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Antonio De Blasi - One of the best experts on this subject based on the ideXlab platform.

  • ReGulation of G Protein-Coupled Receptor kinase subtypes by calcium sensor proteins
    Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 2020
    Co-Authors: Michele Sallese, Luisa Iacovelli, Albana Cumashi, Laura Cuomo, Loredana Capobianco, Antonio De Blasi
    Abstract:

    AbstractG Protein-Coupled Receptor homoloGous desensitization is intrinsically related to the function of a class of S/T kinases named G Protein-Coupled Receptor kinases (GRK). The GRK family is composed of six cloned members, named GRK1 to 6. Studies from different laboratories have demonstrated that different calcium sensor proteins (CSP) can selectively reGulate the activity of GRK subtypes. In the presence of calcium, rhodopsin kinase (GRK1) is inhibited by the photoReceptor-specific CSP recoverin throuGh direct bindinG. Several other recoverin homoloGues (includinG NCS 1, VILIP 1 and hippocalcin) are also able to inhibit GRK1. The ubiquitous calcium-bindinG protein calmodulin (CaM) can inhibit GRK5 with a hiGh affinity (IC50=40–50 nM). A direct interaction between GRK5 and Ca2+/CaM was documented and this bindinG does not influence the catalytic activity of the kinase, but rather reduced GRK5 bindinG to the membrane. These studies suGGest that CSP act as functional analoGues in mediatinG the reGulation of different GRK subtypes by Ca2+. This mechanism is, however, hiGhly selective with respect to the GRK subtypes: while GRK1, but not GRK2 and GRK5, is reGulated by recoverin and other NCS, GRK4, 5 and 6, that belonG to the GRK4 subfamily, are potently inhibited by CaM, which had little or no effect on members of other GRK subfamilies

  • Expression of G protein‐coupled Receptor kinase 4 is associated with breast cancer tumouriGenesis
    The Journal of Pathology, 2008
    Co-Authors: Jun Matsubayashi, Antonio De Blasi, Masakatsu Takanashi, Mingli Xu, Keiki Oikawa, Masao Kinoshita, Koji Fujita, Masami Tanaka, Michel Bouvier, Masahiko Kuroda
    Abstract:

    G-Protein-Coupled Receptor kinases (GRKs) comprise a family of seven mammalian serine/threonine protein kinases that phosphorylate and reGulate aGonist-bound, activated, G-Protein-Coupled Receptors (GPCRs). GRKs and β-arrestins are key participants in the canonical pathways leadinG to phosphorylation-dependent GPCR desensitization, endocytosis, intracellular traffickinG and resensitization. Here we show that GRK4 isoforms are expressed in human breast cancer but not in normal epithelia. In addition, GRK4-over-expressinG cells activated the mitoGen-activated protein kinase (MAPK) mediated by ERK 1/2 and JNK phosphorylation in breast cancer-derived cell lines. Furthermore, suppression of β-arrestins decreased GRK4-stimulated ERK 1/2 or JNK phosphorylations. These data indicate that hiGh-level expression of GRK4 may activate MAPK siGnallinG pathways mediated by β-arrestins in breast cancer cells, suGGestinG that GRK4 may be implicated in breast cancer carcinoGenesis. CopyriGht © 2008 PatholoGical Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

  • the G protein coupled Receptor kinase Grk4 mediates homoloGous desensitization of metabotropic Glutamate Receptor 1
    The FASEB Journal, 2000
    Co-Authors: Michele Sallese, Marianna Storto, E Durbano, Thomas Launey, Ferdinando Nicoletti, Thomas Knopfel, Lorena Salvatore, G Sala, Antonio De Blasi
    Abstract:

    G-Protein-Coupled Receptor kinases (GRKs) are involved in the reGulation of many G-Protein-Coupled Receptors. As opposed to the other GRKs, such as rhodopsin kinase (GRK1) or β-adrenerGic Receptor ...

  • ReGulation of G-Protein-Coupled Receptor kinase subtypes by calcium sensor proteins.
    The FASEB Journal, 1999
    Co-Authors: Luisa Iacovelli, Michele Sallese, Stefania Mariggiò, Antonio De Blasi
    Abstract:

    The process of G-Protein-Coupled Receptor (GPCR) homoloGous desensitization is intrinsically related to the function of a class of S/T kinases named G-Protein-Coupled Receptor kinases (GRK). GRK family is so far composed of six cloned members, named GRK1 to 6, which are classified into three subfamilies: GRK1 is alone in the first (rhodopsin kinase subfamily), GRK2 and 3 form the second [β-adrenerGic Receptor kinase (βARK) subfamily], and GRK4, 5, and 6 constitute the third (GRK4 subfamily). Recent studies from different laboratories have demonstrated that different calcium sensor proteins (CSP) can selectively reGulate the activity of GRK subtypes. In the presence of calcium, rhodopsin kinase (GRK1) is inhibited by the photoReceptor-specific CSP recoverin throuGh direct bindinG. Several other recoverin homoloGues (includinG NCS 1, VILIP 1, and hippocalcin) are also able to inhibit GRK1 in a calcium-dependent manner. The ubiquitous calcium bindinG protein calmodulin (CaM) can inhibit GRK5 with a hiGh affi...

Robin A. Felder - One of the best experts on this subject based on the ideXlab platform.

  • abstract 616 caveolin 1 cav1 inhibits G protein coupled Receptor kinase type 4 Grk4 kinase activity
    Hypertension, 2012
    Co-Authors: Robert E Van Sciver, John J Gildea, Dora Bigler Wang, Robin A. Felder
    Abstract:

    In human renal proximal tubule cells, the dopamine-1 Receptor (D1R) has been shown to increase cAMP production and neGatively reGulate sodium transport. Defects in D1R siGnalinG have been associated with SNPs in G-Protein-Coupled Receptor kinase type 4 (GRK4) which hyperphosphorylates and decreases D1R function, and the D1R uncouplinG phenotype is fully reverted by reducinG GRK4 expression with siRNA. We have also shown that CAV1 co-immunoprecipitates with GRK4, and that the normal D1R inhibition of the sodium transporter, NaKATPase alpha, can be blocked usinG siRNA to CAV1. We therefore hypothesized that CAV1 directly physically interacts with GRK4 and inhibits its kinase activity. UsinG purified human GRK4 and CAV1 proteins and an in-vitro peptide homoGeneous kinase assay, we investiGated the effects of caveolin-1 (CAV1) on the kinase activity of GRK4. By overexpressinG and isolatinG a tandem affinity purified protein (TAP taGGed) functional version of human CAV1 isolated from a human renal proximal tub...

  • Abstract 653: G-Protein-Coupled Receptor Kinase 4 Binds Preferentially To The Caveolin-1{alpha} Isoform In Rat Renal Proximal Tubule Cells
    Hypertension, 2012
    Co-Authors: Dora Bigler Wang, John J Gildea, Robin A. Felder
    Abstract:

    Caveolins, localized in lipid rafts of plasma membranes, tether and reGulate siGnalinG complexes into functional units and have been shown to inhibit G-Protein-Coupled Receptor kinases GRK2 and GRK5 via the caveolin scaffoldinG domain. In human renal proximal tubule cells (RPTC), the dopamine-1-Receptor (D1R) is phosphorylated and inhibited by G Protein-Coupled Receptor kinase 4 (GRK4). Defects in D1R couplinG leads to sodium-retention and a rise in blood pressure. We showed earlier that chronic disruption of lipid rafts or Caveolin-1 (Cav1) protein expression in the kidney induces hypertension in rats by relievinG the steric inhibition of Cav1 on GRK4. Here we extend these studies by examininG caveolin expression in renal proximal tubule cells microdissected from Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR). We discovered a siGnificant decrease in Cav1 and Cav2 expression in SHR compared to WKY (98 ±1.2% reduction; n=3, P

  • Desensitization of human renal D1 dopamine Receptors by G Protein-Coupled Receptor kinase 4
    Kidney International, 2002
    Co-Authors: Hidetsuna Watanabe, Chikh Bengra, P. A. Jose, Jing Xu, Robin A. Felder
    Abstract:

    Desensitization of human renal D 1 dopamine Receptors by G Protein-Coupled Receptor kinase 4. BackGround The D 1 dopamine Receptor, expressed in several nephron seGments, participates in the reGulation of water and electrolyte transport. Because the renal D 1 Receptor is desensitized in Genetic hypertension, we souGht to determine the mechanism(s) of the desensitization of D 1 Receptors endoGenously expressed in renal proximal tubules. Methods The mechanisms involved in the homoloGous desensitization of the D 1 Receptor in human renal proximal tubule cells were studied by measurinG the production of cAMP in response to stimulation or inhibition of G Protein-Coupled Receptor kinase (GRK) activity and expression. Protein expression was assessed by immunoblottinG. Results In human renal proximal tubule cells, the D 1 aGonist, fenoldopam, increased cAMP accumulation (73 ± 2%). Fenoldopam pre-treatment decreased the responsiveness to subsequent fenoldopam stimulation (t 1/2 ≅ 20 min) with complete desensitization at 30 minutes. Recovery occurred Gradually (t 1/2 ≅ 20 min) with full recovery at 60 minutes. Forskolin pretreatment minimally affected the fenoldopam effect, indicatinG a minor involvement of protein kinase A in the homoloGous desensitization process. Because GRKs are involved in the homoloGous desensitization process, we determined the consequences of inhibition of GRK expression and activity. Heparin, an inhibitor of GRK activity, decreased the expression of GRK2 and GRK4 and attenuated the desensitization of the D 1 Receptor (85 ± 1%). Antisense oliGonucleotides (GRK4> GRK2) blunted the D 1 Receptor desensitization. However, the first 20 minutes of homoloGous desensitization were not affected by either heparin or GRK antisense oliGonucleotides. Conclusion These studies document the critical role of GRK4, relative to GRK2, in the homoloGous desensitization of D 1 Receptors in renal proximal tubule cells. However, the early phase of homoloGous desensitization is reGulated by a non-GRK-mediated pathway.

Federico Mayor - One of the best experts on this subject based on the ideXlab platform.

  • G Protein-Coupled Receptor kinase 2 (GRK2) as a multifunctional siGnalinG hub
    Cellular and Molecular Life Sciences, 2019
    Co-Authors: Petronila Penela, Catalina Ribas, Francisco Sánchez-madrid, Federico Mayor
    Abstract:

    AccumulatinG evidence indicates that G Protein-Coupled Receptor kinase 2 (GRK2) is a versatile protein that acts as a siGnalinG hub by modulatinG G Protein-Coupled Receptor (GPCR) siGnalinG and also via phosphorylation or scaffoldinG interactions with an extensive number of non-GPCR cellular partners. GRK2 multifunctionality arises from its multidomain structure and from complex mechanisms of reGulation of its expression levels, activity, and localization within the cell, what allows the precise spatio-temporal shapinG of GRK2 tarGets. A better understandinG of the GRK2 interactome and its modulation mechanisms is helpinG to identify the GRK2-interactinG proteins and its substrates involved in the participation of this kinase in different cellular processes and pathophysioloGical contexts.

  • DeGradation of the G Protein-Coupled Receptor Kinase 2 by the Proteasome Pathway
    Journal of Biological Chemistry, 1998
    Co-Authors: Petronila Penela, Ana Ruiz-gómez, José G. Castaño, Federico Mayor
    Abstract:

    Abstract GRK2 is a ubiquitous member of the G Protein-Coupled Receptor kinase (GRK) family and has been shown to play a key role in determininG the desensitization and resensitization patterns of a variety of G Protein-Coupled Receptors. In this report, we show that GRK2 is actively deGraded by the proteasome proteolytic pathway, unveilinG a new mechanism for the rapid reGulation of its expression levels. InterestinGly, activation of β2-adrenerGic Receptors (β2AR) markedly increases GRK2 ubiquitination and deGradation throuGh the proteasome pathway. In addition, blockinG GRK2 deGradation notably alters β2AR siGnalinG and internalization, consistent with a relevant physioloGical role for GRK2 proteasomal deGradation. Activity-dependent modulation of GRK2 cellular levels emerGes as an important mechanism for modulatinG the cellular response to aGonists actinG throuGh G Protein-Coupled Receptors.

  • The subcellular and cellular distribution of G Protein-Coupled Receptor kinase 2 in rat brain
    Neuroscience, 1998
    Co-Authors: Cristina Murga, Petronila Penela, Francisco Zafra, Federico Mayor
    Abstract:

    Abstract G Protein-Coupled Receptor kinase 2 has been found to phosphorylate and thus reGulate the activity of several G Protein-Coupled Receptors implicated in neuronal siGnallinG pathways. AlthouGh this kinase was initially described as a soluble protein, our laboratory has recently found that a siGnificant amount of G Protein-Coupled Receptor kinase 2 is associated with microsomal membranes in liver and different types of cultured cells. In the present report we show that hiGh G Protein-Coupled Receptor kinase 2 specific activity and protein levels are present in microsomal fractions of rat brain homoGenates. On the other hand, immunochemical detection usinG a new antibody raised aGainst the N-terminus of the kinase revealed a specific and widely distributed staininG in different areas of the central nervous system, and the association of G Protein-Coupled Receptor kinase 2 with intracellular structures in nervous cells. Our results further suGGest that this Receptor kinase may be involved in the modulation of G Protein-Coupled Receptor-mediated neurotransmission and that association with microsomal membranes may play a role in G Protein-Coupled Receptor kinase 2 functions in the brain.

  • G-Protein-Coupled Receptor kinases
    Kidney International, 1996
    Co-Authors: Martin J Lohse, Rainer Winstel, Cornelius Krasel, Federico Mayor
    Abstract:

    G-Protein-Coupled Receptor kinases. β-AdrenerGic Receptors are prototypes of the many G-Protein-Coupled Receptors. Activation and inactivation of these Receptors are reGulated by multiple mechanisms which can affect either their function or their expression. The most obvious chanGes of such Receptor systems are induced by activation of the Receptors themselves by their respective aGonists, and this process is called Receptor desensitization. One of these mechanisms of desensitization is due to the actions of specific Receptor kinases, termed the G-Protein-Coupled Receptor kinases (GRKs). These kinases specifically phosphorylate only the aGonist-occupied form of such Receptors. This phosphorylation is then followed by bindinG of inhibitor proteins, called arrestins, to the Receptors. BindinG of arrestins results in displacement of the G-proteins from the Receptors and hence causes uncouplinG of Receptors and G-proteins. Recent data indicate that the function and subcellular distribution of GRKs is itself subject to reGulation. Various mechanisms have evolved to anchor the different GRKs to the plasma membrane. In addition, recent data indicate that GRKs can also associate with intracellular membranes where they may exert as yet unknown functions. A pathophysioloGical role for GRKs can be inferred from recent studies on heart failure as well as the observation that chronic treatment with various aGonists or antaGonists for G-Protein-Coupled Receptors results in alterations of GRK expression.

Michele Sallese - One of the best experts on this subject based on the ideXlab platform.

  • ReGulation of G Protein-Coupled Receptor kinase subtypes by calcium sensor proteins
    Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 2020
    Co-Authors: Michele Sallese, Luisa Iacovelli, Albana Cumashi, Laura Cuomo, Loredana Capobianco, Antonio De Blasi
    Abstract:

    AbstractG Protein-Coupled Receptor homoloGous desensitization is intrinsically related to the function of a class of S/T kinases named G Protein-Coupled Receptor kinases (GRK). The GRK family is composed of six cloned members, named GRK1 to 6. Studies from different laboratories have demonstrated that different calcium sensor proteins (CSP) can selectively reGulate the activity of GRK subtypes. In the presence of calcium, rhodopsin kinase (GRK1) is inhibited by the photoReceptor-specific CSP recoverin throuGh direct bindinG. Several other recoverin homoloGues (includinG NCS 1, VILIP 1 and hippocalcin) are also able to inhibit GRK1. The ubiquitous calcium-bindinG protein calmodulin (CaM) can inhibit GRK5 with a hiGh affinity (IC50=40–50 nM). A direct interaction between GRK5 and Ca2+/CaM was documented and this bindinG does not influence the catalytic activity of the kinase, but rather reduced GRK5 bindinG to the membrane. These studies suGGest that CSP act as functional analoGues in mediatinG the reGulation of different GRK subtypes by Ca2+. This mechanism is, however, hiGhly selective with respect to the GRK subtypes: while GRK1, but not GRK2 and GRK5, is reGulated by recoverin and other NCS, GRK4, 5 and 6, that belonG to the GRK4 subfamily, are potently inhibited by CaM, which had little or no effect on members of other GRK subfamilies

  • the G protein coupled Receptor kinase Grk4 mediates homoloGous desensitization of metabotropic Glutamate Receptor 1
    The FASEB Journal, 2000
    Co-Authors: Michele Sallese, Marianna Storto, E Durbano, Thomas Launey, Ferdinando Nicoletti, Thomas Knopfel, Lorena Salvatore, G Sala, Antonio De Blasi
    Abstract:

    G-Protein-Coupled Receptor kinases (GRKs) are involved in the reGulation of many G-Protein-Coupled Receptors. As opposed to the other GRKs, such as rhodopsin kinase (GRK1) or β-adrenerGic Receptor ...

  • ReGulation of G-Protein-Coupled Receptor kinase subtypes by calcium sensor proteins.
    The FASEB Journal, 1999
    Co-Authors: Luisa Iacovelli, Michele Sallese, Stefania Mariggiò, Antonio De Blasi
    Abstract:

    The process of G-Protein-Coupled Receptor (GPCR) homoloGous desensitization is intrinsically related to the function of a class of S/T kinases named G-Protein-Coupled Receptor kinases (GRK). GRK family is so far composed of six cloned members, named GRK1 to 6, which are classified into three subfamilies: GRK1 is alone in the first (rhodopsin kinase subfamily), GRK2 and 3 form the second [β-adrenerGic Receptor kinase (βARK) subfamily], and GRK4, 5, and 6 constitute the third (GRK4 subfamily). Recent studies from different laboratories have demonstrated that different calcium sensor proteins (CSP) can selectively reGulate the activity of GRK subtypes. In the presence of calcium, rhodopsin kinase (GRK1) is inhibited by the photoReceptor-specific CSP recoverin throuGh direct bindinG. Several other recoverin homoloGues (includinG NCS 1, VILIP 1, and hippocalcin) are also able to inhibit GRK1 in a calcium-dependent manner. The ubiquitous calcium bindinG protein calmodulin (CaM) can inhibit GRK5 with a hiGh affi...

  • Two Isoforms of G Protein-Coupled Receptor Kinase 4 Identified by Molecular CloninG
    Biochemical and Biophysical Research Communications, 1994
    Co-Authors: Michele Sallese, M.s. Lombardi, A. Deblasi
    Abstract:

    Abstract UsinG PCR we found that G Protein-Coupled Receptor kinase4 (GRK4) mRNA is expressed only in brain out of several tissues tested. In the brain two amplification products were Generated. Sequence analysis revealed that the two fraGments differed only by the presence or absence of an in-frame-sequence of 96 bp/32 aminoacids, located near the N-terminal of the kinase. This demonstrates the existence of two isoforms of GRK4 which were named GRK4A and GRK4B in the presence or absence of the insert, respectively. This is the first evidence that, within the GRKs Gene family, different isoforms do exist.

Daisuke Asai - One of the best experts on this subject based on the ideXlab platform.

  • DesiGn of substrates and inhibitors of G Protein-Coupled Receptor kinase 2 (GRK2) based on its phosphorylation reaction
    Amino Acids, 2020
    Co-Authors: Jeong-hun Kang, Riki Toita, Masaharu Murata, Takahito Kawano, Daisuke Asai
    Abstract:

    The G Protein-Coupled Receptor kinase (GRK) family consists of seven cytosolic serine/threonine (Ser/Thr) protein kinases, and amonG them, GRK2 is involved in the reGulation of an enormous ranGe of both G Protein-Coupled Receptors (GPCRs) and non-GPCR substrates that participate in or reGulate many critical cellular processes. GRK2 dysfunction is associated with multiple diseases, includinG cancers, brain diseases, cardiovascular and metabolic diseases, and therefore GRK2-specific substrates/inhibitors are needed not only for studies of GRK2-mediated cellular functions but also for GRK2-tarGeted druG development. Here, we first review the structure, reGulation and functions of GRK2, and its synthetic substrates and inhibitors. We then hiGhliGht recent work on synthetic peptide substrates/inhibitors as promisinG tools for fundamental studies of the physioloGical functions of GRK2, and as candidates for applications in clinical diaGnostics.

  • A hiGh-affinity peptide substrate for G Protein-Coupled Receptor kinase 2 (GRK2)
    Amino Acids, 2019
    Co-Authors: Daisuke Asai, Masaharu Murata, Riki Toita, Takahito Kawano, Hideki Nakashima, Jeong-hun Kang
    Abstract:

    We synthesized a previously identified β-tubulin-derived G Protein-Coupled Receptor kinase 2 (GKR2) peptide (GR-11-1; DEMEF T EAESNMN) and its amino-terminal extension (GR-11-1-N; GEGMDEMEF T EAESNMN) and carboxyl-terminal extension (GR-11-1-C; DEMEF T EAESNMNDLVSEYQ) peptides with the aim of findinG a hiGh-affinity peptide substrate for GRK2. GR-11-1-C showed hiGh affinity for GRK2, but very low affinity for GKR5. Its specificity and sensitivity for GKR2 were Greater than those of GR-11-1 and GR-11-1-N. These findinGs should be useful in desiGninG tools for probinG GKR2-mediated intracellular siGnalinG pathways, as well as GRK2-specific druGs.