G-protein-coupled receptors: evolving views on physiological signalling: symposium on G-protein-coupled receptors: evolving concepts and new techniques.

Department of Pharmacology, Vanderbilt University Medical Center, 23rd Avenue South @ Pierce, Room 442 Robinson Research Building, Nashville, Tennessee 37232-6600, USA.
EMBO Reports (Impact Factor: 7.86). 10/2006; 7(9):866-9. DOI: 10.1038/sj.embor.7400788
Source: PubMed


Available from: Michael Holinstat, Aug 04, 2014
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    ABSTRACT: Tec family kinases play critical roles in the activation of immune cells. In particular, Itk is important for the activation of T cells via the T cell Receptor (TcR), however, molecules that cooperate with Itk to activate downstream targets remain little explored. Here we show that Itk interacts with the heterotrimeric G-protein α subunit Gα13 during TcR triggering. This interaction requires membrane localization of both partners, and is partially dependent on GDP- and GTP-bound states of Gα13. Furthermore, we find that Itk interacts with Gα13 via the zinc binding regions within its Tec homology domain. The interaction between Itk and Gα13 also results in tyrosine phosphorylation of Gα13, however this is not required for the interaction. Itk enhances Gα13 mediated activation of serum response factor (SRF) transcriptional activity dependent on its ability to interact with Gα13, but its kinase activity is not required to enhance SRF activity. These data reveal a new pathway regulated by Itk in cells, and suggest cross talk between Itk and G-protein signaling downstream of the TcR.
    The international journal of biochemistry & cell biology 02/2013; DOI:10.1016/j.biocel.2013.02.011 · 4.24 Impact Factor
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    ABSTRACT: Background Adaptive responses in fungi result from the interaction of membrane receptors and extracellular ligands. Many different classes of receptors have been described in eukaryotic cells. Recently a new family of receptors classified as belonging to the progesterone-adiponectin receptor (PAQR) family has been identified. These receptors have the seven transmembrane domains characteristic of G-protein coupled receptors, but their activity has not been associated directly to G proteins. They share sequence similarity to the eubacterial hemolysin III proteins. Results A new receptor, SsPAQR1 (Sporothrixschenckiiprogesterone-adiponectinQ receptor1), was identified as interacting with Sporothrix schenckii G protein alpha subunit SSG-2 in a yeast two-hybrid assay. The receptor was identified as a member of the PAQR family. The cDNA sequence revealed a predicted ORF of 1542 bp encoding a 514 amino acids protein with a calculated molecular weight of 57.8 kDa. Protein domain analysis of SsPAQR1 showed the 7 transmembrane domains (TM) characteristic of G protein coupled receptors and the presence of the distinctive motifs that characterize PAQRs. A yeast-based assay specific for PAQRs identified progesterone as the agonist. S. schenckii yeast cells exposed to progesterone (0.50 mM) showed an increase in intracellular levels of 3′, 5′ cyclic adenosine monophosphate (cAMP) within the first min of incubation with the hormone. Different progesterone concentrations were tested for their effect on the growth of the fungus. Cultures incubated at 35°C did not grow at concentrations of progesterone of 0.05 mM or higher. Cultures incubated at 25°C grew at all concentrations tested (0.01 mM-0.50 mM) with growth decreasing gradually with the increase in progesterone concentration. Conclusion This work describes a receptor associated with a G protein alpha subunit in S. schenckii belonging to the PAQR family. Progesterone was identified as the ligand. Exposure to progesterone increased the levels of cAMP in fungal yeast cells within the first min of incubation suggesting the connection of this receptor to the cAMP signalling pathway. Progesterone inhibited the growth of both the yeast and mycelium forms of the fungus, with the yeast form being the most affected by the hormone.
    BMC Microbiology 09/2012; 12(1):194. DOI:10.1186/1471-2180-12-194 · 2.98 Impact Factor
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    ABSTRACT: Ouardouz M (2014) GDPßS Activates Excitatory Synapses in CA1 Pyramidal Cells by Disinhibiting the PKA Activating Pathway. J Neurol Neurophysiol 5: 235. doi:10.4172/2155-9562.1000235 Copyright: © 2014 Ouardouz M. Objective: During the early postnatal brain developmental stages, excitatory synapses mediated by AMPA receptors are weak or silent. Activity-dependent insertion of AMPA receptors into synapses depends on the activation of protein kinase A. In this work, we investigated the effect of Guanosine 5'-[βthiol] diphosphate (GDP ßS) on excitatory and inhibitory synaptic currents in CA1 pyramidal cells at postnatal days 9-12. Methods: Whole-cell patch-clamp recordings from identified hippocampal CA1 pyramidal cells were used. GDP βS Was applied through the recording electrode. Results: GDP βS induces an increase in excitatory synaptic current amplitude, but not in the inhibitory synaptic current amplitude. An analysis of the change in excitatory synaptic current amplitude in the presence of GDP βS revealed a progressive increase, which is blocked by the protein kinase A inhibitor Rp-3',5'-cyclic monophosphothioatetriethyl-amine (Rp-cAMP), suggesting that GDP βS inhibits G-protein with a tonic negative control on a protein kinase A activating pathway. In addition, GDP βS has no effect on paired-pulse facilitation, suggesting that the glutamate release machinery is not affected. Moreover, as GDP βS was applied to postsynaptic neurons, the increase in excitatory postsynaptic current amplitude is related to changes at the postsynaptic side. Conclusion: Those results suggest that in developing hippocampal CA1 pyramidal cells, the tonic inhibition of a protein kinase A activating pathway by a G-protein prevents the activation of excitatory synapses.
    01/2014; 5(5). DOI:10.4172/2155-9562.1000235