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Yosef Yarden - One of the best experts on this subject based on the ideXlab platform.

  • Neu Differentiation Factor stimulates phosphorylation and activation of the sp1 transcription Factor
    Molecular and Cellular Biology, 1999
    Co-Authors: Iris Alroy, Lior Soussan, Rony Seger, Yosef Yarden
    Abstract:

    Neu Differentiation Factors (NDFs), or Neuregulins, are epidermal growth Factor-like growth Factors which bind to two tyrosine kinase receptors, ErbB-3 and ErbB-4. The transcription of several genes is regulated by Neuregulins, including genes encoding specific subunits of the acetylcholine receptor at the Neuromuscular junction. Here, we have examined the promoter of the acetylcholine receptor « subunit and delineated a minimal CA-rich sequence which mediates transcriptional activation by NDF (NDF-response element [NRE]). Using gel mobility shift analysis with an NRE oligonucleotide, we detected two complexes that are induced by treatment with Neuregulin and other growth Factors and identified Sp1, a constitutively expressed zinc finger phosphoprotein, as a component of one of these complexes. Phosphatase treatment, two-dimensional gel electrophoresis, and an in-gel kinase assay indicated that Sp1 is phosphorylated by a 60-kDa kinase in response to NDF-induced signals. Moreover, Sp1 seems to act downstream of all members of the ErbB family and thus may funnel the signaling of the ErbB network into the nucleus. Protein phosphorylation plays an important role in the transfer of the signal from the cell surface into the nucleus (27). Several pathways of signal transduction have been described, including intracellular hormone receptors which are themselves transcription Factors; direct interaction between cell surface receptors and transcription Factors which, upon modification, translocate to the nucleus; and linear cascades of protein kinases, e.g., the mitogen-activated protein kinases (MAPKs) (reviewed in reference 55), that serve as the link between cell surface receptors and nuclear transcription Factors. One of the best-characterized families of surface receptors that stimulate transcription through MAPKs is the ErbB family, which consists of four receptors, ErbB-1 [epidermal growth Factor receptor (EGFR)], ErbB-2, ErbB-3, and ErbB-4. Upon ligand binding, these receptors form different combinations of homo- and heterodimers, thereby increasing the diversification potential of signaling and tightly tuning MAPK activation (51). Each ErbB protein consists of a large extracellular ligand-binding domain, a single transmembrane segment, and an intracellular portion containing a tyrosine kinase subdomain and a carboxyterminal tail region. Multiple ligands exist for ErbB-1, ErbB-3, and ErbB-4, which appear to induce distinct homo- and heterodimers of ErbB proteins. The ligands for ErbB-3 and ErbB-4, Neu Differentiation Factors (NDFs) or Neuregulins, are peptide growth Factors which bind to and activate their cognate receptors. The biological activity of Neuregulins, inferred from the phenotypes of knockout mice and cell lines grown in culture (reviewed in reference 11), depicts a role in epithelial cell-mesenchyme and other types of inductive cell-cell interactions. Different isoforms of Neuregulins, also called NDF, heregulin, or the acetylcholine receptor (AChR)-inducing activity, were isolated as activities which lead to ErbB-2 tyrosine phosphorylation (26, 48, 65) or to induction of AChR in the Neuromuscular synapse (19), respectively. Only later was it established that the isoforms of the Neuregulin family of ligands do not bind directly to ErbB-2 but interact with both ErbB-3 and ErbB-4 (58, 62). In situ hybridization analyses indicated that NDF is expressed predominantly in parenchymal organs and in the embryonic central and peripheral nervous systems, in adult

  • morphogenetic effects of Neuregulin Neu Differentiation Factor in cultured epithelial cells
    Molecular Biology of the Cell, 1998
    Co-Authors: Alexander Chausovsky, Yosef Yarden, Ilan Tsarfaty, Benjamin Geiger, Alexander D Bershadsky
    Abstract:

    Neuregulin, or Neu Differentiation Factor, induces cell proliferation or Differentiation through interaction with members of the ErbB family of receptor tyrosine kinases. We report that Neuregulin can also induce profound morphogenic responses in cultured epithelial cells of different origins. These effects include scattering of small epithelial islands and rearrangement of larger cell islands into ordered ring-shaped arrays with internal lumens. The ring-forming cells are interconnected by cadherin- and β-catenin-containing adherens junctions. In confluent cultures, Neuregulin treatment induces formation of circular lumenlike gaps in the monolayer. Both cell scattering and ring formation are accompanied by a marked increase in cell motility that is independent of hepatocyte growth Factor/scatter Factor and its receptor (c-Met). Affinity-labeling experiments implied that a combination of ErbB-2 with ErbB-3 mediates the morphogenic signal of Neuregulin in gastric cells. Indeed, a similar morphogenic effect could be reconstituted in nonresponsive cells by coexpression of ErbB-2 and -3. We conclude that a heterodimer between the kinase-defective Neuregulin receptor, ErbB-3, and the coreceptor, ErbB-2, mediates the morphogenetic action of Neuregulin.

  • Alternative Intracellular Routing of ErbB Receptors May Determine Signaling Potency
    Journal of Biological Chemistry, 1998
    Co-Authors: Hadassa Waterman, Benjamin Geiger, Ilana Sabanai, Yosef Yarden
    Abstract:

    Abstract The ErbB signaling module consists of four receptor tyrosine kinases and several dozen ligands that activate specific homo- and heterodimeric complexes of ErbB proteins. Combinatorial ligand/receptor/effector interactions allow large potential for signal diversification. Here we addressed the possibility that turn-off mechanisms enhance the diversification potential. Concentrating on ErbB-1 and two of its ligands, epidermal growth Factor (EGF) and transforming growth Factor α (TGF-α), and the Neu Differentiation Factor (NDF/Neuregulin) and one of its receptors, ErbB-3, we show that ligand binding variably accelerates endocytosis of the respective ligand-receptor complex. However, unlike the EGF-activated ErbB-1, which is destined primarily to degradation in lysosomes, NDF and TGF-α direct their receptors to recycling, probably because these ligands dissociate from their receptors earlier along the endocytic pathway. In the case of NDF, structural, as well as biochemical, analyses imply that ligand degradation occurs at a relatively late endosomal stage. Attenuation of receptor down-regulation by this mechanism apparently confers to both NDF and TGF-α more potent and prolonged signaling activity. In conclusion, alternative endocytic trafficking of ligand-ErbB complexes may tune and diversify signal transduction by EGF family ligands.

  • activity dependent regulation of Neu Differentiation Factor Neuregulin expression in rat brain
    Proceedings of the National Academy of Sciences of the United States of America, 1998
    Co-Authors: Raya Eilam, Ronit Pinkaskramarski, Barry J Ratzkin, Menahem Segal, Yosef Yarden
    Abstract:

    Neu Differentiation Factor (NDF/Neuregulin) is widely expressed in the central and peripheral nervous systems, where it functions as a mediator of the interactions between nerve cells and Schwann, glia, oligodendrocyte, and muscle cells, to control cellular proliferation, Differentiation, and migration. NDF binds to two receptor tyrosine kinases, ErbB-3 and ErbB-4. Here we demonstrate that NDF and its ErbB-4 receptor are highly reactive to changes in ambient Neuronal activity in the rodent brain in a region-selective manner. Generation of epileptic seizures by using kainic acid, a potent glutamate analog, elevated levels of NDF transcripts in limbic cortical areas, hippocampus, and amygdala. Concomitantly, ErbB-4 mRNA was increased with a similar spatial distribution, but transcription of the other NDF receptor, ErbB-3, did not change. A more moderate stimulation, forced locomotion, was accompanied by an increase in NDF transcripts and protein in the hippocampus and in the motor cortex. Similar changes were found with ErbB-4, but not ErbB-3. Last, a pathway-specific tetanic stimulation of the perforant path, which produced long-term potentiation, was followed by induction of NDF expression in the ipsilateral dentate gyrus and CA3 area of the hippocampus. Taken together, these results indicate that NDF is regulated by physiological activity and may play a role in Neural plasticity.

  • Activity-dependent regulation of Neu Differentiation Factor/Neuregulin expression in rat brain
    Proceedings of the National Academy of Sciences of the United States of America, 1998
    Co-Authors: Raya Eilam, Barry J Ratzkin, Ronit Pinkas-kramarski, Menahem Segal, Yosef Yarden
    Abstract:

    Neu Differentiation Factor (NDF/Neuregulin) is widely expressed in the central and peripheral nervous systems, where it functions as a mediator of the interactions between nerve cells and Schwann, glia, oligodendrocyte, and muscle cells, to control cellular proliferation, Differentiation, and migration. NDF binds to two receptor tyrosine kinases, ErbB-3 and ErbB-4. Here we demonstrate that NDF and its ErbB-4 receptor are highly reactive to changes in ambient Neuronal activity in the rodent brain in a region-selective manner. Generation of epileptic seizures by using kainic acid, a potent glutamate analog, elevated levels of NDF transcripts in limbic cortical areas, hippocampus, and amygdala. Concomitantly, ErbB-4 mRNA was increased with a similar spatial distribution, but transcription of the other NDF receptor, ErbB-3, did not change. A more moderate stimulation, forced locomotion, was accompanied by an increase in NDF transcripts and protein in the hippocampus and in the motor cortex. Similar changes were found with ErbB-4, but not ErbB-3. Last, a pathway-specific tetanic stimulation of the perforant path, which produced long-term potentiation, was followed by induction of NDF expression in the ipsilateral dentate gyrus and CA3 area of the hippocampus. Taken together, these results indicate that NDF is regulated by physiological activity and may play a role in Neural plasticity.

Stephen P Ethier - One of the best experts on this subject based on the ideXlab platform.

  • phosphatidylinositol 3 kinase recruitment by p185erbb 2 and erbb 3 is potently induced by Neu Differentiation Factor heregulin during mitogenesis and is constitutively elevated in growth Factor independent breast carcinoma cells with c erbb 2 gene am
    Cell Growth & Differentiation, 1996
    Co-Authors: Stephen P Ethier
    Abstract:

    Amplification and overexpression of the c-erbB-2 gene in 21 MT-2 and 21 MT-i human breast carcinoma cells results in progressively elevated levels of constitutively tyrosine-phosphorylated pi85��2 and is associated with progressive insulin-like growth Factor (IGF) and combined IGF/epidermal growth Factor (EGF) independence in culture. In addition, the Neu Differentiation Factor/heregulins (HRGs), a family of ligands that activate pi85�B2 through direct binding to erbB-3 or erbB-4, are potent mitogens for various nonneoplastic mammary epithelial cells and carcinoma cell lines in the absence of both IGF and EGF in culture. We have investigated the ability of ligand induction with HRGs or the constitutive activation of p1 ff5eftB2 in the 2i MT breast carcinoma cells to induce the recruitment of phosphatidylinositol 3-kinase (P13K) by pi85ethB2 and ethB-3. HRG was found to potently induce the recruitment of the Mr 85’000 regulatory subunit of P13K by phosphotyrosine proteins in both nonneoplastic Hi6N-2 mammary epithelial cells (which express normal c-ethB-2 levels) and in the 21 MT-2 and 21 MT-I cell lines, which were all isolated from a single patient with intraductal and invasive ductal carcinoma of the breast and express c-erbB-3 but not c-erbB-4 in culture. The activation of P13K in these cells was also associated with high-level mitogenic responsiveness to HRG, as well as the IGF/ EGF-independent proliferation of the 21 MT cell lines in culture. The recruitment of P13K by phosphotyrosine proteins during Iigand-induced activation, or that seen

  • Phosphatidylinositol 3-kinase recruitment by p185erbB-2 and erbB-3 is potently induced by Neu Differentiation Factor/heregulin during mitogenesis and is constitutively elevated in growth Factor-independent breast carcinoma cells with c-erbB-2 gene am
    Cell Growth & Differentiation, 1996
    Co-Authors: Stephen P Ethier
    Abstract:

    Amplification and overexpression of the c-erbB-2 gene in 21 MT-2 and 21 MT-i human breast carcinoma cells results in progressively elevated levels of constitutively tyrosine-phosphorylated pi85��2 and is associated with progressive insulin-like growth Factor (IGF) and combined IGF/epidermal growth Factor (EGF) independence in culture. In addition, the Neu Differentiation Factor/heregulins (HRGs), a family of ligands that activate pi85�B2 through direct binding to erbB-3 or erbB-4, are potent mitogens for various nonneoplastic mammary epithelial cells and carcinoma cell lines in the absence of both IGF and EGF in culture. We have investigated the ability of ligand induction with HRGs or the constitutive activation of p1 ff5eftB2 in the 2i MT breast carcinoma cells to induce the recruitment of phosphatidylinositol 3-kinase (P13K) by pi85ethB2 and ethB-3. HRG was found to potently induce the recruitment of the Mr 85’000 regulatory subunit of P13K by phosphotyrosine proteins in both nonneoplastic Hi6N-2 mammary epithelial cells (which express normal c-ethB-2 levels) and in the 21 MT-2 and 21 MT-I cell lines, which were all isolated from a single patient with intraductal and invasive ductal carcinoma of the breast and express c-erbB-3 but not c-erbB-4 in culture. The activation of P13K in these cells was also associated with high-level mitogenic responsiveness to HRG, as well as the IGF/ EGF-independent proliferation of the 21 MT cell lines in culture. The recruitment of P13K by phosphotyrosine proteins during Iigand-induced activation, or that seen

  • growth Factor independent proliferation of rat mammary carcinoma cells by autocrine secretion of Neu Differentiation Factor heregulin and transforming growth Factor alpha
    Molecular Carcinogenesis, 1996
    Co-Authors: Stephen P Ethier, Beatrice C Langton, Cheryl A Dilts
    Abstract:

    Serially transplantable rat mammary tumor (RMT) cells are not dependent on exogenous epidermal growth Factor (EGF) and insulin-like growth Factor-I for continuous growth in serum-free medium. Previously, we found that conditioned medium obtained from these cells contained EGF-like mitogenic activity and stimulated tyrosine phosphorylation of a 185-kDa protein in EGF-dependent mammary epithelial cells. This protein is distinct from the EGF receptor and resembles a 185-kDa tyrosine-phosphorylated protein present in RMT cells themselves. The results of the studies reported here indicate that the tyrosine-phosphorylated p185 detected in growth Factor-independent RMT cells and in human mammary epithelial cells exposed to RMT-conditioned medium was activated erbB-2 protein. Partial purification of the activating Factor present in RMT-conditioned medium yielded a heparin-binding growth Factor with biochemical properties similar to those of Neu Differentiation Factor/heregulin (NDF/HRG). RNA-polymerase chain reaction analysis demonstrated that RMT cells expressed mRNA for NDF/HRG, and western-blot analysis confirmed the presence of the 45-kDa secreted form of NDF/HRG in conditioned medium from the growth Factor-independent RMT cells. The biological activity of partially purified rat NDF/HRG was examined and found to be the same as that of the pure growth Factor. In addition, we found that RMT-conditioned medium, fractionated on an anion-exchange column and by reverse-phase high-pressure liquid chromatography, contained a potent EGF-like growth Factor that was distinct from NDF/HRG. This Factor competes with 125I-EGF for binding to EGF receptors and has an apparent molecular mass of 6600 Da. This Factor copurifies by high-pressure liquid chromatography with pure transforming growth Factor-alpha (TGF-alpha), and the cells are positive for TGF-alpha mRNA. Thus, growth Factor-independent RMT cells also synthesize and secrete TGF-alpha. These results indicate that growth Factor-independent cells secrete two growth Factors with overlapping biological activities and suggest that autocrine loops mediated by these Factors are important in the growth Factor-independent proliferation of the RMT cells.

  • Growth Factor-independent proliferation of rat mammary carcinoma cells by autocrine secretion of Neu-Differentiation Factor/heregulin and transforming growth Factor-alpha.
    Molecular Carcinogenesis, 1996
    Co-Authors: Stephen P Ethier, Beatrice C Langton, Cheryl A Dilts
    Abstract:

    Serially transplantable rat mammary tumor (RMT) cells are not dependent on exogenous epidermal growth Factor (EGF) and insulin-like growth Factor-I for continuous growth in serum-free medium. Previously, we found that conditioned medium obtained from these cells contained EGF-like mitogenic activity and stimulated tyrosine phosphorylation of a 185-kDa protein in EGF-dependent mammary epithelial cells. This protein is distinct from the EGF receptor and resembles a 185-kDa tyrosine-phosphorylated protein present in RMT cells themselves. The results of the studies reported here indicate that the tyrosine-phosphorylated p185 detected in growth Factor-independent RMT cells and in human mammary epithelial cells exposed to RMT-conditioned medium was activated erbB-2 protein. Partial purification of the activating Factor present in RMT-conditioned medium yielded a heparin-binding growth Factor with biochemical properties similar to those of Neu Differentiation Factor/heregulin (NDF/HRG). RNA-polymerase chain reaction analysis demonstrated that RMT cells expressed mRNA for NDF/HRG, and western-blot analysis confirmed the presence of the 45-kDa secreted form of NDF/HRG in conditioned medium from the growth Factor-independent RMT cells. The biological activity of partially purified rat NDF/HRG was examined and found to be the same as that of the pure growth Factor. In addition, we found that RMT-conditioned medium, fractionated on an anion-exchange column and by reverse-phase high-pressure liquid chromatography, contained a potent EGF-like growth Factor that was distinct from NDF/HRG. This Factor competes with 125I-EGF for binding to EGF receptors and has an apparent molecular mass of 6600 Da. This Factor copurifies by high-pressure liquid chromatography with pure transforming growth Factor-alpha (TGF-alpha), and the cells are positive for TGF-alpha mRNA. Thus, growth Factor-independent RMT cells also synthesize and secrete TGF-alpha. These results indicate that growth Factor-independent cells secrete two growth Factors with overlapping biological activities and suggest that autocrine loops mediated by these Factors are important in the growth Factor-independent proliferation of the RMT cells.

  • Expression and activation of erbB-2 and epidermal growth Factor receptor in lung adenocarcinomas.
    British Journal of Cancer, 1995
    Co-Authors: W. J. Rachwal, Stephen P Ethier, P. F. Bongiorno, Mark B. Orringer, Richard I. Whyte, David G. Beer
    Abstract:

    ErbB-2 and EGFR (epidermal growth Factor receptor) are expressed in lung adenocarcinomas and associated with a poor prognosis. Immunocytochemical analysis revealed erbB-2 and EGFR coexperession as a characteristic feature of most lung adenocarcinomas, and at levels of receptor expression present in bronchial epithelial cells. In primary lung tumours and cell lines, erbB-2 detected using Western blot analysis demonstrated low-level phosphotyrosine staining of the 185 kDa band, as compared with breast cancer cell lines. A549 and A427 lung adenocarcinoma cells treated with Neu Differentiation Factor (NDF) showed increased erbB-2 phosphotyrosine staining, but to a much lesser extent than breast cancer cells. The lung cells were examined for expression of the potential autocrine growth Factors NDF and transforming growth Factor alpha (TGF-alpha) by Northern blot analysis. Both NDF and TFG-alpha mRNA were abundantly expressed in the A549 cells. NDF mRNA was highest during active cell proliferation and decreased in confluent cells or after treatment with the growth-inhibitory steroid dexamethasone. Primary tumours and cell lines expressed EGFR, showing higher basal level phosphotyrosine staining than erbB-2. Treatment with NDF and EGF (epidermal growth Factor) stimulated cell growth, and in A549 cells the presence of both Factors provided an additive increase in cell growth. The growth stimulus that ligand-activated erbB-2 and EGFR provides to lung adenocarcinoma cells may establish a background of continued cell proliferation over which other critical transforming events may occur.

Cheryl A Dilts - One of the best experts on this subject based on the ideXlab platform.

  • growth Factor independent proliferation of rat mammary carcinoma cells by autocrine secretion of Neu Differentiation Factor heregulin and transforming growth Factor alpha
    Molecular Carcinogenesis, 1996
    Co-Authors: Stephen P Ethier, Beatrice C Langton, Cheryl A Dilts
    Abstract:

    Serially transplantable rat mammary tumor (RMT) cells are not dependent on exogenous epidermal growth Factor (EGF) and insulin-like growth Factor-I for continuous growth in serum-free medium. Previously, we found that conditioned medium obtained from these cells contained EGF-like mitogenic activity and stimulated tyrosine phosphorylation of a 185-kDa protein in EGF-dependent mammary epithelial cells. This protein is distinct from the EGF receptor and resembles a 185-kDa tyrosine-phosphorylated protein present in RMT cells themselves. The results of the studies reported here indicate that the tyrosine-phosphorylated p185 detected in growth Factor-independent RMT cells and in human mammary epithelial cells exposed to RMT-conditioned medium was activated erbB-2 protein. Partial purification of the activating Factor present in RMT-conditioned medium yielded a heparin-binding growth Factor with biochemical properties similar to those of Neu Differentiation Factor/heregulin (NDF/HRG). RNA-polymerase chain reaction analysis demonstrated that RMT cells expressed mRNA for NDF/HRG, and western-blot analysis confirmed the presence of the 45-kDa secreted form of NDF/HRG in conditioned medium from the growth Factor-independent RMT cells. The biological activity of partially purified rat NDF/HRG was examined and found to be the same as that of the pure growth Factor. In addition, we found that RMT-conditioned medium, fractionated on an anion-exchange column and by reverse-phase high-pressure liquid chromatography, contained a potent EGF-like growth Factor that was distinct from NDF/HRG. This Factor competes with 125I-EGF for binding to EGF receptors and has an apparent molecular mass of 6600 Da. This Factor copurifies by high-pressure liquid chromatography with pure transforming growth Factor-alpha (TGF-alpha), and the cells are positive for TGF-alpha mRNA. Thus, growth Factor-independent RMT cells also synthesize and secrete TGF-alpha. These results indicate that growth Factor-independent cells secrete two growth Factors with overlapping biological activities and suggest that autocrine loops mediated by these Factors are important in the growth Factor-independent proliferation of the RMT cells.

  • Growth Factor-independent proliferation of rat mammary carcinoma cells by autocrine secretion of Neu-Differentiation Factor/heregulin and transforming growth Factor-alpha.
    Molecular Carcinogenesis, 1996
    Co-Authors: Stephen P Ethier, Beatrice C Langton, Cheryl A Dilts
    Abstract:

    Serially transplantable rat mammary tumor (RMT) cells are not dependent on exogenous epidermal growth Factor (EGF) and insulin-like growth Factor-I for continuous growth in serum-free medium. Previously, we found that conditioned medium obtained from these cells contained EGF-like mitogenic activity and stimulated tyrosine phosphorylation of a 185-kDa protein in EGF-dependent mammary epithelial cells. This protein is distinct from the EGF receptor and resembles a 185-kDa tyrosine-phosphorylated protein present in RMT cells themselves. The results of the studies reported here indicate that the tyrosine-phosphorylated p185 detected in growth Factor-independent RMT cells and in human mammary epithelial cells exposed to RMT-conditioned medium was activated erbB-2 protein. Partial purification of the activating Factor present in RMT-conditioned medium yielded a heparin-binding growth Factor with biochemical properties similar to those of Neu Differentiation Factor/heregulin (NDF/HRG). RNA-polymerase chain reaction analysis demonstrated that RMT cells expressed mRNA for NDF/HRG, and western-blot analysis confirmed the presence of the 45-kDa secreted form of NDF/HRG in conditioned medium from the growth Factor-independent RMT cells. The biological activity of partially purified rat NDF/HRG was examined and found to be the same as that of the pure growth Factor. In addition, we found that RMT-conditioned medium, fractionated on an anion-exchange column and by reverse-phase high-pressure liquid chromatography, contained a potent EGF-like growth Factor that was distinct from NDF/HRG. This Factor competes with 125I-EGF for binding to EGF receptors and has an apparent molecular mass of 6600 Da. This Factor copurifies by high-pressure liquid chromatography with pure transforming growth Factor-alpha (TGF-alpha), and the cells are positive for TGF-alpha mRNA. Thus, growth Factor-independent RMT cells also synthesize and secrete TGF-alpha. These results indicate that growth Factor-independent cells secrete two growth Factors with overlapping biological activities and suggest that autocrine loops mediated by these Factors are important in the growth Factor-independent proliferation of the RMT cells.

  • mitogenic activity of Neu Differentiation Factor heregulin mimics that of epidermal growth Factor and insulin like growth Factor i in human mammary epithelial cells
    Journal of Cellular Physiology, 1995
    Co-Authors: Kristine E Kokeny, Cheryl A Dilts, Stephen P Ethier
    Abstract:

    Recently, a family of growth Factors has been described that activates erbB-2 receptors. These Factors, known as the Neu Differentiation Factors (NDF) or heregulins (HRG), induce tyrosine phosphorylation of erbB-2 receptors as a result of their direct interaction with either erbB-3 or erbB-4 receptors. Although it is known that expression of erbB-2 receptors has relevance in human breast cancer progression, how erbB-2, -3 and -4 receptors regulate mammary epithelial cell proliferation is not known. Therefore, experiments were carried out to study the mitogenic activity of NDF/HRG on the human mammary epithelial cell line MCF1 OA which can be cultured continuously under serum-free conditions. MCF-1 OA cells, like primary cultures of normal human mammary epithelial cells, express an absolute requirement for exogenous epidermal growth Factor (EGF) and insulinlike growth Factor I (IGF-I) for growth. The results of these experiments indicate that NDF/HRG can induce tyrosine phosphorylation of pl85erbB-2 in MCF-1OA cells and is mitogenic for these cells. This is consistent with the coexpression of erbB-2 and erbB-3 mRNA that we have observed in MCF-1 OA cells. In addition, we found that NDF/HRG can substitute for either EGF or IGF-I to stimulate proliferation of these cells. The ability to substitute for both EGF and IGF-I is a unique property of NDF/HRG and is not shared by other members of the EGF or IGF family of growth Factors, nor by other Factors that we have studied. A striking isoform specificity was also observed which indicated that the p-isoforms of NDF/HRG were greater than ten times more mitogenic than the a-isoforms. We also examined the mitogenic activity of NDF/HRG on MCF-1OA cells that overexpress the erbB-2 receptor as a result of infection with a retroviral vector containing the human c-erbB-2 gene (MCF-1 OAerbB-2 cells). These studies indicated that MCF-1 OAerbB-2 cells have increased sensitivity to the mitogenic effects of NDF/ HRG and that these cells are responsive to the a-isoforms of NDF/HRG at physiological concentrations. Thus, NDF/HRG is a dual specificity growth Factor for human mammary epithelial cells, and the responsiveness of the cells to NDF/HRG is influenced by the level of expression of erbB-2 receptors. 0 1995 Wiley-Liss, Inc.

  • Mitogenic activity of Neu Differentiation Factor/heregulin mimics that of epidermal growth Factor and insulin-like growth Factor-I in human mammary epithelial cells
    Journal of Cellular Physiology, 1995
    Co-Authors: Kristine E Kokeny, Cheryl A Dilts, Stephen P Ethier
    Abstract:

    Recently, a family of growth Factors has been described that activates erbB-2 receptors. These Factors, known as the Neu Differentiation Factors (NDF) or heregulins (HRG), induce tyrosine phosphorylation of erbB-2 receptors as a result of their direct interaction with either erbB-3 or erbB-4 receptors. Although it is known that expression of erbB-2 receptors has relevance in human breast cancer progression, how erbB-2, -3 and -4 receptors regulate mammary epithelial cell proliferation is not known. Therefore, experiments were carried out to study the mitogenic activity of NDF/HRG on the human mammary epithelial cell line MCF1 OA which can be cultured continuously under serum-free conditions. MCF-1 OA cells, like primary cultures of normal human mammary epithelial cells, express an absolute requirement for exogenous epidermal growth Factor (EGF) and insulinlike growth Factor I (IGF-I) for growth. The results of these experiments indicate that NDF/HRG can induce tyrosine phosphorylation of pl85erbB-2 in MCF-1OA cells and is mitogenic for these cells. This is consistent with the coexpression of erbB-2 and erbB-3 mRNA that we have observed in MCF-1 OA cells. In addition, we found that NDF/HRG can substitute for either EGF or IGF-I to stimulate proliferation of these cells. The ability to substitute for both EGF and IGF-I is a unique property of NDF/HRG and is not shared by other members of the EGF or IGF family of growth Factors, nor by other Factors that we have studied. A striking isoform specificity was also observed which indicated that the p-isoforms of NDF/HRG were greater than ten times more mitogenic than the a-isoforms. We also examined the mitogenic activity of NDF/HRG on MCF-1OA cells that overexpress the erbB-2 receptor as a result of infection with a retroviral vector containing the human c-erbB-2 gene (MCF-1 OAerbB-2 cells). These studies indicated that MCF-1 OAerbB-2 cells have increased sensitivity to the mitogenic effects of NDF/ HRG and that these cells are responsive to the a-isoforms of NDF/HRG at physiological concentrations. Thus, NDF/HRG is a dual specificity growth Factor for human mammary epithelial cells, and the responsiveness of the cells to NDF/HRG is influenced by the level of expression of erbB-2 receptors. 0 1995 Wiley-Liss, Inc.

Elior Peles - One of the best experts on this subject based on the ideXlab platform.

  • erbb 3 and erbb 4 function as the respective low and high affinity receptors of all Neu Differentiation Factor heregulin isoforms
    Journal of Biological Chemistry, 1994
    Co-Authors: Eldad Tzahar, Elior Peles, Gil Levkowitz, Sara Lavi, Devarajan Karunagaran, L Yi, D Chang, A Yayon
    Abstract:

    Abstract Neu Differentiation Factor (NDF or heregulin) elevates tyrosine phosphorylation of the ErbB-2 receptor tyrosine kinase, and it was, therefore, thought to function as a ligand of this receptor. However, several lines of evidence raised the possibility that the interaction between NDF and ErbB-2 involves another molecule, which belongs to the family of epidermal growth Factor receptors. To address this question we constructed soluble chimeric proteins between alkaline phosphatase and the extracellular domains of ErbB-2 and either ErbB-3 or ErbB-4, two newly recognized members of the epidermal growth Factor receptor family. Using the soluble proteins we found that beta isoforms of NDF specifically bind to the ErbB-3 and ErbB-4 receptors but not to the soluble ErbB-2 protein. When ectopically expressed in monkey fibroblasts, the full-length ErbB-3 and ErbB-4 receptors conferred specific binding to NDF. In these cells ErbB-3 displayed lower ligand binding affinity than ErbB-4, but like the latter receptor it preferred to bind the beta isoform over the alpha class of NDFs. These results indicate that both ErbB-3 and ErbB-4 function as physiological receptors of all NDF isoforms and suggest that a still unknown ligand of ErbB-2 exists.

  • Neu and its ligands: From an oncogene to Neural Factors
    BioEssays, 1993
    Co-Authors: Elior Peles, Yosef Yarden
    Abstract:

    Transmembrane receptor tyrosine kinases that bind to peptide Factors transmit essential growth and Differentiation signals. A growing list of orphan receptors, of which some are oncogenic, holds the promise that many unknown ligands may be discovered by tracking the corresponding surface molecules. The Neu gene (also called erbB-2 and HER-2) encodes such a receptor tyrosine kinase whose oncogenic potential is released in the developing rodent nervous system through a point mutation. Amplification and overexpression of Neu are thought to contribute to malignancy of certain human adenocarcinomas. The search for soluble Factors that interact with the Neu receptor led to the discovery of a 44 kDa glyco-protein that induces phenotypic Differentiation of cultured mammary tumor cells to growth-arrested and milk-producing cells. The Neu Differentiation Factor (NDF or heregulin), however, also acts as a mitogen for epithelial, Schwann and glial cells. Multiple forms of the Factor are produced by alternative splicing and their expression is confined predominantly to the central and to the peripheral nervous systems. One identified Neuronal function of this family of polypeptides is to control the formation of Neuromuscular junctions, but their physiological role in secretory epithelia is still unknown. Other open questions relate to the transmembrane topology of various precursors, the identity of a putative co-receptor, the possible existence of additional ligands of Neu and the functional significance of the interaction between Neu and at least three highly related receptor tyrosine kinases.

  • Neu Differentiation Factor heregulin induces expression of intercellular adhesion molecule 1 implications for mammary tumors
    Cancer Research, 1993
    Co-Authors: Sarah S Bacus, Elior Peles, Dot Chin, Carolyn R. Zelnick, Andrei V Gudkov, Randi Stern, Ilana Stancovski, Noa Benbaruch, Hannan Farbstein, Ruth Lupu
    Abstract:

    Neu Differentiation Factor (NDF, also called heregulin) is a 44-kilodalton glycoprotein that stimulates tyrosine phosphorylation of the Neu/HER-2 receptor and induces phenotypic Differentiation of certain mammary cancer cell lines to growth-arrested and milk-producing cells. To determine which molecules participate in the concomitant morphological alterations, we analyzed the expression of several cytoskeletal and surface molecules and found that NDF elevated the expression of the intercellular adhesion molecule 1 (ICAM-1) in cultured AU-565 human adenocarcinoma cells. The levels of both the protein and the mRNA of ICAM-1 were elevated after 3–5 days of treatment with NDF. Elevated expression of ICAM-1 was induced also by γ-interferon and by the tumor-promoting phorbol ester (PMA), albeit with different kinetics. Down-regulation of protein kinase C or its inhibition by calphostin C partially inhibited the effect of NDF, implying that the induction of ICAM-1 may be mediated by protein kinase C. NDF transcripts were detectable in 3 of 9 human mammary tumors, suggesting that the in vitro effect of the Factor may be relevant to breast cancer. By selecting Neu-positive human mammary tumors ( n = 39), we found a significant correlation ( P < 0.001) between the expression of ICAM-1 and histological features of invasive ductal carcinoma with a prominent carcinoma in situ component. When cultured in vitro the cells of these tumors grew in clusters and formed domelike structures reminiscent of comedo-type carcinoma in situ . In addition, the majority of patients with tumors that coexpressed ICAM-1 and Neu had no lymph node involvement, unlike most Neu-positive but ICAM-1-negative tumors, which metastasized to the lymphatic system. Taken together, our observations suggest that the induction of ICAM-1 by NDF may affect the morphology, Differentiation state, and metastasis of Neu-expressing mammary tumor cells.

  • cell type specific interaction of Neu Differentiation Factor ndf heregulin with Neu her 2 suggests complex ligand receptor relationships
    The EMBO Journal, 1993
    Co-Authors: Elior Peles, R Benlevy, Eldad Tzahar, Yosef Yarden
    Abstract:

    The Neu/HER-2 receptor tyrosine kinase is overexpressed in some types of human adenocarcinomas, including tumors of the breast and the ovary. A 44 kDa glycoprotein that elevates tyrosine phosphorylation of Neu has been isolated and named Neu Differentiation Factor (NDF), or heregulin. Here we show that NDF affects tyrosine phosphorylation of Neu in human tumor cells of breast, colon and Neuronal origin, but not in ovarian cells that overexpress the receptor. By using monoclonal antibodies (mAbs) to Neu, we found that the ovarian receptor is immunologically and biochemically similar to the mammary p185Neu. Nevertheless, unlike breast-derived Neu, the ovarian protein did not display covalent cross-linking to radiolabeled NDF, and was devoid of ligand-induced association with phosphatidylinositol 3'-kinase. Direct binding analysis showed that NDF binds with high affinity (Kd approximately 10(-9) M) to mammary cells, but its weak association with ovarian cells is probably mediated by heparin-like molecules. Similar to the endogenous receptor, the ectopically overexpressed Neu of mammary cells, but not of ovarian and fibroblastic cells, exhibited elevated levels of NDF-induced phosphorylation and covalent cross-linking of the radiolabeled Factor. Taken together, our results imply that NDF binding to cells requires both Neu and an additional cellular component, whose identity is still unknown, but its tissue distribution is more restricted than the expression of the Neu gene.

  • Cell-type specific interaction of Neu Differentiation Factor (NDF/heregulin) with Neu/HER-2 suggests complex ligand-receptor relationships
    The EMBO Journal, 1993
    Co-Authors: Elior Peles, Eldad Tzahar, R. Ben-levy, Yosef Yarden
    Abstract:

    The Neu/HER-2 receptor tyrosine kinase is overexpressed in some types of human adenocarcinomas, including tumors of the breast and the ovary. A 44 kDa glycoprotein that elevates tyrosine phosphorylation of Neu has been isolated and named Neu Differentiation Factor (NDF), or heregulin. Here we show that NDF affects tyrosine phosphorylation of Neu in human tumor cells of breast, colon and Neuronal origin, but not in ovarian cells that overexpress the receptor. By using monoclonal antibodies (mAbs) to Neu, we found that the ovarian receptor is immunologically and biochemically similar to the mammary p185Neu. Nevertheless, unlike breast-derived Neu, the ovarian protein did not display covalent cross-linking to radiolabeled NDF, and was devoid of ligand-induced association with phosphatidylinositol 3'-kinase. Direct binding analysis showed that NDF binds with high affinity (Kd approximately 10(-9) M) to mammary cells, but its weak association with ovarian cells is probably mediated by heparin-like molecules. Similar to the endogenous receptor, the ectopically overexpressed Neu of mammary cells, but not of ovarian and fibroblastic cells, exhibited elevated levels of NDF-induced phosphorylation and covalent cross-linking of the radiolabeled Factor. Taken together, our results imply that NDF binding to cells requires both Neu and an additional cellular component, whose identity is still unknown, but its tissue distribution is more restricted than the expression of the Neu gene.

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