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K Werrbach-Perez

Publications and source records attributed to K Werrbach-Perez.

At least 37 records · Page 2Linked to original sources
PubMed1990

Role of nerve growth factor in oxidant-antioxidant balance and neuronal injury. II. A conditioning lesion paradigm.

The PC12 rat pheochromocytoma cell line is a nerve growth factor (NGF) responsive line that is protected by NGF from the toxic effects of hydrogen peroxide induced peroxidation. In part, NGF protection of PC12 cells acts through a shift in oxidant-antioxidant metabolism by the enhancement of catalase activity. When PC12 cells are used in a conditioning lesion paradigm to study the effects of an initial sublethal peroxidative insult on subsequent responses to injury, a low dose conditioning lesion protects even in the absence of NGF. The magnitude of the protective effect exerted by the conditioning lesion, however, is augmented in the presence of NGF, since a significant cytoprotective effect is observed over a wider range of H2O2 concentrations. Neuronal injury due to treatment with a high dose of H2O2 (5 mM) has a cytotoxic effect that cannot be prevented by NGF treatment and is, in itself, not conditioning in nature. This in vitro model system lends itself to the development of explanations regarding the salutory effects of conditioning lesions at the molecular level.

Animals↗
PubMed1990

Characterization of functional nerve growth factor-receptors in a CNS glial cell line: monoclonal antibody 217c recognizes the nerve growth factor-receptor on C6 glioma cells.

The biological effects of nerve growth factor (NGF) have been shown to be mediated by the high-affinity form of the nerve growth factor receptor (NGF-R) in sympathetic and sensory neurons, and in PC12 cells. We report here that the central nervous system C6 rat glioma cell line likewise expresses functional high-affinity NGF-Rs. The expression of NGF-R mRNA in C6 cells can be up-regulated by cycloheximide and its own ligand, NGF; and it can be rapidly down-regulated by epidermal growth factor (EGF). Furthermore, C6 cells display NGF responsiveness by expressing c-fos mRNA within 30 minutes of treatment with NGF; and after 4-5 days of NGF exposure, C6 cells cease dividing as measured by [3H]-thymidine uptake, change shape, and reveal neurite-like processes. Scatchard analysis of [125I]-labelled NGF bound to solubilized C6 cells confirms the presence of both high- and low-affinity receptor protein. Crosslinking radiolabeled NGF to its receptor in the presence or absence of excess unlabeled NGF, followed by immunoprecipitation with monoclonal antibody (mAb) 192-IgG (a known anti-NGF-R antibody) and SDS-PAGE reveals a 100 kD band corresponding to the NGF/NGF-R complex. An identical band is observed when the immunoprecipitation is carried out with mAb 217c, suggesting that the 217c epitope is related to NGF-R. The 217c antibody was generated against C6 cells and shown to be a cell surface antibody (Peng et al., Science 215:1102-4, 1982); several investigators have used it subsequently as an immunocytochemical marker for Schwann cells. The significance of NGF-Rs in a CNS glial cell line is unclear, but association of NGF with the control of proliferation and/or differentiation of primitive glial cells is suggested.

Animals↗
PubMed1990

Reverse-phase high-performance liquid chromatography of nerve growth factor receptor-like proteins identified with monoclonal antibodies.

Human neuroblastoma SK-N-SH-SY5Y (SY5Y) and rat pheochromocytoma PC12 cells are model cell lines used in the study of nerve growth factor (NGF) effect. The effects of NGF are initiated by binding to cell surface receptors (NGFR). The amino acid sequence for NGFR has been deduced based on the identification of a single gene for NGFR. However, there are two kinds of NGF binding activities and several reported molecular weights of NGFR. We report here on the demonstration of NGFR-like proteins from PC12 and SY5Y cells by sequential lectin chromatography, reverse-phase HPLC, and SDS-PAGE analysis of immunoprecipitates obtained with NGFR-specific monoclonal antibodies. For both human and rodent NGFR, there was a tendency for the higher molecular-weight species of NGFR-like proteins to be eluted in more hydrophobic fractions. Also, the expression of different species of NGFR could be modified by treatment with retinoic acid (RA). These results are consistent with the hypothesis that the different molecular species of NGFR may result from the generation of a truncated form of NGFR, the presence of sugar residues on the NGFR protein, dimer formation between NGFR, or the association of NGFR with a receptor-associated protein.

Adrenal Gland Neoplasms↗
PubMed1990

Nerve growth factor activity and aging in CNS.

This is a discussion of aging in CNS and the influence of the nerve growth factor (NGF) protein. The paper considers neuronal plasticity and neuronotrophic substances, neuronal cell death and the nerve growth factor protein, including its effects, receptors, and model systems for the study of CNS aging.

Aging↗
PubMed1988

Nerve growth factor binding in aged rat central nervous system: effect of acetyl-L-carnitine.

The nerve growth factor protein (NGF) has been demonstrated to affect neuronal development and maintenance of the differentiated state in certain neurons of the peripheral and central nervous system (CNS) of mammals. In the CNS, NGF has sparing effects on cholinergic neurons of the rodent basal forebrain (BF) following lesions where it selectively induces choline acetyltransferase (ChAT). NGF also induces ChAT in the areas to which BF provides afferents. In aged rats, there is a reduction in the NGF-binding capacity of sympathetic ganglia. Here, we wish to report that there is a decrease in the NGF-binding capacity of the hippocampus and basal forebrain of aged (26-month-old) rats as compared to 4-month-old controls but no change in NGF binding in cerebellum. In all instances, equilibrium binding dissociation constants did not differ significantly. Treatment of rats with acetyl-L-carnitine, reported to improve cognitive performance of aged rats, ameliorates these age-related deficits.

Acetylcarnitine↗
PubMed1987

Effect of retinoic acid on nerve growth factor receptors.

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.

Cell Line↗
PubMed1987

De novo synthesis of NGF subunits in S-180 mouse sarcoma cell line.

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 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 in 35S-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.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Effect of nerve growth factor on catecholamine metabolism in a human neuroblastoma clone (SY5Y).

The neuroblastoma line SK-N-SH-SY5Y (SY5Y) is a thrice subcloned nearly diploid clonal line of human origin. When grown in 15% fetal calf serum in Ham's F-12 medium as herein described, SY5Y has neuroblast-like properties in its undifferentiated state. Treatment with nerve growth factor results in morphological and physiological differentiation not unlike that elicited by nerve growth factor in sympathetic ganglia primary cultures. Careful examination of catecholamine synthesizing enzyme specific activities and catecholamine concentrations in nerve growth factor-treated SY5Y cells showed a small elevation of tyrosine hydroxylase, no change in dopamine-beta-hydroxylase or in dopamine or norepinephrine intracellular concentrations. This is consistent with the interpretation that nerve growth factor acts as a permissive or trophic factor, and not necessarily as an instructive or specifying factor in this system.

Catecholamines↗
PubMed1981

Membrane properties of a human neuroblastoma II: Effects of differentiation.

The SK-N-SH cell line is a human neuroblastoma which when grown under standard culture conditions remains relatively undifferentiated. The undifferentiated SK-N-SH cells are relatively inexcitable: they show only partial active responses to injections of current pulses and lack the depolarizing component of the action potential generating mechanism [Kuramoto et al, 1977]. In this study we report on the membrane properties of two subclones of the SK-N-SH, the SK-N-SH-IN (referred to as IN) and the SK-N-SH-Sy5Y (referred to as 5Y) which exhibit extensive morphological differentiation when grown with 1mM dibutyryl cAMP. Fully differentiated IN and 5Y cells have higher resting membrane potentials, in the range of -50 to -80 mV, and higher input resistance and time constants than do the undifferentiated SK-N-SH parental cell line. After 1 week in culture the differentiated IN and 5Y cells exhibit spike potentials in response to injection of current to the cell body. The presence of the Na2+-dependent depolarization was verified directly by the use of tetrodotoxin (TTX) and indirectly in experiments where veratridine (0.1 mM) markedly enhanced the influx of 22Na+. Taken together, the data indicate that generation of action potentials in these human neuroblastoma cells is to a large extent a function of morphological differentiation.

Acetylcholine↗
PubMed1980

Cerebral neuroblastoma with elevated nerve growth factor.

Cerebral neuroblastoma is often difficult to differentiate by clinical criteria from other central nervous system neoplasm. This report is of a young child with cerebral neuroblastoma and elevated nerve growth factor. This case illustrates the need for further studies into the usefulness of nerve growth factor in differentiating cerebral neuroblastoma from other central nervous system tumors.

Brain Neoplasms↗
PubMedDate not supplied

Nerve growth factor and neuronal cell death.

The regulation of neuronal cell death by the neuronotrophic factor, nerve growth factor (NGF), has been described during neural development and following injury to the nervous system. Also, reduced NGF activity has been reported for the aged NGF-responsive neurons of the sympathetic nervous system and cholinergic regions of the central nervous system (CNS) in aged rodents and man. Although there is some knowledge of the molecular structure of the NGF and its receptor, less is known as to the mechanism of action of NGF. Here, a possible role for NGF in the regulation of oxidant--antioxidant balance is discussed as part of a molecular explanation for the known effects of NGF on neuronal survival during development, after injury, and in the aged CNS.

Amino Acid Sequence↗
PubMedDate not supplied

NGF-mediated alteration of NF-kappaB binding activity after partial immunolesions to rat cholinergic basal forebrain neurons.

There are age-associated cognitive and cholinergic deficits in the neurotrophin-dependent cholinergic basal forebrain neurons (CBFNs). There are also increases in the activity of the transcription factor NF-kappaB in the aged rodent brain that may reflect chronic enhancement of stress response signaling. We used partial immunolesions (PIL) to CBFN to examine the role of endogenous NGF on choline acetyltransferase (ChAT) activity and NGF-mediated NF-kappaB alteration after cholinergic deafferentation. We injected 192 IgG-saporin, an immunotoxin selectively taken up by neurotrophin receptor p75(NTR)-bearing neurons, into lateral ventricles, followed by infusions of anti-NGF to assess NF-kappaB, ChAT and NGF responses to PIL after anti-NGF infusion. Treatment with anti-NGF decreased ChAT activity by 17-34% in the cortex, hippocampus, and olfactory bulb and PIL decreased ChAT activity by 47-73%. Changes in AChE activity levels paralleled those observed for ChAT after PIL. NGF protein levels in the olfactory bulb, but not the cortex or hippocampus, increased significantly after PIL treatment. Infusion of anti-NGF abolished the PIL-induced eight-fold NGF increase in CNS. NF-kappaB binding activity to the IgG-kappaB and ChAT specific NF-kappaB consensus sequences, increased in the cortex but not hippocampus after PIL followed by anti-NGF infusion. It is likely that immunolesion-induced changes in ambient NGF levels may perturb NF-kappaB activity.

Acetylcholinesterase↗
PubMedDate not supplied

Repeated immunolesions display diminished stress response signal.

Cholinergic basal forebrain neurons (CBFNs) retrogradely transport neurotrophins released in the hippocampus and cortex as part of a general response to injury in a process that is impaired in the aged rodent and can be spared by the exogenous addition of pharmacological doses of nerve growth factor (NGF). This observation suggests that components of stress response signal transduction pathways in the aged CNS can be exogenously activated. The extent and mechanism of the endogenous stimulation of NGF in response to injury can be mimicked via treatment with 192 IgG-saporin of rat CNS, an immunolesion model. Here we report on the use of a conditioning lesion paradigm to determine if repeated partial immunolesions have a conditioning effect on the immunolesion-induced increases in NGF protein or decreases in choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activity. We report that chronic repeated immunolesions, as used here, were not as effective as a one time equivalent immunolesion in terms of induced NGF protein increases or decreasing ChAT and AChE activity in the hippocampus and cortex. Thus, chronic lesions resulting in cholinergic impairment typical of the aged CNS may differ from acute toxic models as a result of desensitization due to a conditioning effect of chronic subthreshold lesioning events in the CNS.

Acetylcholinesterase↗