scholarly journals Ligand-binding and -scavenging of the chemerin receptor GPR1

2021 ◽  
Author(s):  
Tobias F. Fischer ◽  
Anne S. Czerniak ◽  
Tina Weiß ◽  
Clara T. Schoeder ◽  
Philipp Wolf ◽  
...  
Keyword(s):  
Binding Mode ◽  
Loop Structure ◽  
Ligand Specificity ◽  
Extracellular Loop ◽  
Extracellular Loops ◽  
C Terminus ◽  
Loop 2 ◽  
G Protein Coupled ◽  
Migration Of Macrophages

AbstractTight regulation of cytokines is essential for the initiation and resolution of inflammation. Chemerin, a mediator of innate immunity, mainly acts on chemokine-like receptor 1 (CMKLR1) to induce the migration of macrophages and dendritic cells. The role of the second chemerin receptor, G protein-coupled receptor 1 (GPR1), is still unclear. Here we demonstrate that GPR1 shows ligand-induced arrestin3 recruitment and internalization. The chemerin C-terminus triggers this activation by folding into a loop structure, binding to aromatic residues in the extracellular loops of GPR1. While this overall binding mode is shared between GPR1 and CMKLR1, differences in their respective extracellular loop 2 allowed for the design of the first GPR1-selective peptide. However, our results suggest that ligand-induced arrestin recruitment is not the only mode of action of GPR1. This receptor also displays constitutive internalization, which allows GPR1 to internalize inactive peptides efficiently by an activation-independent pathway. Our results demonstrate that GPR1 takes a dual role in regulating chemerin activity: as a signaling receptor for arrestin-based signaling on one hand, and as a scavenging receptor with broader ligand specificity on the other. Graphic abstract

scholarly journals Ligand-Induced and -Independent Internalization of the Chemerin Receptor GPR1

2021 ◽  
Author(s):  
Tobias F. Fischer ◽  
Anne S. Czerniak ◽  
Tina Weiß ◽  
Clara T. Schoeder ◽  
Philipp Wolf ◽  
...  
Keyword(s):  
Binding Mode ◽  
Loop Structure ◽  
Ligand Specificity ◽  
Extracellular Loop ◽  
Extracellular Loops ◽  
C Terminus ◽  
Loop 2 ◽  
G Protein Coupled ◽  
Migration Of Macrophages

Abstract 1. Tight regulation of cytokines is essential for the initiation and resolution of inflammation. Chemerin, a mediator of innate immunity, mainly acts on chemokine-like receptor 1 (CMKLR1) to induce the migration of macrophages and dendritic cells. The role of the second chemerin receptor, G protein-coupled receptor 1 (GPR1), is still unclear. Here we demonstrate that GPR1 shows ligand-induced arrestin3 recruitment and internalization. The chemerin C-terminus triggers this activation by folding into a loop structure, binding to aromatic residues in the extracellular loops of GPR1. While this overall binding mode is shared between GPR1 and CMKLR1, differences in their respective extracellular loop 2 allowed for the design of the first GPR1-selective peptide. However, our results suggest that ligand-induced arrestin recruitment is not the only mode of action of GPR1. This receptor also displays constitutive internalization and recycling, which allows GPR1 to internalize inactive peptides efficiently by an activation-independent pathway. Our results demonstrate that GPR1 takes a dual role in regulating chemerin activity: As a signaling receptor for arrestin-based signaling on one hand, and as a scavenging receptor with broader ligand specificity on the other.

scholarly journals FSH receptor-specific residues L501 and I505 in extracellular loop 2 are essential for its function

2015 ◽  
Vol 54 (3) ◽  
pp. 193-204 ◽  
Author(s):  
Antara A Banerjee ◽  
Madhavi Dupakuntla ◽  
Bhakti R Pathak ◽  
Smita D Mahale
Keyword(s):  
Amino Acids ◽  
Hek293 Cells ◽  
Fsh Receptor ◽  
Receptor Function ◽  
Extracellular Loop ◽  
Camp Production ◽  
Transfected Cells ◽  
Erk Phosphorylation ◽  
Loop 2

The extracellular loop 2 (EL2) of FSH receptor (FSHR) plays a pivotal role in various events downstream of FSH stimulation. Because swapping the six FSHR-specific residues in EL2 (chimeric EL2M) with those from LH/choriogonadotropin receptor resulted in impaired internalization of FSH–FSHR complex and low FSH-induced cAMP production, six substitution mutants of EL2 were generated to ascertain the contribution of individual amino acids to the effects shown by chimeric EL2M. Results revealed that L501F mainly and I505V to a lesser extent contribute to the diminished receptor function in chimeric EL2M. HEK293 cells stably expressing WT and chimeric EL2M FSHR were generated to track the fate of the receptors post FSH induction. The chimeric EL2M FSHR stable clone showed weak internalization and cAMP response similar to transiently transfected cells. Furthermore, reduced FSH-induced ERK phosphorylation was also observed. The interaction of activated chimeric EL2M and L501F FSHR with β-arrestins was weak compared with WT FSHR, thus explaining the impaired internalization of chimeric EL2M and corroborating the indispensable role of EL2 in receptor function.

scholarly journals Differential phosphorylation signals control endocytosis of GPR15

2017 ◽  
Vol 28 (17) ◽  
pp. 2267-2281 ◽  
Author(s):  
Yukari Okamoto ◽  
Sojin Shikano
Keyword(s):  
Surface Density ◽  
Functional Role ◽  
Control Cell ◽  
Phosphorylation Site ◽  
Hek293 Cells ◽  
C Terminus ◽  
Differential Phosphorylation ◽  
G Protein Coupled

GPR15 is an orphan G protein–coupled receptor (GPCR) that serves for an HIV coreceptor and was also recently found as a novel homing receptor for T-cells implicated in colitis. We show that GPR15 undergoes a constitutive endocytosis in the absence of ligand. The endocytosis was clathrin dependent and partially dependent on β-arrestin in HEK293 cells, and nearly half of the internalized GPR15 receptors were recycled to the plasma membrane. An Ala mutation of the distal C-terminal Arg-354 or Ser-357, which forms a consensus phosphorylation site for basophilic kinases, markedly reduced the endocytosis, whereas phosphomimetic mutation of Ser-357 to Asp did not. Ser-357 was phosphorylated in vitro by multiple kinases, including PKA and PKC, and pharmacological activation of these kinases enhanced both phosphorylation of Ser-357 and endocytosis of GPR15. These results suggested that Ser-357 phosphorylation critically controls the ligand-independent endocytosis of GPR15. The functional role of Ser-357 in endocytosis was distinct from that of a conserved Ser/Thr cluster in the more proximal C-terminus, which was responsible for the β-arrestin– and GPCR kinase–dependent endocytosis of GPR15. Thus phosphorylation signals may differentially control cell surface density of GPR15 through endocytosis.

The role of the extracellular loops of the CGRP receptor, a family B GPCR

2012 ◽  
Vol 40 (2) ◽  
pp. 433-437 ◽  
Author(s):  
James Barwell ◽  
Michael J. Woolley ◽  
Mark Wheatley ◽  
Alex C. Conner ◽  
David R. Poyner
Keyword(s):  
Surface Expression ◽  
Receptor Activation ◽  
Receptor Expression ◽  
Cell Surface Expression ◽  
Calcitonin Receptor ◽  
Transmembrane Helices ◽  
Extracellular Loops ◽  
Calcitonin Gene ◽  
G Protein Coupled

The CGRP (calcitonin gene-related peptide) receptor is a family B GPCR (G-protein-coupled receptor). It consists of a GPCR, CLR (calcitonin receptor-like receptor) and an accessory protein, RAMP1 (receptor activity-modifying protein 1). RAMP1 is needed for CGRP binding and also cell-surface expression of CLR. There have been few systematic studies of the ECLs (extracellular loops) of family B GPCRs. However, they are likely to be especially important for the interaction of the N-termini of the peptide agonists that are the natural agonists for these receptors. We have carried out alanine scans on all three ECLs of CLR, as well as their associated juxtamembrane regions. Residues within all three loops influence CGRP binding and receptor activation. Mutation of Ala203 and Ala206 on ECL1 to leucine increased the affinity of CGRP. Residues at the top of TM (transmembrane) helices 2 and 3 influenced CGRP binding and receptor activation. L351A and E357A in TM6/ECL3 reduced receptor expression and may be needed for CLR association with RAMP1. ECL2 seems especially important for CLR function; of the 16 residues so far examined in this loop, eight residues reduce the potency of CGRP at stimulating cAMP production when mutated to alanine.

scholarly journals A unique hormonal recognition feature of the human glucagon-like peptide-2 receptor

Cell Research ◽  
2020 ◽  
Vol 30 (12) ◽  
pp. 1098-1108 ◽  
Author(s):  
Wen Sun ◽  
Li-Nan Chen ◽  
Qingtong Zhou ◽  
Li-Hua Zhao ◽  
Dehua Yang ◽  
...  
Keyword(s):  
Drug Targets ◽  
Receptor Activation ◽  
Ligand Specificity ◽  
Middle Region ◽  
Transmembrane Helices ◽  
Intestinal Hormones ◽  
Functional Studies ◽  
C Terminus ◽  
Class B ◽  
G Protein Coupled

AbstractGlucagon-like peptides (GLP-1 and GLP-2) are two proglucagon-derived intestinal hormones that mediate distinct physiological functions through two related receptors (GLP-1R and GLP-2R) which are important drug targets for metabolic disorders and Crohn’s disease, respectively. Despite great progress in GLP-1R structure determination, our understanding on the differences of peptide binding and signal transduction between these two receptors remains elusive. Here we report the electron microscopy structure of the human GLP-2R in complex with GLP-2 and a Gs heterotrimer. To accommodate GLP-2 rather than GLP-1, GLP-2R fine-tunes the conformations of the extracellular parts of transmembrane helices (TMs) 1, 5, 7 and extracellular loop 1 (ECL1). In contrast to GLP-1, the N-terminal histidine of GLP-2 penetrates into the receptor core with a unique orientation. The middle region of GLP-2 engages with TM1 and TM7 more extensively than with ECL2, and the GLP-2 C-terminus closely attaches to ECL1, which is the most protruded among 9 class B G protein-coupled receptors (GPCRs). Functional studies revealed that the above three segments of GLP-2 are essential for GLP-2 recognition and receptor activation, especially the middle region. These results provide new insights into the molecular basis of ligand specificity in class B GPCRs and may facilitate the development of more specific therapeutics.

cDNA cloning of a novel G protein-coupled receptor with a large extracellular loop structure

1996 ◽  
Vol 1305 (1-2) ◽  
pp. 39-43 ◽  
Author(s):  
Aleksandra Roglić ◽  
Eric R. Prossnitz ◽  
Stacey L. Cavanagh ◽  
Zhixing Pan ◽  
Aihua Zou ◽  
...  
Keyword(s):  
G Protein ◽  
Cdna Cloning ◽  
Loop Structure ◽  
Extracellular Loop ◽  
G Protein Coupled Receptor ◽  
Large Extracellular Loop ◽  
G Protein Coupled

scholarly journals Characterization of feline ASCT1 and ASCT2 as RD-114 virus receptor

2013 ◽  
Vol 94 (7) ◽  
pp. 1608-1612 ◽  
Author(s):  
Sayumi Shimode ◽  
Rie Nakaoka ◽  
Hiroko Shogen ◽  
Takayuki Miyazawa
Keyword(s):  
Endogenous Retrovirus ◽  
Amino Acid Transporters ◽  
Extracellular Loop ◽  
Virus Receptor ◽  
Metabolic Role ◽  
Virus Receptors ◽  
Sodium Dependent ◽  
Loop 2

RD-114 virus is a replication-competent feline endogenous retrovirus (ERV). RD-114 virus had been thought to be xenotropic; however, recent findings indicate that RD-114 virus is polytropic and can infect and grow efficiently in feline cells. Receptor(s) for RD-114 virus has not been identified and characterized in cats. In this study, we confirmed that two feline sodium-dependent neutral amino acid transporters (ASCTs), fASCT1 and fASCT2, function as RD-114 virus receptors. By chimeric analyses of feline and murine ASCTs, we revealed that extracellular loop 2 of both fASCT1 and fASCT2 determines the susceptibility to RD-114 virus. Further, we revealed ubiquitous expression of these genes, consistent with the general metabolic role of the ASCT molecules. Our study indicates that RD-114 virus may reinfect tissues and cells in cats, once the virus is activated. Implications of the involvement of RD-114 virus in feline oncogenesis are also discussed.

scholarly journals Amphotropic Murine Leukemia Virus Entry Is Determined by Specific Combinations of Residues from Receptor Loops 2 and 4

1999 ◽  
Vol 73 (4) ◽  
pp. 3169-3175 ◽  
Author(s):  
Mikkel D. Lundorf ◽  
Finn S. Pedersen ◽  
Bryan O’Hara ◽  
Lene Pedersen
Keyword(s):  
Murine Leukemia Virus ◽  
Leukemia Virus ◽  
Membrane Topology ◽  
Chimeric Proteins ◽  
Receptor Function ◽  
Amphotropic Murine Leukemia Virus ◽  
Extracellular Loops ◽  
Loop 2 ◽  
Murine Leukemia

ABSTRACT Pit2 is the human receptor for amphotropic murine leukemia virus (A-MuLV); the related human protein Pit1 does not support A-MuLV entry. Interestingly, chimeric proteins in which either the N-terminal or the C-terminal part of Pit2 was replaced by the Pit1 sequence all retained A-MuLV receptor function. A possible interpretation of these observations is that Pit1 harbors sequences which can specify A-MuLV receptor function when presented in a protein context other than Pit1, e.g., in Pit1-Pit2 hybrids. We reasoned that such Pit1 sequences might be identified if presented in the Neurospora crassa protein Pho-4. This protein is distantly related to Pit1 and Pit2, predicted to have a similar membrane topology with five extracellular loops, and does not support A-MuLV entry. We show here that introduction of the Pit1-specific loop 2 sequence conferred A-MuLV receptor function upon Pho-4. Therefore, we conclude that (i) a functional A-MuLV receptor can be constructed by combining sequences from two proteins each lacking A-MuLV receptor function and that (ii) a Pit1 sequence can specify A-MuLV receptor function when presented in another protein context than that provided by Pit1 itself. Previous results indicated a role of loop 4 residues in A-MuLV entry, and the presence of a Pit2-specific loop 4 sequence was found here to confer A-MuLV receptor function upon Pho-4. Moreover, the introduction of a Pit1-specific loop 4 sequence, but not of a Pit2-specific loop 4 sequence, abolished the A-MuLV receptor function of a Pho-4 chimera harboring the Pit1-specific loop 2 sequence. Together, these data suggest that residues in both loop 2 and loop 4 play a role in A-MuLV receptor function. A-MuLV is, however, not dependent on the specific Pit2 loop 2 and Pit2 loop 4 sequences for entry; rather, the role played by loops 2 and 4 in A-MuLV entry can be fulfilled by several different combinations of loop 2 and loop 4 sequences. We predict that the residues in loops 2 and 4, identified in this study as specifying A-MuLV receptor function, are to be found among those not conserved among Pho-4, Pit1, and Pit2.

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