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Identification of the Mind Bomb1 Interaction Domain in Zebrafish DeltaD. PLoS One 2015; 10:e0127864. [PMID: 26020642 PMCID: PMC4447371 DOI: 10.1371/journal.pone.0127864] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 04/09/2015] [Indexed: 11/19/2022] Open
Abstract
Ubiquitylation promotes endocytosis of the Notch ligands like Delta and Serrate and is essential for them to effectively activate Notch in a neighboring cell. The RING E3 ligase Mind bomb1 (Mib1) ubiquitylates DeltaD to facilitate Notch signaling in zebrafish. We have identified a domain in the intracellular part of the zebrafish Notch ligand DeltaD that is essential for effective interactions with Mib1. We show that elimination of the Mind bomb1 Interaction Domain (MID) or mutation of specific conserved motifs in this domain prevents effective Mib1-mediated ubiquitylation and internalization of DeltaD. Lateral inhibition mediated by Notch signaling regulates early neurogenesis in zebrafish. In this context, Notch activation suppresses neurogenesis, while loss of Notch-mediated lateral inhibition results in a neurogenic phenotype, where too many cells are allowed to become neurons. While Mib1-mediated endocytosis of DeltaD is essential for effective activation of Notch in a neighboring cell (in trans) it is not required for DeltaD to inhibit function of Notch receptors in the same cell (in cis). As a result, forms of DeltaD that have the MID can activate Notch in trans and suppress early neurogenesis when mRNA encoding it is ectopically expressed in zebrafish embryos. On the other hand, when the MID is eliminated/mutated in DeltaD, its ability to activate Notch in trans fails but ability to inhibit in cis is retained. As a result, ectopic expression of DeltaD lacking an effective MID results in a failure of Notch-mediated lateral inhibition and a neurogenic phenotype.
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2
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Carney L, Pierce A, Rijnen M, Gonzalez Sanchez MB, Hamzah HG, Zhang L, Tamura T, Whetton AD. THOC5 couples M-CSF receptor signaling to transcription factor expression. Cell Signal 2008; 21:309-16. [PMID: 19015024 DOI: 10.1016/j.cellsig.2008.10.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Revised: 10/24/2008] [Accepted: 10/24/2008] [Indexed: 10/21/2022]
Abstract
THOC5 is a nuclear/cytoplasmic protein member of the spliceosome complex which potentiates C/EBP expression in adipocyte differentiation. As C/EBP family members are important regulators of myelopoiesis and THOC5 is highly expressed in neutrophil/macrophage progenitor cells we assessed the role of THOC5 in cytokine-stimulated monocytic development. M-CSF stimulated maturation of the NFS60 cell line was associated with enhanced THOC5 expression and phosphorylation. THOC5 was also shown to form a complex with C/EBPbeta. Ectopic expression of THOC5 mimicked M-CSF mediated cell maturation and enhanced protein expression of the myeloid transcription factors C/EBPbeta, C/EBPalpha, Pu-1 and also GAB2 (a PI-3 Kinase and macrophage development regulator). Increased THOC5 expression also mimicked M-CSF stimulated increases in the lipid second messenger PtdInsP(3). Inhibition of THOC5-induced increases in PtdInsP(3) levels abrogated the elevated levels of C/EBPbeta. Thus THOC5 expression can potentiate receptor signalling to transcription factor expression and monocyte differentiation.
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Affiliation(s)
- Louise Carney
- Stem Cell and Leukaemia Proteomics laboratory, Faculty of Medical and Human Sciences, University of Manchester, Christie Hospital, Wilmslow Road, Manchester M20 9BX, UK
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Chase A, Schultheis B, Kreil S, Baxter J, Hidalgo-Curtis C, Jones A, Zhang L, Grand FH, Melo JV, Cross NCP. Imatinib sensitivity as a consequence of a CSF1R-Y571D mutation and CSF1/CSF1R signaling abnormalities in the cell line GDM1. Leukemia 2008; 23:358-64. [PMID: 18971950 DOI: 10.1038/leu.2008.295] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Imatinib is usually a highly effective treatment for myeloproliferative neoplasms (MPNs) associated with ABL, PDGFRA or PDGFRB gene fusions; however, occasional imatinib-responsive patients have been reported without abnormalities of these genes. To identify novel imatinib-sensitive lesions, we screened 11 BCR-ABL-negative cell lines and identified GDM1, derived from a patient with an atypical MPN (aMPN), as being responsive to imatinib. Screening of genes encoding known imatinib targets revealed an exon 12 mutation in the colony-stimulating factor 1 receptor (CSF1R; c-FMS) with a predicted Y571D amino-acid substitution. CSF1R in GDM1 was constitutively phosphorylated, but rapidly dephosphorylated on exposure to imatinib. Y571D did not transform FDCP1 cells to growth factor independence, but resulted in a significantly increased colony growth compared with controls, constitutive CSF1R phosphorylation and elevated CSF1R signaling. We found that GDM1 expresses CSF1, and CSF1 neutralization partially inhibited proliferation, suggesting the importance of both autocrine and intrinsic mechanisms of CSF1R activation. An extensive screen of CSF1R in aMPNs and acute myeloid leukemia identified three additional novel missense variants. None of these variants were active in transformation assays and are therefore likely to be previously unreported rare polymorphisms or non-pathogenic passenger mutations.
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Affiliation(s)
- A Chase
- Wessex Regional Genetics Laboratory, Salisbury and Human Genetics Division, University of Southampton, Southampton, UK.
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Irvine KM, Burns CJ, Wilks AF, Su S, Hume DA, Sweet MJ. A CSF‐1 receptor kinase inhibitor targets effector functions and inhibits pro‐inflammatory cytokine production from murine macrophage populations. FASEB J 2006; 20:1921-3. [PMID: 16877523 DOI: 10.1096/fj.06-5848fje] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
CSF-1 regulates macrophage differentiation, survival, and function, and is an attractive therapeutic target for chronic inflammation and malignant diseases. Here we describe the effects of a potent and selective inhibitor of CSF-1R-CYC10268-on CSF-1R-dependent signaling. In in vitro kinase assays, CYC10268 was active in the low nanomolar range and showed selectivity over other kinases such as Abl and Kit. CYC10268 blocked survival mediated by CSF-1R in primary murine bone marrow-derived macrophages (BMM) and in the factor-dependent cell line Ba/F3, in which the CSF-1R was ectopically expressed. CYC10268 also inhibited CSF-1 regulated signaling (Akt, ERK-1/2), gene expression (urokinase plasminogen activator, toll-like receptor 9, and apolipoprotein E), and priming of LPS-inducible cytokine production in BMM. In thioglycollate-elicited peritoneal macrophages (TEPM), which survive in the absence of exogenous CSF-1, CYC10268 impaired LPS-induced cytokine production and regulated expression of known CSF-1 target genes. These observations support the conclusion that TEPM are CSF-1 autocrine and that CSF-1 plays a central role in macrophage effector functions during inflammation. CSF-1R inhibitors such as CYC10268 provide a powerful tool to dissect the role of the CSF-1/CSF-1R signaling system in a range of biological systems and have potential for a number of therapeutic applications.
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Affiliation(s)
- Katharine M Irvine
- Cooperative Research Centre for Chronic Inflammatory Diseases and Special Research Centre for Functional and Applied Genomics, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
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5
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Rohde CM, Schrum J, Lee AWM. A juxtamembrane tyrosine in the colony stimulating factor-1 receptor regulates ligand-induced Src association, receptor kinase function, and down-regulation. J Biol Chem 2004; 279:43448-61. [PMID: 15297464 DOI: 10.1074/jbc.m314170200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent literature implicates a regulatory function of the juxtamembrane domain (JMD) in receptor tyrosine kinases. Mutations in the JMD of c-Kit and Flt3 are associated with gastrointestinal stromal tumors and acute myeloid leukemias, respectively. Additionally, autophosphorylated Tyr559 in the JMD of the colony stimulating factor-1 (CSF-1) receptor (CSF-1R) binds to Src family kinases (SFKs). To investigate SFK function in CSF-1 signaling we established stable 32D myeloid cell lines expressing CSF-1Rs with mutated SFK binding sites (Tyr559-TFI). Whereas binding to I562S was not significantly perturbed, Y559F and Y559D exhibited markedly decreased CSF-1-dependent SFK association. All JMD mutants retained intrinsic kinase activity, but Y559F, and less so Y559D, showed dramatically reduced CSF-1-induced autophosphorylation. CSF-1-mediated wild-type (WT)-CSF-1R phosphorylation was not markedly affected by SFK inhibition, indicating that lack of SFK binding is not responsible for diminished Y559F phosphorylation. Unexpectedly, cells expressing Y559F were hyperproliferative in response to CSF-1. Hyperproliferation correlated with prolonged activation of Akt, ERK, and Stat5 in the Y559F mutant. Consistent with a defect in receptor negative regulation, c-Cbl tyrosine phosphorylation and CSF-1R/c-Cbl co-association were almost undetectable in the Y559F mutant. Furthermore, Y559F underwent reduced multiubiquitination and delayed receptor internalization and degradation. In conclusion, we propose that Tyr559 is a switch residue that functions in kinase regulation, signal transduction and, indirectly, receptor down-regulation. These findings may have implications for the oncogenic conversion of c-Kit and Flt3 with JMD mutations.
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Affiliation(s)
- Cynthia M Rohde
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor 48109, USA
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Irusta PM, Luo Y, Bakht O, Lai CC, Smith SO, DiMaio D. Definition of an inhibitory juxtamembrane WW-like domain in the platelet-derived growth factor beta receptor. J Biol Chem 2002; 277:38627-34. [PMID: 12181311 DOI: 10.1074/jbc.m204890200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A variety of tumors contain activating mutations in the cytoplasmic juxtamembrane domain of the type III family of receptor-tyrosine kinases, and some constructed mutations in this domain induce ligand-independent receptor activation. To explore the role of this domain in regulation of receptor activity, we subjected the juxtamembrane domain of the murine platelet-derived growth factor (PDGF) beta receptor to alanine-scanning mutagenesis. The mutant receptors were expressed in Ba/F3 cells and tested for constitutive tyrosine phosphorylation, association with phosphatidylinositol 3'-kinase, and their ability to induce cell survival and proliferation in the absence of interleukin-3. The mutant receptors accumulated to similar levels and appeared to undergo a normal PDGF-induced increase in tyrosine phosphorylation. Alanine substitutions at numerous positions located throughout the juxtamembrane domain caused constitutive receptor activation, as did an alanine insertion in the membrane-proximal segment of the juxtamembrane domain and a six-amino acid deletion in the center of the domain. It is possible to model the PDGF receptor juxtamembrane domain as a short alpha-helix followed by a three-stranded beta-sheet very similar to the known structures of WW domains. Strikingly, the activating mutations clustered in the central portions of the first and second beta strands and along one face of the beta-sheet, whereas the loops connecting the strands were largely devoid of mutationally sensitive positions. These findings provide strong support for the model that the activating mutations in the juxtamembrane region stimulate receptor activity by disrupting an inhibitory WW-like domain.
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Affiliation(s)
- Pablo M Irusta
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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Wybenga-Groot LE, Baskin B, Ong SH, Tong J, Pawson T, Sicheri F. Structural basis for autoinhibition of the Ephb2 receptor tyrosine kinase by the unphosphorylated juxtamembrane region. Cell 2001; 106:745-57. [PMID: 11572780 DOI: 10.1016/s0092-8674(01)00496-2] [Citation(s) in RCA: 236] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Eph receptor tyrosine kinase family is regulated by autophosphorylation within the juxtamembrane region and the kinase activation segment. We have solved the X-ray crystal structure to 1.9 A resolution of an autoinhibited, unphosphorylated form of EphB2 comprised of the juxtamembrane region and the kinase domain. The structure, supported by mutagenesis data, reveals that the juxtamembrane segment adopts a helical conformation that distorts the small lobe of the kinase domain, and blocks the activation segment from attaining an activated conformation. Phosphorylation of conserved juxtamembrane tyrosines would relieve this autoinhibition by disturbing the association of the juxtamembrane segment with the kinase domain, while liberating phosphotyrosine sites for binding SH2 domains of target proteins. We propose that the autoinhibitory mechanism employed by EphB2 is a more general device through which receptor tyrosine kinases are controlled.
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Affiliation(s)
- L E Wybenga-Groot
- Program in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Ontario M5G 1X5, Toronto, Canada
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Dey A, She H, Kim L, Boruch A, Guris DL, Carlberg K, Sebti SM, Woodley DT, Imamoto A, Li W. Colony-stimulating factor-1 receptor utilizes multiple signaling pathways to induce cyclin D2 expression. Mol Biol Cell 2000; 11:3835-48. [PMID: 11071910 PMCID: PMC15040 DOI: 10.1091/mbc.11.11.3835] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Colony-stimulating factor-1 (CSF-1) induces expression of immediate early gene, such as c-myc and c-fos and delayed early genes such as D-type cyclins (D1 and D2), whose products play essential roles in the G1 to S phase transition of the cell cycle. Little is known, however, about the cytoplasmic signal transduction pathways that connect the surface CSF-1 receptor to these genes in the nucleus. We have investigated the signaling mechanism of CSF-1-induced D2 expression. Analyses of CSF-1 receptor autophosphorylation mutants show that, although certain individual mutation has a partial inhibitory effect, only multiple combined mutations completely block induction of D2 in response to CSF-1. We report that at least three parallel pathways, the Src pathway, the MAPK/ERK kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway, and the c-myc pathway, are involved. Induction of D2 is partially inhibited in Src(-/-) bone marrow-derived macrophages and by Src inhibitor PP1 and is enhanced in v-Src-overexpressing cells. Activation of myc's transactivating activity selectively induces D2 but not D1. Blockade of c-myc expression partially blocks CSF-1-induced D2 expression. Complete inhibition of the MEK/ERK pathway causes 50% decrease of D2 expression. Finally, simultaneous inhibition of Src, MEK activation, and c-myc expression additively blocks CSF-1-induced D2 expression. This study indicates that multiple signaling pathways are involved in full induction of a single gene, and this finding may also apply broadly to other growth factor-inducible genes.
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Affiliation(s)
- A Dey
- The Ben May Institute for Cancer Research, University of Chicago, Chicago, Illinois 60637, USA
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Tang S, Liu H, Chen G, Rao Q, Geng Y, Zheng G, Zheng D, Wu K. Internalization and half-life of membrane-bound macrophage colony-stimulating factor. ACTA ACUST UNITED AC 2000. [DOI: 10.1007/bf02898990] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Zisch AH, Pazzagli C, Freeman AL, Schneller M, Hadman M, Smith JW, Ruoslahti E, Pasquale EB. Replacing two conserved tyrosines of the EphB2 receptor with glutamic acid prevents binding of SH2 domains without abrogating kinase activity and biological responses. Oncogene 2000; 19:177-87. [PMID: 10644995 DOI: 10.1038/sj.onc.1203304] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Eph receptor tyrosine kinases play key roles in pattern formation during embryonic development, but little is known about the mechanisms by which they elicit specific biological responses in cells. Here, we investigate the role of tyrosines 605 and 611 in the juxtamembrane region of EphB2, because they are conserved Eph receptor autophosphorylation sites and demonstrated binding sites for the SH2 domains of multiple signaling proteins. Mutation of tyrosines 605 and 611 to phenylalanine impaired EphB2 kinase activity, complicating analysis of their function as SH2 domain binding sites and their contribution to EphB2-mediated signaling. In contrast, mutation to the negatively charged glutamic acid disrupted SH2 domain binding without reducing EphB2 kinase activity. By using a panel of EphB2 mutants, we found that kinase activity is required for the changes in cell-matrix and cell - cell adhesion, cytoskeletal organization, and activation of mitogen-activated protein (MAP) kinases elicited by EphB2 in transiently transfected cells. Instead, the two juxtamembrane SH2 domain binding sites were dispensable for these effects. These results suggest that phosphorylation of tyrosines 605 and 611 is critical for EphB2-mediated cellular responses because it regulates EphB2 kinase activity.
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Affiliation(s)
- A H Zisch
- The Burnham Institute, 10901 N. Torrey Pines Road, La Jolla, California, CA 92037, USA
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Wolf I, Rohrschneider LR. Fiz1, a novel zinc finger protein interacting with the receptor tyrosine kinase Flt3. J Biol Chem 1999; 274:21478-84. [PMID: 10409713 DOI: 10.1074/jbc.274.30.21478] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The receptor tyrosine kinase Flt3 has been shown to play a role in proliferation and survival of hematopoietic progenitor cells as well as differentiation of early B lymphoid progenitors. However, the signaling events that control growth or differentiation are not completely understood. In order to identify new signaling molecules interacting with the cytoplasmic domain of Flt3, we performed a yeast two-hybrid screen. In addition to several SH2 domain-containing proteins, we have isolated a novel Flt3 interacting zinc finger protein (Fiz1) with 11 C(2)H(2)-type zinc fingers. Fiz1 binds to the catalytic domain of Flt3 but not to the structurally related receptor tyrosine kinases Kit, Fms, and platelet-derived growth factor receptor. This association is independent of kinase activity. The interaction between Flt3 and Fiz1 detected in yeast was confirmed by in vitro and in vivo coprecipitation assays. Fiz1 mRNA is expressed in all murine cell lines and tissues tested. Anti-Fiz1 antibodies recognize a 60-kDa protein, which is localized in the nucleus as well as in the cytoplasm. Together, these results identified a novel class of interaction between a receptor tyrosine kinase and a signaling molecule which is independent of the well established SH2 domain/phosphotyrosine binding.
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Affiliation(s)
- I Wolf
- Fred Hutchinson Cancer Research Center, Division of Basic Sciences, Seattle, Washington 98109-1024, USA.
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Uden M, Morley GM, Dibb NJ. Evidence that downregulation of the M-CSF receptor is not dependent upon receptor kinase activity. Oncogene 1999; 18:3846-51. [PMID: 10445847 DOI: 10.1038/sj.onc.1202743] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The downregulation of tyrosine kinase receptors attenuates signalling and is thought to be dependent upon intrinsic receptor kinase activity, largely because down-regulation is inhibited by a kinase-inactivating mutation of an invariant lysine residue of the receptors for EGF, insulin, M-CSF and PDGF. We confirmed that this mutation inhibited the degradation of the M-CSF receptor. However, two different kinase inactivating mutations of the invariant amino acids Gly 591 and Glu 633 did not prevent M-CSF-induced receptor degradation, so demonstrating that receptor kinase activity is not essential for this process. Three other kinase-inactivating mutations were found to cause constitutive receptor degradation in the absence of M-CSF, most probably by disrupting the structure of the activating loop of the kinase domain. It is known that extensive movement of the A-loop is necessary for kinase activation and is normally induced by ligand-binding. It is therefore suggested that some aspect or consequence of the change in structure of the A-loop caused by ligand binding also activates receptor downregulation, so ensuring that downregulation is coupled to but is not necessarily dependent upon receptor kinase activity.
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Affiliation(s)
- M Uden
- Cell Signalling Unit, Division of Paediatrics, Obstetrics and Gynaecology, Imperial College School of Medicine, Hammersmith Hospital, London, UK
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Sachsenmaier C, Sadowski HB, Cooper JA. STAT activation by the PDGF receptor requires juxtamembrane phosphorylation sites but not Src tyrosine kinase activation. Oncogene 1999; 18:3583-92. [PMID: 10380880 DOI: 10.1038/sj.onc.1202694] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Activation of the platelet-derived growth factor (PDGF) receptor tyrosine kinase induces tyrosine phosphorylation of Signal Transducer and Activator of Transcription (STAT) proteins. Since the PDGF receptor also activates the Src tyrosine kinase, it is possible that Src mediates tyrosine phosphorylation of STATs in PDGF-treated cells. Consistent with a role for Src in STAT activation, we found that a PDGF receptor juxtamembrane tyrosine residue required for Src activation is necessary and sufficient for activation of STATs 1 and 3. To test the Src requirement further, we made other mutations in the PDGF receptor juxtamembrane region that increased or decreased Src binding. In epithelial and fibroblast cells, PDGF activated STAT1, 3 and 6 in the absence of detectable binding and activation of Src. In addition, PDGF induced c-myc RNA expression and DNA synthesis even though Src was not detectably activated. The activation of MAP kinase and the induction of c-fos gene expression both correlated with STAT but not Src activation by the receptor. We conclude that juxtamembrane tyrosine phosphorylation is necessary for both Src tyrosine kinase and STAT activation by the betaPDGF receptor, but that both processes are regulated independently by this region.
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Affiliation(s)
- C Sachsenmaier
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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The Related Adhesion Focal Tyrosine Kinase (RAFTK) Is Tyrosine Phosphorylated and Participates in Colony-Stimulating Factor-1/Macrophage Colony-Stimulating Factor Signaling in Monocyte-Macrophages. Blood 1998. [DOI: 10.1182/blood.v91.10.3967.3967_3967_3973] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
RAFTK, a novel nonreceptor protein kinase, has been shown to be involved in focal adhesion signal transduction pathways in neuronal PC12 cells, megakaryocytes, platelets, and T cells. Because focal adhesions may modulate cytoskeletal functions and thereby alter phagocytosis, cell migration, and adhesion in monocyte-macrophages, we investigated the role of RAFTK signaling in these cells. RAFTK was abundantly expressed in THP1 monocytic cells as well as in primary alveolar and peripheral blood-derived macrophages. Colony-stimulating factor-1 (CSF-1)/macrophage colony-stimulating factor (M-CSF) stimulation of THP1 cells increased the tyrosine phosphorylation of RAFTK; similar increases in phosphorylation were also detected after lipopolysaccharide stimulation. RAFTK was phosphorylated with similar kinetics in THP1 cells and peripheral blood-derived macrophages. Immunoprecipitation analysis showed associations between RAFTK and the signaling molecule phosphatidylinositol-3 (PI-3) kinase. PI-3 kinase enzyme activity also coprecipitated with the RAFTK antibody, further confirming this association. The CSF-1/M-CSF receptor c-fms and RAFTK appeared to associate in response to CSF-1/M-CSF treatment of THP1 cells. Inhibition of RAFTK by a dominant-negative kinase mutant reduced CSF-1/M-CSF–induced MAPK activity. These data indicate that RAFTK participates in signal transduction pathways mediated by CSF-1/M-CSF, a cytokine that regulates monocyte-macrophage growth and function.
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The Related Adhesion Focal Tyrosine Kinase (RAFTK) Is Tyrosine Phosphorylated and Participates in Colony-Stimulating Factor-1/Macrophage Colony-Stimulating Factor Signaling in Monocyte-Macrophages. Blood 1998. [DOI: 10.1182/blood.v91.10.3967] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractRAFTK, a novel nonreceptor protein kinase, has been shown to be involved in focal adhesion signal transduction pathways in neuronal PC12 cells, megakaryocytes, platelets, and T cells. Because focal adhesions may modulate cytoskeletal functions and thereby alter phagocytosis, cell migration, and adhesion in monocyte-macrophages, we investigated the role of RAFTK signaling in these cells. RAFTK was abundantly expressed in THP1 monocytic cells as well as in primary alveolar and peripheral blood-derived macrophages. Colony-stimulating factor-1 (CSF-1)/macrophage colony-stimulating factor (M-CSF) stimulation of THP1 cells increased the tyrosine phosphorylation of RAFTK; similar increases in phosphorylation were also detected after lipopolysaccharide stimulation. RAFTK was phosphorylated with similar kinetics in THP1 cells and peripheral blood-derived macrophages. Immunoprecipitation analysis showed associations between RAFTK and the signaling molecule phosphatidylinositol-3 (PI-3) kinase. PI-3 kinase enzyme activity also coprecipitated with the RAFTK antibody, further confirming this association. The CSF-1/M-CSF receptor c-fms and RAFTK appeared to associate in response to CSF-1/M-CSF treatment of THP1 cells. Inhibition of RAFTK by a dominant-negative kinase mutant reduced CSF-1/M-CSF–induced MAPK activity. These data indicate that RAFTK participates in signal transduction pathways mediated by CSF-1/M-CSF, a cytokine that regulates monocyte-macrophage growth and function.
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Gommerman JL, Rottapel R, Berger SA. Phosphatidylinositol 3-kinase and Ca2+ influx dependence for ligand-stimulated internalization of the c-Kit receptor. J Biol Chem 1997; 272:30519-25. [PMID: 9374546 DOI: 10.1074/jbc.272.48.30519] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We have evaluated the role of phosphatidylinositol 3-kinase (PI3-kinase) and Ca2+ influx in ligand-stimulated internalization of the c-Kit receptor. The wild type (wt) c-Kit receptor and YF719, a mutant receptor in which the SH2-mediated binding site for the p85 subunit of PI3-kinase is disrupted, were expressed in DA-1 cells. YF719 internalized with similar kinetics as wt c-Kit although the receptor remained localized close to the plasma membrane. However, in the absence of extracellular Ca2+, or in the presence of the competitive Ca2+ influx blocker Ni2+, the YF719 mutant failed to internalize. Failure to internalize in the absence of Ca2+ was also observed for the wt c-Kit receptor in cells that were pretreated with the PI3-kinase inhibitor, wortmannin. Following stimulation with ligand, clathrin heavy chains were found to co-immunoprecipitate with c-Kit. However, under conditions in which PI3-kinase activity is inhibited and Ca2+ influx is blocked, clathrin failed to co-immunoprecipitate with c-Kit. Our results demonstrate that both Ca2+ influx and PI3-kinase activity influence c-Kit endocytosis, and inhibition of these two signals disrupts the earliest stages of ligand-mediated internalization.
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Affiliation(s)
- J L Gommerman
- Wellesley Hospital Research Institute and Department of Immunology, University of Toronto, Toronto, Ontario, Canada M4Y 1J3.
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17
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Chuang PI, Young BA, Thiagarajan RR, Cornejo C, Winn RK, Harlan JM. Cytoplasmic domain of E-selectin contains a non-tyrosine endocytosis signal. J Biol Chem 1997; 272:24813-8. [PMID: 9312078 DOI: 10.1074/jbc.272.40.24813] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
E-selectin is an activation-dependent, endothelial cell-restricted adhesion molecule that is internalized and degraded rapidly once expressed on the cell surface. Tyrosine-containing structural motifs play an important role in the internalization of a number of integral proteins, and the membrane-proximal E-selectin cytoplasmic tyrosine residue (Tyr582) conforms to the endocytosis motif proposed previously. To determine the endocytosis motif in E-selectin, we selectively introduced truncation, substitution, and deletion mutations to the cytoplasmic tail of E-selectin. We analyzed the internalization kinetics of surface-expressed wild-type and mutant E-selectin constructs in transiently transfected Chinese hamster ovary cells using 125I-labeled E-selectin monoclonal antibody (125I-P6E2) in an acid elution assay. Interestingly, truncation immediately membrane proximal to Tyr582 (DeltaDGS construct) did not alter internalization kinetics significantly (DeltaDGS versus wild-type, mean surface half-life = 42 versus 45 min, respectively). Thus, it appears that the tyrosine residues are not required for internalization of E-selectin. Additional analyses indicated that Ser581 was necessary but alone was insufficient for surface E-selectin endocytosis. Thus, we conclude that there exists a novel non-tyrosine-containing endocytosis signal in the cytoplasmic tail which involves Ser581 and residues membrane-proximal to it.
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Affiliation(s)
- P I Chuang
- Department of Medicine, University of Washington, Seattle, Washington 98195, USA.
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18
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Katz ML, Rice LM, Gao CL. Dietary carnitine supplements slow disease progression in a putative mouse model for hereditary ceroid-lipofuscinosis. J Neurosci Res 1997; 50:123-32. [PMID: 9379488 DOI: 10.1002/(sici)1097-4547(19971001)50:1<1::aid-jnr1>3.0.co;2-n] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The childhood ceroid-lipofuscinoses are a group of autosomal recessively inherited disorders characterized by massive accumulation of autofluorescent lysosomal storage bodies in neurons as well as other cell types. The storage body accumulation is accompanied by severe degeneration of the central nervous system that results in blindness, cognitive and psychomotor degeneration, and premature death. On the basis of pathologic and biochemical criteria, a hereditary disease in the mnd mouse strain has been proposed as a model for certain types of human ceroid-lipofuscinosis. Experimental evidence suggests that the storage body accumulation in humans with juvenile and late-infantile ceroid-lipofuscinosis is linked to altered carnitine biosynthesis. On the basis of the latter observation, a study was performed to determine whether dietary carnitine supplements could slow the disease progression in the mnd mouse model. Carnitine supplementation begun at 4 weeks of age did not slow the retinal degeneration that is characteristic of this disease. It did, however, significantly elevate brain carnitine levels, slow the accumulation of autofluorescent storage bodies in brain neurons, and prolong the lifespans of the treated animals. These findings suggest that there is a link between carnitine biosynthesis and the disease pathology and indicate that carnitine supplementation may be beneficial in slowing the disease progression in humans with certain types of hereditary ceroid-lipofuscinosis.
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Affiliation(s)
- M L Katz
- University of Missouri School of Medicine, Mason Eye Institute, Columbia 65212, USA.
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19
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Beslu N, LaRose J, Casteran N, Birnbaum D, Lecocq E, Dubreuil P, Rottapel R. Phosphatidylinositol-3' kinase is not required for mitogenesis or internalization of the Flt3/Flk2 receptor tyrosine kinase. J Biol Chem 1996; 271:20075-81. [PMID: 8702727 DOI: 10.1074/jbc.271.33.20075] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Flt3/Flk2 is a receptor tyrosine kinase that is expressed on early hematopoietic progenitor cells. Flt3/Flk2 belongs to a family of receptors, including Kit and colony-stimulating factor-1R, which support growth and differentiation within the hematopoietic system. The Flt3/Flk2 ligand, in combination with other growth factors, stimulates the proliferation of hematopoietic progenitors of both lymphoid and myeloid lineages in vitro. We report that phosphatidylinositol 3'-kinase (PI3K) binds to a unique site in the carboxy tail of murine Flt3/Flk2. In distinction to Kit and colony-stimulating factor-1R, mutant receptors unable to couple to PI3K and expressed in rodent fibroblasts or in the interleukin 3-dependent cell line Ba/F3 provide a mitogenic signal comparable to wild-type receptors. Flt3/Flk2 receptors that do not bind to PI3K also normally down-regulate, a function ascribed to PI3K in the context of other receptor systems. These data point to the existence of other unidentified pathways that, alone or in combination with PI3K, transduce these cellular responses following the activation of Flt3/Flk2.
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Affiliation(s)
- N Beslu
- Molecular Hematology Laboratory, Unite 119, Institut National de la Santé et de la Recherche Mèdicale, 27 Bd Lei Roure, 13009 Marseille, France
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20
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Peng X, Greene LA, Kaplan DR, Stephens RM. Deletion of a conserved juxtamembrane sequence in Trk abolishes NGF-promoted neuritogenesis. Neuron 1995; 15:395-406. [PMID: 7646892 DOI: 10.1016/0896-6273(95)90043-8] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Deletion of a conserved juxtamembrane sequence (KFG) in the Trk NGF receptor resulted in impaired neurite outgrowth, somatic hypertrophy, and induction of c-fos, c-jun, and TIS1 immediate-early genes. In contrast, these receptors retained the ability to mediate NGF-promoted survival and TIS8 and TIS11 immediate-early gene induction. The mutated receptor also mediated unimpaired autophosphorylation; SHC, PLC-gamma 1, and ERK tyrosine phosphorylation; and PI-3 kinase and ERK activation. However, SNT protein tyrosine phosphorylation, which wild-type receptors mediate via a ras-independent pathway, was undetectable. These findings indicate that the KFG sequence is indispensable for activating a ras-independent NGF signaling pathway involved in promoting neuronal differentiation and highlight potential roles of non-tyrosine-containing receptor domains in growth factor signal transduction.
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MESH Headings
- 1-Phosphatidylinositol 4-Kinase
- Adaptor Proteins, Signal Transducing
- Adaptor Proteins, Vesicular Transport
- Amino Acid Sequence
- Animals
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Cell Size
- Culture Media, Serum-Free
- Isoenzymes/metabolism
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Nerve Growth Factors/pharmacology
- Nerve Tissue Proteins/metabolism
- Neurites/drug effects
- Neurites/physiology
- Neurites/ultrastructure
- PC12 Cells
- Phospholipase C gamma
- Phosphorylation
- Phosphotransferases (Alcohol Group Acceptor)/metabolism
- Protein Processing, Post-Translational
- Proteins/metabolism
- Proto-Oncogene Proteins/chemistry
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/physiology
- Rats
- Receptor Protein-Tyrosine Kinases/chemistry
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor Protein-Tyrosine Kinases/physiology
- Receptor, trkA
- Receptors, Nerve Growth Factor/chemistry
- Receptors, Nerve Growth Factor/genetics
- Receptors, Nerve Growth Factor/physiology
- Sequence Deletion
- Shc Signaling Adaptor Proteins
- Signal Transduction
- Src Homology 2 Domain-Containing, Transforming Protein 1
- Type C Phospholipases/metabolism
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Affiliation(s)
- X Peng
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
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21
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Nesterov A, Kurten RC, Gill GN. Association of epidermal growth factor receptors with coated pit adaptins via a tyrosine phosphorylation-regulated mechanism. J Biol Chem 1995; 270:6320-7. [PMID: 7534311 DOI: 10.1074/jbc.270.11.6320] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We investigated the mechanism by which ligand-activated epidermal growth factor receptors (EGFR) associate with coated pit adaptor protein (AP) complexes. In vivo association, assayed by coimmunoprecipitation of AP with mutant EGFR, required tyrosine kinase activity, intact autophosphorylation sites, and the regulatory carboxyl terminus of EGFR. The role of autophosphorylation of EGFR in interaction with AP was examined in vitro using a BIAcore instrument. Purified active EGFR, immobilized on the biosensor surface, was reversibly autophosphorylated or dephosphorylated by treatment with ATP or phosphatase. Autophosphorylation of EGFR significantly increased AP binding. Once formed, EGFR AP complexes were resistant to disassembly by dephosphorylation of EGFR or competition with phosphotyrosine, indicating that phosphorylated tyrosine residues do not directly participate in AP binding. Induction of conformational changes in EGFR by treatment with urea increased AP binding up to 10-fold in the absence of EGFR autophosphorylation. A recombinant EGFR carboxyl terminus specifically bound the AP complex and each of the isolated alpha- and beta-subunits of AP2. We conclude that tyrosine autophosphorylation of EGFR exposes structural motif(s) in the carboxyl terminus of EGFR that interact specifically with AP2.
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Affiliation(s)
- A Nesterov
- Department of Medicine, University of California at San Diego, La Jolla 92093
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