L E Burton

University of Southern California, Los Angeles, CA, United States

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Publications (25)155.82 Total impact

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    ABSTRACT: K-252b, a protein kinase inhibitor, has been shown earlier to inhibit nerve growth factor actions on cholinergic neurons of the basal forebrain. In the present study, K-252b was found to prevent trophic actions of two other neurotrophins, brain-derived neurotrophic factor, and neurotrophin-3, on central cholinergic and dopaminergic neurons, peripheral sensory neurons, and PC 12 pheochromocytoma cells, when used at >2 μM concentration. Comparable actions of nonneurotrophin growth factors were not affected. Surprisingly, at 0.1-100 nM, K-252b selectively enhanced the trophic action of neurotrophin-3 on central cholinergic neurons, peripheral sensory neurons, and PC 12 cells. In PC 12 cells, K-252b potentiated the neurotrophin-3-induced tyrosine phosphorylation of trk, a protein kinase responsible for transmitting neurotrophin signals. Of the three structurally related nerve growth factor inhibitors, K-252a, K-252b, and staurosporine, only the first two also mediated neurotrophin-3 potentiation. These findings indicate that K-252b generally and selectively potentiates the neurotrophic action of neurotrophin-3 and suggest that this action involves trk-type neurotrophin receptors.
    Journal of Neurochemistry 10/2006; 59(2):715 - 722. · 3.97 Impact Factor
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    ABSTRACT: The recombinant human nerve growth factor (hNGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), neurotrophin 4/5 (NT4/5), and murine NGF (mNGF) dimers all undergo rapid unfolding and dissociation to monomer in GdnHCl. Fluorescence spectroscopy, reversed-phase high-performance liquid chromatography, and size-exclusion chromatography were used to show that this monomer M1 converts slowly to a more fully unfolded monomer, M2, by a first order process with half-lives of 22, 2.5, 1.6, and 0.73 h for hNGF, mNGF, NT-3, and BDNF, respectively, at 25 degrees C. Linear Arrhenius plots for the conversion of M1 to M2 yielded activation energies of 27, 22, 24, and 24 kcal/mol for hNGF, mNGF, NT-3, and BDNF, respectively. The refolding of these neurotrophins from 5 M GdnHCl was also first order with NT-3 the slowest to refold and BDNF the fastest. Threading of the N-terminus out through the cystine-knot loop present in each of these proteins is proposed as the slow step in unfolding. The number of amino acids in the cystine-knot loop (14 for hNGF, mNGF, NT-3, and BDNF; 21 for NT4/5), and the number and position of the proline residues in this loop (2 for hNGF; 1 for mNGF, NT-3, BDNF, and NT4/5) correlate with the relative rates of unfolding. The smaller the loop and the greater the number of prolines, the more hindered and slower the unfolding.
    Protein Science 01/1999; 8(11):2513-2518. · 2.74 Impact Factor
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    ABSTRACT: The unfolding of recombinant human beta-NGF (NGF) in guanidine hydrochloride (GdnHCl) was found to be time dependent with the denaturation midpoint moving to lower GdnHCl concentration over time. Dissociation and extensive unfolding of the NGF dimer occurred rapidly in 5 M GdnHCl, but further unfolding of the molecule occurred over many days at 25 degrees C. Fluorescence spectroscopy, size-exclusion and reversed-phase HPLC, ultra-centrifugation, and proton NMR spectroscopy were used to ascertain that the slow unfolding step was between two denatured monomeric states of NGF (M1 and M2). Proton NMR showed the monomer formed at early times in GdnHCl (M1) had little beta-sheet structure, but retained residual structure in the tryptophan indole and high-field methyl regions of the spectrum. This residual structure was lost after prolonged incubation in GdnHCl giving a more fully unfolded monomer, M2. From kinetic unfolding experiments in 5 M GdnHCl it was determined that the conversion of M1 to M2 had an activation energy of 26.5 kcal/mol, a half-life of 23 h at 25 degrees C, and the rate of formation of M2 was dependent on the GdnHCl concentration between 5 and 7.1 M GdnHCl. These properties of the slow unfolding step are inconsistent with a proline isomerization mechanism. The rate of formation of the slow folding monomer M2 increases with truncation of five and nine amino acids from the NGF N-terminus. A model for the slow unfolding reaction is proposed where the N-terminus threads through the cystine knot to form M2, a loop-threading reaction, increasing the conformational freedom of the denatured state.
    Protein Science 09/1996; 5(8):1554-66. · 2.74 Impact Factor
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    ABSTRACT: Neurotrophins are a family of highly conserved proteins that affect the development and maintenance of distinct neuronal populations. Neurotrophins exist in vivo as homodimers, but we show that neurotrophins can exist as heterodimers in vitro and are pluripotent, being able to bind and to activate different Trk tyrosine kinase receptors as well as promote neuronal differentiation in PC12 cells as effectively as wild type homodimers. These asymmetric neurotrophin dimers allow unique characterization of neurotrophin structure-function relationships with Trk receptors. The chimeric Trk activities of these heterodimers suggest an alternative model of neurotrophin-Trk receptor activation in which the critical Trk-interacting elements may be attributed to a single protomer.
    Journal of Biological Chemistry 10/1995; 270(39):23104-10. · 4.65 Impact Factor
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    ABSTRACT: Limited proteolysis and site-directed mutagenesis of human nerve growth factor (hNGF) was utilized to determine the role of the NH2 terminus in p140TrkA (TrkA) receptor function. Purified (6-118)hNGF, representing deletion of the first 5 NH2-terminal residues, is 9-fold less potent than (1-118)hNGF in displacing 125I-hNGF from TrkA. The deletion of a further 4 residues to form (10-118)hNGF is nearly 300-fold less potent. (6-118)hNGF is only 2-4-fold less potent than (1-118)hNGF in eliciting TrkA autophosphorylation and PC12 cell neurite outgrowth, suggesting that the first 5 residues of the NH2 terminus are necessary for full TrkA binding activity but may be less critical for potent receptor activation and intracellular signaling. In contrast, purified mutant H4D results in a nearly 1000-fold loss in TrkA binding at 4 degrees C relative to (1-118)hNGF, at least 10-fold less potency of TrkA autophosphorylation, and 30-fold loss of potency in PC12 cell differentiation. NH2-terminal hBDNF/hNGF and hNT3/hNGF chimeric mutants further affected these activities suggesting that the NH2-terminal sequence specificity of hNGF contributes to structural interactions necessary for TrkA receptor binding and ligand-induced signaling. The potency of binding of all hNGF variants to the low affinity NGF receptor p75 was largely unaffected indicating distinct structural contributions of the NH2-terminal region of hNGF to the binding to TrkA versus p75.
    Journal of Biological Chemistry 12/1994; 269(44):27679-86. · 4.65 Impact Factor
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    ABSTRACT: This phase I double-masked, randomized, placebo-controlled study evaluated the safety of single intravenous or subcutaneous doses of recombinant human nerve growth factor (rhNGF) in healthy human volunteers at doses ranging from 0.03 to 1 micrograms/kg. No life-threatening adverse events were seen at any dose. At doses above 0.1 microgram/kg, subjects reported mild to moderate muscle pain, primarily in the bulbar and truncal musculature. The duration and severity of these myalgias varied in a dose-dependent manner, and women appeared to be more susceptible than men. Intravenous rhNGF produced earlier and more pronounced systemic effects than did identical subcutaneous doses. Subjects receiving subcutaneous rhNGF noted hyperalgesia at the injection site, a local effect persisting up to 7 weeks, that also varied in a dose-dependent manner. Antibodies to NGF were not detected in any subject. These results indicate that systemically administered rhNGF exerts a characteristic and reproducible biological effect in healthy subjects at very low doses and in a dose-dependent manner.
    Annals of Neurology 09/1994; 36(2):244-6. · 11.19 Impact Factor
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    ABSTRACT: Cholinergic neurons of the basal nucleus complex (BNC) respond to nerve growth factor (NGF), the first member of a polypeptide gene family that also includes brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5). NGF, BDNF, and NT-3 are enriched in hippocampus. In addition, NGF and, more recently, BDNF have been shown to stimulate the cholinergic differentiation and enhance the survival of BNC cells in vitro. The present investigation was designed to test, in a comparative fashion, the in vivo effects of human recombinant NGF, BDNF, and NT-3 with confirmed activities in vitro on cholinergic and gamma-aminobutyric acid (GABA)-ergic BNC neurons. The specific questions asked were whether and, to what extent, biologically active recombinant neurotrophins stimulate the transmitter phenotypes of intact cholinergic and GABAergic neurons of the BNC, and whether, and to what extent, recombinant neurotrophins protect the transmitter phenotypes of axotomized cholinergic and GABAergic neurons of the BNC following complete transections of the fimbria-fornix (measured by ChAT enzyme activity and ChAT immunoreactivity and ChAT, p75NGFR, and GAD mRNA hybridization). Our results confirm the profound stimulatory and protective effects of recombinant NGF on the transmitter phenotype of cholinergic BNC neurons at the mRNA and protein levels. The effect of NGF on injured cholinergic neurons of the BNC is very specific and saturated at a dose of 20 micrograms/2 weeks. BDNF appeared to increase moderately p75NGFR expression in both intact and axotomized cholinergic neurons and to exert minor effects on some cholinergic markers (e.g., ChAT immunoreactivity). NT-3 had no effects on cholinergic neurons or the BNC. Moreover, NGF, BDNF, and NT-3 had no influence on GABAergic BNC neurons. Taken together, these results indicate that, despite their significant sequence homologies and their shared abundance in target fields of BNC neurons, NGF, BDNF, and NT-3 show striking differences in their efficacies as cholinergic trophic factors. GABAergic neurons of the BNC are resistant to neurotrophins. The results of the present investigation establish that NGF excels among neurotrophins as a trophic factor for intact and injured basal forebrain cholinergic neurons.
    The Journal of Comparative Neurology 06/1994; 343(2):247-62. · 3.66 Impact Factor
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    ABSTRACT: Members of the NGF family of proteins act as neurotrophic agents for defined populations of peripheral and central neurons during embryonic and postnatal development. We have studied the presence of receptors for brain-derived neurotrophic factor (BDNF) and neurotrophin-3 and -4/5 (NT-3, NT-4/5) by cross-linking radioiodinated neurotrophins to specific cell surface receptors. We have identified neurotrophin receptors representing full-length TrkB and TrkC and their truncated forms (lacking a functional cytoplasmic kinase domain) in neuronal as well as in non-neuronal tissues. During chicken embryonic and early postnatal brain development, expression of full-length TrkB and TrkC proteins preceded the onset of the truncated forms of these receptors. A similar pattern was also observed in mouse embryonic and early postnatal brain. The relative levels of neurotrophin receptors in the basal forebrain and in the hippocampus did not change significantly with age in mice. High levels of receptors for the three neurotrophins were detected in the nigrostriatal system. Full-length TrkB and TrkC receptors were found in chicken and rat embryonic ventral spinal cord, as well as on purified motoneurons. Again, truncated TrkB appeared significantly later than the full-length form on spinal motoneurons. In chicken embryonic retina and optic tectum we detected full-length TrkB and TrkC; however, the optic tectum also expressed large amounts of the truncated form of TrkB. TrkC but not TrkB was detected in chicken embryonic skeletal muscle, suggesting that NT-3 may have a novel function in this tissue. The presence of neurotrophin receptors in a wide variety of embryonic and postnatal tissues underlines the significant role of BDNF, NT-3, and NT-4/5 in embryonic and postnatal development. The regulation of the ratio of full-length versus truncated neurotrophin receptors may play an important role in the development, maturation, and maintenance of various neuronal networks.
    Journal of Neuroscience 05/1994; 14(4):2054-68. · 6.91 Impact Factor
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    ABSTRACT: We have studied the effect of human recombinant neurotrophin-4/5 (NT-4/5) on the survival of developing PNS neurons from embryonic mice and chickens. NT-4/5 transiently supported mouse NGF-dependent trigeminal and jugular neurons at early stages of target field innervation and mouse brain-derived neurotrophic factor (BDNF)-dependent no-dose neurons during the phase of naturally occurring cell death. NT-4/5 was as potent as BDNF in supporting the survival of these neuronal populations. Surprisingly, NT-4/5 was 3 orders of magnitude less potent than BDNF as a survival factor for early chick dorsomedial trigeminal sensory neurons and did not support the survival of chick BDNF-dependent trigeminal mesencephalic or ventrolateral trigeminal sensory neurons at any of the developmental stages tested. Thus, NT-4/5 is a survival factor for certain embryonic mouse cranial sensory neurons. It is the first species-specific neurotrophin to be identified and it can discriminate at high concentrations between different BDNF-responsive chick neurons.
    Journal of Neuroscience 12/1993; 13(11):4961-7. · 6.91 Impact Factor
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    ABSTRACT: This report describes the post-translational modifications of recombinant human differentiation-stimulating factor, a 180-residue glycoprotein that is secreted from transfected Chinese hamster ovary cells. Peptide peptides containing six potential N-glycosylation sites were analyzed to determine that Asn residues 9, 34, 63, 73, 96, and 116 were utilized. Additional peptides, generated by tryptic digestion of peptic fragments, allowed the assignments of three intrachain disulfide bonds (Cys-18 to Cys-131, Cys-12 to Cys-134, and Cys-60 to Cys-163).
    Archives of Biochemistry and Biophysics 06/1993; 302(2):484-9. · 3.37 Impact Factor
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    ABSTRACT: Neurotrophic factors regulate the developmental survival and differentiation of specific neuronal populations. Brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) are members of the nerve growth factor (NGF) protein family, also known as the neurotrophins. Insights into the different roles of neurotrophins can be gained by studying the expression of their functional receptors. Here we report the development of procedures for their radiolabeling and efficient crosslinking to specific cell-surface receptors. BDNF and NT-3 receptors in cell lines and tissue preparations expressing receptors for the 2 neurotrophins have been identified using this affinity crosslinking procedure. Like NGF, BDNF and NT-3 crosslinked to the low affinity NGF receptor (p75NGFR) on PC12 cells. BDNF and NT-3 also crosslinked to cells expressing p145trkB protein, producing an approximately 160 kD neurotrophin-receptor complex. Crosslinking of the 2 neurotrophins in vivo to specific trk family members in many areas of the central nervous system also produced a 160 kD receptor complex. However, in all brain regions a complex of approx. 100 kD could also be identified, all or most of which represents crosslinking to a truncated form of trkB. The broad distribution of BDNF and NT-3 receptors throughout the CNS suggests that neurotrophins may have yet unrecognized functions on specific neuronal populations. BDNF and NT-3 receptors were also found in brain areas in which the neurotrophins themselves are also synthesized, suggesting that beyond long-range trophic effects, these proteins may also act as autocrine or short-range paracrine regulators.
    Journal of Neuroscience Research 05/1993; 34(6):601-13. · 2.97 Impact Factor
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    ABSTRACT: The amino terminus of nerve growth factor (NGF) is susceptible to proteolytic cleavage. A comparison of the bioactivity of highly purified full-length recombinant human (1-118)rhNGF and NH2-terminal truncated (10-118)rhNGF revealed lower potency of (10-118)rhNGF with regard to early NGF responses in neuron-like PC12 cells. Approximately 50 times higher concentrations of (10-118)rhNGF than (1-118)rhNGF were required to elicit the same extent of tyrosine phosphorylation of key enzymes in different second messenger pathways, i.e. the NGF receptor tyrosine kinase p140trkA, phospholipase C gamma-1, and the extracellular signal-regulated kinase ERK1. A similar reduced potency for induction of the transcription factor c-Fos was observed with (10-118)rhNGF compared to (1-118)rhNGF. The lower potency of (10-118)rhNGF in triggering early responses correlated with its 40-fold lower affinity for PC12 cells. Whereas (10-118)rhNGF had a more than 300-fold lower affinity for the high affinity receptor p140trkA than (1-118)rhNGF, amino-terminal truncation of NGF changed its affinity for the low affinity receptor p75NGFR only slightly (5-10-fold). These observations suggest that amino acids 1-9 of NGF are important for binding to the signal transducing receptor p140trkA. Proteolytic cleavage of the NGF amino terminus, therefore, reduces its potency in starting several second messenger pathways leading to neuronal differentiation of PC12 cells.
    Journal of Biological Chemistry 12/1992; 267(32):22707-10. · 4.65 Impact Factor
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    ABSTRACT: Recombinant human nerve growth factor (rhNGF) was expressed and secreted by Chinese hamster ovary cells and purified to homogeneity using ion-exchange and reversed-phase (RP) chromatography. The isolated product was shown to be consistent with a 120-amino-acid residue polypeptide chain by amino acid composition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), RP-HPLC, and mass spectrometry and with an N-terminal sequence consistent with that expected from the cDNA for human nerve growth factor. By size-exclusion chromatography, rhNGF behaves like a noncovalent dimer. Limited enzymatic digests of the 120-residue monomer produced additional species of 118 (trypsin, removal of the C-terminal Arg119-Ala120 sequence) and 117 (trypsin plus carboxypeptidase B, removal of the C-terminal Arg118-Arg119-Ala120 sequence) residues. Each of these species was isolated by high-performance ion-exchange chromatography and characterized by amino acid and N-terminal sequence analyses, SDS-PAGE, RP-HPLC, and mass spectrometry. All three species were present in the digests as both homodimeric and heterodimeric combinations and found to be equipotent in both the chick dorsal root ganglion cell survival and rat pheochromocytoma neurite extension assays.
    Journal of Neurochemistry 12/1992; 59(5):1675-83. · 3.97 Impact Factor
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    ABSTRACT: Purified recombinant human nerve growth factor (rhNGF) and submaxillary gland-derived murine NGF (muNGF) were characterized by amino acid composition, polyacrylamide gel electrophoresis (PAGE), reversed-phase HPLC (RP-HPLC), and high-performance ion-exchange chromatography (HPIEC). Limited tryptic digest of the N and C termini of the 120-residue form of rhNGF produced a species of 109 residues (10-118). The previously observed natural murine analogue of this variant, muNGF lacking the first eight N-terminal amino acids, was also isolated as a homodimer. Both species were purified using HPIEC and characterized by amino acid analysis, N-terminal sequence, PAGE, and RP-HPLC analysis. Each of the four homodimeric species was evaluated in some or all of the following biological assays for NGF: chick dorsal root and sympathetic ganglion assays and rat pheochromocytoma-12 cell line neurite extension assay. The 118-residue homodimeric versions of both rhNGF and muNGF displayed equivalent bioactivity, whereas the N terminal-modified molecules presented activity reduced by 50- to 100-fold. Utilizing HPIEC, we have examined the ability of the monomeric forms of any two of the homogeneous dimeric species of rhNGF to recombine. We have shown that not only can all of the previously described species form dimers by recombination, but an interspecies dimer can be created between muNGF and rhNGF.
    Journal of Neurochemistry 12/1992; 59(5):1937-45. · 3.97 Impact Factor
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    ABSTRACT: Cell culture studies with dissociated primary cultures from embryonic rat brain revealed that brain-derived neurotrophic factor (BDNF) promotes the developmental differentiation of both basal forebrain cholinergic and mesencephalic dopaminergic neurons. These studies suggested that, in the adult brain, BDNF may be able to protect cholinergic and dopaminergic neurons from degenerative changes induced by axotomy, similar to the known protective action of NGF in cholinergic neurons. Testing this hypothesis, we found that intraventricular administration of recombinant human BDNF (rhBDNF) to adult rats with transections of the fimbria significantly reduces axotomy-induced degenerative changes of the cholinergic cells in the basal forebrain. No such effect was seen on the dopaminergic neurons of the ventral mesencephalon after transection of their axons ascending in the medial forebrain bundle. Injected in equal amounts, rhBDNF and recombinant human NGF had quantitatively different effects on the cholinergic neurons. BDNF sustained only part of the population of cholinergic neurons affected by the lesion, whereas the entire population was protected by NGF treatment.
    Journal of Neuroscience 12/1992; 12(11):4391-402. · 6.91 Impact Factor
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    ABSTRACT: Complement plays a role in activating the inflammatory response and has been implicated in the pathogenesis of some inflammatory diseases. With a view toward controlling unwanted C activation, we evaluated the C regulator, human decay accelerating factor (DAF). Three forms of recombinant DAF were purified from transfected Chinese hamster ovary cells: glycophosphatidylinositol (GPI)-linked membrane DAF (mDAF) extracted from cell membranes; spontaneously shed soluble DAF (sDAF) derived from mDAF; and a novel secreted protein (seDAF), generated by deletion of the signal for GPI attachment. We show that all three molecules inhibit both the classical and alternative pathways of C activation. The following observations indicate that mDAF extracted from Chinese hamster ovary cells reincorporates into RBC membranes via its GPI anchor: 1) cells that are preincubated with mDAF and then washed remain fully protected from C-mediated hemolysis; 2) incubation with phosphatidylinositol-specific phospholipase C abolishes this protection; and 3) sDAF and seDAF, which lack a GPI anchor, do not associate with cell membranes. mDAF is a more potent inhibitor of C-mediated hemolysis than either sDAF or seDAF, suggesting that incorporation into cell membranes greatly enhances the efficiency with which DAF inhibits C activation on the cell surface. In contrast, C activation in the fluid phase is inhibited by sDAF and seDAF, but not by mDAF, possibly due to interference by serum lipoproteins. A reversed passive Arthus reaction in guinea pigs was used to evaluate the ability of recombinant seDAF to inhibit C activation in vivo. When administered at dermal sites, seDAF reduced the severity of immune complex-mediated inflammatory reactions induced by a reversed passive Arthus reaction, as judged by both gross and histologic examination. These data indicate that seDAF may be useful as an anti-inflammatory therapeutic.
    The Journal of Immunology 10/1992; 149(5):1736-43. · 5.52 Impact Factor
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    ABSTRACT: K-252b, a protein kinase inhibitor, has been shown earlier to inhibit nerve growth factor actions on cholinergic neurons of the basal forebrain. In the present study, K-252b was found to prevent trophic actions of two other neurotrophins, brain-derived neurotrophic factor, and neurotrophin-3, on central cholinergic and dopaminergic neurons, peripheral sensory neurons, and PC12 pheochromocytoma cells, when used at greater than 2 microM concentration. Comparable actions of nonneurotrophin growth factors were not affected. Surprisingly, at 0.1-100 nM, K-252b selectively enhanced the trophic action of neurotrophin-3 on central cholinergic neurons, peripheral sensory neurons, and PC12 cells. In PC12 cells, K-252b potentiated the neurotrophin-3-induced tyrosine phosphorylation of trk, a protein kinase responsible for transmitting neurotrophin signals. Of the three structurally related nerve growth factor inhibitors, K-252a, K-252b, and staurosporine, only the first two also mediated neurotrophin-3 potentiation. These findings indicate that K-252b generally and selectively potentiates the neurotrophic action of neurotrophin-3 and suggest that this action involves trk-type neurotrophin receptors.
    Journal of Neurochemistry 09/1992; 59(2):715-22. · 3.97 Impact Factor
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    ABSTRACT: Basal forebrain cholinergic neurons respond to nerve growth factor (NGF), and it has been suggested that the administration of NGF might prevent their degeneration in patients with Alzheimer's disease. One major prerequisite to be fulfilled before the consideration of clinical trials of NGF in patients with Alzheimer's disease is the demonstration that human NGF affects basal forebrain cholinergic neurons in primates. In the present study, we used a recombinant human nerve growth factor (rhNGF), which we previously showed to be active on rat basal forebrain cholinergic neurons, in nonhuman primates with a unilateral transection of the fornix (a well-established model for the induction of retrograde degenerative changes in septal cholinergic neurons). After the lesion, one group of animals received rhNGF and a second group received vehicle solution for 2 weeks. In animals receiving vehicle, the medial septal nucleus ipsilateral to the lesion showed reductions in number (55%) and size of cell bodies immunoreactive for NGF receptor and choline acetyltransferase. In Nissl stains, many cells showed reduced size and basophilia. The rhNGF completely prevented alterations in the number and size of NGF receptor- and choline acetyltransferase-immunoreactive neurons in the medial septal nucleus and reversed atrophy in a subpopulation of large, basophilic medial septal nucleus neurons, as identified by Nissl stains. The effects of rhNGF were identical to those of mouse NGF, which we have previously used in the same primate lesion paradigm. The restoration of the phenotype of injured cholinergic septal neurons by rhNGF in the monkey raises the possibility that this factor may be used to ameliorate acetylcholine-dependent memory impairments that occur in aged nonhuman primates. In concert, results of the present investigation provide critical information for the future use of NGF in patients with neurological disorders that affect NGF-responsive cells in the peripheral and central nervous systems.
    Annals of Neurology 01/1992; 30(6):831-40. · 11.19 Impact Factor
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    ABSTRACT: Brain-derived neurotrophic factor (BDNF) is a 27-kDa basic protein of noncovalently linked 13.5-kD subunits related to nerve growth factor and is produced by the central nervous system (CNS). BDNF has been shown to promote the survival of neurons located in or directly connected with the CNS and is likely to function in adjusting the cell number within neuronal populations to the need of this projection field. Here we describe the primary structure of a human BDNF cDNA, the biological activities of pure recombinant human BDNF, and the tissue distribution of rat BDNF. BDNF mRNA can be found in some peripheral tissues as well as in the CNS, and recombinant human BDNF is a potent neurotrophic factor for primary peripheral sensory neurons.
    Endocrinology 10/1991; 129(3):1289-94. · 4.72 Impact Factor
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    ABSTRACT: Cholinergic neurons in the basal forebrain magnocellular complex (BFMC) respond to nerve growth factor (NGF) during development and in adult life, and it has been suggested that the administration of NGF might ameliorate some of the abnormalities that occur in neurological disorders associated with degeneration of this population of neurons. A prerequisite for the introduction of NGF in clinical trials is the availability of active recombinant human NGF (rhNGF). The present investigation was designed to test, in vivo, the efficacy of a preparation of rhNGF. Axons of cholinergic neurons of the BFMC in the rat were transected in the fimbria-fornix; this manipulation alters the phenotype and, eventually, causes retrograde degeneration of these neurons. Our investigation utilized two lesion paradigms (resection and partial transection of fibers in the fimbria-fornix), two different strains of rats, and two delivery systems. Following lesions, animals were allowed to survive for 2 weeks, during which time one group received intraventricular mouse NGF (mNGF), a second group received rhNGF, and a third group received vehicle alone. In animals receiving vehicle, there was a significant reduction in the number (resection: 70%; transection: 50%) and some reduction in size of choline acetyltransferase- or NGF receptor-immunoreactive cell bodies within the medial septal nucleus ipsilateral to the lesion. Treatment with either mNGF or rhNGF completely prevented these alterations in the number and size of cholinergic neurons. The rhNGF was shown to be equivalent in efficacy with mNGF. Thus, rhNGF is effective in preventing axotomy-induced degenerative changes in cholinergic neurons of the BFMC. Our results, taken together with the in vitro effects of rhNGF (42), indicate that an active rhNGF is now available for further in vivo studies in rodents and primates with experimentally induced or age-associated lesions of basal forebrain cholinergic neurons. These investigations provide essential information for the consideration of future utilization of rhNGF for treatment of human neurological disorders, including Alzheimer's disease.
    Experimental Neurology 06/1991; 112(2):161-73. · 4.65 Impact Factor

Publication Stats

2k Citations
155.82 Total Impact Points

Institutions

  • 1991–1992
    • University of Southern California
      • Department of Biological Sciences
      Los Angeles, CA, United States