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Robert J Lefkowitz - One of the best experts on this subject based on the ideXlab platform.
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Beta Arrestin 1 and galphaq 11 coordinately activate rhoa and stress fiber formation following receptor stimulation
Journal of Biological Chemistry, 2005Co-Authors: William G Barnes, Graeme Milligan, Eric Reiter, Jonathan D Violin, Xiurong Ren, Robert J LefkowitzAbstract:Beta-Arrestins were initially shown, in conjunction with G protein-coupled receptor kinases, to be involved in the desensitization and internalization of activated seven-transmembrane receptors. Recently, Beta-Arrestin 2 has been shown to act as a signal mediator in mitogen-activated protein kinase cascades and to play a positive regulatory role in chemotaxis. We now show that Beta-Arrestin 1 is required to activate the small GTPase RhoA leading to the re-organization of stress fibers following the activation of the angiotensin II type 1A receptor. This angiotensin II type 1A receptor-directed RhoA activation and stress fiber formation also require the activation of the heterotrimeric G protein G(alphaq/11). Whereas neither Beta-Arrestin 1 nor G(alphaq/11) activation alone is sufficient to robustly activate RhoA, the concurrent recruitment of Beta-Arrestin 1 and activation of G(alphaq/11) leads to full activation of RhoA and to the subsequent formation of stress fibers.
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Beta Arrestin 1 and 2 differentially regulate heptahelical receptor signaling and trafficking
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: Trudy A Kohout, Fang-tsyr Lin, Stephen J. Perry, David A Conner, Robert J LefkowitzAbstract:The two widely coexpressed isoforms of Beta-Arrestin (termed Beta Arrestin 1 and 2) are highly similar in amino acid sequence. The Beta-Arrestins bind phosphorylated heptahelical receptors to desensitize and target them to clathrin-coated pits for endocytosis. To better define differences in the roles of Beta-Arrestin 1 and 2, we prepared mouse embryonic fibroblasts from knockout mice that lack one of the Beta-Arrestins (Beta arr1-KO and Beta arr2-KO) or both (Beta arr1/2-KO), as well as their wild-type (WT) littermate controls. These cells were analyzed for their ability to support desensitization and sequestration of the Beta(2)-adrenergic receptor (Beta(2)-AR) and the angiotensin II type 1A receptor (AT(1A)-R). Both Beta arr1-KO and Beta arr2-KO cells showed similar impairment in agonist-stimulated Beta(2)-AR and AT(1A)-R desensitization, when compared with their WT control cells, and the Beta arr1/2-KO cells were even further impaired. Sequestration of the Beta(2)-AR in the Beta arr2-KO cells was compromised significantly (87% reduction), whereas in the Beta arr1-KO cells it was not. Agonist-stimulated internalization of the AT(1A)-R was only slightly reduced in the Beta arr1-KO but was unaffected in the Beta arr2-KO cells. In the Beta arr1/2-KO cells, the sequestration of both receptors was dramatically reduced. Comparison of the ability of the two Beta-Arrestins to sequester the Beta(2)-AR revealed Beta-Arrestin 2 to be 100-fold more potent than Beta-Arrestin 1. Down-regulation of the Beta(2)-AR was also prevented in the Beta arr1/2-KO cells, whereas no change was observed in the single knockout cells. These findings suggest that sequestration of various heptahelical receptors is regulated differently by the two Beta-Arrestins, whereas both isoforms are capable of supporting receptor desensitization and down-regulation.
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Beta Arrestin 1 and 2 differentially regulate heptahelical receptor signaling and trafficking
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: Trudy A Kohout, Stephen J. Perry, David A Conner, Robert J LefkowitzAbstract:The two widely coexpressed isoforms of β-Arrestin (termed βArrestin 1 and 2) are highly similar in amino acid sequence. The β-Arrestins bind phosphorylated heptahelical receptors to desensitize and target them to clathrin-coated pits for endocytosis. To better define differences in the roles of β-Arrestin 1 and 2, we prepared mouse embryonic fibroblasts from knockout mice that lack one of the β-Arrestins (βarr1-KO and βarr2-KO) or both (βarr1/2-KO), as well as their wild-type (WT) littermate controls. These cells were analyzed for their ability to support desensitization and sequestration of the β2-adrenergic receptor (β2-AR) and the angiotensin II type 1A receptor (AT1A-R). Both βarr1-KO and βarr2-KO cells showed similar impairment in agonist-stimulated β2-AR and AT1A-R desensitization, when compared with their WT control cells, and the βarr1/2-KO cells were even further impaired. Sequestration of the β2-AR in the βarr2-KO cells was compromised significantly (87% reduction), whereas in the βarr1-KO cells it was not. Agonist-stimulated internalization of the AT1A-R was only slightly reduced in the βarr1-KO but was unaffected in the βarr2-KO cells. In the βarr1/2-KO cells, the sequestration of both receptors was dramatically reduced. Comparison of the ability of the two β-Arrestins to sequester the β2-AR revealed β-Arrestin 2 to be 100-fold more potent than β-Arrestin 1. Down-regulation of the β2-AR was also prevented in the βarr1/2-KO cells, whereas no change was observed in the single knockout cells. These findings suggest that sequestration of various heptahelical receptors is regulated differently by the two β-Arrestins, whereas both isoforms are capable of supporting receptor desensitization and down-regulation.
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Enhanced morphine analgesia in mice lacking Beta-Arrestin 2.
Science (New York N.Y.), 1999Co-Authors: Laura M. Bohn, Robert J Lefkowitz, Marc G Caron, Raul R. Gainetdinov, Karsten Peppel, Fang-tsyr LinAbstract:The ability of morphine to alleviate pain is mediated through a heterotrimeric guanine nucleotide binding protein (G protein)-coupled heptahelical receptor (GPCR), the mu opioid receptor (muOR). The efficiency of GPCR signaling is tightly regulated and ultimately limited by the coordinated phosphorylation of the receptors by specific GPCR kinases and the subsequent interaction of the phosphorylated receptors with Beta-Arrestin 1 and Beta-Arrestin 2. Functional deletion of the Beta-Arrestin 2 gene in mice resulted in remarkable potentiation and prolongation of the analgesic effect of morphine, suggesting that muOR desensitization was impaired. These results provide evidence in vivo for the physiological importance of Beta-Arrestin 2 in regulating the function of a specific GPCR, the muOR. Moreover, they suggest that inhibition of Beta-Arrestin 2 function might lead to enhanced analgesic effectiveness of morphine and provide potential new avenues for the study and treatment of pain, narcotic tolerance, and dependence.
Michele Sallese - One of the best experts on this subject based on the ideXlab platform.
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interferon Beta 1a counteracts effects of activation on the expression of g protein coupled receptor kinases 2 and 3 Beta Arrestin 1 and regulators of g protein signalling 2 and 16 in human mononuclear leukocytes
Cellular Signalling, 2002Co-Authors: Maurizio Giorelli, Michele Sallese, Luisa Iacovelli, P Livrea, Giovanni Defazio, Loredana Capobianco, Antonietta Picascia, Davide Martino, Maria Stella Aniello, Maria TrojanoAbstract:Activation regulates the responsiveness of G-protein-coupled receptors (GPCRs) on T cells, and modifications in the activity of GPCRs characterize lymphocytes from some immune disorders such as multiple sclerosis (MS) and rheumatoid arthritis (RA). Some lines of evidence suggest that such an effect is connected with the altered expression of some GPCRs regulatory proteins. Herein we demonstrate that phitoemagglutinin (PHA)-induced activation leads to differential expression of G-protein-coupled receptor kinase (GRK) 2, GRK3, Beta-Arrestin-1, regulators of G-protein signalling (RGS) 2, and RGS16 and decreases responsiveness of mononuclear leukocytes (MNL) to the Beta-adrenergic agonist isoproterenol. Interferon Beta-1a (IFN Beta-1a), which is known to ameliorate the course of MS, counteracts the activation-induced effects on the expression of these GPCR regulatory proteins in MNL. Furthermore, IFN Beta-1a quenches the effects of PHA on the isoproterenol-induced accumulation of cyclic AMP (cAMP). We suggest that regulation of GPCRs responsiveness may be a relevant property of IFN Beta-1a in MS.
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assignment of the Beta Arrestin 1 gene arrb1 to human chromosome 11q13
Genomics, 1994Co-Authors: G. Calabrese, Anna Stornaiuolo, Michele Sallese, Giandomenico Palka, Elisena Morizio, Antonio De BlasiAbstract:Two types of proteins play a major role in determining homologous desensitization of G-coupled receptors: {Beta}-adrenergic receptor kinase ({Beta}ARK), which phosphorylates the agonist-occupied receptor, and its functional cofactor, {Beta}-Arrestin. {Beta}ARK is a member of a multigene family, consisting of six known subtypes, which have also been named G-protein-coupled receptor kinases (GRK 1 to 6) due to the apparently unique functional association of such kinases with this receptor family. The gene for {Beta}ARK1 has been localized to human chromosome 11q13. The four members of the Arrestin/{Beta}-Arrestin gene family identified so far are Arrestin, X-Arrestin, {Beta}-Arrestin 1, and {Beta}-Arrestin 2. Here the authors report the chromosome mapping of the human gene for {Beta}-Arrestin 1 (ARRB1) to chromosome 11q13 by fluorescence in situ hybridization (FISH). Two-color FISH confirmed that the two genes coding for the functionally related proteins {Beta}ARK1 and {Beta}Arrestin 1 both map to 11q13. 16 refs., 1 fig., 1 tab.
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chromosome mapping of the human Arrestin sag β Arrestin 2 arrb2 and β adrenergic receptor kinase 2 adrbk2 genes
Genomics, 1994Co-Authors: G. Calabrese, Anna Stornaiuolo, Michele Sallese, Giandomenico Palka, Liborio Stuppia, Antonio De BlasiAbstract:Two types of proteins play a major role in determining homologous desensitization of G-coupled receptors: {Beta}-adrenergic receptor kinase ({Beta}ARK), which phosphorylates the agonist-occupied receptor and its functional cofactor, {Beta}-Arrestin. Both {Beta}ARK and {Beta}-Arrestin are members of multigene families. The family of G-protein-coupled receptor kinases includes rhodopsin kinase, {Beta}ARK1, {Beta}ARK2, IT11-A (GRK4), GRK5, and GRK6. The Arrestin/{Beta}-Arrestin gene family includes Arrestin (also known as S-antigen), {Beta}-Arrestin 1, and {Beta}-Arrestin 2. Here we report the chromosome mapping of the human genes for Arrestin (SAG), {Beta}Arrestin 2 (ARRB2), and {Beta}ARK2 (ADRBK2) by fluorescence in situ hybridization (FISH). FISH results confirmed the assignment of the gene coding for Arrestin (SAG) to chromosome 2 and allowed us to refine its localization to band q37. The gene coding for {Beta}-Arrestin 2 (ARRB2) was mapped to chromosome 17p13 and that coding for {Beta}ARK2 (ADRBK2) to chromosome 22q11. 17 refs., 1 fig.
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chromosome mapping of the human Arrestin sag Beta Arrestin 2 arrb2 and Beta adrenergic receptor kinase 2 adrbk2 genes
Genomics, 1994Co-Authors: G. Calabrese, Anna Stornaiuolo, Michele Sallese, Giandomenico Palka, Liborio Stuppia, Antonio De BlasiAbstract:Two types of proteins play a major role in determining homologous desensitization of G-coupled receptors: {Beta}-adrenergic receptor kinase ({Beta}ARK), which phosphorylates the agonist-occupied receptor and its functional cofactor, {Beta}-Arrestin. Both {Beta}ARK and {Beta}-Arrestin are members of multigene families. The family of G-protein-coupled receptor kinases includes rhodopsin kinase, {Beta}ARK1, {Beta}ARK2, IT11-A (GRK4), GRK5, and GRK6. The Arrestin/{Beta}-Arrestin gene family includes Arrestin (also known as S-antigen), {Beta}-Arrestin 1, and {Beta}-Arrestin 2. Here we report the chromosome mapping of the human genes for Arrestin (SAG), {Beta}Arrestin 2 (ARRB2), and {Beta}ARK2 (ADRBK2) by fluorescence in situ hybridization (FISH). FISH results confirmed the assignment of the gene coding for Arrestin (SAG) to chromosome 2 and allowed us to refine its localization to band q37. The gene coding for {Beta}-Arrestin 2 (ARRB2) was mapped to chromosome 17p13 and that coding for {Beta}ARK2 (ADRBK2) to chromosome 22q11. 17 refs., 1 fig.
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Molecular analysis of human Beta-Arrestin-1: cloning, tissue distribution, and regulation of expression. Identification of two isoforms generated by alternative splicing.
The Journal of biological chemistry, 1993Co-Authors: G. Parruti, Michele Sallese, F. Peracchia, G Ambrosini, M Masini, D Rotilio, A De BlasiAbstract:Abstract The cDNA for human Beta-Arrestin-1 was cloned by polymerase chain reaction (PCR) and identified based on its remarkably high amino acid identity (98.6%) with the bovine sequence. Two alternatively spliced isoforms of human Beta-Arrestin-1, differing only in the presence or absence of 24 base pairs/8 amino acids within the sequence, were identified and called Beta-Arrestin-1A and Beta-Arrestin-1B, respectively. Both isoforms were found in all tissues tested. Southern blot analysis revealed the existence of a single gene for Beta-Arrestin-1, suggesting that the two isoforms are generated by alternative mRNA splicing. The possible presence of similar isoforms was investigated for the other members of the Arrestin/Beta-Arrestin gene family by PCR. Two isoforms of Arrestin were revealed in bovine peripheral blood leukocytes. The expression of Beta-Arrestin-1 was studied in several human tissues and cell types. High levels of Beta-Arrestin-1 mRNA and immunoreactivity were found in peripheral blood leukocytes. The possible regulation of the expression of Beta-Arrestin-1 was also investigated. Our work documents for the first time that the expression of Beta-Arrestin-1 is modulated by intracellular cAMP. Using two cell types, human endothelial cells and smooth muscle cells, we found that 6-8-h treatments with the cAMP-inducing agents cholera toxin, forskolin, iloprost, and isoproterenol raised Beta-Arrestin-1 mRNA by 2-4-fold. Forskolin preferentially increased Beta-Arrestin-1A expression in smooth muscle cells, as assessed by PCR. Beta-Arrestin-1 immunoreactivity was 2-3-fold higher in smooth muscle cells exposed to forskolin for 8 h, compared with untreated controls. We conclude that (i) the finding of alternatively spliced isoforms of Beta-Arrestin-1 and Arrestin documents a novel mechanism to generate diversity within the Arrestin/Beta-Arrestin gene family; (ii) the abundant expression of Beta-Arrestin-1 in peripheral blood leukocytes further supports our previous suggestion of a major role for the Beta ARK/Beta-Arrestin system in regulating receptor-mediated immune functions; (iii) the increased expression of Beta-Arrestin-1 by cAMP suggests a new mechanism for the regulation of receptor-mediated responses.
Antonio De Blasi - One of the best experts on this subject based on the ideXlab platform.
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assignment of the Beta Arrestin 1 gene arrb1 to human chromosome 11q13
Genomics, 1994Co-Authors: G. Calabrese, Anna Stornaiuolo, Michele Sallese, Giandomenico Palka, Elisena Morizio, Antonio De BlasiAbstract:Two types of proteins play a major role in determining homologous desensitization of G-coupled receptors: {Beta}-adrenergic receptor kinase ({Beta}ARK), which phosphorylates the agonist-occupied receptor, and its functional cofactor, {Beta}-Arrestin. {Beta}ARK is a member of a multigene family, consisting of six known subtypes, which have also been named G-protein-coupled receptor kinases (GRK 1 to 6) due to the apparently unique functional association of such kinases with this receptor family. The gene for {Beta}ARK1 has been localized to human chromosome 11q13. The four members of the Arrestin/{Beta}-Arrestin gene family identified so far are Arrestin, X-Arrestin, {Beta}-Arrestin 1, and {Beta}-Arrestin 2. Here the authors report the chromosome mapping of the human gene for {Beta}-Arrestin 1 (ARRB1) to chromosome 11q13 by fluorescence in situ hybridization (FISH). Two-color FISH confirmed that the two genes coding for the functionally related proteins {Beta}ARK1 and {Beta}Arrestin 1 both map to 11q13. 16 refs., 1 fig., 1 tab.
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chromosome mapping of the human Arrestin sag β Arrestin 2 arrb2 and β adrenergic receptor kinase 2 adrbk2 genes
Genomics, 1994Co-Authors: G. Calabrese, Anna Stornaiuolo, Michele Sallese, Giandomenico Palka, Liborio Stuppia, Antonio De BlasiAbstract:Two types of proteins play a major role in determining homologous desensitization of G-coupled receptors: {Beta}-adrenergic receptor kinase ({Beta}ARK), which phosphorylates the agonist-occupied receptor and its functional cofactor, {Beta}-Arrestin. Both {Beta}ARK and {Beta}-Arrestin are members of multigene families. The family of G-protein-coupled receptor kinases includes rhodopsin kinase, {Beta}ARK1, {Beta}ARK2, IT11-A (GRK4), GRK5, and GRK6. The Arrestin/{Beta}-Arrestin gene family includes Arrestin (also known as S-antigen), {Beta}-Arrestin 1, and {Beta}-Arrestin 2. Here we report the chromosome mapping of the human genes for Arrestin (SAG), {Beta}Arrestin 2 (ARRB2), and {Beta}ARK2 (ADRBK2) by fluorescence in situ hybridization (FISH). FISH results confirmed the assignment of the gene coding for Arrestin (SAG) to chromosome 2 and allowed us to refine its localization to band q37. The gene coding for {Beta}-Arrestin 2 (ARRB2) was mapped to chromosome 17p13 and that coding for {Beta}ARK2 (ADRBK2) to chromosome 22q11. 17 refs., 1 fig.
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chromosome mapping of the human Arrestin sag Beta Arrestin 2 arrb2 and Beta adrenergic receptor kinase 2 adrbk2 genes
Genomics, 1994Co-Authors: G. Calabrese, Anna Stornaiuolo, Michele Sallese, Giandomenico Palka, Liborio Stuppia, Antonio De BlasiAbstract:Two types of proteins play a major role in determining homologous desensitization of G-coupled receptors: {Beta}-adrenergic receptor kinase ({Beta}ARK), which phosphorylates the agonist-occupied receptor and its functional cofactor, {Beta}-Arrestin. Both {Beta}ARK and {Beta}-Arrestin are members of multigene families. The family of G-protein-coupled receptor kinases includes rhodopsin kinase, {Beta}ARK1, {Beta}ARK2, IT11-A (GRK4), GRK5, and GRK6. The Arrestin/{Beta}-Arrestin gene family includes Arrestin (also known as S-antigen), {Beta}-Arrestin 1, and {Beta}-Arrestin 2. Here we report the chromosome mapping of the human genes for Arrestin (SAG), {Beta}Arrestin 2 (ARRB2), and {Beta}ARK2 (ADRBK2) by fluorescence in situ hybridization (FISH). FISH results confirmed the assignment of the gene coding for Arrestin (SAG) to chromosome 2 and allowed us to refine its localization to band q37. The gene coding for {Beta}-Arrestin 2 (ARRB2) was mapped to chromosome 17p13 and that coding for {Beta}ARK2 (ADRBK2) to chromosome 22q11. 17 refs., 1 fig.
Martin J Lohse - One of the best experts on this subject based on the ideXlab platform.
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agonist selective receptor specific interaction of human p2y receptors with Beta Arrestin 1 and 2
Journal of Biological Chemistry, 2008Co-Authors: Carsten Hoffmann, Nicole Ziegler, Susanne Reiner, Cornelius Krasel, Martin J LohseAbstract:Abstract Interaction of G-protein-coupled receptors with β-Arrestins is an important step in receptor desensitization and in triggering “alternative” signals. By means of confocal microscopy and fluorescence resonance energy transfer, we have investigated the internalization of the human P2Y receptors 1, 2, 4, 6, 11, and 12 and their interaction with β-Arrestin-1 and -2. Co-transfection of each individual P2Y receptor with β-Arrestin-1-GFP or β-Arrestin-2-YFP into HEK-293 cells and stimulation with the corresponding agonists resulted in a receptor-specific interaction pattern. The P2Y1 receptor stimulated with ADP strongly translocated β-Arrestin-2-YFP, whereas only a slight translocation was observed for β-Arrestin-1-GFP. The P2Y4 receptor exhibited equally strong translocation for β-Arrestin-1-GFP and β-Arrestin-2-YFP when stimulated with UTP. The P2Y6, P2Y11, and P2Y12 receptor internalized only when GRK2 was additionally co-transfected, but β-Arrestin translocation was only visible for the P2Y6 and P2Y11 receptor. The P2Y2 receptor showed a β-Arrestin translocation pattern that was dependent on the agonist used for stimulation. UTP translocated β-Arrestin-1-GFP and β-Arrestin-2-YFP equally well, whereas ATP translocated β-Arrestin-1-GFP to a much lower extent than β-Arrestin-2-YFP. The same agonist-dependent pattern was seen in fluorescence resonance energy transfer experiments between the fluorescently labeled P2Y2 receptor and β-Arrestins. Thus, the P2Y2 receptor would be classified as a class A receptor when stimulated with ATP or as a class B receptor when stimulated with UTP. The ligand-specific recruitment of β-Arrestins by ATP and UTP stimulation of P2Y2 receptors was further found to result in differential stimulation of ERK phosphorylation. This suggests that the two different agonists induce distinct active states of this receptor that show differential interactions with β-Arrestins.
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Expression of Beta-Arrestins and Beta-adrenergic receptor kinases in the failing human heart.
Circulation research, 1994Co-Authors: Martin Ungerer, E Erdmann, M Bohm, G. Parruti, M Puzicha, A Deblasi, Martin J LohseAbstract:The Beta-adrenergic receptor system of the failing human heart is markedly desensitized. We have recently postulated that this desensitization may in part be caused by an increase in Beta-adrenergic receptor kinase (Beta ARK) expression. Beta ARK is thought to effect desensitization by acting in concert with an inhibitor protein, called Beta-Arrestin. Two isoforms have been identified both for Beta ARK and for Beta-Arrestin. In the present study, we have investigated the expression of the individual isoforms of Beta-Arrestin and of Beta ARK in left ventricles from failing and control human hearts. mRNAs for all four proteins, Beta-Arrestin-1, Beta-Arrestin-2, Beta ARK-1, and Beta ARK-2, were identified in human heart. Quantitation by reverse-transcription polymerase chain reactions showed that in heart failure there were no changes of the mRNA levels for Beta-Arrestin-1 and Beta-Arrestin-2, a slight (< 50%) increase of the mRNA for Beta ARK-2, and a threefold increase for Beta ARK-1 mRNA. At the protein level, Beta-Arrestin-1 was readily detected by Western blotting in human heart. Its absolute values were approximately 350 fmol/mg cytosolic protein, and its expression was not changed in heart failure. Beta-Arrestin-2 levels were too low to be detectable using the same methods. Beta ARK levels as determined by enzymatic activity were approximately 20 fmol/mg cytosolic protein (Beta ARK-1 plus Beta ARK-2) and thus almost 20-fold lower than those of Beta-Arrestin. Beta ARK levels were increased approximately twofold in heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)
Trudy A Kohout - One of the best experts on this subject based on the ideXlab platform.
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Beta Arrestin 1 and 2 differentially regulate heptahelical receptor signaling and trafficking
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: Trudy A Kohout, Fang-tsyr Lin, Stephen J. Perry, David A Conner, Robert J LefkowitzAbstract:The two widely coexpressed isoforms of Beta-Arrestin (termed Beta Arrestin 1 and 2) are highly similar in amino acid sequence. The Beta-Arrestins bind phosphorylated heptahelical receptors to desensitize and target them to clathrin-coated pits for endocytosis. To better define differences in the roles of Beta-Arrestin 1 and 2, we prepared mouse embryonic fibroblasts from knockout mice that lack one of the Beta-Arrestins (Beta arr1-KO and Beta arr2-KO) or both (Beta arr1/2-KO), as well as their wild-type (WT) littermate controls. These cells were analyzed for their ability to support desensitization and sequestration of the Beta(2)-adrenergic receptor (Beta(2)-AR) and the angiotensin II type 1A receptor (AT(1A)-R). Both Beta arr1-KO and Beta arr2-KO cells showed similar impairment in agonist-stimulated Beta(2)-AR and AT(1A)-R desensitization, when compared with their WT control cells, and the Beta arr1/2-KO cells were even further impaired. Sequestration of the Beta(2)-AR in the Beta arr2-KO cells was compromised significantly (87% reduction), whereas in the Beta arr1-KO cells it was not. Agonist-stimulated internalization of the AT(1A)-R was only slightly reduced in the Beta arr1-KO but was unaffected in the Beta arr2-KO cells. In the Beta arr1/2-KO cells, the sequestration of both receptors was dramatically reduced. Comparison of the ability of the two Beta-Arrestins to sequester the Beta(2)-AR revealed Beta-Arrestin 2 to be 100-fold more potent than Beta-Arrestin 1. Down-regulation of the Beta(2)-AR was also prevented in the Beta arr1/2-KO cells, whereas no change was observed in the single knockout cells. These findings suggest that sequestration of various heptahelical receptors is regulated differently by the two Beta-Arrestins, whereas both isoforms are capable of supporting receptor desensitization and down-regulation.
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Beta Arrestin 1 and 2 differentially regulate heptahelical receptor signaling and trafficking
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: Trudy A Kohout, Stephen J. Perry, David A Conner, Robert J LefkowitzAbstract:The two widely coexpressed isoforms of β-Arrestin (termed βArrestin 1 and 2) are highly similar in amino acid sequence. The β-Arrestins bind phosphorylated heptahelical receptors to desensitize and target them to clathrin-coated pits for endocytosis. To better define differences in the roles of β-Arrestin 1 and 2, we prepared mouse embryonic fibroblasts from knockout mice that lack one of the β-Arrestins (βarr1-KO and βarr2-KO) or both (βarr1/2-KO), as well as their wild-type (WT) littermate controls. These cells were analyzed for their ability to support desensitization and sequestration of the β2-adrenergic receptor (β2-AR) and the angiotensin II type 1A receptor (AT1A-R). Both βarr1-KO and βarr2-KO cells showed similar impairment in agonist-stimulated β2-AR and AT1A-R desensitization, when compared with their WT control cells, and the βarr1/2-KO cells were even further impaired. Sequestration of the β2-AR in the βarr2-KO cells was compromised significantly (87% reduction), whereas in the βarr1-KO cells it was not. Agonist-stimulated internalization of the AT1A-R was only slightly reduced in the βarr1-KO but was unaffected in the βarr2-KO cells. In the βarr1/2-KO cells, the sequestration of both receptors was dramatically reduced. Comparison of the ability of the two β-Arrestins to sequester the β2-AR revealed β-Arrestin 2 to be 100-fold more potent than β-Arrestin 1. Down-regulation of the β2-AR was also prevented in the βarr1/2-KO cells, whereas no change was observed in the single knockout cells. These findings suggest that sequestration of various heptahelical receptors is regulated differently by the two β-Arrestins, whereas both isoforms are capable of supporting receptor desensitization and down-regulation.