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  • 1
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Programmed cell death, the intrinsic form of apoptosis, plays an integral role in those neurodegenerative events associated with age-related neuropathology. Neurotrophins (NTs), such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and NT-3, are required for survival of certain neurons, and thus their clinical use to counteract age- and pathology-associated neurodegeneration has been suggested, although mechanistic descriptions for NT cell rescue from apoptosis are not definitive. Here we attempted to isolate the individual actions of high-affinity tyrosine kinase (Trk) receptors and p75NGFR, the common low-affinity NT receptor, in NT rescue of apoptotic PC12 cells. Our results showed that whereas inhibiting Trk receptor phosphorylation abolishes NGF rescue of serum-deprived PC12 cells from apoptosis, TrkA suppression with antisense oligonucleotides did not. Also, although BDNF did not rescue naive serumless PC12 cells, which lack the BDNF-specific TrkB receptor, it significantly increased survival of TrkA-suppressed serum-starved PC12 cells. These data confirm the hypothesis that binding of any NT to Trk-free p75NGFR-bearing cells blocks apoptosis but also suggest that if Trk receptors are expressed, prohibiting Trk phosphorylation also blocks NT-mediated rescue from apoptosis.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 62 (1994), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Nerve growth factor (NGF) is a member of the neuro- trophin family and is required for the survival and maintenance of peripheral sympathetic and sensory ganglia. In the CNS, NGF regulates cholinergic expression by basal forebrain cholinergic neurons. NGF also stimulates cellular resistance to oxidative stress in the PC12 cell line and protects PC12 cells from the toxic effects of reactive oxygen species. The hypothesis that NGF protection involves changes in antioxidant enzyme expression was tested by measuring its effects on catalase and glutathione per- oxidase (GSH Px) mRNA expression in PC12 cells. NGF increased catalase and GSH Px mRNA levels in PC 12 cells in a time- and dose-dependent manner. There was also a corresponding increase in the enzyme activities of catalase and GSH Px. Thus, NGF can provide cytoprotection to PC12 cells by inducing the free radical scavenging enzymes catalase and GSH Px.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 68 (1997), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: PC12 cells are known to undergo programmed cell death (apoptosis) when they are deprived of serum. Nerve growth factor (NGF) rescues PC12 cells from serum deprivation-induced apoptosis. In the present study, we examined the effects of retinoic acid (RA), a classic morphogen, on apoptosis in PC12 cells after serum deprivation and NGF-mediated rescue. In naive PC12 cells, all trans-RA treatment induced cell death in the presence of NGF. RA also abolished the protective effects of dibutyryl cyclic AMP or insulin under serum-free conditions. The death process was accompanied by nuclear condensation and DNA fragmentation, typical of apoptosis. In addition, RA also increased the extent of apoptosis in PC12 cells after serum deprivation. Cycloheximide, an inhibitor of protein synthesis, did not abolish the effects of RA on serum-deprived PC12 cells. RA also decreased thymidine incorporation and proliferation in NGF-treated PC12 cells. Furthermore, although the total DNA binding activity of the AP-1 transcription factor was not changed after RA treatment, RA decreased a specific AP-1 transcriptional activity. It is surprising that differentiated PC12 cells resisted the toxic effects of RA. These data suggest that RA might function as an endogenous inducer of apoptosis during neural differentiation by a mechanism distinct from that of serum deprivation.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 71 (1998), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Apoptosis in the nervous system is a necessary event during the development of the nervous system and is also present after genotoxic events, be they chronic as in aging or more acute after trauma and ischemia. Apoptotic events reflect an interplay between intrinsic signaling events that rely on cytokines, neurotransmitters, and growth factors and responses to extrinsic events that increase levels of radical oxygen species. Both intrinsically and extrinsically driven signal-transduction pathways act via transcription factors that regulate the coordinated timely expression of stress-response genes as part of a decision-making process that can commit cells to apoptosis or survival. Here we discuss the role of two transcription factors that participate in apoptosis in the nervous system: the activator protein AP-1 and nuclear factor κB.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 34 (1980), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 247 (1987), S. 67-73 
    ISSN: 1432-0878
    Schlagwort(e): NGF ; Retinoic acid ; Neuroblastoma ; NGF ; receptors ; Cell culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Retinoic acid (RA), a naturally occurring metabolite of vitamin A, increased the number of receptors for nerve growth factor (NGF) in cultured human neuroblastoma cells (LA-N-1), as indicated by an immunofluorescence assay of cell surface receptors and by specific binding of 125I-NGF to solubilized receptors. Analysis of 125I-NGF binding showed that RA increased the number of both high affinity and low affinity receptors for NGF without affecting the equilibrium dissociation constants. Neurite outgrowth similar to that produced by NGF occurred following RA-treatment in LA-N-1 cells, in the SY5Y subclone of SK-N-SH human neuroblastoma cells and in explanted chick dorsal root ganglia (DRG). Whether morphological changes following RA treatment are directly related to the increase in NGF receptors is unknown. Data presented here are consistent with literature reports that RA modifies cell surface glycoproteins, including those that act as cell surface receptors for epidermal growth factor and insulin.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Neurochemical research 12 (1987), S. 875-883 
    ISSN: 1573-6903
    Schlagwort(e): NGF ; S180 sarcoma ; neuronotrophic factors ; NGF subunits
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract It is an accepted hypothesis that the nerve growth factor protein (NGF) plays an important role in the development of vertebrate sympathetic and sensory ganglia and has effects on some central neurons. The best known NGF species is that isolated from the mouse submaxillary gland, MSG-NGF. MSG-NGF can be isolated as a subunit containing protein, 7S-NGF, made up of three dissimilar subunits called alpha-, beta-, and gamma-NGF. Beta-NGF is the biologically active subunit and its synthesis in vivo and in vitro has been demonstrated. Less is known about the synthesis of the alpha- and gamma-NGF or the assembly of the subunits into the 7S complex. In order to develop a clonal model system for the study of NGF synthesis, processing and secretion, affinity chromatography techniques were applied to cell extracts of S180 mouse sarcoma, a cell line known to synthesize NGF. After incubating S180 cells in35S-Methionine, cell extracts were exposed to antibody directed against alpha-NGF, gamma-NGF or beta-NGF covalently bound to Sepharose beads in order to elute and characterize the desired NGF subunits. Parallel experiments using immunoabsorbed [35S]Methionine-beta-NGF were carried out in the presence or absence of excess NGF, in order to demonstrate the specificity of this procedure. Affinity chromatography with a substrate analogue to arginine ester bound to Sepharose beads was also used to isolate de novo synthesized gamma-NGF. We were able to show that the S180 line synthesized alpha-, beta-, and gamma-NGF indistiguishable from alpha-, beta-, and gamma-NGF isolated from mouse submaxillary gland in terms of antigenic and physicochemical properties, and biological and enzymatic activities. These results are consistent with the hypothesis that NGF is synthesized, assembled and secreted by a single cell type.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1573-6903
    Schlagwort(e): NGF ; PC12 ; apoptotic cell death ; serum deprivation ; AP-1
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rat pheochromocytoma (PC12) cells exhibit apoptotic cell death when deprived of serum and can be rescued by nerve growth factor (NGF). We characterized AP-1 DNA binding activity in PC12 cells after serum deprivation in the presence or absence of NGF or other neurotrophic agents. There was a decline in AP-1 DNA binding activity concomitant with apoptosis in PC12 cells after serum deprivation. Treatment of serum-deprived PC12 with NGF induced persistent AP-1 binding activity that was blocked by the Trk receptor inhibitor K252a. PC12 cells treated with dibutyryl cyclic AMP or insulin also displayed increased AP-1 DNA binding activity. While NGF somewhat increased c-Fos and c-Jun protein levels transiently, it had a more robust and persistent stimulatory effect on Jun B protein levels. AP-1 transcriptional activity increased after NGF, dibutyryl cAMP, or insulin treatment under serum free conditions. Curcumin, which inhibits AP-1 activity, blocked the NGF-mediated rescue. These results would suggest that the rescue of serum-deprived PC12 cells from apoptosis requires increasing endogenous levels of specific Fos/Jun components of AP-1.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1573-6903
    Schlagwort(e): Neuron degeneration ; acetyl-l-carnitine arginine amide ; nerve growth factor ; neurite outgrowth ; PC12 cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Senescence of the central nervous system is characterized by a progressive loss of neurons that can result in physiological and behavioral impairments. Reduction in the levels of central neurotrophic factors or of neurotrophin receptors may be one of the causes of the onset of these degenerative events. Thus, a proper therapeutic approach would be to increase support to degenerating neurons with trophic factors or to stimulate endogenous neurotrophic activity. Here we report that acetyl-l-carnitine arginine amide (ST-857) is able to stimulate neurite outgrowth in rat pheochromocytoma PC12 cells in a manner similar to that elicited by nerve growth factor (NGF). Neurite induction by ST-857 requires de novo mRNA synthesis and is independent of the action of several common trophic factors. The integrity of the molecular structure of ST-857 is essential for its activity, as the single moieties of the molecule have no effect on PC12 cells, whether they are tested separately or together. Also, minor chemical modifications of ST-857, such as the presence of the arginine moiety at a position other than the amino one, completely abolish its neuritogenic effect. Lastly, the presence of ST-857 in the culture medium competes with the high affinity NGF binding in a dose dependent fashion. These results, although preliminary, are suggestive of a possible role for ST-857 in the development of therapeutic strategies to counteract degenerative diseases of the CNS.
    Materialart: Digitale Medien
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