Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: CAS:7440-70-2 (calcium)
 333,191 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Interleukin 8 (IL-8) and melanocyte growth-stimulatory activity/gro (MGSA) are structurally related proinflammatory cytokines that are chemoattractants and activators of neutrophils. Recently, cDNA clones encoding a high affinity IL-8 receptor (IL-8R-A) and a "low affinity" IL-8 receptor (IL-8R-B) have been isolated from human cDNA libraries. These two receptors have 77% amino acid identity and are members of the G protein-coupled superfamily of receptors with seven transmembrane domains. We have expressed these two receptors in mammalian cells and find that in this system both receptors bind IL-8 with high affinity (Kd approximately 2 nM). The receptor affinities differ for MGSA, however. IL-8R-A binds MGSA with low affinity (Kd approximately 450 nM); IL-8R-B binds MGSA with high affinity (Kd approximately 2 nM). The transfected cells respond to ligand binding with a transient increase in the intracellular Ca2+ concentration. A Ca2+ response is found for IL-8R-A following the binding of IL-8; no response is found for MGSA. A Ca2+ response for IL-8R-B follows the binding of both ligands. Blot hybridization with oligonucleotide probes specific for the two receptors shows that mRNA for both receptors is present in human neutrophils. Analysis of IL-8 and MGSA binding data on neutrophils as well as Ca2+ response and desensitization data shows that the presence of these two IL-8 receptors on the cell surface can account for the profile of these two ligands on neutrophils.
 ...
PMID:Characterization of two high affinity human interleukin-8 receptors. 137 93

Gro beta and IL-8 are two members of the small induced secreted (SIS) cytokine family (C-X-C subgroup) with proinflammatory activities on neutrophils. In order to assess whether or not the interaction with their receptors results in similar biological actions, we compared the two cytokines in five different bioassays. Gro beta showed similar biological activities as IL-8 in tests of chemotaxis, induction of the respiratory burst, and induction of interleukin 6 (IL-6) production. However, for two other biological activities: augmentation of the expression of CD11b on the cell surface and rapid elevation of the intracellular calcium concentration, maximal effects required 100 times more gro beta than IL-8. Taken together, these results suggest that the stimulation of the IL-8 or gro beta receptor evokes three similar responses, but that only the activation of the IL-8 receptor and not that of gro beta results in elevated CD11b expression and calcium mobilization in human neutrophils.
 ...
PMID:The biological activities of gro beta and IL-8 on human neutrophils are overlapping but not identical. 147 97

IP-10, a small, gamma-interferon-inducible protein with structural homology to interleukin-8 (IL-8), was prepared by automated chemical synthesis and compared with synthetic IL-8, GRO alpha and neutrophil-activating peptide 2 (NAP-2) for neutrophil stimulating activity. The following functions were tested: cytosolic free calcium changes, chemotaxis in vitro, respiratory burst, exocytosis of azurophil and specific granules from cytochalasin B-pretreated cells, and competition for IL-8 receptor binding. At 1, 10, 100 and 1000 nM, IP-10 was inactive in all assays, in contrast to the reference peptides which exhibited the expected neutrophil stimulating effects. In addition, IP-10 did not induce neutrophil accumulation after intradermal injection in rats, and did not act as IL-8 antagonist.
 ...
PMID:IP-10, a gamma-interferon-inducible protein related to interleukin-8, lacks neutrophil activating properties. 150 87

Interleukin-8 (IL-8) is a member of a family of pro-inflammatory cytokines. Although the best characterized activities of IL-8 include the chemoattraction and activation of neutrophils, other members of this family have a wide range of specific actions including the chemotaxis and activation of monocytes, the selective chemotaxis of memory T cells, the inhibition of hematopoietic stem cell proliferation, and the induction of neutrophil infiltration in vivo. A complementary DNA encoding the IL-8 receptor from human neutrophils has now been isolated. The amino acid sequence shows that the receptor is a member of the superfamily of receptors that couple to guanine nucleotide binding proteins (G proteins). The sequence is 29% identical to that of receptors for the other neutrophil chemoattractants, fMet-Leu-Phe and C5a. Mammalian cells transfected with the IL-8 receptor cDNA clone bind IL-8 with high affinity and respond specifically to IL-8 by transiently mobilizing calcium. The IL-8 receptor may be part of a subfamily of related G protein-coupled receptors that transduce signals for the IL-8 family of pro-inflammatory cytokines.
 ...
PMID:Structure and functional expression of a human interleukin-8 receptor. 184 Jul 1

Interleukin-8 (IL-8) is an inflammatory cytokine that activates neutrophil chemotaxis, degranulation, and the respiratory burst. Neutrophils express receptors for IL-8 that are coupled to guanine nucleotide-binding proteins (G proteins); binding of IL-8 to its receptor induces the mobilization of intracellular calcium stores. A cDNA clone from HL-60 neutrophils, designated p2, has now been isolated that encodes a human IL-8 receptor. When p2 is expressed in oocytes from Xenopus laevis, the oocytes bind 125I-labeled IL-8 specifically and respond to IL-8 by mobilizing calcium stores with an EC50 of 20 nM. This IL-8 receptor has 77% amino acid identity with a second human neutrophil receptor isotype that binds IL-8 with higher affinity. It also exhibits 69% amino acid identity with a protein reported to be an N-formyl peptide receptor from rabbit neutrophils, but less than 30% identity with all other known G protein-coupled receptors, including the human N-formyl peptide receptor.
 ...
PMID:Cloning of complementary DNA encoding a functional human interleukin-8 receptor. 189 16

Recently a rabbit cDNA (F3R) was characterized as binding and causing calcium mobilization induced by the formyl-methionine-leucine-phenylalanine peptide (fMLP). In the study reported here, cloned DNAs were isolated from rabbit genomic DNA by PCR based on the sequence of F3R. The cloned DNAs have several differences in the DNA sequence compared to the reported F3R sequence that alter the predicted protein sequence. COS-7 cells transfected with these clones in a mammalian expression vector bind human IL-8 with high affinity, but do not bind fMLP. We therefore believe that the cDNAs isolated encode the rabbit IL-8 receptor.
 ...
PMID:Molecular characterization of the interleukin-8 receptor. 189

To define the molecular mechanisms of cross-regulation among chemoattractant receptors, we stably coexpressed, in a rat basophilic leukemia (RBL-2H3) cell line, epitope-tagged receptors for the chemoattractants formylmethionylleucylphenylalanine (fMLP), a peptide of the fifth component of the complement system (C5a), and interleukin-8 (IL-8). All the expressed receptors underwent homologous phosphorylation and desensitization upon agonist stimulation. When co-expressed, epitope-tagged C5a receptor (ET-C5aR) and epitope-tagged IL-8 receptor (ET-IL-8RA) were cross-phosphorylated by activation of the other. Activation of epitope-tagged fMLP receptor (ET-FR) also cross-phosphorylated ET-C5aR and ET-IL-8RA, but ET-FR was totally resistant to cross-phosphorylation. Similarly, C5a and IL-8 stimulation of [35S]guanosine 5'-3-O-(thio) triphosphate (GTP gamma S) binding and Ca2+ mobilization were cross-desensitized by each other and by fMLP. Stimulation of [35S]GTP gamma S binding by fMLP was also not cross-desensitized by C5a or IL-8, however, Ca2+ mobilization was, suggesting a site of inhibition distal to G protein activation. Consistent with this desensitization of Ca2+ mobilization, inositol 1,4,5-trisphosphate release in RBL-2H3 cells expressing both ET-C5aR and ET-FR revealed that fMLP and C5a cross-desensitized each other's ability to stimulate phosphoinositide hydrolysis. Taken together, these results indicate that receptor cross-phosphorylation correlates directly with desensitization at the level of G protein activation. The ET-FR was resistant to this process. Of note, cross-desensitization of ET-FR at the level of phosphoinositide hydrolysis and Ca2+ mobilization was demonstrated in the absence of receptor phosphorylation. This suggests a new form of chemoattractant cross-regulation at a site distal to receptor/G protein coupling, involving the activity of phospholipase C.
 ...
PMID:Cross-desensitization of chemoattractant receptors occurs at multiple levels. Evidence for a role for inhibition of phospholipase C activity. 749 54

It has been established that IL-8 triggers angiogenesis in vivo, but this effect may be mediated either by IL-8-recruited leukocytes or by direct actions of IL-8 upon endothelial cells (EC). We have approached this question by examining interactions of recombinant human IL-8 with cultured large vessel and microvascular human EC. We are unable to detect specific IL-8 binding to cultured human umbilical vein endothelial cells (HUVEC) or leukocyte-like IL-8 receptor mRNA expression by either cultured HUVEC or human dermal microvascular endothelial cells (DMEC). We find no alteration of cytoplasmic calcium concentration ([Ca2+]i) in either cell type in response to IL-8 treatment. Finally, we find no IL-8-induced change in EC proliferative rates in the presence or absence of endothelial cell growth factor. Our data favour an indirect action for IL-8 as an angiogenic factor.
 ...
PMID:IL-8 and angiogenesis: evidence that human endothelial cells lack receptors and do not respond to IL-8 in vitro. 754 79

We have characterized the IL-8-induced signal transduction processes in T lymphocytes. A basal level of IL-8 receptor expression was shown on mixed PBL, as identified by using phycoerythrin (PE)-coupled IL-8, and this expression was increased following IL-2 stimulation. Scatchard analysis of T cells revealed competitive binding of IL-8 with a Kd of 0.55 nM, with approximately 1200 receptors per cell, on freshly isolated T cells. After 24 h in culture following purification, reverse transcriptase PCR (RT-PCR) analyses show the mRNA for only the type B IL-8R on these cultured T lymphocytes and the cell line MOLT-4. Stimulation of T lymphocytes or T cell clones with IL-8 led to generation of inositol trisphosphate and calcium flux. In addition, when T cells were prelabeled with [3H]oleic acid, IL-8 caused a long lasting, time- and dose-related increase in [3H]phosphatidylethanol (PtE), indicating activation of phospholipase D (PLD). By contrast, this IL-8-dependent PLD activity was undetectable in IL-8-stimulated neutrophils. PLD activation appeared to be downstream of protein kinase C, because several inhibitors abrogated the increase in [3H]PtE, whereas guanosine-5'-O-(3-thiotriphosphate (GTP(gamma)S) and inositol trisphosphorothioate (IP3S3) both increased the generation of [3H]PtE. Together, these results demonstrate that the IL-8RB receptor is sufficient to mediate phospholipase C (PLC) and PLD activation in T lymphocytes, but not in neutrophils, and indicate an important difference in receptor usage and signal transduction pathways between IL-8-stimulated lymphocytes and neutrophils.
 ...
PMID:IL-8-induced signal transduction in T lymphocytes involves receptor-mediated activation of phospholipases C and D. 770 9

Interleukin-8 (IL-8) has at least two binding regions for both the A and the B type IL-8 receptors. This study defines an important region between Cys7 and Cys50 that, together with the Glu4-Leu5-Arg6 sequence of the NH2 terminus, accounts for the high affinity binding of IL-8 to the IL-8 A receptor on leukocytes. Utilizing rabbit IL-8 that shares 82% sequence identity with human IL-8, but has 200-fold lower binding affinity for the IL-8 A receptor, residues of the human homologue were sequentially exchanged into the rabbit molecule. Replacement of rabbit His13 and Thr15 with Tyr13 and Lys15 of the human molecule converted the low affinity binding of the rabbit IL-8 to the high affinity binding of human IL-8 as shown by both competitive binding and by Ca2+ mobilization. As a corollary, replacement of the Tyr13 and Lys15 of the human IL-8 with His13 and Thr15 of the rabbit IL-8 reduced binding activity of this mutated human IL-8 200-fold. The site of interaction on the IL-8 receptor type A for the Tyr13 and Lys15 sequence was found to be in the NH2-terminal region of this receptor. A structural pattern of the binding between IL-8 and the A type IL-8 receptor is proposed.
 ...
PMID:The role of Tyr13 and Lys15 of interleukin-8 in the high affinity interaction with the interleukin-8 receptor type A. 773 76


1 2 3 4 5 6 7 8 9 10 Next >>