular endothelial growth factor. We conclude that vGPCR contributes to the development of the angioproliferative lesions observed in these mice and suggest that this chemokine receptor may play a role in the pathogenesis of KS in humans.
Lack of Coreceptor Allows Survival of Chronically Stimulated Double-Negative α/β T Cells
Authors: Hamad Abdel Rahim A. , Srikrishnan Ananth , Mirmonsef Paria , Broeren Chris P.M. , June Carl H. , Pardoll Drew , Schneck Jonathan P.
Published: July 2002

Lymphoproliferative diseases are characterized by massive accumulation of CD4−CD8−B220+ (double-negative [DN]) T cells in peripheral organs. Although evidence indicates these cells are derived from mature autoreactive α/β T cells, the significance of coreceptor downregulation is not known. In this study, we examined the role CD4 coreceptor plays in the survival of repeatedly stimulated T cells. CD4+/+ and CD4−/− T cells from AND T cell receptor (TCR) transgenic mice exhibited similar phenotypes after antigenic stimulation, but the CD4−/− T cells survived in much larger numbers than the CD4+/+ cells upon primary and secondary major histocompatibility complex (MHC)/peptide stimulation. Enhanced survival of CD4−/− T cells was due to decreased apoptosis rather than enhanced proliferation. Similarly, circumvention of the CD4/MHC interaction by using a surrogate TCR ligand that does not engage CD4 led to significant enhancement of CD4+/+ cells than when stimulated with MHC/peptide. Finally, we generated DN B220+ T cells using an in vitro model system and showed they were more tolerant to chronic stimulation than CD4+/+ cells. Together, these results indicate that coreceptor engagement controls expansion of normal T cells. In the absence of coreceptor, T cells survive chronic stimulation and express B220 as seen in autoimmune lymphoproliferative diseases.
A Secreted Chemokine Binding Protein Encoded by Murine Gammaherpesvirus-68 Is Necessary for the Establishment of a Normal Latent Load
Authors: Bridgeman Anne , Stevenson Philip G. , Simas J. Pedro , Efstathiou Stacey
Published: July 2002

Herpesviruses encode a variety of proteins with the potential to disrupt chemokine signaling, and hence immune organization. However, little is known of how these might function in vivo. The B cell–tropic murine gammaherpesvirus-68 (MHV-68) is related to the Kaposi's sarcoma–associated herpesvirus (KSHV), but whereas KSHV expresses small chemokine homologues, MHV-68 encodes a broad spectrum chemokine binding protein (M3). Here we have analyzed the effect on viral pathogenesis of a targeted disruption of the M3 gene. After intranasal infection, an M3 deficiency had surprisingly little effect on lytic cycle replication in the respiratory tract or the initial spread of virus to lymphoid tissues. However, the amplification of latently infected B cells in the spleen that normally drives MHV-68–induced infectious mononucleosis failed to occur. Thus, there was a marked reduction in latent virus recoverable by in vitro reactivation, latency-associated viral tRNA transcripts detectable by in situ hybridization, total viral DNA load, and virus-driven B cell activation. In vivo CD8+ T cell depletion largely reversed this deficiency, suggesting that the chemokine neutralization afforded by M3 may function to block effective CD8+ T cell recruitment into lymphoid tissue during the expansion of latently infected B cell numbers. In the absence of M3, MHV-68 was unable to establish a normal latent load.
Characterization of Ether-à-go-go Channels Present in Photoreceptors Reveals Similarity to IKx, a K+ Current in Rod Inner Segments
Authors: Frings Stephan , Brüll Nicole , Dzeja Claudia , Angele Albert , Hagen Volker , Kaupp U. Benjamin , Baumann Arnd
Published: July 2002

In this study, we describe two splice variants of an ether-à-go-go (EAG) K+ channel cloned from bovine retina: bEAG1 and bEAG2. The bEAG2 polypeptide contains an additional insertion of 27 amino acids in the extracellular linker between transmembrane segments S3 and S4. The heterologously expressed splice variants differ in their activation kinetics and are differently modulated by extracellular Mg2+. Cooperativity of modulation by Mg2+ suggests that each subunit of the putative tetrameric channel binds a Mg2+ ion. The channels are neither permeable to Ca2+ ions nor modulated by cyclic nucleotides. In situ hybridization localizes channel transcripts to photoreceptors and retinal ganglion cells. Comparison of EAG currents with IKx, a noninactivating K+ current in the inner segment of rod photoreceptors, reveals an intriguing similarity, suggesting that EAG polypeptides are involved in the formation of Kx channels.
Antisense Knock Out of the Inositol 1,3,4,5-Tetrakisphosphate Receptor GAP1IP4BP in the Human Erythroleukemia Cell Line Leads to the Appearance of Intermediate Conductance K(Ca) Channels that Hyperpolarize the Membrane and Enhance Calcium Influx
Authors: Lu Xinghua , Fein Alan , Feinstein Maurice B. , O'Rourke Flavia A.
Published: July 2002

To study the role of the inositol 1,3,4,5-trisphosphate–binding protein GAP1IP4BP in store-operated Ca2+ entry, we established a human erythroleukemia (HEL) cell line in which the expression of GAP1IP4BP was substantially reduced by transfection with a vector containing antisense DNA under control of a Rous Sarcoma virus promoter and the Escherichia coli LacI repressor (AS-HEL cells). Control cells were transfected with vector lacking antisense DNA (V-HEL cells). GAP1IP4BP protein, which is a member of the GTPase-activating protein (GAP1) family, was reduced by 85% in AS-HEL cells and was further reduced by 96% by treatment with isopropylthio-β-d- galactoside to relieve LacI repression. The loss of GAP1IP4BP was associated with both a membrane hyperpolarization and a substantially increased Ca2+ entry induced by thrombin or thapsigargin. The activation of intermediate conductance Ca2+-activated K+ channels in AS-HEL cells (not seen in V-HEL cells) was responsible for the membrane hyperpolarization and the enhanced Ca2+ entry, and both were blocked by charybdotoxin. Stimulated V-HEL cells did not hyperpolarize and basal Ca2+ influx was unaffected by charybdotoxin. In V-HEL cells hyperpolarized by removal of extracellular K+, the thapsigargin-stimulated Ca2+ influx was increased. Expression of mRNA for the human Ca2+-activated intermediate conductance channel KCa4 was equivalent in both AS-HEL and V-HEL cells, suggesting that the specific appearance of calcium-activated potassium current (IK(Ca)) in AS-HEL cells was possibly due to modulation of preexisting channels. Our results demonstrate that GAP1IP4BP, likely working through a signaling pathway dependent on a small GTP-binding protein, can regulate the function of K(Ca) channels that produce a hyperpolarizing current that substantially enhances the magnitude and time course of Ca2+ entry subsequent to the release of internal Ca2+ stores.
On statistical limit points
Authors: Kostyrko P. , Mačaj M. , Šalát T. , Strauch O.
Published: July 2002

The set of all statistical limit points of a given sequence

x
n

x_n

is characterized as an

F
σ

F_\sigma

-set. It is also characterized in terms of discontinuity points of distribution functions of

x
n

x_n

.
On Jacobian Ideals Invariant by a Reducible 𝑠ℓ(2,𝐂) Action
Authors: Yu Yung
Published: July 2002

This paper deals with a reducible

s
ℓ
(
2
,

C

)

s\ell (2, \mathbf {C})

action on the formal power series ring. The purpose of this paper is to confirm a special case of the Yau Conjecture: suppose that

s
ℓ
(
2
,

C

)

s\ell (2, \mathbf {C})

acts on the formal power series ring via

(
0.1
)

(0.1)

. Then
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper I left-parenthesis f right-parenthesis equals left-parenthesis script l Subscript i 1 Baseline right-parenthesis circled-plus left-parenthesis script l Subscript i 2 Baseline right-parenthesis circled-plus midline-horizontal-ellipsis circled-plus left-parenthesis script l Subscript i Sub Subscript s Subscript Baseline right-parenthesis">

I
(
f
)
=
(

ℓ

i

1

)
⊕
(

ℓ

i

2

)
⊕
⋯
⊕
(

ℓ

i

s

)

I(f)=(\ell _{i_{1}})\oplus (\ell _{i_{2}})\oplus \cdots \oplus (\ell _{i_{s}})

modulo some one dimensional

s
ℓ
(
2
,

C

)

s\ell (2, \mathbf {C})

representations where

(

ℓ

i

)

(\ell _{i})

is an irreducible

s
ℓ
(
2
,

C

)

s\ell (2, \mathbf {C})

representation of dimension

ℓ

i

\ell _{i}

or empty set and
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartSet script l Subscript i 1 Baseline comma script l Subscript i 2 Baseline comma ellipsis comma script l Subscript i Sub Subscript s Subscript Baseline EndSet subset-of-or-equal-to StartSet script l 1 comma script l 2 comma ellipsis comma script l Subscript r Baseline EndSet">

{

ℓ

i

1

,

ℓ

i

2

,
…
,

ℓ

i

s

}
⊆
{

ℓ

1

,

ℓ

2

,
…
,

ℓ

r

}

\{\ell _{i_{1}},\ell _{i_{2}},\ldots ,\ell _{i_{s}}\}\subseteq \{\ell _{1},\ell _{2},\ldots ,\ell _{r}\}

. Unlike classical invariant theory which deals only with irreducible action and 1–dimensional representations, we treat the reducible action and higher dimensional representations succesively.
Periodic traveling waves and locating oscillating patterns in multidimensional domains
Authors: Alikakos Nicholas , Bates Peter , Chen Xinfu
Published: July 2002

We establish the existence and robustness of layered, time-periodic solutions to a reaction-diffusion equation in a bounded domain in

R

n

\mathbb {R}^n

, when the diffusion coefficient is sufficiently small and the reaction term is periodic in time and bistable in the state variable. Our results suggest that these patterned, oscillatory solutions are stable and locally unique. The location of the internal layers is characterized through a periodic traveling wave problem for a related one-dimensional reaction-diffusion equation. This one-dimensional problem is of independent interest and for this we establish the existence and uniqueness of a heteroclinic solution which, in constant-velocity moving coodinates, is periodic in time. Furthermore, we prove that the manifold of translates of this solution is globally exponentially asymptotically stable.
A brief history of the classification of the finite simple groups
Authors: Solomon Ronald
Published: July 2002

We present some highlights of the 110-year project to classify the finite simple groups.
𝐿₁ stability for 2×2 systems of hyperbolic conservation laws
Authors: Liu Tai-Ping , Yang Tong
Published: July 2002

In this paper, we study the evolution of the

L
1

L_1

distance of solutions for systems of

2
×
2

2\times 2

hyperbolic conservation laws. For the approximate solutions constructed by Glimm’s scheme with the aid of the wave tracing method, we introduce a nonlinear functional which is equivalent to the

L
1

L_1

distance between solutions, nonincreasing in time, and expressed explicitly in terms of the wave patterns of the solutions. This functional reveals the nonlinear mechanism of wave interactions and coupling which affect the

L
1

L_1

topology.
Pitx2a Expression Alters Actin-Myosin Cytoskeleton and Migration of HeLa Cells through Rho GTPase Signaling
Authors: Wei Qize , Adelstein Robert S.
Published: July 2002

We ectopically expressed the transcription factor Pitx2a, one of the Pitx2 isoforms, in HeLa cells by using a tetracycline-inducible expression system and examined whether Pitx2a was capable of modulating Rho GTPase signaling and altering the cell's cytoskeleton. Ectopic expression of Pitx2a induced actin-myosin reorganization, leading to increased cell spreading, suppression of cell migration, and the strengthening of cell-cell adhesion, marked by the accumulation and localization of β-catenin and N-cadherin to the sites of cell-cell contacts. Moreover, Pitx2a expression resulted in activation of the Rho GTPases Rac1 and RhoA, and the dominant negative Rac1 mutant N17Rac1 inhibited cell spreading and disrupted localization of β-catenin to the sites of cell-cell contacts. Both reorganization of actin-myosin and cell spreading require phosphatidylinositol 3-kinase activity, which is also necessary for activation of the Rho GTPase proteins. Pitx2a induced the expression of Trio, a guanine nucleotide exchange factor for Rac1 and RhoA, which preceded cell spreading, and the expression of Trio protein was down-regulated after the changes in cell spreading and cell morphology were initiated. In addition, Pitx2a also induces cell cycle arrest at G0/G1, most likely due to the accumulation of the tumor suppressor proteins p53 and p21. Our data indicate that the transcriptional activities initiated in the nucleus by Pitx2a result in profound changes in HeLa cell morphology, migration, and proliferation.
FingerPRINTScan: intelligent searching of the PRINTS motif database.
Authors: Scordis P , Flower D R , Attwood T K
Published: July 2002

MOTIVATION: By identifying an unknown gene or protein as a member of a known family, we can infer a wealth of previously compiled information pertinent to that family and its members. RESULTS: This paper introduces a method that classifies sequences using familial definitions from the PRINTS database, allowing progress to be made with the identification of distant evolutionary relationships. The approach makes use of the contextual information inherent in a multiple-motif method, and has the power to identify hitherto unidentified relationships in mass genome data. We exemplify our method by a comparison of database searches with uncharacterized sequences from the Caenorhabditis elegans and Saccharomyces cerevisiae genome projects. This analysis tool combines a simple, user-friendly interface with the capacity to provide an 'intelligent', biologically relevant result.
IMPALA: matching a protein sequence against a collection of
PSI-BLAST-constructed position-specific score matrices
Authors: A.Schäffer Alejandro , I.Wolf Yuri , P.Ponting Chris , V.Koonin Eugene , Aravind L. , F.Altschul Stephen
Published: July 2002

Motivation: Many studies have shown that database searches using position-specific score matrices (PSSMs) or profiles as queries are more effective at identifying distant protein relationships than are searches that use simple sequences as queries. One popular program for constructing a PSSM and comparing it with a database of sequences is Position-Specific Iterated BLAST (PSI-BLAST).

Results: This paper describes a new software package, IMPALA, designed for the complementary procedure of comparing a single query sequence with a database of PSI-BLAST-generated PSSMs. We illustrate the use of IMPALA to search a database of PSSMs for protein folds, and one for protein domains involved in signal transduction. IMPALA’s sensitivity to distant biological relationships is very similar to that of PSI-BLAST. However, IMPALA employs a more refined analysis of statistical significance and, unlike PSI-BLAST, guarantees the output of the optimal local alignment by using the rigorous Smith–Waterman algorithm. Also, it is considerably faster when run with a large database of PSSMs than is BLAST or PSI-BLAST when run against the complete non-redundant protein database.

Availability: The IMPALA source code, the wolf1187 database, and the aravind105 database are freely available from the NCBI ftp site ncbi.nlm.nih.gov. The databases may be found in the subdirectory ftp://ncbi.nlm.nih.gov/pub/impala. The source code is in ftp://ncbi.nlm.nih.gov/toolbox/ncbi˙tools. Some IMPALA executables for different implementations of UNIX are in ftp://ncbi.nlm.nih.gov/blast/executables. IMPALA has been added as a search option on the Blocks Database Server (http://blocks.fhcrc.org/blocks/impala.html)using a library of PSSMs derived from the BLOCKS database.

Contact: schaffer@helix.nih.gov
The hydrophobic cores of proteins predicted by wavelet analysis.
Authors: Hirakawa H , Muta S , Kuhara S
Published: July 2002

MOTIVATION: In the process of protein construction, buried hydrophobic residues tend to assemble in a core of a protein. Methods used to predict these cores involve use or no use of sequential alignment. In the case of a close homology, prediction was more accurate if sequential alignment was used. If the homology was weak, predictions would be unreliable. A hydrophobicity plot involving the hydropathy index is useful for purposes of prediction, and smoothing is essential. However, the proposed methods are insufficient. We attempted to predict hydrophobic cores with a low frequency extracted from the hydrophobicity plot, using wavelet analysis. RESULTS: The cores were predicted at a rate of 68.7%, by cross-validation. Using wavelet analysis, the cores of non-homologous proteins can be predicted with close to 70% accuracy, without sequential alignment. AVAILABILITY: The program used in this study is available from Intergalactic Reality (http://www.intergalact.com). CONTACT: hirakawa@grt.kyushu-u.ac.jp, kuhara@grt.kyushu-u.ac.jp
DIALIGN 2: improvement of the segment-to-segment approach to multiple sequence alignment.
Authors: Morgenstern B
Published: July 2002

MOTIVATION: The performance and time complexity of an improved version of the segment-to-segment approach to multiple sequence alignment is discussed. In this approach, alignments are composed from gap-free segment pairs, and the score of an alignment is defined as the sum of so-called weights of these segment pairs. RESULTS: A modification of the weight function used in the original version of the alignment program DIALIGN has two important advantages: it can be applied to both globally and locally related sequence sets, and the running time of the program is considerably improved. The time complexity of the algorithm is discussed theoretically, and the program running time is reported for various test examples. AVAILABILITY: The program is available on-line at the Bielefeld University Bioinformatics Server (BiBiServ) http://bibiserv.TechFak.Uni-Bielefeld.DE/dial ign/