Previously, we reported that lysophosphatidic acid (LPA)-induced adenosine 3',5'-cyclic monophosphate (cAMP) production by human diploid fibroblasts depends on the age of the fibroblasts. In this study, we examined the role of A-kinase anchoring proteins (AKAP) in the regulation of LPA-stimulated cAMP production in senescent fibroblasts. We found that levels of protein kinase C (PKC)-dependent AKAPs, such as Gravin and AKAP79, were elevated in senescent cells. Co-immunoprecipitation experiments revealed that Gravin and AKAP79 do not associate with adenylyl cyclase type 2 (AC2) but bind to AC4/6, which interacts with calcium-dependent PKCs alpha/beta both in young and senescent fibroblasts. When the expression of Gravin and AKAP79 was blocked by small interference RNA transfection, the basal level of cAMP was greatly reduced and the cAMP status after LPA treatment was also reversed. Protein kinase A showed a similar pattern in terms of its basal activity and LPA-dependent modulation. These data suggest that Gravin and to a lesser extent, AKAP79, may play important roles in maintaining the basal AC activity and in coupling the AC systems to inhibitory signals such as Gialpha in young cells, and to stimulatory signals such as PKCs in senescent cells. This study also demonstrates that Gravin is especially important for the long-term activation of PKC by LPA in senescent cells. We conclude that LPA-dependent increased level of cAMP in senescent human diploid fibroblasts is associated with increases in Gravin levels resulting in its increased binding with and activation of calcium-dependent PKC alpha/beta and AC4/6.
Interacting selectively and non-covalently with any protein or protein complex (a complex of two or more proteins that may include other nonprotein molecules).
Evidence
1:
Inferred from Physical InteractionIntAct
Binding of epidermal growth factor (EGF) to its receptor leads to receptor dimerization, assembly of protein complexes, and activation of signaling networks that control key cellular responses. Despite their fundamental role in cell biology, little is known about protein complexes associated with the EGF receptor (EGFR) before growth factor stimulation. We used a modified membrane yeast two-hybrid system together with bioinformatics to identify 87 candidate proteins interacting with the ligand-unoccupied EGFR. Among them was histone deacetylase 6 (HDAC6), a cytoplasmic lysine deacetylase, which we found negatively regulated EGFR endocytosis and degradation by controlling the acetylation status of alpha-tubulin and, subsequently, receptor trafficking along microtubules. A negative feedback loop consisting of EGFR-mediated phosphorylation of HDAC6 Tyr(570) resulted in reduced deacetylase activity and increased acetylation of alpha-tubulin. This study illustrates the complexity of the EGFR-associated interactome and identifies protein acetylation as a previously unknown regulator of receptor endocytosis and degradation.
J. Biol. Chem. 275, 19025-19034 (2000)[PubMed:10858453]
Agonist-induced desensitization and resensitization of G-protein-linked receptors involve the interaction of receptors with protein kinases, phosphatases, beta-arrestin, and clathrin organized by at least one scaffold protein. The dynamic composition of the signaling complexes and the role of the scaffold protein AKAP250 (gravin) in agonist-induced attenuation and recovery of beta-adrenergic receptors were explored by co-immunoprecipitation of target elements, antisense suppression, and confocal microscopy. Gravin associated with unstimulated receptor, and the association was increased significantly after agonist stimulation for up to 60 min. Agonist stimulation also induced a robust association of the receptor-gravin complex with protein kinases A and C, G-protein-linked receptor kinase-2, beta-arrestin, and clathrin. Confocal microscopy of the green fluorescence protein-tagged beta(2)-adrenergic receptor showed that the receptor underwent sequestration after agonist stimulation. Suppression of gravin expression via antisense oligodeoxynucleotides disrupted agonist-induced association of the receptor with G-protein-linked receptor kinase-2, beta-arrestin, and clathrin as well as receptor recovery from desensitization. Gravin deficiency also inhibited agonist-induced sequestration. These data reveal that gravin-mediated formation of signaling complexes with protein kinases/phosphatases, beta-arrestin, and clathrin is essential in agonist-induced internalization and resensitization of G-protein-linked receptors.
A series of molecular signals that proceeds with an activated receptor promoting the exchange of GDP for GTP on the alpha-subunit of an associated heterotrimeric G-protein complex. The GTP-bound activated alpha-G-protein then dissociates from the beta- and gamma-subunits to further transmit the signal within the cell. The pathway begins with receptor-ligand interaction, or for basal GPCR signaling the pathway begins with the receptor activating its G protein in the absence of an agonist, and ends with regulation of a downstream cellular process, e.g. transcription.
J. Biol. Chem. 275, 19025-19034 (2000)[PubMed:10858453]
Agonist-induced desensitization and resensitization of G-protein-linked receptors involve the interaction of receptors with protein kinases, phosphatases, beta-arrestin, and clathrin organized by at least one scaffold protein. The dynamic composition of the signaling complexes and the role of the scaffold protein AKAP250 (gravin) in agonist-induced attenuation and recovery of beta-adrenergic receptors were explored by co-immunoprecipitation of target elements, antisense suppression, and confocal microscopy. Gravin associated with unstimulated receptor, and the association was increased significantly after agonist stimulation for up to 60 min. Agonist stimulation also induced a robust association of the receptor-gravin complex with protein kinases A and C, G-protein-linked receptor kinase-2, beta-arrestin, and clathrin. Confocal microscopy of the green fluorescence protein-tagged beta(2)-adrenergic receptor showed that the receptor underwent sequestration after agonist stimulation. Suppression of gravin expression via antisense oligodeoxynucleotides disrupted agonist-induced association of the receptor with G-protein-linked receptor kinase-2, beta-arrestin, and clathrin as well as receptor recovery from desensitization. Gravin deficiency also inhibited agonist-induced sequestration. These data reveal that gravin-mediated formation of signaling complexes with protein kinases/phosphatases, beta-arrestin, and clathrin is essential in agonist-induced internalization and resensitization of G-protein-linked receptors.
Any process that activates or increases the frequency, rate or extent of the chemical reactions and pathways resulting in the formation of the nucleotide cAMP (cyclic AMP, adenosine 3',5'-cyclophosphate).
Evidence
1:
Inferred from Mutant PhenotypeUniProtKB
Previously, we reported that lysophosphatidic acid (LPA)-induced adenosine 3',5'-cyclic monophosphate (cAMP) production by human diploid fibroblasts depends on the age of the fibroblasts. In this study, we examined the role of A-kinase anchoring proteins (AKAP) in the regulation of LPA-stimulated cAMP production in senescent fibroblasts. We found that levels of protein kinase C (PKC)-dependent AKAPs, such as Gravin and AKAP79, were elevated in senescent cells. Co-immunoprecipitation experiments revealed that Gravin and AKAP79 do not associate with adenylyl cyclase type 2 (AC2) but bind to AC4/6, which interacts with calcium-dependent PKCs alpha/beta both in young and senescent fibroblasts. When the expression of Gravin and AKAP79 was blocked by small interference RNA transfection, the basal level of cAMP was greatly reduced and the cAMP status after LPA treatment was also reversed. Protein kinase A showed a similar pattern in terms of its basal activity and LPA-dependent modulation. These data suggest that Gravin and to a lesser extent, AKAP79, may play important roles in maintaining the basal AC activity and in coupling the AC systems to inhibitory signals such as Gialpha in young cells, and to stimulatory signals such as PKCs in senescent cells. This study also demonstrates that Gravin is especially important for the long-term activation of PKC by LPA in senescent cells. We conclude that LPA-dependent increased level of cAMP in senescent human diploid fibroblasts is associated with increases in Gravin levels resulting in its increased binding with and activation of calcium-dependent PKC alpha/beta and AC4/6.
Any process that increases the rate, frequency, or extent of the protein kinase A signaling cascade. The PKA signaling cascade is the series of reactions, mediated by the intracellular serine/threonine kinase protein kinase A, which occurs as a result of a single trigger reaction or compound.
Evidence
1:
Inferred from Mutant PhenotypeUniProtKB
Previously, we reported that lysophosphatidic acid (LPA)-induced adenosine 3',5'-cyclic monophosphate (cAMP) production by human diploid fibroblasts depends on the age of the fibroblasts. In this study, we examined the role of A-kinase anchoring proteins (AKAP) in the regulation of LPA-stimulated cAMP production in senescent fibroblasts. We found that levels of protein kinase C (PKC)-dependent AKAPs, such as Gravin and AKAP79, were elevated in senescent cells. Co-immunoprecipitation experiments revealed that Gravin and AKAP79 do not associate with adenylyl cyclase type 2 (AC2) but bind to AC4/6, which interacts with calcium-dependent PKCs alpha/beta both in young and senescent fibroblasts. When the expression of Gravin and AKAP79 was blocked by small interference RNA transfection, the basal level of cAMP was greatly reduced and the cAMP status after LPA treatment was also reversed. Protein kinase A showed a similar pattern in terms of its basal activity and LPA-dependent modulation. These data suggest that Gravin and to a lesser extent, AKAP79, may play important roles in maintaining the basal AC activity and in coupling the AC systems to inhibitory signals such as Gialpha in young cells, and to stimulatory signals such as PKCs in senescent cells. This study also demonstrates that Gravin is especially important for the long-term activation of PKC by LPA in senescent cells. We conclude that LPA-dependent increased level of cAMP in senescent human diploid fibroblasts is associated with increases in Gravin levels resulting in its increased binding with and activation of calcium-dependent PKC alpha/beta and AC4/6.
The process of targeting specific proteins to particular membrane-bounded subcellular organelles. Usually requires an organelle specific protein sequence motif.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
My favorites 
My labels 
Login
