Showing papers by "Axel Ullrich published in 1994"
TL;DR: The biological relevance of the VEGF/Flk-1 receptor/ligand system for angiogenesis is investigated using a retrovirus encoding a dominant-negative mutant of the Flk- 1/VEGF receptor to infect endothelial target cells in vivo, and tumour growth is prevented in nude mice.
Abstract: ANGIOGENESIS, the sprouting of capillaries from pre-existing blood vessels, is a fundamental process in the formation of the vascular system during embryonic development. In adulthood, angiogenesis takes place during corpus luteum formation and in pathological conditions such as wound healing, diabetic retinopathy, and tumorigenesis. Vascularization is essential for solid tumour growth and is thought to be regulated by tumour cell-produced factors, which have a chemotactic and mitogenic effect on endothelial cells1–4. Vascular endothelial growth factor (VEGF), a homodimeric glycoprotein of relative molecular mass 45,000, is the only mitogen, however, that specifically acts on endothelial cells, and it may be a major regulator of tumour angiogenesis in vivo5,6. Its expression has been shown to be upregulated by hypoxia, and its cell-surface receptor, FIk-1, is exclusively expressed in endothelial cells7,8. Here we investigate the biological relevance of the VEGF/Flk-1 receptor/ligand system for angiogenesis using a retrovirus encoding a dominant-negative mutant of the Flk-1/VEGF receptor to infect endothelial target cells in vivo, and find that tumour growth is prevented in nude mice. Our results emphasize the central role of the FIk-1/VEGF system in angiogenesis in general and in the development of solid tumours in particular.
1,348 citations
TL;DR: In this article, the authors examined whether the differential activation of MAP kinases forms the basis of the differential response of the cells to the two factors, and they found that the distinct effects of nerve growth factor and epidermal growth factor on PC12 cell differentiation can be explained by differences in the extent and duration of activation of p42 and p44 MAP kinase in response to two factors.
438 citations
TL;DR: Mutagenesis of the specific binding sites for src homology 2 domain‐containing substrates within the Trk cytoplasmic domain suggests a non‐essential function of PI3′‐K and reveals a major role for the signal controlled by the SHC binding site at tyrosine 490 and a co‐operative function of the PLC gamma‐mediated pathway for neuronal differentiation of PC12 cells.
Abstract: Differentiation and survival of neuronal cell types requires the action of neurotrophic polypeptides such as nerve growth factor (NGF). In the central and peripheral nervous system and the phaeochromocytoma cell model PC12, NGF exerts its effects through the activation of the signalling capacity of Trk, a receptor tyrosine kinase (RTK) which upon interaction with NGF becomes phosphorylated on tyrosines and thereby acquires the potential to interact with signal-transducing proteins such as phospholipase C-gamma (PLC gamma), phosphatidylinositol-3'-kinase (PI3'-K) and SHC. Mutagenesis of the specific binding sites for these src homology 2 (SH2) domain-containing substrates within the Trk cytoplasmic domain suggests a non-essential function of PI3'-K and reveals a major role for the signal controlled by the SHC binding site at tyrosine 490 and a co-operative function of the PLC gamma-mediated pathway for neuronal differentiation of PC12 cells.
303 citations
TL;DR: Functional characterization reveals stimulatory effects of 90K on host defense systems, such as natural killer cell and lymphokine-activated killer cell activity, and indicates that its immunostimulatory effects may be mediated through the induction of interleukin-2 and possibly other cytokines.
196 citations
TL;DR: This work has identified proteins of 110, 80, 65, and 43 kDa in human embryonic fibroblasts that bind specifically to the SH3 domain of phospholipase C gamma, a primary substrate of receptor tyrosine kinases, and characterized the 110-kDa band as the microtubule-activated GTPase dynamin.
141 citations
TL;DR: The usefulness of dominant-negative mutants of the PDGF receptor are demonstrated for the evaluation of the role of the receptor in tumorigenesis and the ability of cells expressing the truncated receptor to grow as xenografts in nude mice was impaired.
123 citations
TL;DR: The role of the protooncogene product p95vav in signal transduction was investigated by characterizing its interactions with proteins that may represent components of a novel signaling pathway.
91 citations
TL;DR: The high-resolution NMR structure of the complex between the amino-terminal SH3 domain of GRB2 and a ten amino acid peptide derived from the guanine nucleotide releasing factor Sos is determined.
Abstract: Src-homology 3 (SH3) domains mediate signal transduction by binding to proline-rich motifs in target proteins. We have determined the high-resolution NMR structure of the complex between the amino-terminal SH3 domain of GRB2 and a ten amino acid peptide derived from the guanine nucleotide releasing factor Sos. The NMR data show that the peptide adopts the conformation of a left-handed polyproline type II helix and interacts with three major sites on the SH3 domain. The orientation of the bound peptide is opposite to that of proline-rich peptides bound to the SH3 domains of AbI, Fyn and p85.
90 citations
TL;DR: A 6.2-kb full-length clone encoding a distinct protein-tyrosine phosphatase (PTP), PTPD1, was isolated from a human skeletal muscle cDNA library and found to be efficiently phosphorylated by and associated with the src kinase pp60src.
Abstract: A 6.2-kb full-length clone encoding a distinct protein-tyrosine phosphatase (PTP; EC 3.1.3.48), PTPD1, was isolated from a human skeletal muscle cDNA library. The cDNA encodes a protein of 1174 amino acids with N-terminal sequence homology to the ezrin-band 4.1-merlin-radixin protein family, which also includes the two PTPs H1 and MEG1. The PTP domain is positioned in the extreme C-terminal part of PTPD1, and there is an intervening sequence of about 580 residues without any apparent homology to known proteins separating the ezrin-like and the PTP domains. Thus, PTPD1 and the closely related, partially characterized, PTPD2 belong to the same family as PTPH1 and PTPMEG1, but because of distinct features constitute a different PTP subfamily. Northern blot analyses indicate that PTPD1 and PTPD2 are expressed in a variety of tissues. In transient coexpression experiments PTPD1 was found to be efficiently phosphorylated by and associated with the src kinase pp60src.
86 citations
TL;DR: In this paper, the three-dimensional structure of the carboxy-terminal SH3 domain of GRB2 (GRB2 C-SH3) was determined by NMR spectroscopy.
65 citations
TL;DR: Evidence is provided that both interferon‐α and ‐γ can enhance the secretion of 90K and augment the level of specific mRNA expression in 3 ovarian carcinoma cell lines (OVCAR‐3, HTB‐77 and SKOV‐6).
Abstract: Antigen 90K is produced by several tumor-cell lines and by patients with cancer. Its function has not yet been clarified, although recent reports suggest that it plays a role in the tumor-host relationship-for example by stimulation of natural killer and lymphokine-activated killer-cell activity. Previous studies have indicated that 90K expression may be under the influence of interferon-alpha. Here, we provide evidence that both interferon-alpha and -gamma can enhance the secretion of 90K and augment the level of specific mRNA expression in 3 ovarian carcinoma cell lines (OVCAR-3, HTB-77 and SKOV-6). However, interferon-gamma leads to depletion of cellular 90K whereas interferon-alpha increases both secreted and cellular 90K levels. In equimolar concentrations, Interferon-alpha was always superior to interferon-gamma in augmenting 90K protein or mRNA levels. Combinations of TNF with interferon-gamma were highly synergistic both in reducing cell proliferation and in increasing 90K secretion and mRNA expression. This synergism was seen to a lesser extent with interferon-alpha. (C) 1994 Wiley-Liss, Inc.
TL;DR: These results demonstrate for the first time that the changes in cellular homeostasis directly induced by deleted IP3R subunits are largely compensated by indirect coordinate changes apparently aimed to keep near normal the signaling properties of the cells, and that modulation of intracellular Ca2+ channels induces profound consequences that differentially affect growth and oncogenesis.
TL;DR: Thinner forms of PTP1B retained the same characteristics as the full-length mammalian enzyme, but are not subject to inhibition of enzymic activity mediated by the C-terminus, and it can be assumed that the catalytic domains are advantageous for crystallization studies in comparison to the natural enzyme.
Abstract: Protein phosphotyrosine phosphatases are believed to be involved in the regulation of the activity of cellular proteins, such as receptor tyrosine kinases, by controlling their phosphorylation status. One of the best described and characterized protein of this class of enzymes is the phosphotyrosine phosphatase 1B. To obtain sufficient quantities for structural investigations, truncated forms of PTP1B encompassing the catalytic domain were over-expressed in Escherichia coli and purified to apparent homogeneity by conventional chromatography. The activity of these purified enzymes has been compared with the wild-type enzyme expressed in mammalian cells. By measuring the activities against p-nitrophenyl phosphate, the pH dependence of this activity, and responses to different modulators, it could be demonstrated that the truncated forms of PTP1B retained the same characteristics as the full-length mammalian enzyme, but are not subject to inhibition of enzymic activity mediated by the C-terminus. Due to their improved solubility, it can be assumed that the catalytic domains are advantageous for crystallization studies in comparison to the natural enzyme. In a screening for crystallization conditions, we obtained protein crystals indicating that the quality of the purified protein is sufficient for crystallographic studies.
TL;DR: Solution phase screening with dual cleavable libraries is being used for growth inhibition of human tumor cell lines and initial in vitro leads have been identified in each of these areas of anticancer drug discovery.
Abstract: A technology for chemical synthesis and testing of libraries of millions of chemical entities has been developed for rapid molecular and cellular screening for drug leads. Each individual compound in the library is on a separate resin bead. Screening for binding activity can be conducted directly on the beads. Biological activity is assessed in solution phase assay by cleaving a portion of the compound from each bead. The molecular structure of the compound of interest is obtained by automated peptide sequencing from the bead of origin. We have applied this technology to anticancer drug discovery as well as to other pharmaceutical targets. For anticancer drug development, current molecular targets include B-cell lymphoma, the EGF receptor, and the HER2-neu receptor. Solution phase screening with dual cleavable libraries is being used for growth inhibition of human tumor cell lines. Initial in vitro leads have been identified in each of these areas of anticancer drug discovery.
Patent•
23 Mar 1994
TL;DR: A protein tyrosine phosphatase designated PTP-S31 and its subfamily are identified in this paper, as are nucleic acid molecules coding therefor, and methods for screening molecules which can bind to PTPS31 proteins or glycoproteins and inhibit or stimulate their enzymatic activity.
Abstract: A protein tyrosine phosphatase designated PTP-S31 and its subfamily are identified, as are nucleic acid molecules coding therefor. Included in this family are PTP-S31 proteins or glycoproteins having one, two, or three identified amino acid changes in previously defined consensus sequences in the catalytic phosphatase domains of known protein tyrosine phosphatases. The PTP-S31 proteins or glycoproteins may be produced by recombinant means. Antibodies to PTP-S31 proteins or glycoproteins and nucleic acid constructs coding therefor, and methods for screening molecules which can bind to PTP-S31 proteins or glycoproteins and inhibit or stimulate their enzymatic activity, are provided.
TL;DR: This investigation has generated two independent mutations of amino acids Phe381 and Phe382 of the insulin receptor that cause a slight impairment of intracellular processing and transport of the mutant receptors.
Patent•
04 Nov 1994
TL;DR: In this article, a method for treating a disorder by administering a therapeutically effective amount of IR-95 to a patient in need of such treatment was proposed, for example a patient suffering from an autoimmune disorder.
Abstract: The invention provides a method for treating a disorder by administering a therapeutically effective amount of IR-95 to a patient in need of such treatment. The disorders treated include cancers, bacterial infections, and viral infections. The invention also provides a method for suppressing an immune response by admininstering a therapeutically effective amount of an IR-95 antagonist to an organism in need of such treatment, for example a patient suffering from an autoimmune disorder.
Patent•
22 Apr 1994
TL;DR: In this paper, the authors presented a novel cytoplasmic tyrosine kinases isolated from megakaryocytes (megakaryocyte kinases or MKKs) which are involved in cellular signal transduction pathways and the use of these novel proteins in the diagnosis and treatment of disease.
Abstract: The present invention relates to novel cytoplasmic tyrosine kinases isolated from megakaryocytes (megakaryocyte kinases or MKKs) which are involved in cellular signal transduction pathways and to the use of these novel proteins in the diagnosis and treatment of disease. The present invention further relates to specific megakaryocyte kinases, designated MKK1, MKK2 and MKK3, and their use as diagnostic and therapeutic agents.