51
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Baldwin AN, Shooter EM. Zone mapping of the binding domain of the rat low affinity nerve growth factor receptor by the introduction of novel N-glycosylation sites. J Biol Chem 1995; 270:4594-602. [PMID: 7876230 DOI: 10.1074/jbc.270.9.4594] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The binding of NGF (nerve growth factor) to the rat low affinity nerve growth factor receptor (p75NGFR) has been studied by site-directed mutagenesis of the receptor. Introduction of non-native N-glycosylation sites within the binding domain indicates that the second of the characteristic cysteine-rich repeats may be particularly important to NGF binding. Two mutants of the second repeat, S42N and S66N, are glycosylated and bind NGF at a drastically reduced level, while still maintaining a conformation recognized by the monoclonal antibody against p75, MC192. Alanine substitution at these sites does not affect NGF binding. Two other mutations that result in local structural changes in the second repeat also greatly decrease binding. One of these altered residues, Ser50, appears to play an essential structural role, since it cannot be replaced by Asn, Ala, or Thr without loss of both NGF binding and MC192 recognition on a Western. Glycosylation of selected sites in the other repeats has little effect on NGF binding or antibody recognition. The introduction of non-native N-glycosylation sites may provide a generally useful scanning technique for the study of protein-protein interactions.
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Affiliation(s)
- A N Baldwin
- Department of Neurobiology, Stanford University School of Medicine, California 94305
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52
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Schmidt J. Depolarization-transcription coupling in excitable cells. Rev Physiol Biochem Pharmacol 1995; 127:251-79. [PMID: 8533010 DOI: 10.1007/bfb0048269] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- J Schmidt
- Department of Biochemistry and Cell Biology, State University of Stony Brook, NY 11794, USA
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53
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Rosen LB, Ginty DD, Greenberg ME. Calcium regulation of gene expression. ADVANCES IN SECOND MESSENGER AND PHOSPHOPROTEIN RESEARCH 1995; 30:225-53. [PMID: 7695991 DOI: 10.1016/s1040-7952(05)80009-6] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- L B Rosen
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
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54
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Kobayashi M, Kurihara K, Matsuoka I. Retinoic acid induces BDNF responsiveness of sympathetic neurons by alteration of Trk neurotrophin receptor expression. FEBS Lett 1994; 356:60-5. [PMID: 7988722 DOI: 10.1016/0014-5793(94)01238-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The expression of high affinity neurotrophin receptors (TrkA, TrkB, and TrkC) determines the survival response of different populations of neurons to specific members of the neurotrophin family, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3). However, the mechanism which controls the expression of neurotrophin receptors during neuronal development is largely unknown. Here we show that the treatment of the cultured sympathetic neurons from newborn rat superior cervical ganglia (SCG) with retinoic acid (RA), a derivative of vitamin A, suppressed the expression of trkA mRNA and induced the expression of trkB mRNA. Expression of the functional TrkB receptor was confirmed by the emergence of trophic dependence of these neurons on BDNF in the absence of NGF. Differential regulation of trk mRNAs by RA provides a possible model for the establishment of neurotrophin dependence of peripheral neurons.
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Affiliation(s)
- M Kobayashi
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
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55
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Verdi JM, Anderson DJ. Neurotrophins regulate sequential changes in neurotrophin receptor expression by sympathetic neuroblasts. Neuron 1994; 13:1359-72. [PMID: 7993627 DOI: 10.1016/0896-6273(94)90421-9] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We have examined the mechanisms controlling the induction of the two NGF receptors, trkA and p75, in proliferating neuroblasts immuno-isolated from thoracolumbar embryonic sympathetic ganglia. Contrary to prior studies, we find that induction of p75 follows rather than precedes that of trkA; this late induction is consistent with the fact that p75 functions at relatively late stages of sympathetic development. trkA induction is apparently not controlled by a cell-intrinsic mechanism. Rather, this receptor is induced by environmental signals including NT-3, which also acts as an interim survival factor for these neuroblasts. trkA induction by NT-3 is consequent to its promotion of mitotic arrest, as anti-mitotic drugs also efficiently induce trkA. p75 expression is induced in trkA-expressing cells by NGF. Thus, the development of sympathetic neurons involves sequential actions of different neurotrophins, which also regulate the expression of their own and each other's receptors.
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Affiliation(s)
- J M Verdi
- Division of Biology, California Institute of Technology, Pasadena 91125
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56
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Abstract
The low-affinity p75 molecule and trk tyrosine kinases serve as receptors for target-derived neurotrophins. While the mechanism by which receptor tyrosine kinases impart intracellular signaling has become well understood, the precise roles of the p75 receptor are not fully defined. The p75 neurotrophin receptor belongs to a family of transmembrane molecules which also serve as receptors for the tumor necrosis factor family of cytokines. Each receptor shares a common extracellular structure highlighted by conserved cysteine-rich repeats. Because NGF, BDNF, NT-3, and NT-4/5 bind to p75 with similar affinity, p75 may either act as a common subunit in a neurotrophin receptor complex with trk family members, or act by independent mechanisms to mediate biological actions of each neurotrophin.
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Affiliation(s)
- M V Chao
- Department of Cell Biology and Anatomy, Cornell University Medical College, New York, New York 10021
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57
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Zhong W, Zaheer A, Lim R. Ciliary neurotrophic factor (CNTF) enhances the effects of nerve growth factor on PC12 cells. Brain Res 1994; 661:56-62. [PMID: 7834385 DOI: 10.1016/0006-8993(94)91180-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The rat pheochromocytoma cell line PC12 responds readily to nerve growth factor (NGF) but poorly to ciliary neurotrophic factor (CNTF). However, in a selected line derived from PC12 that normally responded weakly to NGF, CNTF potentiated the effect of NGF with respect to inhibition of proliferation, neurite outgrowth, and choline acetyltransferase (ChAT) induction. ChAT activity was assayed enzymatically, and an increase in the mRNA of ChAT was also detected by means of reverse transcription-polymerase chain reaction (RT-PCR). The PCR product was verified by sequencing and by Southern hybridization using a specific oligonucleotide probe. The presence of CNTF receptor in PC12 cells was confirmed by RT-PCR for its mRNA. The results indicate that PC12 responds to CNTF mainly when used in combination with NGF, and suggest an interaction between the two growth factors.
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Affiliation(s)
- W Zhong
- Department of Neurology (Division of Neurochemistry and Neurobiology), University of Iowa College of Medicine, Iowa City
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58
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Dobrowsky RT, Werner MH, Castellino AM, Chao MV, Hannun YA. Activation of the sphingomyelin cycle through the low-affinity neurotrophin receptor. Science 1994; 265:1596-9. [PMID: 8079174 DOI: 10.1126/science.8079174] [Citation(s) in RCA: 492] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The role of the low-affinity neurotrophin receptor (p75NTR) in signal transduction is undefined. Nerve growth factor can activate the sphingomyelin cycle, generating the putative-lipid second messenger ceramide. In T9 glioma cells, addition of a cell-permeable ceramide analog mimicked the effects of nerve growth factor on cell growth inhibition and process formation. This signaling pathway appears to be mediated by p75NTR in T9 cells and NIH 3T3 cells overexpressing p75NTR. Expression of an epidermal growth factor receptor-p75NTR chimera in T9 cells imparted to epidermal growth factor the ability to activate the sphingomyelin cycle. These data demonstrate that p75NTR is capable of signaling independently of the trk neurotrophin receptor (p140trk) and that ceramide may be a mediator in neurotrophin biology.
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Affiliation(s)
- R T Dobrowsky
- Departments of Medicine and Cell Biology, Duke University Medical Center, Durham, NC 27710
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59
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Kendall G, Ensor E, Brar-Rai A, Winter J, Latchman DS. Nerve growth factor induces expression of immediate-early genes NGFI-A (Egr-1) and NGFI-B (nur 77) in adult rat dorsal root ganglion neurons. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1994; 25:73-9. [PMID: 7984055 DOI: 10.1016/0169-328x(94)90280-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We have used primary cultures of adult rat dorsal root ganglia (DRG), enriched in sensory neurons, to investigate the induction of immediate-early genes by NGF and a variety of other growth factors. Using the polymerase chain reaction we have quantitatively amplified specific mRNA transcripts induced by NGF, in the presence and absence of the protein synthesis inhibitor cycloheximide. NGFIA (Egr-1) and NGFIB (nur 77) mRNAs were elevated in level within 60 min of NGF treatment and independently of de novo protein synthesis. This was consistent with the behaviour of immediate-early genes. These kinetics were seen at a range of NGF concentrations. NGFIA and NGFIB mRNAs were also found to be induced in DRG cultures by a variety of other growth factors. Different patterns of induction of NGFIA and NGFIB mRNA observed in DRG cultures suggested that transcript-specific pathways of signal transduction were operating within neurons, dependent upon the particular growth factor stimulus. Comparison of data reported from growth factor treatment of other cell types with data from DRG cultures also revealed patterns of NGFIA and NGFIB mRNA induction specific to DRG neurons.
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Affiliation(s)
- G Kendall
- Department of Molecular Pathology, University College London Medical School, UK
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60
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Ip NY, Boulton TG, Li Y, Verdi JM, Birren SJ, Anderson DJ, Yancopoulos GD. CNTF, FGF, and NGF collaborate to drive the terminal differentiation of MAH cells into postmitotic neurons. Neuron 1994; 13:443-55. [PMID: 8060620 DOI: 10.1016/0896-6273(94)90359-x] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The differentiation of neuronal cell progenitors depends on complex interactions between intrinsic cellular programs and environmental cues. Such interactions have recently been explored using an immortalized sympathoadrenal progenitor cell line, MAH. These studies have revealed that depolarizing conditions, in combination with exposure to FGF, can induce responsiveness to NGF. Here we report that CNTF, which utilizes an intracellular signaling pathway distinct from that of both FGF and NGF, can collaborate with FGF to promote efficiently the differentiation of MAH progenitor cells to a stage remarkably reminiscent of NGF-dependent, postmitotic sympathetic neurons. We also find that similar collaborative interactions can occur during transdifferentiation of normal cultured chromaffin cells into sympathetic neurons.
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Affiliation(s)
- Nancy Y Ip
- Regeneron Pharmaceuticals, Inc., Tarrytown, New York 10591
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61
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Hantzopoulos PA, Suri C, Glass DJ, Goldfarb MP, Yancopoulos GD. The low affinity NGF receptor, p75, can collaborate with each of the Trks to potentiate functional responses to the neurotrophins. Neuron 1994; 13:187-201. [PMID: 8043276 DOI: 10.1016/0896-6273(94)90469-3] [Citation(s) in RCA: 231] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
NGF and the other neurotrophins all bind to the low affinity NGF receptor (LNGFR). Although early studies suggested that the LNGFR was absolutely required for the formation of a functional neurotrophin receptor, current evidence indicates that the Trk family of receptor tyrosine kinases, in the absence of the LNGFR, can directly bind to and mediate responses to the neurotrophins. Here we describe a functional approach, in fibroblasts, designed to assay for the ability of the LNGFR to potentiate Trk-mediated responses to the neurotrophins. We report that although collaboration between the LNGFR and the Trks could be detected in this system, a truncated form of the LNGFR displayed a much more dramatic ability to interact functionally with each of the Trks, potentiating masked autocrine loops as well as responses to limiting amounts of exogenously provided neurotrophins.
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62
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Abstract
The molecular cloning of new neuroactive growth factors and their receptors has greatly enhanced our understanding of important interactions among receptors and signaling molecules. These studies have begun to illuminate some of the mechanisms that allow for specificity in neuronal signaling. Model cell systems, such as the PC-12 pheochromocytoma cell line, express receptors for these different neurotrophic factors, leading to comparisons of signaling pathways for these factors. Upon binding their ligands, these receptors undergo phosphorylation on tyrosine residues, which directs their interaction with signaling proteins containing src homology (SH2) domains, sequences that mediate associations with tyrosine-phosphorylated proteins. These SH2 proteins translate the tyrosine kinase activity of receptors into downstream events that result in the specific cellular response. Investigations such as these have revealed that molecular specificity in signaling pathways may arise from combinatorial diversity in interactions between receptors and key regulatory proteins.
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Affiliation(s)
- A R Saltiel
- Department of Signal Transduction, Parke-Davis Pharmaceutical Research Division of Warner-Lambert Co., Ann Arbor, Michigan 48105
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63
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Verdi JM, Ip N, Yancopoulos GD, Anderson DJ. Expression of trk in MAH cells lacking the p75 low-affinity nerve growth factor receptor is sufficient to permit nerve growth factor-induced differentiation to postmitotic neurons. Proc Natl Acad Sci U S A 1994; 91:3949-53. [PMID: 8171018 PMCID: PMC43700 DOI: 10.1073/pnas.91.9.3949] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We have transfected MAH cells, an immortalized sympathoadrenal progenitor cell line, with a plasmid encoding the 140-kDa Trk protein, a nerve growth factor (NGF) receptor with protein-tyrosine kinase activity. NGF promotes neurite outgrowth and proliferation from such cells, indicating that Trk is sufficient to mediate such responses in the absence of significant levels of the endogenous 75-kDa low-affinity NGF receptor (p75). These initial NGF responses are indistinguishable from those evoked by basic fibroblast growth factor (bFGF). However, NGF is sufficient to promote terminal differentiation of a approximately 8% of trk-transfected MAH cells to postmitotic, NGF-dependent neurons, whereas all cells eventually die in medium with bFGF. Other environmental signals (such as depolarization or ciliary neurotrophic factor) can cooperate with NGF to enhance production of postmitotic NGF-dependent neurons in trk-transfected MAH cells. The terminal differentiation of sympathetic neurons thus involves sequential and cooperative actions of different growth and neurotrophic factors, as well as cell-intrinsic changes in the response to these factors.
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Affiliation(s)
- J M Verdi
- Division of Biology, California Institute of Technology, Pasadena 91125
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64
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Verdi JM, Birren SJ, Ibáñez CF, Persson H, Kaplan DR, Benedetti M, Chao MV, Anderson DJ. p75LNGFR regulates Trk signal transduction and NGF-induced neuronal differentiation in MAH cells. Neuron 1994; 12:733-45. [PMID: 7512816 DOI: 10.1016/0896-6273(94)90327-1] [Citation(s) in RCA: 270] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have examined NGF-induced signal transduction events and neuronal differentiation in MAH cells, a neuronal progenitor cell line, in which the expression of the two NGF receptors, p140trk (Trk) and p75LNGFR (p75), has been independently manipulated. Coexpression of a large molar excess of p75 substantially enhances the NGF-induced tyrosine autophosphorylation of Trk, compared with cells expressing Trk alone. MAH cells expressing both Trk and p75 stop dividing and acquire a mature neuronal morphology more rapidly and with greater efficiency than MAH cells expressing Trk alone. These biochemical and biological influences of p75 are not observed using a mutant form of NGF that binds Trk but not p75. These data provide evidence that p75 can modulate signal transduction through Trk in a neuronal progenitor cell context and that such modulation has functional consequences for the neuronal differentiation pathway induced by NGF.
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Affiliation(s)
- J M Verdi
- Division of Biology, California Institute of Technology, Pasadena 91125
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65
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Kojima M, Ikeuchi T, Hatanaka H. Nerve growth factor induces trkA mRNA expression in cultured basal forebrain cholinergic neurons from 17-day fetal rats. Neurosci Lett 1994; 169:47-50. [PMID: 8047291 DOI: 10.1016/0304-3940(94)90353-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We first examined the basal forebrain tissues for developmental changes in expression of the high-affinity NGF receptor (trkA) gene. Our reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed that trkA mRNA is present in those tissues of postnatal rats, but not in those of fetal rats. Then we determined the effect of NGF on trkA gene expression in serum-free cultures of basal forebrain neurons from 17-day fetal rats. NGF was found to induce trkA mRNA 36 h after the addition of NGF, while no trkA mRNA was detected in the absence of NGF.
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Affiliation(s)
- M Kojima
- Division of Protein Biosynthesis, Institute for Protein Research, Osaka University, Japan
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66
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Mahadeo D, Kaplan L, Chao M, Hempstead B. High affinity nerve growth factor binding displays a faster rate of association than p140trk binding. Implications for multi-subunit polypeptide receptors. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37458-6] [Citation(s) in RCA: 116] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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67
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Abstract
Developmental cell death is a major event of neurogenesis, and emphasis has systematically been placed on the roles of either the peripheral targets or central postsynaptic neurons in the control of neuronal survival. In this article, the main types of experimental design used to test the control of neuronal death by the afferent supply are compared with analogous data indicating neurotrophic support by the targets. It is argued that targets and afferents may have equivalent roles and interact in the control of neuron numbers during development of the vertebrate nervous system. Possible mechanisms of anterograde trophic control include contact-mediated cell interactions, activity-dependent processes mediated by neurotransmitters or neuromodulators, modulation of the levels of cytoplasmic free calcium and the involvement of neurotrophic factors.
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Affiliation(s)
- R Linden
- Instituto de Biofisica da UFRJ, Cidade Universitaria, Brazil
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68
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Ross AH, Lachyankar MB, Poluha DK, Loy R. Axonal transport of the trkA high-affinity NGF receptor. PROGRESS IN BRAIN RESEARCH 1994; 103:15-21. [PMID: 7533911 DOI: 10.1016/s0079-6123(08)61122-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- A H Ross
- Worcester Foundation for Experimental Biology, Shrewsbury, MA 01545
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69
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Otten U, Scully JL, Ehrhard PB, Gadient RA. Neurotrophins: signals between the nervous and immune systems. PROGRESS IN BRAIN RESEARCH 1994; 103:293-305. [PMID: 7886213 DOI: 10.1016/s0079-6123(08)61144-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- U Otten
- Department of Physiology, University of Basel, Switzerland
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70
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Ehrhard PB, Erb P, Graumann U, Otten U. Expression of nerve growth factor and nerve growth factor receptor tyrosine kinase Trk in activated CD4-positive T-cell clones. Proc Natl Acad Sci U S A 1993; 90:10984-8. [PMID: 7902578 PMCID: PMC47906 DOI: 10.1073/pnas.90.23.10984] [Citation(s) in RCA: 234] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Recent evidence suggests that nerve growth factor (NGF), in addition to its neurotrophic functions, acts as an immunomodulator mediating "cross-talk" between neuronal and immune cells, including T lymphocytes. We have analyzed murine CD4+ T-cell clones for their ability to express transcripts encoding NGF, low-affinity NGF receptor, and trk protooncogene, the signal-transducing receptor subunit for NGF. We show that two CD4+ T-helper (Th) clones, Th0-type clone 8/37 and Th2-type clone D10.G4.1, express NGF and Trk mRNA after appropriate activation with mitogen or with antigen and antigen-presenting cells. NGF and trk induction occurred to a similar extent and over a similar time course in activated 8/37 T cells, raising the possibility that NGF and trk genes are under coordinate control. NGF and NGF receptor expression does not seem to be a universal property of all activated CD4+ T cells, since Th1-type clone 9/9 did not express any of the transcripts after either stimulation. The absence of low-affinity NGF receptor mRNA in resting and activated T cells implies that the low-affinity NGF receptor is not involved in NGF signal transduction in CD4+ T cells. Our finding that activated CD4+ T-cell clones not only express Trk but also synthesize and release biologically active NGF implicates NGF as an autocrine and/or paracrine factor in the development and regulation of immune responses.
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Affiliation(s)
- P B Ehrhard
- Department of Physiology, University of Basel, Switzerland
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71
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Wyatt S, Davies AM. Regulation of expression of mRNAs encoding the nerve growth factor receptors p75 and trkA in developing sensory neurons. Development 1993; 119:635-48. [PMID: 8187634 DOI: 10.1242/dev.119.3.635] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have used a quantitative reverse transcription/polymerase chain reaction amplification technique to study the regulation of p75 mRNA and trkA mRNA expression in developing NGF-dependent trigeminal neurons. Before becoming NGF dependent, these neurons express low levels of p75 and trkA mRNAs in vivo. At this stage in vitro, the level of p75 mRNA is maintained and up-regulated by BDNF, whereas the level of trkA mRNA is sustained independently of neurotrophins and is down-regulated by BDNF. With the acquisition of NGF dependence, p75 and trkA mRNA levels increase markedly in vivo. At this stage in vitro, the level of p75 mRNA is up-regulated by NGF, but this response is lost at later stages. The level of trkA mRNA is sustained in neurons grown with NGF but is not up-regulated by concentrations of NGF above those required to support survival. At no stage during the early development of trigeminal neurons do depolarising levels of potassium ions affect the expression of either p75 mRNA or trkA mRNA. These findings suggest that the expression of p75 and trkA mRNAs are differentially regulated by BDNF and NGF at successive early stages of neuronal development.
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Affiliation(s)
- S Wyatt
- School of Biological and Medical Sciences, University of St. Andrews, Fife, Scotland
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72
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Vogel KS. Development of trophic interactions in the vertebrate peripheral nervous system. Mol Neurobiol 1993; 7:363-82. [PMID: 8179844 DOI: 10.1007/bf02769183] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
During embryogenesis, the neurons of vertebrate sympathetic and sensory ganglia become dependent on neurotrophic factors, derived from their targets, for survival and maintenance of differentiated functions. Many of these interactions are mediated by the neurotrophins NGF, BDNF, and NT3 and the receptor tyrosine kinases encoded by genes of the trk family. Both sympathetic and sensory neurons undergo developmental changes in their responsiveness to NGF, the first neurotrophin to be identified and characterized. Subpopulations of sensory neurons do not require NGF for survival, but respond instead to BDNF or NT3 with enhanced survival. In addition to their classic effects on neuron survival, neurotrophins influence the differentiation and proliferation of neural crest-derived neuronal precursors. In both sympathetic and sensory systems, production of neurotrophins by target cells and expression of neurotrophin receptors by neurons are correlated temporally and spatially with innervation patterns. In vitro, embryonic sympathetic neurons require exposure to environmental cues, such as basic FGF and retinoic acid to acquire neurotrophin-responsiveness; in contrast, embryonic sensory neurons acquire neurotrophin-responsiveness on schedule in the absence of these molecules.
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Affiliation(s)
- K S Vogel
- Molecular Embryology Section; NCI-Frederick Cancer Research and Development Center; ABL-Basic Research Program, MD 21702-1201
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73
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Carvey PM, Ptak LR, Lin D, Lo ES, Buhrfiend CM, Drucker GE, Fields JZ. Alterations in striatal neurotrophic activity induced by dopaminergic drugs. Pharmacol Biochem Behav 1993; 46:195-204. [PMID: 7902982 DOI: 10.1016/0091-3057(93)90340-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The administration of dopaminergic drugs induces a variety of compensatory responses ostensibly designed to reinstate normal dopamine (DA) tone. We have hypothesized that drug-induced alterations in striatal-derived neurotrophic activity contributes to these compensatory processes. This phenomenon has been studied by examining the growth of mesencephalic cultures incubated with cell-free extracts of striatal tissue taken from patients or rats treated with various drugs. Our results reveal that reducing striatal DA tone by administering the DA antagonist haloperidol, the DA neurotoxin 6-hydroxydopamine, or as occurs naturally in Parkinson's disease, increases striatal trophic activity. Conversely, increasing striatal DA tone by administering the indirect DA agonists amphetamine or levodopa reduces trophic activity in the striatum. Kainic acid lesions of the striatum similarly reduce this trophic activity. The implications of these drug-induced alterations in trophic activity are discussed and reviewed.
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Affiliation(s)
- P M Carvey
- Department of Neurological Sciences, Rush-Presbyterian-St. Lukes Medical Center, Chicago, IL 60612
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74
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Benedetti M, Levi A, Chao MV. Differential expression of nerve growth factor receptors leads to altered binding affinity and neurotrophin responsiveness. Proc Natl Acad Sci U S A 1993; 90:7859-63. [PMID: 8356095 PMCID: PMC47242 DOI: 10.1073/pnas.90.16.7859] [Citation(s) in RCA: 232] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The low-affinity p75 neurotrophin receptor is believed to participate with the Trk receptor tyrosine kinase in the formation of high-affinity binding sites for nerve growth factor (NGF). To investigate the functional significance of the two NGF receptors, a truncated p75 receptor was stably expressed in PC12 rat pheochromocytoma cells, yielding cells with greatly reduced levels of wild-type p75 and normal Trk levels. Although these cells were capable of normal differentiation by NGF, very few high-affinity NGF binding sites were detected. These findings indicate that high-affinity binding may be functionally dissociated from biological responses. Furthermore, an increased responsiveness to neurotrophin 3 was observed, as manifested by increased neurite outgrowth. These results suggest that a correct ratio of p75 and p140trk is required to create high-affinity sites and that p75 expression may assist in the discrimination between related but different neurotrophin factors.
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Affiliation(s)
- M Benedetti
- Istituto di Neurobiologia, Consiglio Nazionale delle Ricerche, Rome, Italy
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75
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Black IB. Viktor Hamburger Award review. Environmental regulation of brain trophic interactions. Int J Dev Neurosci 1993; 11:403-10. [PMID: 7901965 DOI: 10.1016/0736-5748(93)90014-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Emerging evidence indicates that trophic interactions that influence brain development are critical throughout life, mediating processes as diverse as learning, memory and regrowth after injury. This review summarizes recent work suggesting that impulse activity regulates trophic interactions in the brain, allowing the conversion of millisecond-to-millisecond signalling into long-term changes in neural circuit function. For example, depolarizing stimuli regulate trophic factor gene expression, an effect mediated by excitatory transmitters. Responsiveness to trophic factors is also regulated by activity, since depolarization increases the expression of trophic receptor genes. Moreover, different excitatory transmitter receptor subtypes mediate trophic or regressive effects, allowing a neural system to precisely memorialize excitatory or inhibitory experiences. A number of open questions are articulated to define potential future directions.
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Affiliation(s)
- I B Black
- Department of Neuroscience and Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854
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76
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Kaplan DR, Matsumoto K, Lucarelli E, Thiele CJ. Induction of TrkB by retinoic acid mediates biologic responsiveness to BDNF and differentiation of human neuroblastoma cells. Eukaryotic Signal Transduction Group. Neuron 1993; 11:321-31. [PMID: 8394722 DOI: 10.1016/0896-6273(93)90187-v] [Citation(s) in RCA: 262] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Retinoic acid (RA) induces the neuronal differentiation of many human neuroblastoma cell lines. In this study, we show that RA treatment of neuroblastoma cells induces the expression of TrkB, the receptor for the neurotrophins BDNF, NT-3, and NT-4/5. BDNF addition to RA-treated SH-SY5Y neuroblastoma cells stimulated the tyrosine phosphorylation of TrkB and neuronal differentiation. RA treatment of KCNR neuroblastoma cells, which constitutively express BDNF mRNA, resulted in the expression of TrkB and differentiation in the absence of added BDNF. Finally, in 15N neuroblastoma cells, which express BDNF mRNA but do not differentiate in response to RA, RA induced only a truncated form of TrkB. 15N cells transfected with full-length TrkB differentiated in the absence of RA. These results indicate that RA induces the neuronal differentiation of neuroblastoma cells by modulating the expression of neurotrophin receptors.
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Affiliation(s)
- D R Kaplan
- ABL-Basic Research Program, National Cancer Institute, Frederick Cancer Research and Development Center, Maryland 21702
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77
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Grimes M, Zhou J, Li Y, Holtzman D, Mobley WC. Neurotrophin signalling in the nervous system. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/s1044-5765(05)80029-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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78
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Miranda RC, Sohrabji F, Toran-Allerand CD. Neuronal colocalization of mRNAs for neurotrophins and their receptors in the developing central nervous system suggests a potential for autocrine interactions. Proc Natl Acad Sci U S A 1993; 90:6439-43. [PMID: 8341652 PMCID: PMC46947 DOI: 10.1073/pnas.90.14.6439] [Citation(s) in RCA: 203] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Development and survival of neurons in the central nervous system are dependent on the activity of a variety of endogenous neurotrophic agents. Using combined isotopic and nonisotopic in situ hybridization histochemistry, we have found that subsets of neurons within the developing forebrain coexpress the mRNAs for both neurotrophins (nerve growth factor, brain-derived neurotrophic factor, and neurotrophin 3) and their receptors (p75NGFR, TrkA, and TrkB). The colocalization of mRNA for neurotrophin receptors and their ligands in presumptive neurotrophin target neurons suggests the potential for autocrine and paracrine mechanisms of action during development. Such mechanisms may ensure the onset of differentiation and survival of specific subsets of neurons prior to and following target innervation.
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Affiliation(s)
- R C Miranda
- Department of Anatomy and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY 10032
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79
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Ehrhard PB, Ganter U, Stalder A, Bauer J, Otten U. Expression of functional trk protooncogene in human monocytes. Proc Natl Acad Sci U S A 1993; 90:5423-7. [PMID: 8390664 PMCID: PMC46732 DOI: 10.1073/pnas.90.12.5423] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
There is increasing evidence that neurotrophins, including nerve growth factor (NGF), exert specific effects on cells of the immune system in addition to their neurotrophic actions. This report shows that human monocytes express the trk protooncogene, encoding the signal-transducing receptor unit for NGF. This receptor is functional, since interaction of NGF with monocytes triggered a respiratory burst, the major component of monocyte cytotoxic activity. During in vitro differentiation of human blood monocytes to macrophages trk expression decreased, suggesting a maturation-dependent trk expression decreased, suggesting a maturation-dependent trk regulation. Treatment of monocytes with Staphylococcus aureus Cowan I, a potent activator of monocytes, stimulated trk mRNA synthesis in a time-dependent way, implying a modulatory role for NGF in immune functions. The finding that dibutyryl cAMP elicited a time-dependent trk induction in monocytes as well as in phorbol ester-differentiated promonocytic U937 cells indicates that adenylate cyclase is involved in monocytic trk regulation. These results suggest that NGF, in addition to its neurotrophic function, is an immunoregulatory cytokine acting on monocytes.
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Affiliation(s)
- P B Ehrhard
- Department of Physiology, University of Basel, Vesalianum, Switzerland
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80
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Abstract
The molecular cloning of genes encoding new neuroactive growth factors and their receptors has greatly enhanced our understanding of important interactions between receptors and signaling molecules. These studies have begun to illuminate some of the mechanisms that allow for specificity in neuronal signaling.
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Affiliation(s)
- A R Saltiel
- Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Co., Ann Arbor
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81
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Lenzi D, Radke K, Wilson M. Symmetrical segregation of potassium channels at cytokinesis. JOURNAL OF NEUROBIOLOGY 1993; 24:675-86. [PMID: 7686965 DOI: 10.1002/neu.480240511] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To determine how voltage-gated ion channels segregate between sibling cells at cytokinesis, we used a whole-cell patch clamp to measure the electrophysiological phenotypes of siblings within 45 min of division. Recently born siblings in an immortalized line of embryonic retinal cells were identified as pairs of spherical cells adhering to one another. All siblings were electrically coupled when cells were simultaneously voltage clamped, whereas nonsiblings were not coupled. Twelve pairs of siblings were electrically isolated by mechanical separation so that their phenotypes could be measured independently. Cells expressed two principal membrane conductances, delayed rectifier-like (IK) and inward rectifier (IK(IR)) potassium currents. Despite qualitative and quantitative variability in IK and IK(IR) expression within the population, each cell of a given pair expressed similar steady-state current densities between -110 and +50 mV. We estimated IK(IR) slope conductance by blocking the current specifically with 5 mM Cs and calculated IK(IR) ratios in siblings and nonsiblings. Three pairs of siblings expressed IK(IR) ratios of approximately 1.2, while ratios in three pairs of adhered nonsiblings varied between 1.6 and 5.4. When currents were sampled continuously through cytokinesis by using the perforated-patch recording mode, current amplitude showed no net change within 30 min of division. Because channel number did not appear to change in siblings during this interval, parental channels were inherited by each daughter in proportion to the area of membrane received. Heterogeneity therefore arises after siblings reenter interphase and is not due to the asymmetrical segregation of channels at cytokinesis.
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Affiliation(s)
- D Lenzi
- Section of Zoology, University of California, Davis 95616
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82
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Itoh T, Sobue G, Yasuda T, Kimata K, Mitsuma T, Takahashi A. Geometric response to nerve growth factor is preserved in aged rat sensory neurons: a single-neuron culture study. Neurobiol Aging 1993; 14:167-76. [PMID: 8487920 DOI: 10.1016/0197-4580(93)90093-q] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We previously established a single-neuron culture system to analyze the primary effects of neurotrophic factors and reported that NGF promoted neurite extension in young adult (4- to 6-month-old) rat dorsal root ganglion (DRG) neurons by promoting neurite arborization. In this study, we demonstrated that the effects of NGF on neurite regeneration in DRG neurons was well preserved in aged rats (20- to 24-month-old and 33-month-old). NGF did not increase the percent process-bearing neurons in aged rats, which indicated that neuronal survival was not promoted by NGF, but it significantly enhanced the number of branching points, total neurite length, and soma size in aged neurons. These effects of NGF on neurite geometry tended to be reduced to some extent in aged neurons and the initiation of neurite-outgrowth in aged neurons was also delayed as compared with young adult neurons. NGF-responsive subpopulation of neurons, found in the entire range of neuronal size, were preserved in aged rats. These findings indicate that NGF could play an important role in regeneration of injured DRG neurons of aged animals.
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Affiliation(s)
- T Itoh
- Department of Neurology, Nagoya University School of Medicine, Japan
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83
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Chao MV, Battleman DS, Benedetti M. Receptors for nerve growth factor. INTERNATIONAL REVIEW OF CYTOLOGY 1993; 137B:169-80. [PMID: 1478819 DOI: 10.1016/s0074-7696(08)62604-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- M V Chao
- Department of Cell Biology and Anatomy, Cornell University Medical College, New York, New York 10021
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84
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Hempstead BL, Rabin SJ, Kaplan L, Reid S, Parada LF, Kaplan DR. Overexpression of the trk tyrosine kinase rapidly accelerates nerve growth factor-induced differentiation. Neuron 1992; 9:883-96. [PMID: 1384575 DOI: 10.1016/0896-6273(92)90241-5] [Citation(s) in RCA: 264] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
To investigate the role of the gp140trk receptor tyrosine kinase in nerve growth factor (NGF)-induced differentiation, we have overexpressed gp140trk in the NGF-responsive PC12 cell line. Here we demonstrate that overexpression of gp140trk results in marked changes in NGF-induced differentiation. Whereas PC12 cells elaborated neurites after 2 days of continuous exposure to NGF, PC12 cells overexpressing gp140trk by 20-fold(trk-PC12) began this process within hours. Compared with wild-type PC12 cells, trk-PC12 exhibited an increase in both high and low affinity NGF-binding sites. Furthermore, trk-PC12 cells displayed an enhanced level of NGF-dependent gp140trk autophosphorylation, and this activity was sustained for many hours following ligand binding. The tyrosine phosphorylation or activity of several cellular proteins, such as PLC-gamma 1, PI-3 kinase, and Erk1 and the expression of the mRNA for the late response gene transin were also sustained as a consequence of gp140trk overexpression. The data indicate that overexpression of gp140trk in PC12 cells markedly accelerates NGF-induced differentiation pathways, possibly through the elevation of gp140trk tyrosine kinase activity.
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Affiliation(s)
- B L Hempstead
- Cornell University Medical School, Division of Hematology, New York, New York 10021
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85
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Affiliation(s)
- M V Chao
- Department of Cell Biology and Anatomy, Cornell University Medical College, New York, New York 10021
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