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Griffin RS, Costigan M, Brenner GJ, Him Eddie Ma C, Scholz J, Moss A, Allchorne AJ, Stahl GL, Woolf CJ. Complement induction in spinal cord microglia results in anaphylatoxin C5a-mediated pain hypersensitivity. J Neurosci 2007; 27:8699-708. [PMID: 17687047 PMCID: PMC6672952 DOI: 10.1523/jneurosci.2018-07.2007] [Citation(s) in RCA: 200] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Microarray expression profiles reveal substantial changes in gene expression in the ipsilateral dorsal horn of the spinal cord in response to three peripheral nerve injury models of neuropathic pain. However, only 54 of the 612 regulated genes are commonly expressed across all the neuropathic pain models. Many of the commonly regulated transcripts are immune related and include the complement components C1q, C3, and C4, which we find are expressed only by microglia. C1q and C4 are, moreover, the most strongly regulated of all 612 regulated genes. In addition, we find that the terminal complement component C5 and the C5a receptor (C5aR) are upregulated in spinal microglia after peripheral nerve injury. Mice null for C5 had reduced neuropathic pain sensitivity, excluding C3a as a pain effector. C6-deficient rats, which cannot form the membrane attack complex, have a normal neuropathic pain phenotype. However, C5a applied intrathecally produces a dose-dependent, slow-onset cold pain in naive animals. Furthermore, a C5aR peptide antagonist reduces cold allodynia in neuropathic pain models. We conclude that induction of the complement cascade in spinal cord microglia after peripheral nerve injury contributes to neuropathic pain through the release and action of the C5a anaphylatoxin peptide.
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Boulay F, Mery L, Tardif M, Brouchon L, Vignais P. Expression cloning of a receptor for C5a anaphylatoxin on differentiated HL-60 cells. Biochemistry 1991; 30:2993-9. [PMID: 2007135 DOI: 10.1021/bi00226a002] [Citation(s) in RCA: 171] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A cDNA clone encoding the human C5a anaphylatoxin receptor has been isolated by expression cloning from a CDM8 expression library prepared from mRNA of human myeloid HL-60 cells differentiated to the granulocyte phenotype with dibutyryladenosine cyclic monophosphate. The cDNA clone was able to transfer to COS-7 cells the capacity to specifically bind iodinated human recombinant C5a. The cDNA was 2.3 kb long, with an open reading frame encoding a 350-residue polypeptide. Cross-linking of iodinated C5a to the plasma membrane of transfected COS cells revealed a complex with an apparent molecular mass of 52-55 kDa, similar to that observed for the constitutively expressed receptor in differentiated HL-60 cells or human neutrophils. Although differentiated HL-60 cells display a single class of binding sites, with a dissociation constant of approximately 800-900 pM, the C5a-R cDNA, expressed in COS cells, generates both high-affinity (1.7 nM) and low-affinity (20-25 nM) receptors. Sequence comparison established that the degree of sequence identity between the C5a receptor and the N-formylpeptide receptor is 34%.
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Abstract
In summary, recent advances in molecular cloning of anaphylatoxins and the anaphylatoxin receptors add new dimensions to our investigations and understanding of the molecular mechanisms involved in anaphylatoxin action. Combining knowledge accumulated from peptide modeling of the ligands with mutagenesis studies of these ligands and their receptors makes it possible to more accurately model interactive sites and understand the sequence of molecular interactions required for cellular activation. In addition, these new developments provide valuable tools for investigating, yet unknown, activities and cellular targets of the anaphylatoxin molecules.
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Review |
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van Beek J, Nicole O, Ali C, Ischenko A, MacKenzie ET, Buisson A, Fontaine M. Complement anaphylatoxin C3a is selectively protective against NMDA-induced neuronal cell death. Neuroreport 2001; 12:289-93. [PMID: 11209937 DOI: 10.1097/00001756-200102120-00022] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The anaphylatoxin C3a is a potent inflammatory polypeptide released at sites of complement activation. To test whether C3a might alter neuronal outcome following an ischemic insult, we determined the effects of purified human C3a on murine primary cortical cell cultures exposed to apoptotic or excitotoxic paradigms. C3a prevented neither serum deprivation-induced apoptotic neuronal death, nor AMPA/kainate-mediated excitotoxicity. However, in mixed cultures of neurons and astrocytes, C3a dose-dependently protected neurons against NMDA toxicity (47% neuroprotection using 100 nM C3a, p < 0.01, n = 12). The neuroprotective effect of C3a was observable only in the presence of astrocytes. These observations suggest that C3a is involved in excitotoxicity-mediated neuronal death through astrocyte stimulation and extend its role beyond immune functions.
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Schäfer B, Piliponsky AM, Oka T, Song CH, Gerard NP, Gerard C, Tsai M, Kalesnikoff J, Galli SJ. Mast cell anaphylatoxin receptor expression can enhance IgE-dependent skin inflammation in mice. J Allergy Clin Immunol 2012; 131:541-8.e1-9. [PMID: 22728083 DOI: 10.1016/j.jaci.2012.05.009] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 05/07/2012] [Accepted: 05/11/2012] [Indexed: 12/29/2022]
Abstract
BACKGROUND Mast cells express receptors for complement anaphylatoxins C3a and C5a (ie, C3a receptor [C3aR] and C5a receptor [C5aR]), and C3a and C5a are generated during various IgE-dependent immediate hypersensitivity reactions in vivo. However, it is not clear to what extent mast cell expression of C3aR or C5aR influences C3a- or C5a-induced cutaneous responses or IgE-dependent mast cell activation and passive cutaneous anaphylaxis (PCA) in vivo. OBJECTIVE We sought to assess whether mouse skin mast cell expression of C3aR or C5aR influences (1) the cells' responsiveness to intradermal injections of C3a or C5a or (2) the extent of IgE-dependent mast cell degranulation and PCA in vivo. METHODS We measured the magnitude of cutaneous responses to intradermal injections of C3a or C5a and the extent of IgE-dependent mast cell degranulation and PCA responses in mice containing mast cells that did or did not express C3aR or C5aR. RESULTS The majority of the skin swelling induced by means of intradermal injection of C3a or C5a required that mast cells at the site expressed C3aR or C5aR, respectively, and the extent of IgE-dependent degranulation of skin mast cells and IgE-dependent PCA was significantly reduced when mast cells lacked either C3aR or C5aR. IgE-dependent PCA responses associated with local increases in C3a levels occurred in antibody-deficient mice but not in mice deficient in FcɛRIγ. CONCLUSION Expression of C3aR and C5aR by skin mast cells contributes importantly to the ability of C3a and C5a to induce skin swelling and can enhance mast cell degranulation and inflammation during IgE-dependent PCA in vivo.
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Research Support, Non-U.S. Gov't |
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Pasupuleti M, Walse B, Nordahl EA, Mörgelin M, Malmsten M, Schmidtchen A. Preservation of antimicrobial properties of complement peptide C3a, from invertebrates to humans. J Biol Chem 2006; 282:2520-8. [PMID: 17132627 DOI: 10.1074/jbc.m607848200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human anaphylatoxin peptide C3a, generated during complement activation, exerts antimicrobial effects. Phylogenetic analysis, sequence analyses, and structural modeling studies paired with antimicrobial assays of peptides from known C3a sequences showed that, in particular in vertebrate C3a, crucial structural determinants governing antimicrobial activity have been conserved during the evolution of C3a. Thus, regions of the ancient C3a from Carcinoscorpius rotundicauda as well as corresponding parts of human C3a exhibited helical structures upon binding to bacterial lipopolysaccharide permeabilized liposomes and were antimicrobial against gram-negative and gram-positive bacteria. Human C3a and C4a (but not C5a) were antimicrobial, in concert with the separate evolutionary development of the chemotactic C5a. Thus, the results demonstrate that, notwithstanding a significant sequence variation, functional and structural constraints imposed on C3a during evolution have preserved critical properties governing antimicrobial activity.
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Research Support, Non-U.S. Gov't |
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Lambris JD, Reid KB, Volanakis JE. The evolution, structure, biology and pathophysiology of complement. IMMUNOLOGY TODAY 1999; 20:207-11. [PMID: 10322298 DOI: 10.1016/s0167-5699(98)01417-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Congress |
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Perret JJ, Raspe E, Vassart G, Parmentier M. Cloning and functional expression of the canine anaphylatoxin C5a receptor. Evidence for high interspecies variability. Biochem J 1992; 288 ( Pt 3):911-7. [PMID: 1472004 PMCID: PMC1131973 DOI: 10.1042/bj2880911] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A cDNA clone, DTJP03, encoding an orphan receptor, was isolated from a canine thyroid library, and found to exhibit 68.6% amino-acid identity with the recently described human C5a receptor. This relatively low similarity first suggested that DTJP03 encoded either a C5a receptor subtype, or the presumably related C3a receptor. Binding studies performed on membranes from COS-7 cells expressing the recombinant receptor demonstrated that DTJP03 encoded a high-affinity C5a receptor, with a Kd of 1.2 nM. C3a was unable to compete for C5a binding. Intracellular free calcium concentrations were measured by Quin-2 fluorescence assays in Chinese hamster ovary cells stably transfected with the canine C5a receptor. C5a addition elicited an increase in the intracellular calcium concentration. Extracellular EGTA partially prevented this response, suggesting that activation of the C5a receptor promotes both the release of calcium from intracellular stores, and the influx of extracellular calcium. Genes encoding C5a-receptor subtypes were subsequently searched for by PCR in genomic DNA from human, canine, rat and bovine sources. The result was the amplification of a single gene fragment from each species, with about 70% identity between any two of them. The canine C5a receptor has therefore to be considered as orthologous to the human C5a receptor described previously. The low similarity between C5a receptors from different mammalian species is quite unusual for a G-protein-coupled receptor.
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Sunyer JO, Boshra H, Li J. Evolution of anaphylatoxins, their diversity and novel roles in innate immunity: Insights from the study of fish complement. Vet Immunol Immunopathol 2005; 108:77-89. [PMID: 16112742 DOI: 10.1016/j.vetimm.2005.07.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Anaphylatoxins are small molecules ( approximately 9 kDa) that are generated as a result of the activation of the complement system. These molecules play an important role in inflammation, and they are responsible for the activation of various innate and adaptive immune processes. The study of these important inflammatory molecules has been restricted to mammalian species so far. Recent studies have shown that teleost fish, unlike any other known animal species, contain multiple forms of the C3a anaphylatoxin, all of which are functionally active and play a prominent role in inducing superoxide production in fish leukocytes. The C5a anaphylatoxin has also been characterized in these animals, and like in mammals, it plays an important role in leukocyte chemotaxis and in triggering the respiratory burst of leukocytes. Interestingly, it has been shown that rainbow trout anaphylatoxins play an unexpected role in enhancing phagocytosis of particles. C5a and C3a receptors have recently been cloned and characterized in rainbow trout, suggesting that the duplication of these receptors from a common ancestor occurred before the emergence of teleosts. The studies derived from these molecules in teleost fish indicate that the basic structure and function of anaphylatoxins and their receptors, have been conserved for more than 300 million years.
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Rothermel E, Rolf O, Götze O, Zwirner J. Nucleotide and corrected amino acid sequence of the functional recombinant rat anaphylatoxin C5a. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1351:9-12. [PMID: 9116048 DOI: 10.1016/s0167-4781(97)00006-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
For bacterial expression of rat anaphylatoxin C5a, the cDNA was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) using rat liver RNA and degenerate primers designed according to the published amino acid sequence [1]. Surprisingly, the amino acid sequence deduced from cDNA differed at positions 55 (N for K), 63 (K for H), 67 (E for N), 68 (S for E) and 69 (H for S) from the published sequence. The overall amino acid composition, however, was unchanged because these 5 amino acids were located at different positions compared to the published sequence. As a consequence, the proposed N-glycosylation site was absent, suggesting O-glycosylation of the mature molecule. Recombinant rat C5a with a 6 histidine tag at the N-terminus was expressed in bacteria, purified and renatured. The peptide was as potent as recombinant human C5a in eliciting lysosomal enzyme release from human granulocytes.
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Comparative Study |
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Johswich K, Klos A. C5L2--an anti-inflammatory molecule or a receptor for acylation stimulating protein (C3a-desArg)? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 598:159-80. [PMID: 17892211 DOI: 10.1007/978-0-387-71767-8_12] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Review |
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Franke AE, Andrews GC, Stimler-Gerard NP, Gerard CJ, Showell HJ. Human C5a anaphylatoxin: gene synthesis, expression, and recovery of biologically active material from Escherichia coli. Methods Enzymol 1988; 162:653-68. [PMID: 3067055 DOI: 10.1016/0076-6879(88)62107-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Bujko K, Rzeszotek S, Hoehlig K, Yan J, Vater A, Ratajczak MZ. Signaling of the Complement Cleavage Product Anaphylatoxin C5a Through C5aR (CD88) Contributes to Pharmacological Hematopoietic Stem Cell Mobilization. Stem Cell Rev Rep 2017; 13:793-800. [PMID: 28918528 PMCID: PMC5730632 DOI: 10.1007/s12015-017-9769-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Several mechanisms have been postulated for orchestrating the mobilization of hematopoietic stem/progenitor cells (HSPCs), and we previously proposed that activation of the complement cascade plays a crucial role in the initiation and execution of the egress of HSPCs from bone marrow (BM) into peripheral blood (PB). In support of this notion, we demonstrated that mice deficient in the mannan-binding lectin (MBL) pathway, which activates the proximal part of the complement cascade, as well as mice deficient in the fifth component of the complement cascade (C5), which is part of the distal part of the complement cascade, are poor mobilizers. To further narrow down on the exact mechanisms and the molecules involved, we performed studies in mice that do not express the receptor C5aR, which binds the C5 cleavage fragments, C5a and C5adesArg. We also employed the plasma stable nucleic acid aptamer AON-D21 that binds and neutralizes C5a and C5adesArg. We present evidence that mice deficient in C5aR or treated with AON-D21 are poor HSPC mobilizers, thereby establishing a critical role for the C5a/C5adesArg-C5aR axis in the mobilization process. While enhancing mobilization is of clinical importance for poor mobilizers, inhibition of the complement cascade could be of therapeutic importance in patients suffering from paroxysmal nocturnal hemoglobinuria (PNH) or acquired hemolytic syndrome (aHUS).
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Hayden MA, Mandecki W. Gene synthesis by serial cloning of oligonucleotides. DNA (MARY ANN LIEBERT, INC.) 1988; 7:571-7. [PMID: 3180998 DOI: 10.1089/dna.1.1988.7.571] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A rapid and simple method of gene synthesis is presented. A gene is constructed by serial additions of individual gene fragments in the 5'----3' direction. The vector used as the synthesis vehicle contains a unique Bsm I site at the amino terminus of the lacZ gene. Plasmid linearized with Bsm I is recircularized in vivo by oligonucleotide-directed double-strand break repair. The synthetic oligonucleotide used to "bridge" the double-strand break carries a 70- to 100-nucleotide insert which constitutes a portion of the gene along with a BsmI site at the 3' end that regenerates the site and allows for another consecutive round of mutagenesis to extend the gene sequence. The process is repeated until the entire gene is assembled. The method uses the beta-galactosidase color assay as a means of screening for correct insert lengths. The only in vitro enzymatic step necessary is a single Bsm I restriction digest of plasmid DNA. No ligation reactions are required. Only one strand of a gene sequence needs to be synthesized chemically. The gene synthesis method presented here was used to construct the human anaphylatoxin complement factor C3a gene.
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Federwisch M, Wollmer A, Emde M, Stühmer T, Melcher T, Klos A, Köhl J, Bautsch W. Tryptophan mutants of human C5a anaphylatoxin: a fluorescence anisotropy decay and energy transfer study. Biophys Chem 1993; 46:237-48. [PMID: 8343570 DOI: 10.1016/0301-4622(93)80017-d] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Three mutants of the anaphylatoxin C5a were prepared with positions 2, 64 and 70, respectively, substituted by tryptophan. The last mutant was additionally labelled at Cys27 for fluorescence energy transfer (FET) measurements. The structural integrity and biological activity of the molecules were not affected. Fluorescence anisotropy decay (FAD) measurements showed that the rotational correlation time for tryptophan decreases in the order: [Trp2]rhC5a > [Trp64]rhC5a > [Trp70]rhC5a, indicating an increasing mobility of the side chain. Measurements of the fluorescence energy transfer from Trp70 to the 1,5-AEDANS group at Cys27 yielded a distance distribution of 2.4 +/- 0.8 nm. This value is compatible with the C-terminal chain being arranged as a slightly stretched helix pointing away from the body of the molecule.
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Bautsch W, Kretzschmar T, Stühmer T, Kola A, Emde M, Köhl J, Klos A, Bitter-Suermann D. A recombinant hybrid anaphylatoxin with dual C3a/C5a activity. Biochem J 1992; 288 ( Pt 1):261-6. [PMID: 1445269 PMCID: PMC1132107 DOI: 10.1042/bj2880261] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
By site-directed mutagenesis of a human complement factor C5a cDNA clone, we have designed a hybrid anaphylatoxin in which three amino acid residues in the C-terminal sequence of human C5a were exchanged to create the native C-terminal human C3a (hC3a) sequence Leu-Gly-Leu-Ala-Arg. This hybrid anaphylatoxin rC5a-(1-69)-LGLAR exhibited true C3a and C5a activity when tested in the guinea pig ileum contraction assay. Quantitative measurements of ATP release from guinea pig platelets revealed about 1% intrinsic C3a activity for this hybrid, while the C5a activity was essentially unchanged. Competitive binding assays confirmed that the rC5a-(1-69)-LGLAR mutant was able to displace radioiodinated rhC5a with a KI of approx. 40 nM and hC3a with a KI of approx. 3.7 microM from guinea pig platelets. Since the C-termini of both human C3a and C5a anaphylatoxins are known to interact with their respective receptors, we conclude that the same peptidic sequence, LGLAR, is able to bind to and activate two different receptors, the C3a receptor as well as the C5a receptor. This clone provides a novel tool for the identification of further receptor-binding residues in both anaphylatoxins, since any mutants may be tested for altered C3a and C5a activity simultaneously.
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Dahlqvist SR, Lundström B, Holmgren G. Trichorhinophalangeal syndrome type I and systemic lupus erythematosus with complement C4A homozygous null alleles in the same family. Ann Rheum Dis 1989; 48:760-4. [PMID: 2802798 PMCID: PMC1003870 DOI: 10.1136/ard.48.9.760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A three generation family from northern Sweden with both trichorhinophalangeal syndrome type I (TRP I) and systemic lupus erythematosus (SLE)-like syndrome with complement C4 homozygous null alleles is described. Five family members in three generations were affected by the TRP I syndrome, indicating autosomal dominant inheritance. Two members had clinical and laboratory signs of SLE and two other members SLE-like syndrome. All living family members in the first and second generation had homozygous C4A null alleles. In three of the adults the two syndromes occurred simultaneously, probably in this family by coincidence.
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Lundwall AB, Wetsel RA, Kristensen T, Whitehead AS, Woods DE, Ogden RC, Colten HR, Tack BF. Isolation and sequence analysis of a cDNA clone encoding the fifth complement component. J Biol Chem 1985; 260:2108-12. [PMID: 2579066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We have used available protein sequence data for the anaphylatoxin (C5a) portion of the fifth component of human complement (residues 19-25) to synthesize a mixed-sequence oligonucleotide probe. The labeled oligonucleotide was then used to screen a human liver cDNA library, and a single candidate cDNA clone of 1.85 kilobase pairs was isolated. Hybridization of the mixed-sequence probe to the complementary strand of the plasmid insert and sequence analysis by the dideoxy method predicted the expected protein sequence of C5a (positions 1-12), amino-terminal to the anticipated priming site. The sequence obtained further predicted an arginine-rich sequence (RPRR) immediately upstream of the N-terminal threonine of C5a, indicating that the promolecule form of C5 is synthesized with a beta alpha-chain orientation as previously shown for pro-C3 and pro-C4. The C5 cDNA clone was sheared randomly by sonication, subcloned into M13 mp8, and sequenced at random by the dideoxy technique, thereby generating a contiguous sequence of 1703 base pairs. This clone contained coding sequence for the C-terminal 262 amino acid residues of the beta-chain, the entire C5a fragment, and the N-terminal 98 residues of the alpha'-chain. The 3' end of the clone had a polyadenylated tail preceded by a polyadenylation recognition site, a 3'-untranslated region, and base pairs homologous to the human Alu concensus sequence. Comparison of the derived partial human C5 protein sequence with that previously determined for murine C3 and human alpha 2-macroglobulin has indicated regions of pronounced sequence similarity. Examination of cytoplasmic RNA prepared from human liver and the human hepatoma cell line Hep G2 by Northern transfer has indicated a C5 mRNA species of about 5.2 kilobase pairs.
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Comparative Study |
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Falus A, Kramer J, Walcz E, Varga Z, Setalo J, Jobst K, Lakatos T, Merétey K. Unequal expression of complement C4A and C4B genes in rheumatoid synovial cells, human monocytoid and hepatoma-derived cell lines. Immunology 1989; 68:133-6. [PMID: 2553583 PMCID: PMC1385517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
C4A and C4B are closely related homologous complement proteins encoded in the class III region of major histocompatibility complex (MHC). The regulation of their expression is under genetic and hormonal control. In this study we investigated the synovial fluid plasma ratio of C4A and C4B of rheumatoid (RA) and osteoarthritis (OA) patients, and a predominance of the C4B gene expression by the synovial macrophages of RA patients was demonstrated. To clarify the tissue specificity of the expression of C4A and C4B genes, human monocytoid cell line U937 and hepatoma-derived HepG2 cells were studied. The gene expression of C4A and C4B were markedly different in these cells since a relative predominance of C4B mRNA in U937 cells and excess of that of C4A in HepG2 cells were detected. Recombinant interferon-gamma (IFN-gamma) up-regulated the expression of C4A gene in both cells, but had apparently no effect on the C4B gene. Our results demonstrate dissimilar expression patterns for the two human C4 genes, suggesting different tissue specific regulation of human C4A and C4B.
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