Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prenylcysteine carboxymethyltransferase (pcCMT) is an enzyme that catalyzes the post-translational carboxymethylation of isoprenylated proteins ensuring a more efficient membrane attachment and proper guiding to a specific target membrane. In this paper, we report on modulation of pcCMT activity in retinoic acid (RA)-treated SH-SY5Y neuroblastoma cells using N-acetyl-S-farnesyl-L-cysteine (AFC) as artificial methyl acceptor. In addition, the methylation of endogenous proteins was followed by the vapor phase equilibrium assay and the storage phosphor screen (P-screen) technique with S-adenosyl-[3H-methyl] methionine (AdoMet) as methyl donor. Methylation of AFC was reduced to 75% of that of the control, the most prominent decrease being observed with the post-nuclear membrane fraction as enzyme source. With regard to protein methylation both screening methods yielded analogous results showing the [3H]-labeling of endogenous proteins in the 21-25kDa molecular mass (MM) range to be diminished by nearly 50%. This questions the role of protein carboxymethylation as an essential component of the differentiation process in SH-SY5Y neuroblastoma cells. The P-screen technique revealed that the methylation of other molecular mass proteins was also affected. Both S-adenosylhomocysteine (AdoHcy) and AFC (AdoHcy being the most effective) inhibited endogenous methylation. An interesting feature was that AFC inhibited the protein methylation proportionally more effective in RA-treated cells. Finally, the levels of three small guanosine-5'-triphosphate (GTP) binding proteins were screened upon differentiation showing rab3A to be increased while rhoA and H-ras were decreased.
 ...
PMID:Prenylcysteine carboxymethyltransferase type III activity is decreased in retinoic acid-treated SH-SY5Y neuroblastoma cells. 1190 19

Serotonin (5-hydroxytryptamine (5-HT)) is an important neurotransmitter that regulates multiple events in the central nervous system. Many of the 5-HT functions are mediated via G protein-coupled receptors that are coupled to multiple heterotrimeric G proteins, including G(s), G(i), and G(q) subfamilies (Martin, G. R., Eglen, R. M., Hamblin, M. W., Hoyer, D., and Yocca, F. (1998) Trends Pharmacol. Sci. 19, 2-4). Here we show for the first time that the 5-hydroxytryptamine 4(a) receptor (5-HT(4(a))) is coupled not only to heterotrimeric G(s) but also to G(13) protein, as assessed both by biochemical and functional assays. Using reconstitution of 5-HT(4(a)) receptor with different G proteins in Spodoptera frugiperda (Sf.9) cells, we have proved that agonist stimulation of receptor-induced guanosine 5'-(3-O-thio)triphosphate binding to Galpha(13) protein. We then determined that expression of 5-HT(4(a)) receptor in mammalian cells induced constitutive- as well as agonist-promoted activation of a transcription factor, serum response element, through the activation of Galpha(13) and RhoA. Finally, we have determined that expression of 5-HT(4(a)) receptor in neuroblastoma x glioma NIE-115 cells cause RhoA-dependent neurite retraction and cell rounding under basal conditions and after agonist stimulation. These data suggest that by activating 5-HT(4(a)) receptor-G(13) pathway, serotonin plays a prominent role in regulating neuronal architecture in addition to its classical role in neurotransmission.
 ...
PMID:5-Hydroxytryptamine 4(a) receptor is coupled to the Galpha subunit of heterotrimeric G13 protein. 1192 94

The cytoskeletal changes that alter cellular morphogenesis and motility depend upon a complex interplay among molecules that regulate actin, myosin, and other cytoskeletal components. The Rho family of GTP binding proteins are important upstream mediators of cytoskeletal organization. Gem and Rad are members of another family of small GTP binding proteins (the Rad, Gem, and Kir family) for which biochemical functions have been mostly unknown. Here we show that Gem and Rad interface with the Rho pathway through association with the Rho effectors, Rho kinase (ROK) alpha and beta. Gem binds ROKbeta independently of RhoA in the ROKbeta coiled-coil region adjacent to the Rho binding domain. Expression of Gem inhibited ROKbeta-mediated phosphorylation of myosin light chain and myosin phosphatase, but not LIM kinase, suggesting that Gem acts by modifying the substrate specificity of ROKbeta. Gem or Rad expression led to cell flattening and neurite extension in N1E-115 neuroblastoma cells. In interference assays, Gem opposed ROKbeta- and Rad opposed ROKalpha-mediated cell rounding and neurite retraction. Gem did not oppose cell rounding initiated by ROKbeta containing a deletion of the Gem binding region, demonstrating that Gem binding to ROKbeta is required for the effects observed. In epithelial or fibroblastic cells, Gem or Rad expression resulted in stress fiber and focal adhesion disassembly. In addition, Gem reverted the anchorage-independent growth and invasiveness of Dbl-transformed fibroblasts. These results identify physiological roles for Gem and Rad in cytoskeletal regulation mediated by ROK.
 ...
PMID:The GTP binding proteins Gem and Rad are negative regulators of the Rho-Rho kinase pathway. 1195 30

Lysophosphatidic acid (LPA) is a serum-borne phospholipid that activates its own G protein-coupled receptors present in numerous cell types. In addition to stimulating cell proliferation, LPA also induces cytoskeletal changes and promotes cell migration in a RhoA- and Rac-dependent manner. Whereas RhoA is activated via Galpha(12/13)-linked Rho-specific guanine nucleotide exchange factors, it is unknown how LPA receptors may signal to Rac. Here we report that the prototypic LPA(1) receptor (previously named Edg2), when expressed in B103 neuroblastoma cells, mediates transient activation of RhoA and robust, prolonged activation of Rac leading to cell spreading, lamellipodia formation, and stimulation of cell migration. LPA-induced Rac activation is inhibited by pertussis toxin and requires phosphoinositide 3-kinase activity. Strikingly, LPA fails to activate Rac in cell types that lack the Rac-specific exchange factor Tiam1; however, enforced expression of Tiam1 restores LPA-induced Rac activation in those cells. Tiam1-deficient cells show enhanced RhoA activation, stress fiber formation, and cell rounding in response to LPA, consistent with Tiam1/Rac counteracting RhoA. We conclude that LPA(1) receptors couple to a G(i)-phosphoinositide 3-kinase-Tiam1 pathway to activate Rac, with consequent suppression of RhoA activity, and thereby stimulate cell spreading and motility.
 ...
PMID:Rac activation by lysophosphatidic acid LPA1 receptors through the guanine nucleotide exchange factor Tiam1. 1239 75

A monoclonal antibody, named C302, was prepared and characterized against botulinum ADP-ribosyltransferase C3 exoenzyme that inactivates RhoA GTP-binding protein, resulting in the neurite outgrowth of human neuroblastoma GOTO cells. C302 bound not to the smaller fragments derived from the protease-treated C3 exoenzyme but to the intact C3 exoenzyme. It seems that the C302 epitope may depend on the three-dimensional structure of C3 exoenzyme molecule. C302 depressed the enzymatic and biological actions of C3 exoenzyme. The dose-dependent depression pattern of C302 on the enzyme activity was similar to that to the biological one. C302 turned the neurite-bearing shape of the C3 exoenzyme-treated GOTO cells into the intact shape. By using of C302 mAb and C3 exoenzyme, the research concerning GTP-binding proteins would be improved.
 ...
PMID:Characterization of a neutralizing monoclonal antibody against botulinum ADP-ribosyltransferase, C3 exoenzyme. 1239 99

The Rho GTPase-activating proteins (RhoGAPs) are a family of multifunctional molecules that transduce diverse intracellular signals by regulating Rho GTPase activities. A novel RhoGAP family member, p200RhoGAP, is cloned in human and mouse. The murine p200RhoGAP shares 86% sequence identity with the human homolog. In addition to a conserved RhoGAP domain at the N terminus, multiple proline-rich motifs are found in the C-terminal region of the molecules. Northern blot analysis revealed a brain-specific expression pattern of p200RhoGAP. The RhoGAP domain of p200RhoGAP stimulated the GTPase activities of Rac1 and RhoA in vitro and in vivo, and the conserved catalytic arginine residue (Arg-58) contributed to the GAP activity. Expression of the RhoGAP domain of p200RhoGAP in Swiss 3T3 fibroblasts inhibited actin stress fiber formation stimulated by lysophosphatidic acid and platelet-derived growth factor-induced membrane ruffling but not Bradykinin-induced filopodia formation. Endogenous p200RhoGAP was localized to cortical actin in naive N1E-115 neuroblastoma cells and to the edges of extended neurites of differentiated N1E-115 cells. Transient expression of the RhoGAP domain and the full-length molecule, but not the catalytic arginine mutants, readily induced a differentiation phenotype in N1E-115 cells. Finally, p200RhoGAP was capable of binding to the Src homology 3 domains of Src, Crk, and phospholipase Cgamma in vitro and became tyrosine-phosphorylated upon association with activated Src in cells. These results suggest that p200RhoGAP is involved in the regulation of neurite outgrowth by exerting its RhoGAP activity and that its cellular activity may be regulated through interaction with Src-like tyrosine kinases.
 ...
PMID:Characterization of a brain-specific Rho GTPase-activating protein, p200RhoGAP. 1245 18

p116Rip is a ubiquitously expressed protein that was originally identified as a putative binding partner of RhoA in a yeast two-hybrid screen. Overexpression of p116Rip in neuroblastoma cells inhibits RhoA-mediated cell contraction induced by lysophosphatidic acid (LPA); so far, however, the function of p116Rip is unknown. Here we report that p116Rip localizes to filamentous actin (F-actin)-rich structures, including stress fibers and cortical microfilaments, in both serum-deprived and LPA-stimulated cells, with the N terminus (residues 1-382) dictating cytoskeletal localization. In addition, p116Rip is found in the nucleus. Direct interaction or colocalization with RhoA was not detected. We find that p116Rip binds tightly to F-actin (Kd approximately 0.5 microm) via its N-terminal region, while immunoprecipitation assays show that p116Rip is complexed to both F-actin and myosin-II. Purified p116Rip and the F-actin-binding region can bundle F-actin in vitro, as shown by electron microscopy. When overexpressed in NIH3T3 cells, p116Rip disrupts stress fibers and promotes formation of dendrite-like extensions through its N-terminal actin-binding domain; furthermore, overexpressed p116Rip inhibits growth factor-induced lamellipodia formation. Our results indicate that p116Rip is an F-actin-binding protein with in vitro bundling activity and in vivo capability of disassembling the actomyosin-based cytoskeleton.
 ...
PMID:p116Rip is a novel filamentous actin-binding protein. 1273 40

Small GTPases of the rho family regulate the extensive rearrangements of the cytoskeleton that characterize neuronal differentiation. Citron kinase is a target molecule for activated rhoA, previously implicated in control of cytokinesis. We have found that, in addition, it could play an important role in modulating the extension of neuronal processes. Using constitutively active and dominant negative mutants, we showed that citron kinase is involved in the morphologic differentiation of N1E-115 neuroblastoma cells induced by serum starvation. More importantly, quantitative analysis of citron kinase knockout cerebral cortex displayed that this molecule may differentially regulate the morphology of the dendritic compartment in corticocollicular versus callosally-projecting pyramidal neurons.
 ...
PMID:Role of citron kinase in dendritic morphogenesis of cortical neurons. 1278 20

N-methyl-d-aspartate (NMDA) receptors regulate structural plasticity by modulating actin organization within dendritic spines. Herein, we report identification and characterization of p250GAP, a novel GTPase-activating protein for Rho family proteins that interacts with the GluRepsilon2 (NR2B) subunit of NMDA receptors in vivo. The p250GAP mRNA was enriched in brain, with high expression in cortex, corpus striatum, hippocampus, and thalamus. Within neurons, p250GAP was highly concentrated in the postsynaptic density and colocalized with the GluRepsilon2 (NR2B) subunit of NMDA receptors and with postsynaptic density-95. p250GAP promoted GTP hydrolysis of Cdc42 and RhoA in vitro and in vivo. When overexpressed in neuroblastoma cells, p250GAP suppressed the activities of Rho family proteins, which resulted in alteration of neurite outgrowth. Finally, NMDA receptor stimulation led to dephosphorylation and redistribution of p250GAP in hippocampal slices. Together, p250GAP is likely to be involved in NMDA receptor activity-dependent actin reorganization in dendritic spines.
 ...
PMID:p250GAP, a novel brain-enriched GTPase-activating protein for Rho family GTPases, is involved in the N-methyl-d-aspartate receptor signaling. 1285 75

Rho family GTPases are suggested to be pivotal for growth cone behavior, but regulation of their activities in response to environmental cues remains elusive. Here, we describe roles of STEF and Tiam1, guanine nucleotide exchange factors for Rac1, in neurite growth and growth cone remodeling. We reveal that, in primary hippocampal neurons, STEF/Tiam1 are localized within growth cones and essential for formation of growth cone lamellipodia, eventually contributing to neurite growth. Furthermore, experiments using a dominant-negative form demonstrate that STEF/Tiam1 mediate extracellular laminin signals to activate Rac1, promoting neurite growth in N1E-115 neuroblastoma cells. STEF/Tiam1 are revealed to mediate Cdc42 signal to activate Rac1 during lamellipodial formation. We also show that RhoA inhibits the STEF/Tiam1-Rac1 pathway. These data are used to propose a model that extracellular and intracellular information is integrated by STEF/Tiam1 to modulate the balance of Rho GTPase activities in the growth cone and, consequently, to control growth cone behavior.
 ...
PMID:Roles of STEF/Tiam1, guanine nucleotide exchange factors for Rac1, in regulation of growth cone morphology. 1455 Jul 69


<< Previous 1 2 3 4 5 6 Next >>