Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.17 (CaMKII)
 4,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of exogenous GM1 ganglioside on depolarization and ligand-induced Ca2+ signaling were investigated in PC12 cells. Cellular responses to K+ depolarization and bradykinin application in control and GM1-treated cells were examined with respect to: 1) changes in the intracellular Ca2+ concentration ([Ca2+]i) measured using fura-2 fluorescence in single cells, and 2) changes in Ca(2+)-dependent protein kinase activity as assayed by two-dimensional phosphopeptide analysis of the site-specific phosphorylation of tyrosine hydroxylase. Pretreatment of cells with GM1 (10 or 100 microM) enhanced K+ depolarization-stimulated increases in [Ca2+]i and in 32PO4 incorporation into tyrosine hydroxylase phosphopeptide T2, a Ca2+/calmodulin-dependent protein kinase II substrate. In contrast, GM1 treatment had no effect on the transient increases in [Ca2+]i evoked by bradykinin or on bradykinin-induced increases in the site-specific phosphorylation of tyrosine hydroxylase. The depolarization-induced and GM1-enhanced increases in [Ca2+]i and T2 phosphorylation were prevented by removal of external Ca2+ or pretreatment with 1 microM nitrendipine, suggesting that these increases result from Ca2+ entry through dihydropyridine-sensitive Ca2+ channels. The ability of exogenous gangliosides to potentiate increases in [Ca2+]i may underlie their diverse neuritogenic and neurotrophic actions in the nervous system.
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PMID:Modulation of a Ca2+ signaling pathway by GM1 ganglioside in PC12 cells. 144 16

We have investigated the ability of exogenous gangliosides to modulate nerve growth factor (NGF) signal transduction in PC12 cells. The effects of exogenous ganglioside GM1 on multiple protein kinase activities were assayed by analyzing site-specific serine phosphorylation of tyrosine hydroxylase (TyrOHase) by two-dimensional phosphopeptide mapping. In the presence of NGF, exogenous GM1 (1-10 microM) increased 32P incorporation into TyrOHase phosphopeptide T2, a Ca2+/calmodulin-dependent protein kinase substrate whose phosphorylation is not normally affected by NGF treatment. In the absence of NGF, GM1 treatment had no significant effects on TyrOHase phosphorylation. The removal of extracellular Ca2+ or blockade of dihydropyridine-sensitive Ca2+ channels prevented the GM1-induced increases in 32P incorporation into phosphopeptide T2. Exogenous GM1 also potentiated K+ depolarization-induced increases in the phosphorylation of TryOHase. These results suggest that the stimulatory effects of exogenous GM1 ganglioside on NGF actions may be due to its ability to potentiate a Ca(2+)-dependent signaling pathway.
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PMID:Stimulation of a Ca(2+)-dependent protein kinase by GM1 ganglioside in nerve growth factor-treated PC12 cells. 167 13

Purified rat brain Ca2+/calmodulin-dependent protein kinase II (CaM-kinase II) is stimulated by brain gangliosides to a level of about 30% the activity obtained in the presence of Ca2+/calmodulin (CaM). Of the various gangliosides tested, GT1b was the most potent, giving half-maximal activation at 25 microM. Gangliosides GD1a and GM1 also gave activation, but asialo-GM1 was without effect. Activation was rapid and did not require calcium. The same gangliosides also stimulated the autophosphorylation of CaM-kinase II on serine residues, but did not produce the Ca2+-independent form of the kinase. Ganglioside stimulation of CaM-kinase II was also present in rat brain synaptic membrane fractions. Higher concentrations (125-250 microM) of GT1b, GD1a, and GM1 also inhibited CaM-kinase II activity. This inhibition appears to be substrate-directed, as the extent of inhibition is very dependent on the substrate used. The molecular mechanism of the stimulatory effect of gangliosides was further investigated using a synthetic peptide (CaMK 281-309), which contains the CaM-binding, inhibitory, and autophosphorylation domains of CaM-kinase II. Using purified brain CaM-kinase II in which these regulatory domains were removed by limited proteolysis. CaMK 281-309 strongly inhibited kinase activity (IC50 = 0.2 microM). GT1b completely reversed this inhibition, but did not stimulate phosphorylation of the peptide on threonine-286. These results demonstrate that GT1b can partially mimic the effects of Ca2+/CaM on native CaM-kinase II and on peptide CaMK 281-309.
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PMID:Regulation of Ca2+/calmodulin-dependent protein kinase II by brain gangliosides. 215 90

Using a synthesized glycoprotein, beta-galactosidase modified with p-aminophenyl beta-D-galactopyranoside (beta-D-Gal beta-gal), the incorporation of the glycoprotein into bovine brain synaptosomes was studied. The uptake was mediated by a specific receptor to beta-D-galactoside, and was inhibited by GM1 ganglioside. The uptake was found to require energy and to be sensitive to metabolic inhibitors. Kinetic studies on beta-D-Gal beta-gal uptake indicated the presence of a saturable, carrier-mediated transport system in synaptosomes. By subcellular fractionation the beta-D-Gal beta-gal taken up was found in the fractions corresponding to the nucleus and membrane fragments, the soluble cytosomal fractions, and the mitochondria and lysosomes. The uptake was markedly increased by addition of Ca2+ to the incubation medium. The maximal uptake was obtained at pH 8.0 in the presence of 10 mM Ca2+ at 37 degrees C. By addition of a Ca2+ ionophore A23187, beta-D-Gal beta-gal uptake was increased in a dose-dependent way parallel to the increase in the intrasynaptosomal concentration of Ca2+. Preincubation of synaptosomes with calmodulin antagonists such as trifluoperazine and N-(6-aminohexyl)-5-chloro-1-napthalenesulfonamide (W-7) was found to inhibit the uptake markedly, and diazepam, an inhibitor of Ca2+/calmodulin-dependent protein kinase, also inhibited the uptake. At a concentration between 1 and 10 microM, 50% inhibition of the uptake was observed with either inhibitor. On the other hand, the addition of dibutyryl cyclic AMP did not affect the uptake of the glycoprotein into synaptosomes. These results suggest that the incorporation of this macromolecule is dependent on a Ca2+/calmodulin-dependent protein kinase.
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PMID:Incorporation of glycosylated beta-galactosidase into bovine brain synaptosomes. 309 96

We report the isolation of two distinct populations of detergent resistant membrane complexes (DRMCs) from 1-day-old chick brain, utilizing a procedure involving Triton X-100 insolubility and sucrose density gradient centrifugation. The first population is abundant (1.8% of the total homogenate protein), highly enriched for two glycosylphosphatidylinositol (GPI)-anchored proteins (Thy-1 and AvGp50), and not enriched for caveolin. The second population is of relatively low abundance (0.2% of the total homogenate), contains relatively low levels of Thy-1 and AvGp50 enrichment, and is highly enriched in caveolin. Both populations of DRMCs are enriched for cholesterol, ganglioside GM1, total kinase and tyrosine kinase activities, and c-Src and c-Fyn. However, there are differences in the Coomassie-stained protein profiles, phosphoprotein components, tyrosine kinase activity, and electron microscopic morphology when the Thy-1 and AvGp50-enriched DRMCs are compared to the caveolin-rich DRMCs. In addition, the GPI-enriched DRMCs contain CaM kinase type II immunoreactivity, whereas this molecule was undectable in the caveolin-rich DRMCs. The isolation of two distinct DRMC fractions may be representative of unique plasma membrane signaling domains involved in GPI-anchored protein or other receptor-mediated signal transduction within the avian nervous system. Further, we have demonstrated for the first time that nervous system tissue, in particular the hatch chick cerebellum, contains caveolin immunoreactivity.
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PMID:Characterization of two distinct populations of detergent resistant membrane complexes isolated from chick brain tissues. 887 26

Gangliosides are known to be differentiation-inducing molecules in mammalian stem cells. We studied the interaction between the molecular structure of glycosphingolipids (GSLs) and their promoting mechanisms of the phagocytic processes in human polymorphonuclear leukocytes (PMN). The effect of various gangliosides from mammalian tissues on adhesion, phagocytosis, phagosome-lysosome (P-L) fusion and superoxide anion production was examined by human PMN using heat-killed cells of Staphylococcus aureus-coated with GSLs. Gangliosides GM3, GD1a, GD3 and GT1b showed a marked stimulatory effect on the phagocytosis and P-L fusion in a dose-dependent manner, while ganglioside GM1, asialo GM1 and neutral GSLs did not. The relative phagocytic rate of ganglioside GM3-coated S. aureus was the highest among the tested GSLs. Both P-L fusion rate and phagocytosis of S. aureus were elevated significantly when coated with ganglioside GD1a, GD3 or GT1b, and GT1b gave a five times higher rate than that of the non-coated control. These results suggest that the terminal sialic acid moiety is essential for the enhancement of phagocytosis and that the number of sialic acid molecules in the ganglioside is related to the enhancement of the P-L fusion process. On the other hand, the superoxide anion release from PMN was not affected by ganglioside GM2, GM3, GD1a or GT1b. Furthermore, to clarify the trigger or the signal transduction mechanism of phagocytic processes, we examined the effect of protein kinase inhibitors such as H-7, staurosporine (protein kinase C inhibitor), H-89 (protein kinase A inhibitor), genistein (tyrosine kinase inhibitor), ML-7 (myosin light chain kinase inhibitor), and KN-62 (Ca2+/calmodulin-dependent protein kinase II inhibitor) on ganglioside-induced phagocytosis. H-7, staurosporine and KN-62 inhibited ganglioside-induced phagocytosis in the range of concentration without cell damage, while H-89, genistein and ML-7 did not. Moreover, H-7 and KN-62 inhibited ganglioside-induced P-L fusion. These results suggest that protein kinase C and Ca2+/calmodulin-dependent protein kinase II may be involved in the induction of phagocytosis and P-L fusion stimulated by gangliosides.
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PMID:Stimulatory effect of gangliosides on phagocytosis, phagosome-lysosome fusion, and intracellular signal transduction system by human polymorphonuclear leukocytes. 933 83

Cell surface glycoconjugates are thought to mediate cell-cell recognition and play roles in neuronal development and functions. We demonstrated here that exposure of neuronal cells to nanomolar levels of gangliosides Neu5Acalpha 8Neu5Acalpha 3Galbeta 4GlcCer, Galbeta 3GalNAcbeta 4(Neu5Acalpha 8Neu5Acalpha 3)Galbeta 4GlcCer (GD1b), Neu5Acalpha 3Galbeta 3GalNAcbeta 4(Neu5Acalpha 8Neu5Acalpha 3)Galbeta 4GlcCer (GT1b) or its oligosaccharide portion induced a rapid and transient activation of Ca2+/calmodulin-dependent protein kinase II (CaM-KII) in the subplasmalemma. Galbeta 3GalNAcbeta 4(Neu5Acalpha 3)Galbeta 4GlcCer (GM1), GalNAcbeta 4(Neu5Acalpha 3)Galbeta 4GlcCer, Neu5Acalpha 3Galbeta 4GlcCer, Neu5Acalpha 3Galbeta 3GalNAcbeta 4(Neu5Acalpha 3)Galbeta 4GlcCer (GD1a), and Neu5Acalpha 8Neu5Acalpha 3Galbeta 3GalNAcbeta 4(Neu5Acalpha 8Neu5Acalpha 3)-Galbeta 4GlcCer were ineffective. GT1b and GD1b stimulated transient elevation of bulk cytosolic Ca2+ levels while GM1 slightly elevated the levels and GD1a did not. Thus, the cytosolic Ca2+ elevation by the gangliosides may trigger the CaM-KII activation. The treatment was accompanied by peripheral actin polymerization and filopodia formation in NG108-15 cells and primary hippocampal neurons, but not in glial cells. CaM-KII inhibitors blocked both CaM-KII activation and the subsequent filopodia formation. A small G-protein cdc42 was a potential downstream target of CaM-KII activated by the gangliosides. These results suggest that oligosaccharides of the gangliosides serve as potential regulators of the filopodia formation in neuronal cells by triggering the activation of CaM-KII followed by cdc42 up-regulation via a cell surface receptor-like component. The filopodia formation induced by the gangliosides may have a physiological relevance because long-term exposure of hippocampal neurons to GT1b oligosaccharide induced advanced dendritogenesis. Furthermore, exposure of cerebellar neurons to GT1b oligosaccharide facilitated CaM-KII-dependent dendritic outgrowth and branch formation of cerebellar Purkinje neurons, in which actin isoforms were localized to motile structures in dendrites. Thus, the ganglioside/CaM-KII signal plays a role in modulating dendritic morphogenesis by inducing cdc42-mediated actin reorganization.
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PMID:Ganglioside/calmodulin kinase II signal inducing cdc42-mediated neuronal actin reorganization. 1284 50

Attention deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed disorder of school-age children. Although genetic and brain-imaging studies suggest a contribution of altered dopamine (DA) signaling in ADHD, evidence of signaling perturbations contributing to risk is largely circumstantial. The presynaptic, cocaine- and amphetamine (AMPH)-sensitive DA transporter (DAT) constrains DA availability at presynaptic and postsynaptic receptors following vesicular release and is targeted by the most commonly prescribed ADHD therapeutics. Using polymorphism discovery approaches with an ADHD cohort, we identified a hDAT (human DAT) coding variant, R615C, located in the distal C terminus of the transporter, a region previously implicated in constitutive and regulated transporter trafficking. Here, we demonstrate that, whereas wild-type DAT proteins traffic in a highly regulated manner, DAT 615C proteins recycle constitutively and demonstrate insensitivity to the endocytic effects of AMPH and PKC (protein kinase C) activation. The disrupted regulation of DAT 615C parallels a redistribution of the transporter variant away from GM1 ganglioside- and flotillin1-enriched membranes, and is accompanied by altered CaMKII (calcium/calmodulin-dependent protein kinase II) and flotillin-1 interactions. Using C-terminal peptides derived from wild-type DAT and the R615C variant, we establish that the DAT 615C C terminus can act dominantly to preclude AMPH regulation of wild-type DAT. Mutagenesis of DAT C-terminal sequences suggests that phosphorylation of T613 may be important in sorting DAT between constitutive and regulated pathways. Together, our studies support a coupling of DAT microdomain localization with transporter regulation and provide evidence of perturbed DAT activity and DA signaling as a risk determinant for ADHD.
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PMID:Attention deficit/hyperactivity disorder-derived coding variation in the dopamine transporter disrupts microdomain targeting and trafficking regulation. 2251 3