Showing papers by "Walter and Eliza Hall Institute of Medical Research published in 1994"
TL;DR: Results show that the process of positive selection is exquisitely peptide specific and sensitive to extremely low ligand density and support the notion that low efficacy ligands mediate positive selection.
2,715 citations
TL;DR: This review has documented some of the influences impacting on emerging T and B cell repertoires that result in a removal of the most dangerous self-reactive cells and the progressive quantitative and qualitative increase, through positive clonal selection, of other cells specific for the actual foreign antigens encountered by each individual.
794 citations
770 citations
TL;DR: P53-/- mice were radioresistant, but unexpectedly, cycling T lymphoma cells and mitogenically activated T lymphocytes from these animals underwent apoptosis after irradiation or genotoxic drug treatment, suggesting p53 is not the only mediator of apoptosis provoked by DNA damage.
674 citations
TL;DR: Findings indicate that this G1 cyclin can modulate differentiation and collaborate with myc‐like genes in oncogenesis, as well as indicating that this cyclin D1 expression is lymphomagenic.
Abstract: Cyclin D1 is the regulatory subunit of certain protein kinases thought to advance the G1 phase of the cell cycle Deregulated cyclin D1 expression has been implicated in several human neoplasms, most consistently in centrocytic B lymphoma, where the cyclin D1 gene usually has been translocated to an immunoglobulin locus To determine directly whether constitutive cyclin D1 expression is lymphomagenic, transgenic mice were generated having the cyclin D1 gene linked to an immunoglobulin enhancer Despite abundant transgene expression, their lymphocytes were normal in cell cycle activity, size and mitogen responsiveness, but young transgenic animals contained fewer mature B- and T-cells Although spontaneous tumours were infrequent, lymphomagenesis was much more rapid in mice that co-expressed the cyclin D1 transgene and a myc transgene than in mice expressing either transgene alone Moreover, the spontaneous lymphomas of myc transgenic animals often ectopically expressed the endogenous cyclin D1 gene These findings indicate that this G1 cyclin can modulate differentiation and collaborate with myc-like genes in oncogenesis
459 citations
TL;DR: In this paper, two chloroquine-resistant cloned isolates of Plasmodium falciparum were subjected to mefloquine selection to test if this resulted in alterations in chloroquines sensitivity and amplification of the pfmdr1 gene.
Abstract: Two chloroquine-resistant cloned isolates of Plasmodium falciparum were subjected to mefloquine selection to test if this resulted in alterations in chloroquine sensitivity and amplification of the pfmdr1 gene. The mefloquine-resistant lines derived by this selection were shown to have amplified and overexpressed the pfmdr1 gene and its protein product (Pgh1). Macrorestriction maps of chromosome 5, where pfmdr1 is encoded, showed that this chromosome has increased in size in response to mefloquine selection, indicating the presence of a gene(s) in this area of the genome that confers a selective advantage in the presence of mefloquine. Concomitant with the increase in mefloquine resistance was a corresponding increase in the level of resistance to halofantrine and quinine, suggesting a true multidrug-resistance phenotype. The mefloquine-selected parasite lines also showed an inverse relationship between the level of chloroquine resistance and increased pfmdr1 gene copy number. These results have important implications for the derivation of amplified copies of the pfmdr1 gene in field isolates, as they suggest that quinine pressure may be involved.
391 citations
TL;DR: It is demonstrated, in vitro, that lowering the levels of p75NGFR expression in sensory neurons with antisense oligonucleotides largely prevents the NGF-mediated survival of sensory neurons from embryonic day 12 and 15 mice but increases the survival of embryonic day 19 and postnatal day 2 sensory neurons in the absence of NGF.
Abstract: The function of the low-affinity nerve growth factor (NGF) receptor, p75NGFR, in regulating neuronal survival during development is unclear. The sensory deficit in mice with mutated p75NGFR suggests it is necessary for development of sensory neurons; however, whether it is required, in addition to trkA, for signal transduction or is more involved in localization of NGF is unresolved. In this study we demonstrate, in vitro, that lowering the levels of p75NGFR expression in sensory neurons with antisense oligonucleotides largely prevents the NGF-mediated survival of sensory neurons from embryonic day 12 and 15 mice but increases the survival of embryonic day 19 and postnatal day 2 sensory neurons in the absence of NGF. Thus, the p75NGFR is required for NGF-mediated survival in neurons at the stage of target innervation but can mediate an apoptotic signal at a later stage of cell development. Thus, p75NGFR undergoes a switch in function in the perinatal period: during embryogenesis it is required, probably with trkA, to mediate neuronal survival in the presence of NGF, but in the early postnatal period it acts as a constitutive death signal in the absence of NGF.
382 citations
TL;DR: It is demonstrated that the majority of neutrophil migration in both models requires an endothelial selectin but that E-selectin and P- selectin are functionally redundant, which has important implications in the use of selectin antagonists in the treatment of inflammatory disease.
363 citations
TL;DR: The recently discovered transmembrane 4 superfamily comprises a group of cell-surface proteins that are characterized by the presence of four hydrophobic domains, which are presumed to be membrane spanning.
343 citations
TL;DR: The cloning and sequencing of the gene encoding the P. falciparum DHPS enzyme is described and it is shown that it is a bifunctional enzyme that includes dihydro-6-hydroxymethylpterin pyrophosphokinase at the N terminus of DHPS.
Abstract: The enzyme dihydropteroate synthetase (DHPS) from Plasmodium falciparum is involved in the mechanism of action of the sulfone/sulfonamide group of drugs. We describe the cloning and sequencing of the gene encoding the P. falciparum DHPS enzyme and show that it is a bifunctional enzyme that includes dihydro-6-hydroxymethylpterin pyrophosphokinase (PPPK) at the N terminus of DHPS. The gene encodes a putative protein of 83 kDa that contains two domains that are homologous with the DHPS and PPPK enzymes of other organisms. The PPPK-DHPS gene is encoded on chromosome 8 and has two introns. An antibody raised to the PPPK region of the protein was found to recognize a 68-kDa protein that is expressed throughout the asexual life cycle of the parasite. We have determined the sequence of the DHPS portion of the gene from sulfadoxine-sensitive and -resistant P. falciparum clones and identified sequence differences that may have a role in sulfone/sulfonamide resistance.
307 citations
TL;DR: The capacity to bind IL‐11 with high affinity appeared to require coexpression of both NR1 and gp130, the common subunit of the IL‐6, leukaemia inhibitory factor (LIF), oncostatin M (OSM) and ciliary neurotrophic factor (CNTF) receptors.
Abstract: An adult mouse liver cDNA library was screened with oligonucleotides corresponding to the conserved WSXWS motif of the haemopoietin receptor family. Using this method, cDNA clones encoding a novel receptor were isolated. The new receptor, named NR1, was most similar in sequence and predicted structure to the alpha-chain of the IL-6 receptor and mRNA was expressed in the 3T3-L1 pre-adipocytic cell line and in a range of primary tissues. Expression of NR1 in the factor-dependent haemopoietic cell line Ba/F3 resulted in the generation of low affinity receptors for IL-11 (Kd approximately 10 nM). The capacity to bind IL-11 with high affinity (Kd = 300-800 pM) appeared to require coexpression of both NR1 and gp130, the common subunit of the IL-6, leukaemia inhibitory factor (LIF), oncostatin M (OSM) and ciliary neurotrophic factor (CNTF) receptors. The expression of both NR1 and gp130 was also necessary for Ba/F3 cells to proliferate and M1 cells to undergo macrophage differentiation in response to IL-11.
TL;DR: The available binding data indicate that the receptor interaction surface for EGF/TGF-alpha might encompass one complete side of the molecule with a few strong binding determinants, in particular Arg41 and Leu47, which seems unlikely that agonists or antagonists can be developed on the basis of short peptides taken from the primary sequence.
Abstract: Epidermal growth factor (EGF) and transforming growth factor alpha (TGF-α) are ligands for the EGF-receptor and act as mitogens for a variety of tissues. TGF-α, in particular, has been implicated as an autocrine growth factor for several cancer cell lines. Over the last 10 years many groups have examined the structure-function relationships in EGF/TGF-α in attempts to develop antagonists or agonists. In this review the results of these studies are summarised and related to the three-dimensional structure of EGF/TGF-α. The dificulties associated with the purification and characterisation of analogues of EGF/TGF-α and with the biological assays are discussed. It is clear that these difficulties have, in some cases, led to apparently contradicting results. The available binding data indicate that the receptor interaction surface for EGF/TGF-α might encompass one complete side of the molecule with a few strong binding determinants, in particular Arg41 and Leu47. The arginine at position 41 is the most...
TL;DR: Using a combination of size-exclusion chromatography and analytical ultracentrifugation analysis, in the low affinity receptor complex, IL-6 was shown to bind sIL-6R in a stoichiometric ratio of 1:1, whereas the high affinity ternary complex is hexameric consisting of two molecules each of IL- 6, sIL -6R, and sgp-130.
Journal Article•
TL;DR: A detailed analysis of the intracellular distribution of Bcl-2 by immunofluorescence, immunogold electron microscopy, and subcellular fractionation in three mouse cell lines expressing a human bcl2 transgene and measured its importation into isolated mitochondria was performed in this paper.
Abstract: The protein product of the oncogene bcl-2 is a potent inhibitor of apoptotic cell death. The Bcl-2 protein has variously been reported to reside in the nuclear envelope and endoplasmic reticulum or exclusively in the inner membrane of mitochondria. We therefore undertook a detailed analysis of the intracellular distribution of Bcl-2 by immunofluorescence, immunogold electron microscopy, and subcellular fractionation in three mouse cell lines expressing a human bcl-2 transgene and measured its importation into isolated mitochondria. By these methods, the protein was localized to the nuclear envelope, the endoplasmic reticulum, and the outer mitochondrial membrane. Any proposal for the mechanism by which Bcl-2 inhibits apoptosis must therefore accommodate the fact that Bcl-2 localizes to cytoplasmic membranes facing the cytosol.
TL;DR: The average age of humans at their first infection with Plasmodium falciparum is typically less than 1 year in most endemic areas of Papua New Guinea.
Abstract: The average age of humans at their first infection with Plasmodium falciparum is typically less than 1 year in most endemic areas. This has been interpreted as evidence of the high transmissibility of the parasite, with the implication that control of malaria will require high levels of coverage with a potential vaccine. This interpretation is challenged by mathematical models that demonstrate that the long period required to develop immunity to malaria permits a high risk (or low average age) of infection even when parasite transmissibility is low. Patterns of seroconversion to five antigenically distinct isolates of P. falciparum in a highly malarious area of Papua New Guinea indicate that each is only mildly transmissible and that malaria, as a construct of several such independently transmitted strains, has a basic reproductive rate (or transmissibility) that is an order of magnitude lower than other estimates.
TL;DR: Introducing a TCR transgene enabled bcl-2/scid mice to develop normal numbers of CD4+8+ thymocytes even in the absence of immunological selection, suggesting that T cells become competent to respond to bCl-2 protein only after the TCR complex is displayed at the cell surface.
Abstract: Expression of antigen receptors is vital for the development of B and T lymphocytes. In mice with the scid mutation, which are unable to make productive rearrangements of their immunoglobulin and T-cell receptor (TCR) genes, lymphopoiesis aborts at an early stage. The death of the immature lymphocytes by apoptosis is postulated to result from a failure to receive a survival signal induced by receptor engagement. Consistent with this hypothesis, introduction of immunoglobulin or TCR transgenes into scid mice promoted an increase in B- or T-lymphoid cells, respectively. As the protein encoded by the bcl-2 gene can inhibit cell death, we tested whether lymphopoiesis could be rescued in scid mice by crossing in a bcl-2 transgene. Strikingly, the bcl-2/scid mice accumulated almost normal numbers of B-lymphoid cells which lacked surface immunoglobulin but expressed markers of maturity. T-cell development remained blocked. Introducing a TCR transgene enabled bcl-2/scid mice to develop normal numbers of CD4+8+ thymocytes even in the absence of immunological selection, suggesting that T cells become competent to respond to bcl-2 protein only after the TCR complex is displayed at the cell surface.
TL;DR: Although bcl-2 expression hampers the deletion of immature self-reactive cells in the thymus, self-tolerance is maintained, and TCR-MHC interaction may induce positive selection through two signals, one which saves cells from death by increasing BCl-2 synthesis and another which promotes maturation.
Abstract: To explore the role of bcl-2 in T-cell development, a bcl-2 transgene was introduced into mice expressing a T-cell receptor (TCR) transgene encoding reactivity for the mouse male antigen HY presented by the H-2Db class I antigen of the major histocompatibility complex (MHC). Normal thymic development is contingent on the ability of immature thymocytes to interact with self-MHC molecules presented by thymic stroma (positive selection). Thus, thymocyte numbers are low in female anti-HY TCR transgenic mice with a nonselecting (H-2Dd) background. Expression of bcl-2 inhibited the death of nonselectable thymocytes since, strikingly, female H-2Dd bcl-2/TCR transgenic mice developed normal numbers of CD4+CD8+ thymocytes, although these did not mature further into functional T cells. Hence, TCR-MHC interaction may induce positive selection through two signals, one which saves cells from death by increasing Bcl-2 synthesis and another which promotes maturation. Male H-2Db anti-HY TCR transgenic mice normally have a very small thymus, due to deletion of the self-reactive T cells. Expression of bcl-2 reduced the efficiency of deletion, since bcl-2/TCR transgenic male mice accumulated 4- to 6-fold more thymocytes than did TCR transgenic male littermates. Anti-HY TCR-expressing cells were also more numerous in the peripheral lymphoid tissues, but these cells expressed abnormally low levels of CD8 co-receptor and were not responsive to the HY antigen. Thus, although bcl-2 expression hampers the deletion of immature self-reactive cells in the thymus, self-tolerance is maintained.
TL;DR: MSA2 genotyping of a local P. falciparum population revealed an unexpected amount of genetic heterogeneity, mostly due to variation in the repeat region resulting in length polymorphism that can be easily detected by PCR-RFLP.
TL;DR: It is suggested that stem cell differentiation is associated with the development of mitogenic activity by SCF at least in some progenitor cell populations.
TL;DR: The mode of action of the antifolate and quinoline antimalarials and the means used by the parasite to defeat the therapeutic ingenuity are discussed.
TL;DR: Evidence that members of the fibroblast growth factor family, (FGF1 or FGF2) act directly on the neural crest cells in vitro to stimulate proliferation in the presence of serum supports a model of neural crest development, whereby multipotential neural crest precursor cells are stimulated to divide by FGF and subsequent development into sensory neurons is regulated by LIF or other cytokines with a similar signalling mechanism.
Abstract: Two of the key early events in the development of the peripheral nervous system are the proliferation of neural crest precursor cells and their subsequent differentiation into different neural cell types. We present evidence that members of the fibroblast growth factor family, (FGF1 or FGF2) act directly on the neural crest cells in vitro to stimulate proliferation in the presence of serum. These findings correlate with in situ hybridisation analysis, which shows FGF2 mRNA is expressed in cells both in the neural tube and within newly formed sensory ganglia (dorsal root ganglia, DRG) at embryonic day 10 in the mouse, when neural crest precursors are proliferating within the DRG. This data infers an autocrine/paracrine loop for FGF regulation of proliferation. Evidence supporting this notion is provided by the finding that part of the endogenous proliferative activity in the NC cultures is related to FGF. It was also found, in early neural crest cultures, that exogenous FGF completely inhibited neuronal differentiation, probably as a direct consequence of its mitogenic activity. In order to stimulate neuronal differentiation significantly, it was necessary to remove the FGF and replace it with leukemia inhibitory factor (LIF) or related factors. Under these conditions, 50% of the cells differentiated into neurons, which developed a sensory neuron morphology and were immunoreactive for the sensory markers CGRP and substance P. These data support a model of neural crest development, whereby multipotential neural crest precursor cells are stimulated to divide by FGF and subsequent development into sensory neurons is regulated by LIF or other cytokines with a similar signalling mechanism.
TL;DR: Evidence is provided that LIF is acting as a natural trauma factor in vivo and is actively involved in muscle regeneration in vivo, using a muscle crush model.
TL;DR: This unit describes how pGEX vectors can be used in bacterial systems to express foreign polypeptides as fusions with glutathione‐S‐transferase (GST) and several modifications to the expression and purification protocol that may be useful in cases where fusion proteins are insoluble or unstable.
Abstract: This unit describes how pGEX vectors can be used in bacterial systems to express foreign polypeptides as fusions with glutathione-S-transferase (GST). In general, such fusion proteins are soluble and are easily purified from lysed cells under nondenaturing conditions by absorption with glutathione-agarose beads, followed by elution in the presence of free glutathione. Potential applications of the pGEX vectors include the expression and purification of individual polypeptides (including short peptides) for use as immunogens and as biochemical and biological reagents, and in the construction of cDNA expression libraries. This protocol describes production and screening of pGEX transformants and purification of milligram quantities of fusion proteins from 1-liter cultures. The commentary describes several modifications to the expression and purification protocol that may be useful in cases where fusion proteins are insoluble or unstable.
TL;DR: A well-characterized T cell-dependent B cell response in mice expressing transgenic B cl-2 in their B lymphocytes is examined, suggesting that the final size of the memory compartment may be regulated by an apoptotic process, which, in turn, can be influenced by Bcl-2.
TL;DR: The secreted polymorphic antigen associated with merozoites (SPAM) is the first example of a P. falciparum antigen in which a repetitive sequence has features characteristic of a well-defined structural element.
TL;DR: Treatment with a gelfoam containing LIF significantly reduced motoneurone loss and is a potential therapeutic agent for preventing the loss of injured or diseased mot oneurones.
Abstract: THE death of spinal motoneurones after axotomy provides a useful model for studying novel factors which prevent motoneurone loss in vivo. Peripheral nerves of newborn rats were unilaterally transected and treated with either a vehicle solution or leukaemia inhibitory factor (LIF). Compared with the vehicle controls, treatment with a gelfoam containing LIF significantly reduced motoneurone loss: from 38% to 22% after 3 days and from 55% to 38% after 7 days. The loss of motoneurones was further reduced by placing the LIF-containing gelfoam inside a silicone chamber: from 39% to 15% after 7 days, which represented a 62% rescue. Thus, LIF is a potential therapeutic agent for preventing the loss of injured or diseased motoneurones.
TL;DR: The degree of rescue of sensory neurons in vivo by LIF was found to be similar to NGF, which was not surprising as both factors supported the survival of a similar population of sensory neuron in vitro.
Abstract: Leukemia inhibitory factor (LIF) has several characteristics of a neurotrophic factor for sensory neurons. Here we have investigated whether LIF also supports the survival of axotomised sensory neurons in vivo. Newborn rat pups received a unilateral sciatic nerve transection and the injury site was treated with gelfoam soaked in phosphate buffered saline (PBS), nerve growth factor (NGF), or LIF. Neuronal nucleoli in the L5 dorsal root ganglia were counted, appropriate corrections applied, and the resultant neuronal loss expressed as a percentage of the contralateral intact side. In animals where LIF was administered neuronal loss was significantly reduced: 2 days after LIF treatment neuronal loss was 19.5% compared to 43% in PBS-treated animals; 3 days after LIF treatment neuronal loss was 20.4% compared to 40.2% in PBS-treated animals; however, 7 days after LIF treatment there was no significant reduction in the number of neurons lost. The degree of rescue of sensory neurons in vivo by LIF was found to be similar to NGF, which was not surprising as both factors supported the survival of a similar population of sensory neurons in vitro. Rescue was not observed when LIF-containing gelfoam was placed away from the axotomised nerve, suggesting that LIF's action may be associated with its retrograde transport or direct signalling at the site of nerve injury.
TL;DR: It is shown here that Oct-2 is not required for normal immunoglobulin production by mature B lymphocytes Instead, it is essential for a normal proliferative response to polyclonal mitogens.
TL;DR: Analysis of the respiratory tract before and after primary influenza virus infection revealed a virus-induced preferential accumulation of a CD8+ T-cell population that coexpresses mRNA for interleukin-5 and IL-10 with virus dose-dependent high levels of gamma interferon.
Abstract: Analysis of the respiratory tract before and after primary influenza virus infection revealed a virus-induced preferential accumulation of a CD8+ T-cell population that coexpresses mRNA for interleukin-5 (IL-5) and IL-10 with virus dose-dependent high levels of gamma interferon. However, cytokine production in lung tissues was not restricted to the T-cell population, since CD3- cells were found to express mRNA for various cytokines, including IL-4 and particularly IL-6 and granulocyte-macrophage colony-stimulating factor. These data provide in vivo evidence for a local respiratory tract immune response to influenza virus infection dominated by cytokine-producing CD8+ T cells.