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Smith D, Shimamura T, Barbera S, Bejcek BE. NF-kappaB controls growth of glioblastomas/astrocytomas. Mol Cell Biochem 2007; 307:141-7. [PMID: 17828582 DOI: 10.1007/s11010-007-9593-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Accepted: 08/23/2007] [Indexed: 01/06/2023]
Abstract
NF-kappaB is a family of transcription factors that have been shown to be elevated in a variety of tumor types and in some cases central to their survival and growth. Here we present evidence that U-87 MG and U-118 MG growth is regulated by NF-kappaB and controlled by PDGF. NF-kappaB activity was suppressed by a dominant negative mutant of the human PDGF type beta receptor and PDGF-B chain neutralizing antibodies. Creation of cell lines that had inducible expression of shRNAs directed against either c-Rel or RelA inhibited growth almost 90% indicating that NF-kappaB plays a central role in glioblastoma growth.
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Affiliation(s)
- Denise Smith
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008, USA
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2
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Siegfried G, Basak A, Prichett-Pejic W, Scamuffa N, Ma L, Benjannet S, Veinot JP, Calvo F, Seidah N, Khatib AM. Regulation of the stepwise proteolytic cleavage and secretion of PDGF-B by the proprotein convertases. Oncogene 2006; 24:6925-35. [PMID: 16007151 DOI: 10.1038/sj.onc.1208838] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Platelet-derived growth factor-B (PDGF-B) is important for normal tissue growth and maintenance and its overexpression has been linked to several diseases, including cancer, fibrotic disease and atherosclerosis. Here, we show that synthesized as a precursor, proPDGF-B is converted to a mature form by proteolytic cleavage at two sites and its N-terminal cleavage is a prerequisite for processing at its C-terminus. The first cleavage occurs at residues RGRR81/, and the second cleavage close to residues ARPVT190, just before the C-terminal amino-acid sequence crucial for PDGF-B retention to cell surface. Cotransfection of a Furin-deficient cell line LoVo-C5 with proPDGF-B and different PC members revealed that Furin, PACE4, PC5, and PC7 are candidate proPDGF-B convertases. This finding is consistent with the in vitro digestions of a synthetic peptide mimicking the cleavage site of proPDGF-B. The processing of proPDGF-B is blocked by site-directed mutagenesis of the RGRR81/ sequence and by various PC inhibitors. Mutation of the PDGF-A and/or PDGF-B convertase sites, revealed that processing of both A and B chains is required for the formation of mature PDGF-B dimers and that the processing of the B chain controls the level of secreted and matrix-bound PDGF-BB forms. Our findings emphasize the importance of the convertase-directed processing of proPDGF-B at the RGRR81/ sequence for PDGF-B maturation and secretion.
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Affiliation(s)
- Geraldine Siegfried
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, 110 Pine Ave West, Montreal, Quebec, Canada H2W 1R7
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3
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Ostman A. PDGF receptors-mediators of autocrine tumor growth and regulators of tumor vasculature and stroma. Cytokine Growth Factor Rev 2005; 15:275-86. [PMID: 15207817 DOI: 10.1016/j.cytogfr.2004.03.002] [Citation(s) in RCA: 248] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
PDGFs and their cognate tyrosine kinase alpha- and beta-receptors are involved in multiple tumor-associated processes including autocrine growth stimulation of tumor cells, stimulation of tumor angiogenesis and recruitment and regulation of tumor fibroblasts. The recent development of clinically useful PDGF antagonists, like STI571/Glivec, has increased the interest in PDGF receptors as cancer drug targets. Autocrine PDGF receptor signaling occurs in certain malignancies characterized by mutational activation of PDGF or PDGF receptors, for instance, dermatofibrosaracoma protuberans, gastrointestinal stromal tumors, and hypereosinophilic syndrome. The roles of PDGF in regulation of tumor angiogenesis and tumor fibroblasts are more general, and probably occur in most common solid tumors. Concerning tumor angiogenesis recent studies have predominantly focused on the importance of PDGF receptor signaling for tumor pericyte recruitment. PDGF receptors in the tumor stroma have also attracted attention as interesting drug targets because of their function as regulators of tumor interstitial fluid pressure, tumor transvascular transport and tumor drug uptake. In summary, the improved understanding of the role of PDGF signaling in tumor biology, and the introduction of PDGF antagonists, has set the stage for a continued development of PDGF antagonists as novel cancer drugs.
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Affiliation(s)
- Arne Ostman
- Department of Oncology and Pathology, Cancer Center Karolinska, Karolinska Institute, SE-171 76 Stockholm, Sweden.
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4
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Abstract
The most essential kinases involved in cell membrane receptor activation, signal transduction and cell cycle control or programmed cell death and their interconnections are reviewed. In tumours, the genes of many of those kinases are mutated or amplified or the proteins are overexpressed. The use of key kinases offers the possibility to screen in vitro for synthetic small molecule kinase inhibitors. In view of the many interconnections of cellular kinases, their role in preventing or inducing programmed cell death and the possibility that a considerable number of signal transducing proteins are still unknown, cellular test systems are recommended in which the respective key kinase or one of its main partner molecules are overexpressed.
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Affiliation(s)
- H H Sedlacek
- Aventis Pharma Deutschland GmbH, Central Biotechnology, Marburg, Germany.
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5
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Jazayeri A, McGee J, Shimamura T, Cross SB, Bejcek BE. SHP-2 can suppress transformation induced by platelet-derived growth factor. Exp Cell Res 2000; 254:197-203. [PMID: 10640417 DOI: 10.1006/excr.1999.4741] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Signaling by either the type alpha or type beta receptors of platelet-derived growth factor occurs by phosphorylation of at least 10 intra-cytoplasmic tyrosine residues and their subsequent association of secondary signaling molecules with Src homology 2 (SH2) domains. Although the role of several of these secondary signaling molecules in mitogenesis has become increasingly clear, their roles in morphological transformation are not as well defined. Here we present evidence that the SHP-2 phosphatase which associates with Tyr 1009 of the type beta receptor and Tyr 720 of the type alpha receptor may suppress transformation induced by the PDGF B chain. Cotransfection of a dominant negative mutant of the SHP-2 gene and the PDGF B chain gene into mouse fibroblasts that only poorly formed foci with the PDGF B chain alone resulted in larger and more prominent foci. Furthermore, introduction of a wild-type copy of the SHP-2 gene into a tumor cell line, U-87MG, which relies on PDGF expression to form foci in vitro, caused a reversion of phenotype.
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Affiliation(s)
- A Jazayeri
- Wayne State University, Detroit, Michigan 48202, USA
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6
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Affiliation(s)
- K F Chung
- Department of Thoracic Medicine, National Heart & Lung Institute, Imperial College School of Medicine & Royal Brompton Hospital, London SW3 6LY, UK
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7
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Kaetzel DM, Morgan D, Reid JD, Fenstermaker RA. Site-directed mutagenesis of the N-linked glycosylation site in platelet-derived growth factor B-chain results in diminished intracellular retention. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1298:250-60. [PMID: 8980650 DOI: 10.1016/s0167-4838(96)00136-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pulse-chase analysis of human platelet-derived growth factor (PDGF) B-chain was conducted in stably transfected Chinese hamster ovary cells to determine precisely the kinetics of processing, intracellular trafficking and secretion. Newly synthesized 31 kDa monomers of the B-chain (p31) dimerized rapidly via disulfide bonds to a p54 species (t1/2 < 30 min). The p54 dimer was processed to a group of intracellular, cell surface (suramin-releasable) and secreted forms whose rates of appearance and disappearance from the cell were measured over a 48 h period. The newly synthesized p31 species was quantitatively converted to p27 by treatment with endoglycosidase H, consistent with efficient N-glycosylation at a site in the N-terminal propeptide region (Asn63-Met64-Thr65). Interruption of B-chain glycosylation by oligodeoxynucleotide-directed mutagenesis resulted in a significant increase in suramin-releasable forms at the cell surface (p34-38) and a concomitant decrease in accumulation of an intracellular p24 species. The glycosylation-defective mutant exhibited slight increases in receptor binding and mitogenic activity. Our results suggest that N-linked glycosylation of the B-chain is not important for formation of mitogenically active protein, but that it plays a role in early intracellular sorting and proteolytic processing events.
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Affiliation(s)
- D M Kaetzel
- Department of Pharmacology, College of Medicine, Chandler Medical Center, University of Kentucky, Lexington 40536, USA.
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8
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Calara F, Ameli S, Hultgårdh-Nilsson A, Cercek B, Kupfer J, Hedin U, Forrester J, Shah PK, Nilsson J. Autocrine induction of DNA synthesis by mechanical injury of cultured smooth muscle cells. Potential role of FGF and PDGF. Arterioscler Thromb Vasc Biol 1996; 16:187-93. [PMID: 8620331 DOI: 10.1161/01.atv.16.2.187] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To determine whether replication of arterial smooth muscle cells (SMCs) in response to mechanical injury would occur in the absence of serum and other cells, we created an in vitro model in which confluent, growth-arrested cultures of rat SMCs were injured by gentle pressure of a soft plastic tube and then kept in serum-free medium for up to 4 days. Replication of SMCs in and around the injury, as measured by tritiated thymidine incorporation, was noted within 24 hours and peaked at 48 hours after injury, whereas noninjured cells remained quiescent. An increased expression of platelet-derived growth factor (PDGF) A mRNA, noted 6 hours after injury, was followed by an increased PDGF AA immunoreactivity in SMCs in and around the zone of injury at 24 and 48 hours after injury. A PDGF A chain antisense oligonucleotide inhibited 87.0 +/- 4.0% (P < .005) of SMC replication in the injury zone, whereas the corresponding sense oligonucleotide reduced SMC replication by only 37.2%. An antibody to fibroblast growth factor (FGF) almost completely inhibited SMC replication in the injured zone, whereas an antibody to PDGF AA was without effect. Incubation of SMCs with FGF increased PDGF A mRNA levels in SMCs, and 5 mumol/L PDGF A antisense oligonucleotides reduced FGF-induced SMC replication by 62%. Taken together, these results demonstrate that injured rat SMCs in culture release FGF that activates DNA synthesis of neighboring SMCs both by a direct mechanism and by stimulating the production of PDGF AA.
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MESH Headings
- Animals
- Base Sequence
- Cells, Cultured
- DNA/biosynthesis
- Fibroblast Growth Factors/physiology
- Gene Expression Regulation
- Hormones/physiology
- Molecular Sequence Data
- Muscle, Smooth, Vascular/injuries
- Muscle, Smooth, Vascular/pathology
- Oligonucleotide Probes/genetics
- Oligonucleotides, Antisense/pharmacology
- Platelet-Derived Growth Factor/antagonists & inhibitors
- Platelet-Derived Growth Factor/genetics
- Platelet-Derived Growth Factor/physiology
- RNA, Messenger/metabolism
- Rats
- Rats, Inbred Strains
- Stress, Mechanical
- Wounds, Nonpenetrating/metabolism
- Wounds, Nonpenetrating/pathology
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Affiliation(s)
- F Calara
- Division of Cardiology, Cedars-Sinai Medical Center, Los Angeles, Calif, USA
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9
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Abstract
PDGF is an important polypeptide growth factor that plays an essential role during early vertebrate development and is associated with tissue repair and wound healing in the adult vertebrate. Moreover, PDGF is thought to play a role in a variety of pathological phenomena, such as cancer, fibrosis and atherosclerosis. PDGF is expressed as a dimer of A and/or B chains, the precursors of which are encoded by two single copy genes. Although the PDGF genes are expressed coordinately in a number of cell types, they are independently expressed in a majority of cell types. The expression of either PDGF gene can be affected by very diverse extracellular stimuli and the type of response is dependent on the cell type that is exposed to the stimulus. Expression of the PDGF chains can be modulated at every imaginable level: by regulating accessibility of the transcription start site, by varying the transcription initiation rate, by using alternative transcription start sites, by alternative splicing, by using alternative polyadenylation signals, by varying mRNA decay rates, by regulating efficiency of translation, by protein modification, and by regulating secretion. Even upon secretion, the activity of PDGF can be modulated by non-specific or specific PDGF-binding proteins. This review provides an overview of the cell types in which the PDGF genes are expressed, of the factors that are known to affect the expression of PDGF, and of the various levels at which the expression of PDGF genes can be regulated.
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Affiliation(s)
- R P Dirks
- Department of Molecular Biology, University of Nijmegen, The Netherlands
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10
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Chen G, Birnbaum RS, Yablonka-Reuveni Z, Quinn LS. Separation of mouse crushed muscle extract into distinct mitogenic activities by heparin affinity chromatography. J Cell Physiol 1994; 160:563-72. [PMID: 8077294 DOI: 10.1002/jcp.1041600320] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Extracts from gently crushed adult mouse skeletal muscles (CMEs) contain potent myoblast mitogens, and may be used as a model system to investigate myotrophic factors released by adult muscles following injury. CME was separated into four peaks of mitogenic activity by heparin affinity chromatography. The fraction of CME that did not bind to heparin contained transferrin (Tf). Three peaks of mitogenic activity were eluted from the heparin-agarose columns at NaCl concentrations of 0.4 M, 0.9 M, and 2.0 M. A 46 kDa protein that shared antigenicity with the BB isoform of platelet-derived growth factor (PDGF-BB) was present in the 0.4 M NaCl eluant. Mitogenic activity in the 2.0 M NaCl peak eluted identically to purified basic fibroblast growth factor (bFGF), did not act additively to saturating amounts of purified bFGF, and was neutralized by anti-bFGF antibodies. The 0.9 M NaCl eluant acted additively to the combination of three known growth factors for myoblasts, bFGF, insulin-like growth factor 1, and epidermal growth factor, to stimulate C2 myoblast proliferation, suggesting this fraction contains a mitogenic activity which does not utilize (and hence compete for) receptors for the known mitogens for myoblasts. Additionally, the 0.9 M NaCl eluant did not stimulate proliferation of fibroblast-like cells derived from muscle tissue. The unbound, 0.4 M NaCl, 0.9 M NaCl, and 2.0 M NaCl eluants from the heparin-agarose column acted additively to one another to stimulate myoblast proliferation. Our data suggest that Tf, PDGF-BB-like molecules, bFGF-like activity, and an uncharacterized heparin-binding myoblast mitogen could be released after muscle injury and act to stimulate satellite cell proliferation.
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Affiliation(s)
- G Chen
- Department of Biological Structure, University of Washington, Seattle 98195
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11
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Soyombo A, DiCorleto P. Stable expression of human platelet-derived growth factor B chain by bovine aortic endothelial cells. Matrix association and selective proteolytic cleavage by thrombin. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32502-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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12
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Khachigian LM, Chesterman CN. Structural basis for the extracellular retention of PDGF A-chain using a synthetic peptide corresponding to exon 6. Peptides 1994; 15:133-7. [PMID: 8015969 DOI: 10.1016/0196-9781(94)90181-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Alternative splicing of PDGF A-chain exon 6 yields two species that differ by a highly conserved cationic carboxyl-terminus consisting of 18 amino acid residues (A194-211). Previous findings have demonstrated that a synthetic peptide representing A194-211 binds to cultured cells and interferes with the binding and biological activity of several polypeptide growth factors. We now demonstrate that the peptide, which binds to the extracellular matrix in a specific and glycosaminoglycan-dependent manner, can also inhibit the binding of basic FGF to the matrix. The cellular retention signal encoded by exon 6 accounts for differences in the mitogenic responsiveness to conditioned media from Chinese hamster ovary cells transfected with the cDNA for the long and short splice forms of the PDGF A-chain. That the PDGF A-chain exon 6 product may share anionic binding sites with a matrix-resident polypeptide growth factor in the extracellular matrix suggests a role for A194-211 in the storage of PDGF bearing this sequence.
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Affiliation(s)
- L M Khachigian
- University of New South Wales Center for Thrombosis and Vascular Research, Prince of Wales Hospital, Sydney, Australia
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13
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Andersson M, Ostman A, Westermark B, Heldin C. Characterization of the retention motif in the C-terminal part of the long splice form of platelet-derived growth factor A-chain. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)42200-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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14
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Bartold PM. Platelet-derived growth factor stimulates hyaluronate but not proteoglycan synthesis by human gingival fibroblasts in vitro. J Dent Res 1993; 72:1473-80. [PMID: 8227697 DOI: 10.1177/00220345930720110301] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The effect of PDGF-BB on human gingival fibroblasts was monitored in an in vitro system. PDGF was found to be mitogenic for these cells, although it required the presence of low concentrations of fetal calf serum to be active. Proteoglycan and hyaluronate synthesis was analyzed by labeling newly synthesized macromolecules with [35S]-sulfate or [3H]-glucosamine, respectively. Identification of specific glycosaminoglycans was achieved by selective enzymatic or chemical degradations. It was found that cells cultured in the presence of PDGF showed no discernible differences in proteoglycan synthesis relative to the control cultures. There were no alterations in amounts of proteoglycans synthesized, types of sulfated glycosaminoglycans synthesized, or relative hydrodynamic sizes of the proteoglycans. In contrast to the proteoglycans, hyaluronate synthesis was significantly increased in the presence of PDGF. The increase in [3H]-glucosamine incorporation into newly synthesized hyaluronate correlated with an increase in the activity of the enzyme hyaluronate synthetase but could not be accounted for entirely by changes in the specific activity of sugar nucleotide precursors, which did alter slightly under differing culture conditions. It is concluded from these results that PDGF stimulates gingival fibroblasts to proliferate and is associated with a differential effect of proteoglycan and hyaluronate synthesis. These observations may correlate with the observed early events associated with wound healing and repair.
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Affiliation(s)
- P M Bartold
- Department of Dentistry, University of Queensland, Brisbane, Australia
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15
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Van der Meeren A, Seddon MB, Betsholtz CA, Lechner JF, Gerwin BI. Tumorigenic conversion of human mesothelial cells as a consequence of platelet-derived growth factor-A chain overexpression. Am J Respir Cell Mol Biol 1993; 8:214-21. [PMID: 8427711 DOI: 10.1165/ajrcmb/8.2.214] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Overexpression of platelet-derived growth factor (PDGF)-A as well as PDGF-B chain mRNA has previously been reported in human mesothelioma cell lines. In this report, it has been established that the A but not the B chain protein is expressed at detectable levels in cell lysates and conditioned medium from these cell lines. In order to investigate the effect of overexpression of PDGF-A chain in a human mesothelial cell model system, a retroviral vector containing a human PDGF-A chain cDNA insert under the control of the Moloney murine leukemia virus (MoMLV) promoter was inserted into the SV-40 T-antigen immortalized human mesothelial cell line MeT-5A. Selected cells showed overexpression of PDGF-A chain relative to MeT-5A and induced tumors in athymic nude mice. PDGF-A chain overexpression was also found in the tumor specimens excised from the mice. PDGF-A mRNA and protein were expressed at a higher level in the tumor explant cell lines, suggesting a correlation of tumorigenicity with A chain production.
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Affiliation(s)
- A Van der Meeren
- Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
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16
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Palmieri SL, Payne J, Stiles CD, Biggers JD, Mercola M. Expression of mouse PDGF-A and PDGF alpha-receptor genes during pre- and post-implantation development: evidence for a developmental shift from an autocrine to a paracrine mode of action. Mech Dev 1992; 39:181-91. [PMID: 1292572 DOI: 10.1016/0925-4773(92)90045-l] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We examined the expression of platelet-derived growth factor (PDGF)-A and the PDGF alpha-receptor in pre-implantation and early post-implantation mouse embryos. At two-cell and blastocyst stages, all cells express mRNA and protein for both ligand and receptor. In contrast, early post-implantation embryos express PDGF-A chain mRNA in both embryonic ectoderm and in the ectoderm lining the ectoplacental cavity, while mRNA for PDGF alpha-receptor is localized to the mesoderm layers of both embryonic and extra-embryonic membranes. At days 3.5 and 7.5, receptors are demonstrably functional in response to exogenous PDGF-AA. We propose that chronic autostimulation of PDGF alpha-receptors occurs in pre-implantation embryos, whereas, following implantation, early mesoderm development is dependent on stimulation by ectodermally produced PDGF-A.
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Affiliation(s)
- S L Palmieri
- Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, MA
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17
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Abstract
The mitogenic and chemotactic potency of platelet-derived growth factor (PDGF) has linked this polypeptide to the pathogenesis of several disease states including atherosclerosis and neoplasia. We have reviewed the recent literature on aspects relating to the structure, distribution and biology of PDGF and its high-affinity cell-surface and intracellular receptors. In addition to platelets, several normal and tumor cells secrete the mitogen in one or more of three possible dimeric configurations. Alternative splicing of exon 6 in PDGF A-chain RNA results in the formation of two protein species with different carboxy-termini. Initially, it was thought that the longer A-chain variant was processed only by transformed cells. However, recent evidence indicates that alternative splicing occurs in several cells which express the A-chain, including early Xenopus embryos. The functional significance of the exon 6 product, a highly basic region spanned by 18 amino acid residues (A194-211), is not precisely clear. We have summarized recent findings which implicate roles for A194-211 in the processing, secretion, and mitogenesis of the A-chain homodimer, nuclear transport signalling, and heparin binding. Thus, alternative splicing could play an important role in the modulation of the functional properties of the PDGF A-chain variants per se and in the complex interactive network of polypeptide growth factors and cytokines.
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Affiliation(s)
- L M Khachigian
- Department of Haematology, Prince of Wales Hospital, Sydney
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18
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Khachigian L, Chesterman C. Synthetic peptides representing the alternatively spliced exon of the platelet-derived growth factor A-chain modulate mitogenesis stimulated by normal human serum and several growth factors. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42542-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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19
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Bejcek B, Hoffman R, Lipps D, Li D, Mitchell C, Majerus P, Deuel T. The v-sis oncogene product but not platelet-derived growth factor (PDGF) A homodimers activate PDGF alpha and beta receptors intracellularly and initiate cellular transformation. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50729-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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20
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Khachigian LM, Owensby DA, Chesterman CN. A tyrosinated peptide representing the alternatively spliced exon of the platelet-derived growth factor A-chain binds specifically to cultured cells and interferes with binding of several growth factors. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)45996-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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21
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Induction of platelet-derived growth factor alpha- and beta-receptor mRNA and protein by platelet-derived growth factor BB. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54831-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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22
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Khachigian LM, Evin G, Morgan FJ, Owensby DA, Chesterman CN. A crossreactive antipeptide monoclonal antibody with specificity for lysyl-lysine. J Immunol Methods 1991; 140:249-58. [PMID: 1712372 DOI: 10.1016/0022-1759(91)90378-s] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Synthetic peptides meeting certain guidelines have been used as immunogens to generate antibodies with predefined specificity. We have raised and characterized using established methods a monoclonal antibody against a synthetic peptide corresponding to the 18-amino acid carboxyterminal sequence (A194-211) of the platelet-derived growth factor (PDGF) A chain expressed by the U343 human glioma cell line. This antibody was generated in order to carry out structure-function studies on this region of PDGF whose biological significance is not yet clear. Anti-PDGF-A194-211 was found to be a low titre, IgM kappa molecule, with a Kd of 2.8 x 10(-7) M. When antibody reactivity was tested with parent PDGF-AAL (A chain homodimer containing a carboxyterminal extension) significant binding was observed. Surprisingly, 125I-PDGF-AAS, consisting of truncated A chains but lacking the extension was also bound. Moreover, poly-L-lysine, beta-thromboglobulin, PDGF-A194-211, and myoglobin competed dose-dependently with 125I-PDGF-AAL for antibody. 125I-bovine serum albumin was also bound. Examination of the primary sequence of proteins and peptides bound by the antibody revealed only one shared structural motif: a lysyl-lysine moiety. Selected small synthetic peptides containing this and other sequences were used as potential competitors of 125I-PDGF-A194-211 in antibody binding. Lysyl-lysyl-glycyl-glutamic acid [corrected] and lysyl-lysine competed, whereas lysyl-leucine did not. These results suggest that as few as two amino acid residues constitute a functional antigenic determinant and contrast with most previous estimates of the minimum number of residues required. Furthermore, we show that guidelines governing the design of synthetic peptides for their use as antigens to produce monoclonal antibodies of predetermined specificity may be unreliable.
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Affiliation(s)
- L M Khachigian
- Department of Hematology, University of New South Wales, Prince of Wales Hospital, Randwick, NSW, Australia
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23
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Ostman A, Andersson M, Hellman U, Heldin C. Identification of three amino acids in the platelet-derived growth factor (PDGF) B-chain that are important for binding to the PDGF beta-receptor. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)99191-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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24
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Abstract
While the roles of the platelet-derived growth factors (PDGFs) in vascular smooth muscle cells (SMCs) continue to be elucidated, these cells, especially in their activated 'synthetic' state, have also been found to express, and proliferate in response to, many of the other families of polypeptide growth factors, such as the fibroblast growth factors. Other stimulators of DNA synthesis, and particularly of SMC hypertrophy, include the vasoconstrictor hormones such as angiotensin II, as well as physical forces, especially stretch or tension. For many of these ligands, multiple receptors have been identified and their means of signal transduction are being characterized rapidly. Regulatory regions of these genes are being identified as are transcription factors. Complex post-transcriptional regulation has also been shown by the findings that some growth factors are phosphorylated, or translocated to the nucleus or the extracellular matrix. Inhibitors have also been identified. These include some prostaglandins, calcium antagonists, agonists that activate guanylate and adenylate cyclases, inhibitors of angiotensin-converting enzyme, interferon gamma, and heparin. Future studies are likely to show that tyrosine phosphatases and recessive oncogenes also regulate growth. The existence of so many autocrine/paracrine mitogens--together with some experimental data--suggests some redundancy in the system as well as some additive effects. Redundancy may limit the efficacy of antibodies to a single growth factor to block cell proliferation. Their evolutionary conservation implies some unique roles for each growth factor but these have not been apparent from in vitro studies to date. Further insights are apt to come from the increasing recognition that growth factors have other effects--on cell attachment, migration, survival, production of extracellular matrix, thrombosis, vaso-constriction, regulation of cytokine synthesis, and inhibition of growth. Many of these effects may prove to be context-dependent, as with the case of growth inhibition by transforming growth factor-beta. Studies in monolayer cultures may not obtain the same results as studies using cocultures of endothelial and smooth muscle cells, or 3-dimensional matrix cultures, organ cultures, or in the intact animal. In vivo descriptive studies of growth factors expressed in vascular embryogenesis, hypertension, atherosclerosis, acute balloon injury and thrombosis are being supplemented by interventions such as infusions with growth factors, antibodies, and toxin conjugates. These studies, and studies using transgenic mice and homologous recombination, should yield information as to mechanisms and may also suggest new therapies.
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Affiliation(s)
- W Casscells
- Department of Molecular and Cellular Growth Biology, Whittier Institute for Diabetes and Endocrinology, Scripps Institute of Medicine and Science, La Jolla, CA 92037
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25
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Winkles JA, O'Connor ML, Friesel R. Altered regulation of platelet-derived growth factor A-chain and c-fos gene expression in senescent progeria fibroblasts. J Cell Physiol 1990; 144:313-25. [PMID: 2166059 DOI: 10.1002/jcp.1041440218] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The study of human genetic disorders known as premature aging syndromes may provide insight into the mechanisms of cellular senescence. These diseases are clinically characterized by the premature onset and accelerated progression of numerous features normally associated with human aging. Previous studies have indicated that fibroblasts derived from premature aging syndrome patients have in vitro growth properties similar to senescent fibroblasts from normal individuals. As an initial approach to determine whether gene expression is altered in premature aging syndrome fibroblasts, RNA was prepared from various cell strains and used for gel blot hybridization experiments. Although normal fibroblasts only express platelet-derived growth factor (PDGF) A-chain mRNA for a brief period following mitogenic stimulation, one strain of Hutchinson-Gilford (progeria) syndrome fibroblasts, AG3513, constitutively expresses PDGF A-chain mRNA and PDGF-AA homodimers. The PDGF A-chain gene does not appear to be amplified or rearranged in these fibroblasts. AG3513 progeria fibroblasts have properties characteristic of senescent cells, including an altered morphology and a diminished mitogenic response to growth promoters. The diminished response of AG3513 progeria fibroblasts to PDGF stimulation was examined in some detail. Studies using 125I-PDGF-BB, which binds with high affinity to both A- and B-type PDGF receptors, indicate that normal and AG3513 progeria fibroblasts have a similar number of PDGF receptors. Although receptor autophosphorylation occurs normally in PDGF-stimulated AG3513 progeria fibroblasts, c-fos mRNA induction does not. The senescent phenotype of AG3513 fibroblasts is probably unrelated to their constitutive PDGF A-chain gene expression; further studies are necessary in order to directly address this issue. Also, additional analysis of this progeria fibroblast strain may provide information on the control of mitogen-inducible gene expression in normal cells.
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Affiliation(s)
- J A Winkles
- Laboratory of Molecular Biology, Jerome H. Holland Laboratory for the Biomedical Sciences, American Red Cross, Rockville, Maryland 20855
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26
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Mercola M, Wang CY, Kelly J, Brownlee C, Jackson-Grusby L, Stiles C, Bowen-Pope D. Selective expression of PDGF A and its receptor during early mouse embryogenesis. Dev Biol 1990; 138:114-22. [PMID: 2155144 DOI: 10.1016/0012-1606(90)90181-h] [Citation(s) in RCA: 154] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Murine homologs of the PDGF A, PDGF B, and PDGF receptor alpha subunit genes were cloned. These were used, together with a mouse PDGF receptor beta subunit cDNA clone, to monitor gene expression in early postimplantation mouse embryos and in F9 embryonal carcinoma cells. RNAse protection analysis shows that PDGF A chain, but not B chain, mRNA is expressed in 6.5- to 8.5-day embryonic and extraembryonic tissues. Both alpha and beta receptor subunit mRNAs are expressed in early embryos, however, alpha subunit mRNA appears earlier and is more abundant than beta subunit mRNA. Undifferentiated F9 embryonal carcinoma stem cells express abundant levels of A chain, but not B chain, mRNA. Neither of the PDGF receptor genes is expressed in stem cells. Treatment with retinoic acid stimulates expression of both PDGF receptor genes. As in postimplantation mouse embryos, alpha receptor subunit mRNA appears earlier and is substantially more abundant than beta subunit mRNA. Collectively, these data demonstrate that the genes encoding the two chains of PDGF and their receptors are regulated independently during development and suggest that the two systems have some nonoverlapping functions in vivo. PDGF A, but not PDGF B, may be particularly important in modulating early events in mouse embryonic development.
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Affiliation(s)
- M Mercola
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts
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27
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Fibronectin levels are enhanced in human fibroblasts overexpressing the c-sis protooncogene. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)34109-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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28
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Hart CE, Bailey M, Curtis DA, Osborn S, Raines E, Ross R, Forstrom JW. Purification of PDGF-AB and PDGF-BB from human platelet extracts and identification of all three PDGF dimers in human platelets. Biochemistry 1990; 29:166-72. [PMID: 2322537 DOI: 10.1021/bi00453a022] [Citation(s) in RCA: 182] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We have developed a panel of monoclonal antibodies to platelet-derived growth factor (PDGF) which have variable specificities for the three dimeric forms of the molecule (AA, AB, and BB). We have used these antibodies to detect and immunoaffinity purify the individual dimers from human platelet rich plasma. Extracts of outdated platelet preparations were initially chromatographed over CM-Sepharose and then passed over the Sepharose-coupled monoclonal antibodies in series in selectively isolate the three dimeric forms of PDGF. The PDGF eluted from the affinity columns was subsequently further purified by reversed-phase HPLC. From 300 units of outdated platelet preparations, we purified 58 micrograms of PDGF-BB and 140 micrograms of PDGF-AB. Using the monoclonal antibodies to develop PDGF dimer-specific ELISAs, it was observed that all three PDGF dimer forms are present in fresh human platelet extracts and that the ratios of the three dimer forms vary depending upon the extraction conditions used. The identification of all three PDGF dimer forms in human platelets point to the need to view PDGF isolated from human platelets by conventional techniques as a mixture of all three forms and not solely as PDGF-AB.
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Affiliation(s)
- C E Hart
- ZymoGenetics Inc., Seattle, Washington 98105
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29
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Intracellular turnover, novel secretion, and mitogenically active intracellular forms of v-sis gene product in simian sarcoma virus-transformed cells. Implications for intracellular loop autocrine transformation. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)40067-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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30
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Tiesman J, Rizzino A. Recent developments in the structure, function and regulation of platelet-derived growth factor and its receptors. Cytotechnology 1989; 2:333-50. [DOI: 10.1007/bf00364997] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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31
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Eichner W, Jäger V, Herbst D, Hauser H, Hoppe J. Large-scale preparation of recombinant platelet-derived growth factor AA secreted from recombinant baby hamster kidney cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 1989; 185:135-40. [PMID: 2806256 DOI: 10.1111/j.1432-1033.1989.tb15094.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The short isoform of platelet-derived growth factor A (PDGF-A) was expressed in a mammalian host (BHK-21 cell). A cell line was obtained that secreted up to 0.3 micrograms/10(6) cells recombinant PDGF-A chain homodimer/day into the medium. For large-scale production of supernatant, cells were grown either in roller bottles or in 2.5-1 stirred tank fermenters. A simple two-step procedure was developed to purify recombinant PDGF-AA (rPDGF-AA). The first step was adsorption onto porous glass and the final step was reversed-phase high-performance liquid chromatography. The yield was 0.2 mg/l supernatant. A total amount of 20-30 mg pure rPDGF-AA may be obtained from a single fermenter run. Sequence analysis showed the correct amino terminus and no internal proteolytic cleavages. The specific activity was 5 ng/ml for mouse AKR-2B cells. [125I]rPDGF-AA had an affinity constant of approximately 0.5 nM to these cells and 25,000 binding sites were estimated/cell.
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Affiliation(s)
- W Eichner
- Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, Federal Republic of Germany
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32
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Heldin CH, Westermark B. Growth factors as transforming proteins. EUROPEAN JOURNAL OF BIOCHEMISTRY 1989; 184:487-96. [PMID: 2680482 DOI: 10.1111/j.1432-1033.1989.tb15041.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- C H Heldin
- Ludwig Institute for Cancer Research, Biomedical Center, Uppsala, Sweden
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Abstract
Platelet-derived growth factor (PDGF) is a dimeric molecule that occurs as homodimers or heterodimers of related polypeptide chains. Recent data indicate that the isoforms have different functional activities because they bind with different affinities to two distinct receptor types. The activation of at least one of the PDGF receptor types involves receptor dimerization. Furthermore, there are indications that cells respond to PDGF in vivo only when they have been previously stimulated to express the corresponding receptor.
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34
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Affiliation(s)
- B Westermark
- Department of Pathology, University of Uppsala, Sweden
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35
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Ostman A, Bäckström G, Fong N, Betsholtz C, Wernstedt C, Hellman U, Westermark B, Valenzuela P, Heldin CH. Expression of three recombinant homodimeric isoforms of PDGF in Saccharomyces cerevisiae: evidence for difference in receptor binding and functional activities. Growth Factors 1989; 1:271-81. [PMID: 2560933 DOI: 10.3109/08977198908998003] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Three recombinant homodimeric isoforms of platelet-derived growth factor (PDGF) were produced and purified in milligram quantities by expression of PDGF A- and B-chains in yeast cells. Structural analysis of the purified short and long variants of PDGF-AA (PDGF-AAS and PDGF-AAL) and PDGF-BB showed that they had been properly processed and assembled into dimers. PDGF-AAS and PDGF-AAL were found to bind only to the PDGF A-type receptor on human fibroblasts, with affinities of 0.1 and 0.2 nM, respectively. PDGF-BB bound to cells with A- and B-type receptors and to cells with B-type receptor only with affinities of 0.6 nM in both cases. Each fibroblast appeared to express about 4-5 times more B-type receptors than A-type receptors. The maximal mitogenic response to PDGF-BB of human fibroblasts was almost 2-fold higher than that induced by either of the two PDGF-AA forms. The three isoforms of PDGF also stimulated growth in soft agar of human fibroblasts with PDGF-BB inducing a higher maximal response.
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Affiliation(s)
- A Ostman
- Ludwig Institute for Cancer Research, Biomedical Center, Uppsala, Sweden
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