Neurocentre Magendie

Konstantin GLEBOV

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2007-2009 Postdoc U862
2009 Postdoc Nervenklinik, Uniklinikum, Bonn Department Molekulare Zellbiologie, Sigmund-Freud-Str., 53127 Bonn, Germany

3 publication(s) depuis Mai 2005:

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2008 | Acta Biol Hung   IF 0.6
Adult-to-embryo chemical signaling in the regulation of larval development in trochophore animals: cellular and molecular mechanisms
Voronezhskaya E E, Glebov K I, Khabarova M Y, Ponimaskin E G, Nezlin L P

The regulation of larval development by starved adults occurs in both freshwater snails, Helisoma trivolvis and marine polychaetes, Platynereis dumerilii. Serotonin (5-HT) links this environmental signal which is detected by larval apical sensory neurons to changes in larval development. A profile of the stage-dependent expression of 5-HT receptors and coupled G proteins is essential in this regulatory mechanism. The final effect on development depends on the modulation of the activity of the larval digestive system.

09/2007 | Mol Pharmacol   IF 3.9
Localization of the mouse 5-hydroxytryptamine(1A) receptor in lipid microdomains depends on its palmitoylation and is involved in receptor-mediated signaling
Renner U, Glebov K, Lang T, Papusheva E, Balakrishnan S, Keller B, Richter D W, Jahn R, Ponimaskin E

In the present study, we have used wild-type and palmitoylation-deficient mouse 5-hydroxytryptamine(1A) receptor (5-HT1A) receptors fused to the yellow fluorescent protein- and the cyan fluorescent protein (CFP)-tagged alpha(i3) subunit of heterotrimeric G-protein to study spatiotemporal distribution of the 5-HT1A-mediated signaling in living cells. We also addressed the question on the molecular mechanisms by which receptor palmitoylation may regulate communication between receptors and G(i)-proteins. Our data demonstrate that activation of the 5-HT1A receptor caused a partial release of Galpha(i) protein into the cytoplasm and that this translocation is accompanied by a significant increase of the intracellular Ca(2+) concentration. In contrast, acylation-deficient 5-HT1A mutants failed to reproduce both Galpha(i3)-CFP relocation and changes in [Ca(2+)](i) upon agonist stimulation. By using gradient centrifugation and copatching assays, we also demonstrate that a significant fraction of the 5-HT1A receptor resides in membrane rafts, whereas the yield of the palmitoylation-deficient receptor in these membrane microdomains is reduced considerably. Our results suggest that receptor palmitoylation serves as a targeting signal responsible for the retention of the 5-HT1A receptor in membrane rafts. More importantly, the raft localization of the 5-HT1A receptor seems to be involved in receptor-mediated signaling.

05/2005 | Mol Pharmacol   IF 3.9
Palmitoylation of the 5-hydroxytryptamine4a receptor regulates receptor phosphorylation, desensitization, and beta-arrestin-mediated endocytosis
Ponimaskin E, Dumuis A, Gaven F, Barthet G, Heine M, Glebov K, Richter D W, Oppermann M

The mouse 5-hydroxytryptamine4a (5-HT4a) receptor is an unusual member of the G protein-coupled receptor superfamily because it possesses two separate carboxyl-terminal palmitoylation sites, which may allow the receptor to adopt different conformations in an agonist-dependent manner (J Biol Chem 277:2534-2546, 2002). By targeted mutation of the proximal (Cys-328/329) or distal (Cys-386) palmitoylation sites, or a combination of both, we generated 5-HT4a receptor variants with distinct functional characteristics. In this study, we showed that upon 5-HT stimulation, the 5-HT4a receptor undergoes rapid (t(1/2) approximately 2 min) and dose-dependent (EC50 approximately 180 nM) phosphorylation on serine residues by a staurosporine-insensitive receptor kinase. Overexpression of GRK2 significantly reduced the receptor-promoted cAMP formation. The Cys328/329-Ser mutant, which is constitutively active in the absence of ligand, exhibited enhanced receptor phosphorylation under both basal and agonist-stimulated conditions and was more effectively desensitized and internalized via a beta-arrestin-2 mediated pathway compared with the wild-type 5-HT4a. In contrast, G protein activation, phosphorylation, desensitization, and internalization of the other palmitoylation-deficient receptor mutants were affected differently. These findings suggest that palmitoylation plays an important role in modulating 5-HT4a receptor functions and that G protein activation, phosphorylation, desensitization, and internalization depend on the different receptor conformations.