A signaling mechanism from G alpha q-protein-coupled metabotropic glutamate receptors to gene expression: role of the c-Jun N-terminal kinase pathway.

Galphaq-protein-coupled group I metabotropic glutamate receptors (mGluRs) are densely expressed in brain neurons and are actively involved in various cellular activities. In this study, we investigated the role of group I mGluRs in regulating the c-Jun N-terminal kinase (JNK)/stress-activated protein kinase in cultured neurons. We found that selective activation of mGluR5 induced a rapid and transient phosphorylation of JNK.

Phosphorylation of AMPA receptors: mechanisms and synaptic plasticity.

The ionotropic alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor is densely distributed in the mammalian brain and is primarily involved in mediating fast excitatory synaptic transmission. Recent studies in both heterologous expression systems and cultured neurons have shown that the AMPA receptor can be phosphorylated on their subunits (GluR1, GluR2, and GluR4). All phosphorylation sites reside at serine, threonine, or tyrosine on the intracellular C-terminal domain.

How has the sexual behaviour of gay men changed since the onset of AIDS: 1986-2003.

Objective: To report changes in sexual behaviour among gay men in Sydney from 1986 to 2003.

Methods: Baseline data from four studies of gay men in Sydney were used: the Social Aspects of the Prevention of AIDS study (1986/87: 91 HIV-positive and 444 HIV-negative men); the Sydney Men and Sexual Health cohort (1993-95: 237 HIV-positive and 910 HIV-negative men); the Health in Men cohort of HIV-negative gay men (2001-03: 1,148 men); the Positive Health cohort of HIV-positive gay men (2001/02: 237 men). Each sample was recruited and interviewed using similar methods.

Willingness to participate in HIV vaccine trials among HIV-negative gay men in Sydney, Australia.

This study aimed to determine and describe HIV-negative gay men's willingness to participate in HIV vaccine trials. Data were from participants who completed face-to-face interviews during the first 18 months (to the end of 2002) of recruitment into the Health in Men cohort of HIV-negative gay men in Sydney. A key outcome measure was a scale of Willingness to Participate in HIV Vaccine Trials, with scores ranging from 1 (unwilling) to 4 (willing).

Identify lymphatic metastasis-associated genes in mouse hepatocarcinoma cell lines using gene chip.

Aim: In order to obtain lymphogenous metastasis-associated genes, we compared the transcriptional profiles of mouse hepatocarcinoma cell lines Hca-F with highly lymphatic metastasis potential and Hca-P with low lymphatic metastasis potential.

Methods: Total RNA was isolated from Hca-F and Hca-P cells and synthesized into double-stranded cDNA. In vitro transcription double-stranded cDNA was labeled with biotin (i.

The scaffold protein Homer1b/c links metabotropic glutamate receptor 5 to extracellular signal-regulated protein kinase cascades in neurons.

Group I metabotropic glutamate receptors (mGluRs) increase cellular levels of inositol-1,4,5-triphosphate (IP3) and thereby trigger intracellular Ca2+ release. Also, group I mGluRs are organized with members of Homer scaffold proteins into multiprotein complexes involved in postreceptor signaling. In this study, we investigated the relative importance of the IP3/Ca2+ signaling and novel Homer proteins in group I mGluR-mediated activation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) in cultured rat striatal neurons.

Role of protein phosphatase 2A in mGluR5-regulated MEK/ERK phosphorylation in neurons.

The regulation of protein phosphorylation requires coordinated interaction between protein kinases and protein phosphatases (PPs). Recent evidence has shown that the Galphaq-protein-coupled metabotropic glutamate receptor (mGluR) 5 up-regulates phosphorylation of MAPK/ERK1/2. However, signaling mechanisms linking mGluR5 to ERK are poorly understood.

A novel Ca2+-independent signaling pathway to extracellular signal-regulated protein kinase by coactivation of NMDA receptors and metabotropic glutamate receptor 5 in neurons.

The specification and organization of glutamatergic synaptic transmission require the coordinated interaction among glutamate receptors and their synaptic adaptor proteins closely assembled in the postsynaptic density (PSD). Here we investigated the interaction between NMDA receptors and metabotropic glutamate receptor 5 (mGluR5) in the integral regulation of extracellular signal-regulated protein kinase (ERK) and gene expression in cultured rat striatal neurons. We found that coapplication of NMDA and the mGluR5 agonist (S)-3,5-dihydroxyphenylglycine synergistically increased ERK phosphorylation.

Distinct expression of phosphorylated N-methyl-D-aspartate receptor NR1 subunits by projection neurons and interneurons in the striatum of normal and amphetamine-treated rats.

N-methyl-D-aspartate (NMDA) receptors are heteromeric assemblies of subunits (NR1 and NR2A-D), and are enriched in the striatum. Receptor phosphorylation has recently been demonstrated on the NR1 subunit at three serine residues, 897, 896, and 890, which appear to correspond to the level of receptor activity. In this study, expression of phospho-specific NR1 subunits at serine 897 (pNR1S897), serine 896 (pNR1S896), or serine 890 (pNR1S890) in neurochemically identified neurons of the adult rat striatum was detected by using double-immunofluorescent labeling or combined in situ hybridization and immunohistochemistry.

The protein phosphatase 1/2A inhibitor okadaic acid increases CREB and Elk-1 phosphorylation and c-fos expression in the rat striatum in vivo.

Activation of group I metabotropic glutamate receptors (mGluRs) up-regulates transcription factor cyclic AMP response element-binding protein (CREB) and Elk-1 phosphorylation via extracellular signal-regulated kinase 1/2 (ERK1/2) in the striatum in vivo. Protein phosphatase 1/2A further regulates immediate early gene expression by inactivating (dephosphorylating) CREB. In this study, using semi-quantitative immunohistochemical and western blot analyses and in situ hybridization histochemistry, we found that intrastriatal infusion of the protein phosphatase 1/2A inhibitor okadaic acid (0.

Glutamate signaling to Ras-MAPK in striatal neurons: mechanisms for inducible gene expression and plasticity.

Extracellular signals can regulate mitogen-activated protein kinase (MAPK) cascades through a receptor-mediated mechanism in postmitotic neurons of adult mammalian brain. Both ionotropic and metabotropic glutamate receptors (mGluRs) are found to possess such an ability in striatal neurons. NMDA and AMPA receptor signals seem to share a largely common route to MAPK phosphorylation which involves first activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) via Ca2+ influx, followed by subsequent induction of phosphoinositide 3-kinase (PI3-kinase).

Regulation of MAPK/ERK phosphorylation via ionotropic glutamate receptors in cultured rat striatal neurons.

Extracellular signals may regulate mitogen-activated protein kinase (MAPK) cascades through a receptor-mediated mechanism. As a signaling superhighway to the nucleus, active Ras-MAPK cascades phosphorylate transcription factors and facilitate gene expression. In cultured rat striatal neurons, the present work systemically examined the linkage between glutamate receptors and the extracellular signal-regulated kinase 1/2 (ERK1/2) subclass of MAPK.

Effect of ethanol on reductions in norepinephrine electrochemical signal in the rostral ventrolateral medulla and hypotension elicited by I1-receptor activation in spontaneously hypertensive rats.

The mechanism of the antagonistic hemodynamic interaction between ethanol and centrally acting sympatholytics is not known. In this study, we tested the hypothesis that the imidazoline (I1)-receptor modulation of norepinephrine (NE) release within the rostral ventrolateral medulla (RVLM) plays a pivotal role in this clinically relevant hemodynamic interaction. METHOD In anesthetized spontaneously hypertensive rats, the effects of centrally acting sympatholytics on RVLM NE electrochemical signal were investigated by in vivo electrochemistry along with cardiovascular responses in the absence and presence of ethanol.

Contribution of ionotropic glutamate receptors to acute amphetamine-stimulated preproenkephalin mRNA expression in the rat striatum in vivo.

The present study evaluated the possible role of ionotropic glutamate receptors in mediating the inducible preproenkephalin (PPE) mRNA expression in the rat striatum in response to systemic administration of a psychostimulant amphetamine. A single injection of amphetamine (5 mg/kg, i.p.

Adult neural stem/progenitor cells in neurodegenerative repair.

Although the mammalian brain has long been thought to be entirely postmitotic, the recent discovery has confirmed an existence of neural stem or progenitor cells in various regions of the adult mammalian brain. Like embryonic stem cells, adult neural progenitor cells possess the capacity of self-renewal and differentiation potential for neurogenesis or gliogenesis. In addition to the subventricular zone and hippocampus where active cell division naturally occurs, adult neural progenitors with neurogenic potential exist in the striatum and the vicinity of dopaminergic neurons in the substantia nigra.

Metabotropic glutamate receptor 5-regulated Elk-1 phosphorylation and immediate early gene expression in striatal neurons.

The Galphaq protein-coupled metabotropic glutamate receptor subtype-5 (mGluR5) is densely expressed in medium spiny projection neurons of striatum. Emerging evidence suggests a significant role of mGluR5 in the addictive plasticity of striatal neurons that is likely derived from inducible cellular gene expression related to stimulation of mGluR5 and associative signaling proteins. In this study, we found that activation of mGluR5 with a selective agonist (RS)-2-chloro-5-hydroxy-phenylglycine (CHPG) induced a rapid and transient phosphorylation of a transcription regulator Elk-1 in cultured striatal neurons from rat E19 embryos or neonatal day-1 pups.

Group I metabotropic glutamate receptor-mediated calcium signalling and immediate early gene expression in cultured rat striatal neurons.

Group I metabotropic glutamate receptors (mGluRs) are positively coupled to phospholipase C (PLC) via Galphaq-proteins and are expressed in the medium-sized projection neurons of striatum. To characterize the group I mGluR/PLC-sensitive modulation of intracellular Ca2+ ([Ca2+]i) signalling, primary neuronal cultures were prepared from the striatum of E19 rat embryos or neonatal day-1 rat pups. Cytoplasmic Ca2+ signals were examined with fura-2/AM at a signal cell level.

Phosphorylation of cAMP response element-binding protein in cultured striatal neurons by metabotropic glutamate receptor subtype 5.

The metabotropic glutamate receptor subtype 5 (mGluR5) is densely expressed in striatal projection neurons. As a G protein-coupled receptor, mGluR5 may initiate an intracellular cascade that conveys extracellular signals to gene expression. This study investigated the possible role of mGluR5 in the inducible phosphorylation of a nuclear transcription factor, cAMP response element-binding protein (CREB), in primary cultures of striatal neurons from rat E19 embryos or neonatal day-1 pups.

[Relationship between lymph node metastasis and the expressions of E-cadherin, N-cadherin, and matrix metalloproteinase in breast carcinoma].

Background & Objective: There is little ideal predictor available on evaluating the lymph node metastatic potential of breast carcinoma. This study was designed to determine the expression of gene products of E-cadherin (epithelial), N-cadherin (nerve), and matrix metalloproteinase-9 (MMP-9) in breast carcinoma tissue and investigate their association with the invasion and metastasis of breast carcinoma.

Methods: The authors examined the expressions of E-cadherin, N-cadherin, and MMP-9 in 72 cases of breast carcinoma(39 cases with lymph node metastasis and 33 cases without lymph node metastasis) by immunohistochemistry.