bluuebunny/crossref_metadata_2025_split huggingface dataset:
Down‐regulation of protein l‐isoaspartyl methyltransferase in human epileptic hippocampus contributes to generation of damaged tubulin
Authors: Lanthier Julie , Bouthillier Alain , Lapointe Marjolaine , Demeule Michel , Béliveau Richard , Desrosiers Richard R. 
Published: March 2003

AbstractProtein l‐isoaspartyl methyltransferase (PIMT) repairs the damaged proteins which have accumulated abnormal aspartyl residues during cell aging. Gene targeting has elucidated a physiological role for PIMT by showing that mice lacking PIMT died prematurely from fatal epileptic seizures. Here we investigated the role of PIMT in human mesial temporal lobe epilepsy. Using surgical specimens of hippocampus and neocortex from controls and epileptic patients, we showed that PIMT activity and expression were 50% lower in epileptic hippocampus than in controls but were unchanged in neocortex. Although the protein was down‐regulated, PIMT mRNA expression was unchanged in epileptic hippocampus, suggesting post‐translational regulation of the PIMT level. Moreover, several proteins with abnormal aspartyl residues accumulate in epileptic hippocampus. Microtubules component β‐tubulin, one of the major PIMT substrates, had an increased amount (two‐fold) of l‐isoaspartyl residues in the epileptic hippocampus. These results demonstrate that the down‐regulation of PIMT in epileptic hippocampus leads to a significant accumulation of damaged tubulin that could contribute to neuron dysfunction in human mesial temporal lobe epilepsy.
Mechanism of plasminogen activator inhibitor‐1 regulation by oncostatin M and interleukin‐1 in human astrocytes
Authors: Kasza Aneta , Kiss Daniel L. , Gopalan Sunita , Xu Weili , Rydel Russell E. , Koj Aleksander , Kordula Tomasz 
Published: March 2003

AbstractGlial cells that produce and respond to various cytokines mediate inflammatory processes in the brain. Here, we show that oncostatin M (OSM) and interleukin‐1 (IL‐1) regulate the expression of plasminogen activator inhibitor‐1 (PAI‐1) and urokinase‐type plasminogen activator (uPA) in human astrocytes. Using the PAI‐1 reporter constructs we show that the −58 to −51 proximal element mediates activation by both cytokines. This element is already bound by c‐fos/c‐jun heterodimers in unstimulated astrocytes, and treatment with cytokine strongly stimulates both expression of c‐fos and binding of c‐fos/c‐jun heterodimers. In addition, IL‐1 activates an inhibitory mechanism that down‐regulates PAI‐1 expression after longer exposure to this cytokine. Overexpression of dominant‐negative signal transducer and activator of transcription‐1 (STAT1), STAT3, STAT5 and inhibitor of nuclear factor‐κB (IκB) suppressed OSM/IL‐1‐induced expression of the PAI‐1 reporter construct. We conclude that OSM and IL‐1 regulate the PAI‐1 gene expression via up‐regulating c‐fos levels and subsequent binding of c‐fos/c‐jun heterodimers to the proximal element of the PAI‐1 gene.
Increased CNS uptake and enhanced antinociception of morphine‐6‐glucuronide in rats after inhibition of P‐glycoprotein
Authors: Lötsch Jörn , Schmidt Rodolfo , Vetter Gregor , Schmidt Helmut , Niederberger Ellen , Geisslinger Gerd , Tegeder Irmgard 
Published: March 2003

AbstractMorphine‐6‐glucuronide (M6G) is a substrate of P‐glycoprotein (P‐gp), which forms an outward transporter at the blood–brain barrier. Inhibition of P‐gp may therefore be expected to cause increased CNS uptake of M6G. We directly assessed the spinal concentrations of M6G and its antinociceptive effects in rats following pharmacological inhibition of P‐gp. Spinal cord tissue concentrations of M6G were assessed by microdialysis with probes transversally implanted through the dorsal horns of the spinal cord at level L4. Ten rats received M6G intravenously (0.018 mg/kg loading dose plus 0.00115 mg/kg/min for an 8‐h infusion), five of them together with PSC833 to inhibit P‐gp (32‐h infusion, starting 24 h before the addition of M6G). Antinociceptive effects were explored by means of formalin tests. After having obtained evidence for enhanced CNS uptake and antinociception of M6G in the presence of PSC833, additional behavioural experiments were performed in another 32 rats to assess the dose dependency of the antinociceptive effects of M6G either with or without PSC833 in comparison with both PSC833 alone and placebo. Inhibition of P‐gp increased the M6G concentrations in the spinal cord approximately three‐fold whereas the plasma concentrations were increased only by a factor of 1.4, which resulted in a more than doubled spinal cord/plasma concentration ratio (from 0.08 ± 0.03 for M6G alone to 0.17 ± 0.08 for M6G plus PSC833). Antinociceptive effects of M6G were significantly enhanced by inhibition of P‐gp. Inhibition of P‐gp alters the transport of M6G across the blood–brain barrier, resulting in enhanced spinal cord uptake and enhanced antinociception.
Pleiotrophin, an angiogenic and mitogenic growth factor, is expressed in human gliomas
Authors: Mentlein Rolf , Held‐Feindt Janka 
Published: March 2003

AbstractPleiotrophin (PTN) is a mitogenic/angiogenic, 15.3 kDa heparin‐binding peptide that is found in embryonic or early postnatal, but rarely in adult, tissues. Since developmentally regulated factors often re‐appear in malignant cells, we examined PTN expression in human glioma cell lines, cell cultures derived from solid gliomas and glioma sections. PTN mRNA or protein was detected by reverse transcriptase‐polymerase chain reaction, immunohistochemistry, western blot or enzyme‐linked immunoassay in all WHO III and IV grade gliomas and cells analyzed in vitro or in situ. One WHO II grade glioma investigated was PTN negative. In vitro, PTN was synthesized in perinuclear regions of glioma cells, secreted into the cultivation medium, but its production varied considerably between glioma cells cultivated from different solid gliomas or glioma cell lines. In situ, PTN expression was restricted to distinct parts/cells of the tumour. PTN did not influence the proliferation of glioma cells themselves, but stimulated [3H]thymidine incorporation into DNA of microglial cells. Furthermore, in Boyden chamber assays, PTN showed a strong chemotactic effect on murine BV‐2 microglial cells. PTN is supposed to be a paracrine growth/angiogenic factor that is produced by gliomas and contributes to their malignancy by targeting endothelial and microglial cells.
Serotonin synthesis and its light–dark variation in the rat retina
Authors: Chanut Evelyne , Nguyen‐Legros Jeanine , Labarthe Benoît , Trouvin Jean‐Hugues , Versaux‐Botteri Claudine 
Published: March 2003

AbstractRetinal circadian rhythms are driven by an intrinsic oscillator, using chemical signals such as melatonin, secreted by photoreceptor cells. The purpose of the present work was to identify the origin of serotonin, the precursor of melatonin, in the retina of adult rat, where no immunoreactivity for serotonin or tryptophan hydroxylase had ever been detected. To demonstrate local synthesis of serotonin in the rat retina, substrates of tryptophan hydroxylase, the first limiting enzyme in the serotonin pathway, have been used. Tryptophan, in the presence of an inhibitor of aromatic amino acid decarboxylase, enhanced 5‐hydroxytryptophan levels, whereas α‐methyltryptophan, a competitive substrate inhibitor, was hydroxylated into α‐methyl‐5‐hydroxytryptophan. Tryptophan hydroxylase substrate concentration was higher in the dark period than in the light period, and formation of hydroxylated compounds was increased. The presence of tryptophan hydroxylase mRNA in the rat retina was confirmed by RT–PCR. Taken together, the results support the local synthesis of serotonin by tryptophan hydroxylation, this metabolic pathway being required more critically when 5‐HT is used for melatonin synthesis.
Modulation of astrocyte inducible nitric oxide synthase and cytokine expression by interferon β is associated with induction and inhibition of interferon γ‐activated sequence binding activity
Authors: Hua Liwei L. , Kim Mee‐Ohk , Brosnan Celia F. , Lee Sunhee C. 
Published: March 2003

AbstractAlthough interferon (IFN)‐β is firmly established as a therapeutic agent for multiple sclerosis, information regarding its role in astrocyte cytokine production is limited. In primary cultures of human astrocytes, we determined the effects of IFN‐β on astrocyte cytokine [tumor necrosis factor‐alpha (TNF‐α) and interleukin (IL)‐6] and inducible nitric oxide synthase (iNOS) expression by ribonuclease protection assay and ELISA. We found that IFN‐β inhibited astrocyte cytokine/iNOS induced by IL‐1 plus IFN‐γ, but in the absence of IFN‐γ, IFN‐β enhanced IL‐1‐induced cytokine/iNOS expression. Electrophoretic mobility shift analysis (EMSA) demonstrated that IFN‐γ induced sustained IFN‐γ‐activated sequence (GAS) binding, while IFN‐β induced transient GAS binding. When used together, IFN‐β inhibited IFN‐γ‐induced GAS binding activity. Nuclear factor‐kappa B (NF‐κB) activation was not altered by either IFNs, whereas IFN stimulated response element (ISRE) was only activated by IFN‐β and not IFN‐γ. These results suggest that IFN‐β can both mimic and antagonize the effect of IFN‐γ by modulating induction of nuclear GAS binding activity. Our results demonstrating differential regulation of astrocyte cytokine/iNOS induction by IFN‐β are novel and have implications for inflammatory diseases of the human CNS.
Ontogeny and the possible function of a novel epidermal growth factor‐like repeat domain‐containing protein, NELL2, in the rat brain
Authors: Kim Hyun , Ha Chang Man , Choi Jungil , Choi Eun Jung , Jeon Jongrye , Kim Changmee , Park Sang Kyu , Kang Sang Soo , Kim Kyungjin , Lee Byung Ju 
Published: March 2003

AbstractIn this study we investigated the mRNA expression of NELL2, a neural tissue‐specific epidermal growth factor (EGF)‐like repeat domain‐containing protein, in the developing and adult rat CNS using in situ hybridization histochemistry and northern blot analysis. The possible candidates that interact with or be regulated by NELL2 were screened with a cDNA expression array in antisense (AS) NELL2 oligodeoxynucleotide (ODN)‐injected rat hypothalami. NELL2 mRNA was detected as early as embryonic day 10, and was predominant in the CNS throughout the pre‐natal stages. Its expression gradually increased during embryonic development and its strong expression was observed throughout the CNS until embryonic day 20. It was detected in the ventricular zone of the spinal cord, medulla and pons in 12‐day‐old‐embryos, suggesting that NELL2 plays a role in the neurogenesis of these areas. After birth its expression gradually decreased, but high levels of expression could be observed in the tenia tecta, piriform cortex, hippocampus, dentate gyrus, cerebellar cortex, ambiguus nucleus, and inferior olivary nucleus of adult rat brains. The analysis of cDNA expression arrays revealed that the administration of AS NELL2 ODN markedly decreased the expression of several Ca2+‐binding proteins and those involved in the transport and release of vesicles such as EF‐hand Ca2+‐binding protein p22 and rab7. This finding was confirmed by relative reverse transcription‐polymerase chain reaction. The effect of NELL2 on synaptic vesicle content in median eminence (ME) nerve terminals was determined with synaptophysin levels as a marker protein in the AS NELL2 ODN‐injected rat. It was significantly decreased by the AS ODN. These data suggest that NELL2 may play an important role in the development of the CNS as well as maintenance of neural functions, by regulating the intracellular machinery involving Ca2+ signaling, synaptic transport and/or release of vesicles.
Astrocytic but not neuronal increased expression and redistribution of parkin during unfolded protein stress
Authors: Ledesma Maria Dolores , Galvan Cristian , Hellias Bianca , Dotti Carlos , Jensen Poul Henning 
Published: March 2003

AbstractParkin is a ubiquitin ligase that facilitates proteasomal protein degradation and is involved in a common autosomal recessive form of Parkinson's disease. Its expression is part of the unfolded protein response in cell lines where its overexpression protects against unfolded protein stress. How parkin expression is regulated in brain primary cells under stress situations is however, less well established. Here, the cellular and subcellular localization of parkin under basal conditions and during unfolded protein stress was investigated in primary cultures of rat astrocytes and hippocampal neurons. Immunofluorescense microscopy and biochemical analysis demonstrated that parkin is mainly associated with the endoplasmic reticulum (ER) in hippocampal neurons while it is associated with Golgi membranes, the nuclei and light vesicles in astrocytes. The constitutive parkin expression was high in neurons as compared with astrocytes. However, unfolded protein stress elicited a selective increase in astrocytic parkin expression and a change in distribution, whereas neuronal parkin remained largely unmodified. The cell specific differences argue in favour of different cellular binding sites and substrates for the protein and a pathogenic role for astrocytes in Parkinson's disease caused by parkin dysfunction.
Type‐specific inositol 1,4,5‐trisphosphate receptor localization in the vomeronasal organ and its interaction with a transient receptor potential channel, TRPC2
Authors: Brann Jessica H. , Dennis John C. , Morrison Edward E. , Fadool Debra A. 
Published: March 2003

AbstractThe vomeronasal organ (VNO) is the receptor portion of the accessory olfactory system and transduces chemical cues that identify social hierarchy, reproductive status, conspecifics and prey. Signal transduction in VNO neurons is apparently accomplished via an inositol 1,4,5‐trisphosphate (IP3)‐activated calcium conductance that includes a different set of G proteins than those identified in vertebrate olfactory sensory neurons. We used immunohistochemical (IHC) and SDS–PAGE/western analysis to localize three IP3 receptors (IP3R) in the rat VNO epithelium. Type‐I IP3R expression was weak or absent. Antisera for type‐II and ‐III IP3R recognized appropriate molecular weight proteins by SDS–PAGE, and labeled protein could be abolished by pre‐adsorption of the respective antibody with antigenic peptide. In tissue sections, type‐II IP3R immunoreactivity was present in the supporting cell zone but not in the sensory cell zone. Type‐III IP3R immunoreactivity was present throughout the sensory zone and overlapped that of transient receptor potential channel 2 (TRPC2) in the microvillar layer of sensory epithelium. Co‐immunoprecipitation of type‐III IP3R and TRPC2 from VNO lysates confirmed the overlapping immunoreactivity patterns. The protein–protein interaction complex between type‐III IP3R and TRPC2 could initiate calcium signaling leading to electrical signal production in VNO neurons.
Histamine activates tyrosine hydroxylase in bovine adrenal chromaffin cells through a pathway that involves ERK1/2 but not p38 or JNK
Authors: Cammarota Martín , Bevilaqua Lia R. M. , Rostas John A. P. , Dunkley Peter R. 
Published: March 2003

AbstractIn bovine adrenal chromaffin cells (BACC) histamine promotes a rapid increase in the intracellular levels of Ca2+ together with the release of catecholamines and the phosphorylation of the catecholamine biosynthetic enzyme tyrosine hydroxylase (TH). In this study we investigated the role of the mitogen‐activated protein kinases (MAPK) extracellular signal‐regulated kinases (ERK1/2), stress activated protein kinase (p38) and Jun N‐terminal kinases (JNK) on the histamine‐induced activation and phosphorylation of TH. We found that in BACC histamine produced a rapid, long lasting and histamine type‐1 (H1) receptor‐dependent increase in the phosphorylation levels of ERK1/2, p38 and JNK which was accompanied by a H1 receptor‐dependent increase in TH activity. This increase in TH activity was partially blocked by the MEK1/2 inhibitor U0126 but was unaffected by the p38 antagonist SB203580 or the JNK blocker JNKI1. To study the effect of MAPK inhibition on histamine‐induced TH phosphorylation, we generated phospho‐specific antibodies against the different phosphorylated forms of TH. Treatment with U0126 totally inhibited the histamine‐induced phosphorylation of TH at Ser31, without affecting the phosphorylation of either Ser40 or Ser19. Neither SB203580 nor JNKI1 treatments produced any significant modification of the histamine‐induced TH phosphorylation. Our data support the hypothesis that the up‐regulation of the ERK1/2 pathway, but not that of p38 or JNK, promoted by histamine is involved in the phosphorylation of TH at Ser31 and that this phosphorylation event is required for the full activation of this enzyme.
Rac and Cdc42‐dependent regulation of c‐Jun N‐terminal kinases by the δ‐opioid receptor
Authors: Kam Angel Y. F. , Chan Anthony S. L. , Wong Yung H. 
Published: March 2003

AbstractHeptahelical opioid receptors utilize Gi proteins to regulate a multitude of effectors including the classical adenylyl cyclases and the more recently discovered mitogen‐activated protein kinases (MAPKs). The c‐Jun NH2‐terminal kinases (JNKs) belong to one of three subgroups of MAPKs. In NG108‐15 neuroblastoma × glioma hybrid cells that endogenously express δ‐opioid receptors, δ‐agonist dose‐dependently stimulated JNK activity in a pertussis toxin‐sensitive manner. By using COS‐7 cells transiently transfected with the cDNAs of δ‐opioid receptor and hemagglutinin (HA)‐tagged JNK, we delineated the signaling components involved in this pathway. Sequestration of Gβγ subunits by transducin suppressed the opioid‐induced JNK activity. The possible involvement of the small GTPases was also examined. Expression of dominant negative mutants of Rac and Cdc42 blocked the opioid‐induced JNK activation, and a partial inhibition was observed in the presence of the dominant negative mutant of Ras. In contrast, the dominant negative mutant of Rho did not affect the opioid‐induced JNK activation. In addition, the receptor‐mediated JNK activation was dependent on Src family tyrosine kinases, but independent of phosphatidylinositol‐3 kinase and EGF receptor tyrosine kinases. Collectively, these results demonstrate functional regulation of JNK by the δ‐opioid receptor, and this pathway requires Gβγ, Src kinases and the small GTPases Rac and Cdc42.
Regulation of α‐synuclein by bFGF in cultured ventral midbrain dopaminergic neurons
Authors: Rideout Hardy J. , Dietrich Paula , Savalle Magali , Dauer William T. , Stefanis Leonidas 
Published: March 2003

Abstractα‐Synuclein is a neuronal protein that is implicated in the control of synaptic vesicle function and in Parkinson's disease (PD). Consequently, alterations of α‐synuclein levels may play a role in neurotransmission and in PD pathogenesis. However, the factors that regulate α‐synuclein levels are unknown. Growth factors mediate neurotrophic and plasticity effects in CNS neurons, and may play a role in disease states. Here we examine the regulation of α‐synuclein levels in primary CNS neurons, with particular emphasis on dopaminergic neurons. E18 rat cortical neurons and dopaminergic neurons of E14 rat ventral midbrain showed an induction of α‐synuclein protein levels with maturation in culture. Application of basic Fibroblast growth factor (bFGF) promoted α‐synuclein expression selectively within dopaminergic, and not GABAergic or cortical neurons. This induction was blocked by actinomycin D, but not by inhibition of bFGF‐induced glial proliferation. α‐Synuclein levels were not altered by glial‐derived neurotrophic factor (GDNF), or by apoptotic stimuli. We conclude that bFGF promotes α‐synuclein expression in cultured ventral midbrain dopaminergic neurons through a direct transcriptional effect. These results suggest that distinct growth factors may thus mediate plasticity responses or influence disease states in ventral midbrain dopaminergic neurons.
Striatal gene expression of RGS2 and RGS4 is specifically mediated by dopamine D1 and D2 receptors: clues for RGS2 and RGS4 functions
Authors: Taymans Jean‐Marc , Leysen Josée E. , Langlois Xavier 
Published: March 2003

AbstractOf all partners involved in G‐protein coupled receptor (GPCR) signalling, the regulator of G‐protein signalling (RGS) proteins are the only ones showing fast gene expression changes after various stimuli. These expression changes can offer feedback regulation to GPCR signalling as RGS accelerate the return of G‐proteins to their inactive form and exert regulatory functions on intracellular effectors. However, it is not yet known which RGS regulate which receptor transduction pathways in the brain. To start to answer this question, we studied the influence of specific agonists and antagonists of the dopamine D1 and D2 receptors on the gene expression of the five most abundant RGS in the striatum: RGS2, RGS4, RGS8, RGS9 and RGS10. Only changes in RGS2 and RGS4 mRNA levels were observed. The D1 agonist SKF82958 and D2 antagonist haloperidol caused an up‐regulation of RGS2 (+ 38.0% and + 41.6%, respectively). The D1 antagonist SCH23390 and D2 agonist quinpirole caused a down‐regulation of RGS2 (− 25.0% and − 35.0%) and an up‐regulation of RGS4 (+ 57.2% and + 52.5%). D1 and D2 receptors exert opposite effects on RGS2 expression, as they do on cAMP levels, suggesting a cAMP‐mediated transcription of RGS2. This was confirmed by the unique induction of RGS2 (+ 111.1%) observed in the periventricular zone of the striatum after intracerebroventricular injection of forskolin. RGS4 was up‐regulated only when RGS2 was down‐regulated. This suggests that both RGS exert distinct functions. Considering the coupling of D1 and D2 receptors to the intracellular effector adenylate cyclase 5 (AC5) through their respective Gα subunits in the striatum, our data allow us to suggest that RGS2 regulates the D1/Gαolf/AC5 pathway and RGS4 the D2/Gαo/AC5 pathway.