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Udry F, Decembrini S, Gamm DM, Déglon N, Kostic C, Arsenijevic Y. Lentiviral mediated RPE65 gene transfer in healthy hiPSCs-derived retinal pigment epithelial cells markedly increased RPE65 mRNA, but modestly protein level. Sci Rep 2020; 10:8890. [PMID: 32483256 PMCID: PMC7264209 DOI: 10.1038/s41598-020-65657-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 05/08/2020] [Indexed: 12/15/2022] Open
Abstract
The retinal pigment epithelium (RPE) is a monolayer of cobblestone-like epithelial cells that accomplishes critical functions for the retina. Several protocols have been published to differentiate pluripotent stem cells into RPE cells suitable for disease modelling and therapy development. In our study, the RPE identity of human induced pluripotent stem cell (hiPSC)-derived RPE (iRPE) was extensively characterized, and then used to test a lentiviral-mediated RPE65 gene augmentation therapy. A dose study of the lentiviral vector revealed a dose-dependent effect of the vector on RPE65 mRNA levels. A marked increase of the RPE65 mRNA was also observed in the iRPE (100-fold) as well as in an experimental set with RPE derived from another hiPSC source and from foetal human RPE. Although iRPE displayed features close to bona fide RPE, no or a modest increase of the RPE65 protein level was observed depending on the protein detection method. Similar results were observed with the two other cell lines. The mechanism of RPE65 protein regulation remains to be elucidated, but the current work suggests that high vector expression will not produce an excess of the normal RPE65 protein level.
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Affiliation(s)
- Florian Udry
- Department of ophthalmology, Unit of Retinal Degeneration and Regeneration, University of Lausanne, Hôpital ophtalmique Jules-Gonin, 1004, Lausanne, Switzerland
| | - Sarah Decembrini
- Department of ophthalmology, Unit of Retinal Degeneration and Regeneration, University of Lausanne, Hôpital ophtalmique Jules-Gonin, 1004, Lausanne, Switzerland
- Department of Biomedicine, University Hospital Basel & University Basel, Hebelstr. 20, 4031, Basel, Switzerland
| | - David M Gamm
- McPherson Eye Research Institute, Waisman Center and Department of Ophthalmology and Visual Sciences, and University of Wisconsin-Madison, Madison, USA
| | - Nicole Déglon
- Neuroscience Research Center, Laboratory of Neurotherapies and Neuromodulation, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Corinne Kostic
- Department of ophthalmology, Unit of Retinal Degeneration and Regeneration, University of Lausanne, Hôpital ophtalmique Jules-Gonin, 1004, Lausanne, Switzerland
| | - Yvan Arsenijevic
- Department of ophthalmology, Unit of Retinal Degeneration and Regeneration, University of Lausanne, Hôpital ophtalmique Jules-Gonin, 1004, Lausanne, Switzerland.
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2
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Boraldi F, Losi L, Quaglino D. Pigment epithelial-derived factor: a new player in the calcification of dermal elastic fibre? Br J Dermatol 2017; 177:e44-e46. [PMID: 27925161 DOI: 10.1111/bjd.15223] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- F Boraldi
- Department of Life Sciences, University of Modena and Reggio Emilia, Via Campi 287-41125, Modena, Italy
| | - L Losi
- Department of Life Sciences, University of Modena and Reggio Emilia, Via Campi 287-41125, Modena, Italy
| | - D Quaglino
- Department of Life Sciences, University of Modena and Reggio Emilia, Via Campi 287-41125, Modena, Italy
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3
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Belkacemi L, Zhang SX. Anti-tumor effects of pigment epithelium-derived factor (PEDF): implication for cancer therapy. A mini-review. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2016; 35:4. [PMID: 26746675 PMCID: PMC4706649 DOI: 10.1186/s13046-015-0278-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/22/2015] [Indexed: 12/22/2022]
Abstract
Pigment epithelium-derived factor (PEDF) is a secreted glycoprotein and a non-inhibitory member of the serine protease inhibitor (serpin) family. It is widely expressed in human fetal and adult tissues but its expression decreases with age and in malignant tissues. The main anti-cancer activities of PEDF derive from its dual effects, either indirectly on the tumor microenvironment (indirect antitumor action) or directly on the tumor itself (direct antitumor influence). The indirect antitumor activities of PEDF were uncovered from the early findings that it stimulates retinoblastoma cell differentiation and that additionally it possesses anti-angiogenic, anti-tumorigenic and anti-metastatic properties. The mechanisms of its direct antitumor effect, however, have not been fully elucidated. This review highlights recent progress in our understanding of the multifunctional activities of PEDF and, in particular, its anti-cancer signaling mechanisms. Additionally, we discuss the possibility of using novel phosphaplatin compounds that can upregulate PEDF expression as a chemotherapy for cancer treatment.
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Affiliation(s)
- Louiza Belkacemi
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, 77204, USA.
| | - Shaun Xiaoliu Zhang
- Department of Biology and Biochemistry, University of Houston, Houston, TX, 77204, USA. .,Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, 77204, USA.
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4
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Wietecha MS, Król MJ, Michalczyk ER, Chen L, Gettins PG, DiPietro LA. Pigment epithelium-derived factor as a multifunctional regulator of wound healing. Am J Physiol Heart Circ Physiol 2015; 309:H812-26. [PMID: 26163443 DOI: 10.1152/ajpheart.00153.2015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 07/08/2015] [Indexed: 01/12/2023]
Abstract
During dermal wound repair, hypoxia-driven proliferation results in dense but highly permeable, disorganized microvascular networks, similar to those in solid tumors. Concurrently, activated dermal fibroblasts generate an angiopermissive, provisional extracellular matrix (ECM). Unlike cancers, wounds naturally resolve via blood vessel regression and ECM maturation, which are essential for reestablishing tissue homeostasis. Mechanisms guiding wound resolution are poorly understood; one candidate regulator is pigment epithelium-derived factor (PEDF), a secreted glycoprotein. PEDF is a potent antiangiogenic in models of pathological angiogenesis and a promising cancer and cardiovascular disease therapeutic, but little is known about its physiological function. To examine the roles of PEDF in physiological wound repair, we used a reproducible model of excisional skin wound healing in BALB/c mice. We show that PEDF is abundant in unwounded and healing skin, is produced primarily by dermal fibroblasts, binds to resident microvascular endothelial cells, and accumulates in dermal ECM and epidermis. PEDF transcript and protein levels were low during the inflammatory and proliferative phases of healing but increased in quantity and colocalization with microvasculature during wound resolution. Local antibody inhibition of endogenous PEDF delayed vessel regression and collagen maturation during the remodeling phase. Treatment of wounds with intradermal injections of exogenous, recombinant PEDF inhibited nascent angiogenesis by repressing endothelial proliferation, promoted vascular integrity and function, and increased collagen maturity. These results demonstrate that PEDF contributes to the resolution of healing wounds by causing regression of immature blood vessels and stimulating maturation of the vascular microenvironment, thus promoting a return to tissue homeostasis after injury.
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Affiliation(s)
- Mateusz S Wietecha
- Center for Wound Healing and Tissue Regeneration, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois; and
| | - Mateusz J Król
- Center for Wound Healing and Tissue Regeneration, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois; and
| | - Elizabeth R Michalczyk
- Center for Wound Healing and Tissue Regeneration, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois; and
| | - Lin Chen
- Center for Wound Healing and Tissue Regeneration, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois; and
| | - Peter G Gettins
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, Illinois
| | - Luisa A DiPietro
- Center for Wound Healing and Tissue Regeneration, College of Dentistry, University of Illinois at Chicago, Chicago, Illinois; and
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5
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PEDF and its roles in physiological and pathological conditions: implication in diabetic and hypoxia-induced angiogenic diseases. Clin Sci (Lond) 2015; 128:805-23. [PMID: 25881671 PMCID: PMC4557399 DOI: 10.1042/cs20130463] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Pigment epithelium-derived factor (PEDF) is a broadly expressed multifunctional member of the serine proteinase inhibitor (serpin) family. This widely studied protein plays critical roles in many physiological and pathophysiological processes, including neuroprotection, angiogenesis, fibrogenesis and inflammation. The present review summarizes the temporal and spatial distribution patterns of PEDF in a variety of developing and adult organs, and discusses its functions in maintaining physiological homoeostasis. The major focus of the present review is to discuss the implication of PEDF in diabetic and hypoxia-induced angiogenesis, and the pathways mediating PEDF's effects under these conditions. Furthermore, the regulatory mechanisms of PEDF expression, function and degradation are also reviewed. Finally, the therapeutic potential of PEDF as an anti-angiogenic drug is briefly summarized.
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6
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Glycosaminoglycan and Collagen Facilitate the Degradation of Pigment Epithelium-Derived Factor by Chymotrypsin. Biosci Biotechnol Biochem 2014; 77:1628-32. [DOI: 10.1271/bbb.130069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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7
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Affiliation(s)
- Francis H Glorieux
- Shriners Hospital for Children and McGill University, Montreal, QC, Canada
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8
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Thibault RA, Mikos AG, Kasper FK. Protein and mineral composition of osteogenic extracellular matrix constructs generated with a flow perfusion bioreactor. Biomacromolecules 2011; 12:4204-12. [PMID: 22040097 PMCID: PMC3238915 DOI: 10.1021/bm200975a] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
This study investigated the temporal composition of an osteogenic extracellular matrix construct generated by culturing mesenchymal stem cells in an electrospun biodegradable poly(ε-caprolactone) fiber mesh scaffold within a flow perfusion bioreactor. Constructs of different extracellular matrix maturities were analyzed for their protein and mineral composition at several culture durations by liquid chromatography-tandem mass spectrometry, scanning electron microscopy, energy-dispersive X-ray diffraction, X-ray diffraction, and calcium and phosphate assays. The analysis revealed that at short culture durations the cells deposited cellular adhesion proteins as a prerequisite protein network for further bone formation. At the later culture durations, the extracellular matrix was composed of collagen 1, hydroxyapatite, matrix remodeling proteins, and regulatory proteins. These results suggest that the later culture duration constructs would allow for improved bone regeneration due to the ability to mineralize and the capabilities for future remodeling.
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Affiliation(s)
- Richard A. Thibault
- Department of Bioengineering Rice University P.O. Box 1892, MS-142 Houston, TX 77251-1892
| | - Antonios G. Mikos
- Department of Bioengineering Rice University P.O. Box 1892, MS-142 Houston, TX 77251-1892
| | - F. Kurtis Kasper
- Department of Bioengineering Rice University P.O. Box 1892, MS-142 Houston, TX 77251-1892
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9
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Broadhead ML, Dass CR, Choong PFM. Systemically administered PEDF against primary and secondary tumours in a clinically relevant osteosarcoma model. Br J Cancer 2011; 105:1503-11. [PMID: 21979423 PMCID: PMC3242526 DOI: 10.1038/bjc.2011.410] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Background: Pigment epithelium-derived factor (PEDF) is an endogenous glycoprotein with a potential role as a therapeutic for osteosarcoma. Animal studies have demonstrated the biological effects of PEDF on osteosarcoma; however, these results are difficult to extrapolate for human use due to the chosen study design and drug delivery methods. Methods: In this study we have attempted to replicate the human presentation and treatment of osteosarcoma using a murine orthotopic model of osteosarcoma. The effects of PEDF on osteosarcoma cell lines were evaluated in vitro prior to animal experimentation. Orthotopic tumours were induced by intra-tibial injection of SaOS-2 osteosarcoma cells. Treatment with PEDF was delayed until after the macroscopic appearance of primary tumours. Pigment epithelium-derived factor was administered systemically via an implanted intraperitoneal micro-osmotic pump. Results: In vitro, PEDF inhibited proliferation, induced apoptosis and inhibited cell cycling of osteosarcoma cells. Pigment epithelium-derived factor promoted adhesion to Collagen I and inhibited invasion through Collagen I. In vivo, treatment with PEDF caused a reduction in both primary tumour volume and burden of pulmonary metastases. Systemic administration of PEDF did not cause toxic effects on normal tissues. Conclusion: Systemically delivered PEDF is effective in suppressing the size of primary and secondary tumours in an orthotopic murine model of osteosarcoma.
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Affiliation(s)
- M L Broadhead
- Department of Orthopaedics, St Vincent's Hospital Melbourne, Level 3, Daly Wing, 35 Victoria Pde, Fitzroy, VIC 3065, Australia
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10
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Sekiya A, Okano-Kosugi H, Yamazaki CM, Koide T. Pigment epithelium-derived factor (PEDF) shares binding sites in collagen with heparin/heparan sulfate proteoglycans. J Biol Chem 2011; 286:26364-74. [PMID: 21652703 DOI: 10.1074/jbc.m111.252684] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pigment epithelium-derived factor (PEDF) is a collagen-binding protein that is abundantly distributed in various tissues, including the eye. It exhibits various biological functions, such as anti-angiogenic, neurotrophic, and neuroprotective activities. PEDF also interacts with extracellular matrix components such as collagen, heparan sulfate proteoglycans (HSPGs), and hyaluronan. The collagen-binding property has been elucidated to be important for the anti-angiogenic activity in vivo (Hosomichi, J., Yasui, N., Koide, T., Soma, K., and Morita, I. (2005) Biochem. Biophys. Res. Commun. 335, 756-761). Here, we investigated the collagen recognition mechanism by PEDF. We first narrowed down candidate PEDF-binding sequences by taking advantage of previously reported structural requirements in collagen. Subsequent searches for PEDF-binding sequences employing synthetic collagen-like peptides resulted in the identification of one of the critical binding sites for PEDF, human α1(I)(929-938) (IKGHRGFSGL). Further analysis revealed that the collagen recognition by PEDF is sequence- and conformation-specific, and the high affinity binding motif is KGXRGFXGL in the triple helix. The PEDF-binding motif significantly overlapped with the heparin/HSPG-binding motif, KGHRG(F/Y). The interaction of PEDF with collagen I was specifically competed with by heparin but not by chondroitin sulfate-C or hyaluronan. The binding sequences for PEDF and heparin/HSPG also overlapped with the covalent cross-linking sites between collagen molecules. These findings imply a functional relationship between PEDF and HSPGs during angiogenesis, and the interaction of these molecules is regulated by collagen modifications.
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Affiliation(s)
- Atsushi Sekiya
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Tokyo 169-8555, Japan
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11
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Becker J, Semler O, Gilissen C, Li Y, Bolz HJ, Giunta C, Bergmann C, Rohrbach M, Koerber F, Zimmermann K, de Vries P, Wirth B, Schoenau E, Wollnik B, Veltman JA, Hoischen A, Netzer C. Exome sequencing identifies truncating mutations in human SERPINF1 in autosomal-recessive osteogenesis imperfecta. Am J Hum Genet 2011; 88:362-71. [PMID: 21353196 DOI: 10.1016/j.ajhg.2011.01.015] [Citation(s) in RCA: 276] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 01/27/2011] [Accepted: 01/28/2011] [Indexed: 12/25/2022] Open
Abstract
Osteogenesis imperfecta (OI) is a heterogeneous genetic disorder characterized by bone fragility and susceptibility to fractures after minimal trauma. After mutations in all known OI genes had been excluded by Sanger sequencing, we applied next-generation sequencing to analyze the exome of a single individual who has a severe form of the disease and whose parents are second cousins. A total of 26,922 variations from the human reference genome sequence were subjected to several filtering steps. In addition, we extracted the genotypes of all dbSNP130-annotated SNPs from the exome sequencing data and used these 299,494 genotypes as markers for the genome-wide identification of homozygous regions. A single homozygous truncating mutation, affecting SERPINF1 on chromosome 17p13.3, that was embedded into a homozygous stretch of 2.99 Mb remained. The mutation was also homozygous in the affected brother of the index patient. Subsequently, we identified homozygosity for two different truncating SERPINF1 mutations in two unrelated patients with OI and parental consanguinity. All four individuals with SERPINF1 mutations have severe OI. Fractures of long bones and severe vertebral compression fractures with resulting deformities were observed as early as the first year of life in these individuals. Collagen analyses with cultured dermal fibroblasts displayed no evidence for impaired collagen folding, posttranslational modification, or secretion. SERPINF1 encodes pigment epithelium-derived factor (PEDF), a secreted glycoprotein of the serpin superfamily. PEDF is a multifunctional protein and one of the strongest inhibitors of angiogenesis currently known in humans. Our data provide genetic evidence for PEDF involvement in human bone homeostasis.
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Affiliation(s)
- Jutta Becker
- Institute of Human Genetics, University of Cologne, Cologne, Germany
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12
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Gvritishvili AG, Leung KW, Tombran-Tink J. Codon preference optimization increases heterologous PEDF expression. PLoS One 2010; 5:e15056. [PMID: 21152082 PMCID: PMC2994832 DOI: 10.1371/journal.pone.0015056] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Accepted: 10/04/2010] [Indexed: 12/26/2022] Open
Abstract
Pigment epithelium-derived factor (PEDF) is widely known for its neurotrophic and antiangiogenic functions. Efficacy studies of PEDF in animal models are limited because of poor heterologous protein yields. Here, we redesigned the human PEDF gene to preferentially match codon frequencies of E coli without altering the amino acid sequence. Following de novo synthesis, codon optimized PEDF (coPEDF) and the wtPEDF genes were cloned into pET32a containing a 5′ thioredoxin sequence (Trx) and the recombinant Trx-coPEDF or Trx-wtPEDF fusion constructs expressed in native and two tRNA augmented E coli hosts - BL21-CodonPlus(DE3)-RIL and BL21-CodonPlus(DE3)-RP, carrying extra copies of tRNAarg,ile,leu and tRNAarg,pro genes , respectively. Trx-PEDF fusion proteins were isolated using Ni-NTA metal affinity chromatography and PEDF purified after cleavage with factor Xα. Protein purity and identity were confirmed by western blot, MALDI-TOF, and UV/CD spectral analyses. Expression of the synthetic gene was ∼3.4 fold greater (212.7 mg/g; 62.1 mg/g wet cells) and purified yields ∼4 fold greater (41.1 mg/g; 11.3 mg/g wet cell) than wtPEDF in the native host. A small increase in expression of both genes was observed in hosts supplemented with rare tRNA genes compared to the native host but expression of coPEDF was ∼3 fold greater than wtPEDF in both native and codon-bias-adjusted E coli strains. ΔGs at −3 to +50 of the Trx site of both fusion genes were −3.9 kcal/mol. Functionally, coPEDF was equally as effective as wtPEDF in reducing oxidative stress, promoting neurite outgrowth, and blocking endothelial tube formation. These findings suggest that while rare tRNA augmentation and mRNA folding energies can significantly contribute to increased protein expression, preferred codon usage, in this case, is advantageous to translational efficiency of biologically active PEDF in E coli. This strategy will undoubtedly fast forward studies to validate therapeutic utility of PEDF in vivo.
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Affiliation(s)
- Anzor G. Gvritishvili
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Kar Wah Leung
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Joyce Tombran-Tink
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
- Department of Ophthalmology, Penn State University College of Medicine, Hershey, Pennsylvania, United States of America
- * E-mail:
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The yin and yang of VEGF and PEDF: multifaceted neurotrophic factors and their potential in the treatment of Parkinson's Disease. Int J Mol Sci 2010; 11:2875-900. [PMID: 21152280 PMCID: PMC2996745 DOI: 10.3390/ijms11082875] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 07/25/2010] [Accepted: 07/30/2010] [Indexed: 01/01/2023] Open
Abstract
Over the last few decades, vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) have emerged as multifaceted players in not only the pathogenesis, but potential treatment, of numerous diseases. They activate diverse intracellular signaling cascades known to have extensive crosstalk, and have been best studied for their effects in cardiology and cancer biology. Recent work with the two factors indicates that the activity of one growth factor is often directly related to the action of the other. Their respective neuroprotective effects, in particular, raise important questions regarding the treatment of neurodegenerative disorders, including Parkinson’s disease.
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Abstract
Pigment epithelium-derived factor (PEDF) is an endogenously produced glycoprotein with a spectrum of biological roles across diverse pathologies. Recent research has focused on the biochemical properties of PEDF and its associated receptors. This review discusses the recent developments in PEDF biochemistry and how this new knowledge will help progress our understanding of PEDF as a molecular mediator for anti-angiogenesis and -tumorigenesis. Additionally, pathophysiological roles for PEDF in healing and tissue homeostasis are being revealed and our enhanced understanding of the interactions between PEDF and its receptors may yet prove useful in propelling PEDF towards clinical application.
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Affiliation(s)
- Matthew L Broadhead
- Department of Orthopaedics, St Vincent's Hospital, University of Melbourne, Melbourne, Vic., Australia
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15
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Becerra SP, Perez-Mediavilla LA, Weldon JE, Locatelli-Hoops S, Senanayake P, Notari L, Notario V, Hollyfield JG. Pigment epithelium-derived factor binds to hyaluronan. Mapping of a hyaluronan binding site. J Biol Chem 2008; 283:33310-20. [PMID: 18805795 DOI: 10.1074/jbc.m801287200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pigment epithelium-derived factor (PEDF) is a multifunctional serpin with antitumorigenic, antimetastatic, and differentiating activities. PEDF is found within tissues rich in the glycosaminoglycan hyaluronan (HA), and its amino acid sequence contains putative HA-binding motifs. We show that PEDF coprecipitation with glycosaminoglycans in media conditioned by human retinoblastoma Y-79 cells decreased after pretreatments with hyaluronidase, implying an association between HA and PEDF. Direct binding of human recombinant PEDF to highly purified HA was demonstrated by coprecipitation in the presence of cetylpyridinium chloride. Binding of PEDF to HA was concentration-dependent and saturable. The PEDF-HA interactions were sensitive to increasing NaCl concentrations, indicating an ionic nature of these interactions and having affinity higher than PEDF-heparin. Competition assays showed that PEDF can bind heparin and HA simultaneously. PEDF chemically modified with fluorescein retained the capacity for interacting with HA but lacked heparin affinity, suggesting one or more distinct HA-binding regions on PEDF. The HA-binding region was examined by site-directed mutagenesis. Single-point and cumulative alterations at basic residues within the putative HA-binding motif K189A/K191A/R194A/K197A drastically reduced the HA-binding activity without affecting heparin- or collagen I binding of PEDF. Cumulative alterations at sites critical for heparin binding (K146A/K147A/R149A) decreased HA affinity but not collagen I binding. Thus these clusters of basic residues (BXBXXBXXB and BX3AB2XB motifs) in PEDF are functional regions for binding HA. In the spatial PEDF structure they are located in distinct areas away from the collagen-binding site. The HA-binding activity of PEDF may contribute to deposition in the extracellular matrix and to its reported antitumor/antimetastatic effects.
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Borrás T. Chapter 11 What is Functional Genomics Teaching us about Intraocular Pressure Regulation and Glaucoma? CURRENT TOPICS IN MEMBRANES 2008. [DOI: 10.1016/s1063-5823(08)00411-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Pigment epithelium-derived factor inhibits glioma cell growth in vitro and in vivo. Life Sci 2007; 81:1256-63. [DOI: 10.1016/j.lfs.2007.08.025] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Revised: 08/17/2007] [Accepted: 08/20/2007] [Indexed: 11/17/2022]
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18
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Koide T. Designed triple-helical peptides as tools for collagen biochemistry and matrix engineering. Philos Trans R Soc Lond B Biol Sci 2007; 362:1281-91. [PMID: 17581806 PMCID: PMC2440396 DOI: 10.1098/rstb.2007.2115] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Collagens, characterized by a unique triple-helical structure, are the predominant component of extracellular matrices (ECMs) existing in all multicellular animals. Collagens not only maintain structural integrity of tissues and organs, but also regulate a number of biological events, including cell attachment, migration and differentiation, tissue regeneration and animal development. The specific functions of collagens are generally triggered by specific interactions of collagen-binding molecules (membrane receptors, soluble factors and other ECM components) with certain structures displayed on the collagen triple helices. Thus, synthetic triple-helical peptides that mimic the structure of native collagens have been used to investigate the individual collagen-protein interactions, as well as collagen structure and stability. The first part of this article illustrates the design of various collagen-mimetic peptides and their recent applications in matrix biology. Collagen is also acknowledged as one of the most promising biomaterials in regenerative medicine and tissue engineering. However, the use of animal-derived collagens in human could put the recipients at risks of pathogen transmission or allergic reactions. Hence, the production of safe artificial collagen surrogates is currently of considerable interest. The latter part of this article reviews recent attempts to develop artificial collagens as novel biomaterials.
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Affiliation(s)
- Takaki Koide
- Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata 956-8603, Japan.
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19
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Ek ETH, Dass CR, Contreras KG, Choong PFM. Inhibition of orthotopic osteosarcoma growth and metastasis by multitargeted antitumor activities of pigment epithelium-derived factor. Clin Exp Metastasis 2007; 24:93-106. [PMID: 17458711 DOI: 10.1007/s10585-007-9062-1] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2006] [Accepted: 02/16/2007] [Indexed: 10/23/2022]
Abstract
Osteosarcoma is major cause of cancer-related death in the pediatric age group, and this is due to the development of pulmonary metastases that fail to be eradicated with current treatment regimes. Although there have been significant improvements in the long-term survival of such patients, 25-50% with initially non-metastatic disease, subsequently develop metastases and this remains the major cause of death for these patients. In this study, we report the multimodal activity of pigment epithelium-derived factor (PEDF) in inhibiting osteosarcoma growth, angiogenesis and metastasis. In vitro, we found that administration of recombinant PEDF (rPEDF) on two osteosarcoma cell lines (rat UMR 106-01 and human SaOS-2) significantly reduced tumor cell proliferation and increased apoptosis, as well as decreased cell invasion, angiogenesis, and increased adhesion to collagen type-1. Administration of rPEDF upregulated the mRNA expression of phenotypic osteoblast differentiation markers (ALP, pro-alpha(1) collagen and osteocalcin) in a pre-osteoblastic cell line, UMR 201, and also increased mineralized nodule formation in both UMR 106-01 and SaOS-2. In vivo, rPEDF dramatically suppressed primary osteosarcoma growth and the development of macroscopic pulmonary metastases in an orthotopic model of human osteosarcoma (SaOS-2). Interestingly, no activity was seen in tumors grown subcutaneously, suggesting a paracrine interaction between PEDF and the bone microenvironment. Preliminary pharmacoevaluation studies demonstrated rPEDF stability within media containing serum and osteosarcoma cells, and no gross systemic toxicity was observed in vivo with rPEDF administration. These results suggest that PEDF is emerging as an attractive and clinically appealing drug candidate for the treatment of osteosarcoma.
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Affiliation(s)
- Eugene T H Ek
- Department of Orthopaedics, University of Melbourne, St. Vincent's Hospital, P.O. Box 2900, Fitzroy, Melbourne, 3065 VIC, Australia
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20
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Valnickova Z, Petersen SV, Nielsen SB, Otzen DE, Enghild JJ. Heparin Binding Induces a Conformational Change in Pigment Epithelium-derived Factor. J Biol Chem 2007; 282:6661-7. [PMID: 17202143 DOI: 10.1074/jbc.m610471200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pigment epithelium-derived factor (PEDF) is a noninhibitory serpin found in plasma and in the extracellular space. The protein is involved in different biological processes including cell differentiation and survival. In addition, it is a potent inhibitor of angiogenesis. The function is likely associated with binding to cell surface receptors in a heparin-dependent way (Alberdi, E. M., Weldon, J. E., and Becerra, S. P. (2003) BMC Biochem. 4, 1). We have investigated the structural basis for this observation and show that heparin induces a conformational change in the vicinity of Lys(178). This structural change was evident both when binding to intact heparin and specific heparin-derived oligosaccharides at physiological conditions or simply when exposing PEDF to low ionic strength. Binding to other glycosaminoglycans, heparin-derived oligosaccharides smaller than hexadecasaccharides (dp16), or type I collagen did not affect the structure of PEDF. The conformational change is likely to expose the epitope involved in binding to the receptor and thus regulates the interactions with cell surface receptors.
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Affiliation(s)
- Zuzana Valnickova
- Center for Insoluble Protein Structures (inSPIN), Department of Molecular Biology, University of Aarhus, DK-8000 Aarhus, Denmark
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21
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Fernandez-Garcia NI, Volpert OV, Jimenez B. Pigment epithelium-derived factor as a multifunctional antitumor factor. J Mol Med (Berl) 2006; 85:15-22. [PMID: 17106733 DOI: 10.1007/s00109-006-0111-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Revised: 07/14/2006] [Accepted: 08/11/2006] [Indexed: 01/03/2023]
Abstract
The design of new therapeutic strategies for cancer treatment is based on the combination of drugs directed against different tumor compartments, including the tumor cells themselves and components of the stroma, such as the tumor vasculature. Indeed, several antiangiogenic compounds have entered clinical trials for use alone or in combination with conventional cytotoxic drugs. Pigment epithelium-derived factor (PEDF) is a multifunctional natural peptide with complex neurotrophic, neuroprotective, antiangiogenic, and proapoptotic biological activities, any of which could potentially be exploited for therapeutic purposes. This review summarizes recent studies that reveal the antitumor potential of PEDF based on its antiangiogenic properties and its newly discovered direct antitumor effects, which involve the induction of differentiation or apoptosis in tumor cells. We also discuss possible therapeutic applications of PEDF, based on these mechanistic insights and on the identification of functional domains that retain specific biological activities.
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Affiliation(s)
- N I Fernandez-Garcia
- Departamento de Bioquimica, Facultad de Medicina, Instituto de Investigaciones Biomedicas CSIC-UAM, Arturo Duperier 4, 28029, Madrid, Spain
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22
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Kawamura K, Kariya Y, Ono Y, Muramoto A, Ohta K, Fujiwara S. Molecular collaborations between serpins and trefoil factor promote endodermal cell growth and gastrointestinal differentiation in budding tunicates. Dev Growth Differ 2006; 48:309-22. [PMID: 16759281 DOI: 10.1111/j.1440-169x.2006.00865.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present evidence supporting novel collaborations between the serine protease inhibitor (serpin) and the trefoil factor during the budding stage of the tunicate Polyandrocarpa misakiensis. Using a maltose-binding protein/P-serpin fusion protein, two polypeptides of 40 kDa and 45 kDa were pulled down from Polyandrocarpa homogenates. Based on their partial amino acid sequence data, a single cDNA (928 bp) was cloned. It encodes a polypeptide that has five tandem repeats of a trefoil consensus motif. Thus, we termed the cDNA P-trefoil. Both P-trefoil and P-serpin were expressed exclusively by coelomic cells during budding. P-Trefoil was expressed mainly by coelomic cells throughout the asexual life cycle of Polyandrocarpa, while P-Serpin was localized particularly in coelomic cells and in the extracellular matrix in developing buds. The native P-Trefoil protein showed aminopeptidase activity. It induced cell growth in cultured Polyandrocarpa cells at a concentration of 8 microg/mL. P-Serpin reinforced this activity of P-Trefoil. Further, a mixture of P-Trefoil and P-Serpin exhibited the in vitro induction of a gut-specific alkaline phosphatase. These results show for the first time that a serpin can interact with a trefoil factor to play a role in the cellular growth and differentiation of the gastric epithelium.
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Affiliation(s)
- Kazuo Kawamura
- Laboratory of Molecular and Cellular Biotechnology, Faculty of Science, Kochi University, Kochi 780-8520, Japan.
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23
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Ramírez-Castillejo C, Sánchez-Sánchez F, Andreu-Agulló C, Ferrón SR, Aroca-Aguilar JD, Sánchez P, Mira H, Escribano J, Fariñas I. Pigment epithelium-derived factor is a niche signal for neural stem cell renewal. Nat Neurosci 2006; 9:331-9. [PMID: 16491078 DOI: 10.1038/nn1657] [Citation(s) in RCA: 330] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Accepted: 01/30/2006] [Indexed: 12/13/2022]
Abstract
Adult stem cells are characterized by self-renewal and multilineage differentiation, and these properties seem to be regulated by signals from adjacent differentiated cell types and by extracellular matrix molecules, which collectively define the stem cell "niche." Self-renewal is essential for the lifelong persistence of stem cells, but its regulation is poorly understood. In the mammalian brain, neurogenesis persists in two germinal areas, the subventricular zone (SVZ) and the hippocampus, where continuous postnatal neuronal production seems to be supported by neural stem cells (NSCs). Here we show that pigment epithelium-derived factor (PEDF) is secreted by components of the murine SVZ and promotes self-renewal of adult NSCs in vitro. In addition, intraventricular PEDF infusion activated slowly dividing stem cells, whereas a blockade of endogenous PEDF decreased their cycling. These data demonstrate that PEDF is a niche-derived regulator of adult NSCs and provide evidence for a role for PEDF protein in NSC maintenance.
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24
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Baba H, Yonemitsu Y, Nakano T, Onimaru M, Miyazaki M, Ikeda Y, Sumiyoshi S, Ueda Y, Hasegawa M, Yoshino I, Maehara Y, Sueishi K. Cytoplasmic Expression and Extracellular Deposition of an Antiangiogenic Factor, Pigment Epithelium-Derived Factor, in Human Atherosclerotic Plaques. Arterioscler Thromb Vasc Biol 2005; 25:1938-44. [PMID: 15994443 DOI: 10.1161/01.atv.0000175759.78338.1e] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Objective—
To assess the expression and distribution of a neurotrophic/antiangiogenic factor, pigment epithelium-derived factor (PEDF), related to angiogenesis that is a possibly key event during atherogenesis in human atherosclerotic plaques.
Methods and Results—
Twenty fresh aortic samples were used for reverse-transcription polymerase chain reaction (RT-PCR), Western blot, and immunohistochemistry (IHC). In addition, 80 stocked paraffin blocks of coronary arteries from 40 autopsy cases were also used. IHC revealed divergent staining patterns for PEDF in both the aortas and the coronary arteries tested, ie, “cytoplasmic staining” or “extracellular deposition,” were observed, respectively. In the areas showing cytoplasmic staining, double PEDF was expressed in a majority of the foamy macrophages and in some smooth muscle cells, and the PEDF-positive cell frequency was positively correlated with that of microvessels in a cell-rich area in the coronary arteries (
P
<0.0001). Inversely, extracellular deposition of PEDF was seen in acellular areas and was negatively correlated with the number of microvessels (
P
=0.0003).
Conclusions—
These results suggest that PEDF may function as an antiangiogenic factor when it is deposited onto the extracellular matrix. Thus, PEDF may play a significant role in determining the balance of angiogenesis/ antiangiogenesis during atherogenesis.
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Affiliation(s)
- Hiromitsu Baba
- Division of Pathophysiological and Experimental Pathology, Department of Pathology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Fukuoka 812-8582, Japan
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25
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Quan GMY, Ojaimi J, Li Y, Kartsogiannis V, Zhou H, Choong PFM. Localization of pigment epithelium-derived factor in growing mouse bone. Calcif Tissue Int 2005; 76:146-53. [PMID: 15549636 DOI: 10.1007/s00223-004-0068-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2004] [Accepted: 06/28/2004] [Indexed: 10/26/2022]
Abstract
Pigment epithelium-derived factor (PEDF) is a potent anti-angiogenic factor found in a wide range of fetal and adult tissues, where it is thought to play a role in the regulation of angiogenesis during development. The temporal expression of PEDF during endochondral bone formation has not previously been reported. In this study, we analysed the expression pattern of PEDF in growing mouse hindlimbs from newborn day one through to maturation at week 9, using immunohistochemistry and in situ hybridization. PEDF expression was demonstrated in chondrocytes within the resting, proliferative and upper hypertrophic zones of the epiphyseal growth plate. The pattern of expression was consistent throughout the developmental stages of the mouse. In addition, PEDF was expressed by osteoblasts lining the bone spicules in the ossification zone of metaphyseal bone, as well as by osteoblasts lining cortical periosteum. These novel results demonstrate that PEDF is developmentally expressed in both cartilage and bone cells during endochondral bone formation, and strongly suggest that it may play a regulatory role in the processes of chondrocyte and osteoblast differentiation, endochondral ossification, and bone remodelling during growth and development of long bones.
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Affiliation(s)
- Gerald M Y Quan
- Department of Orthopaedics, University of Melbourne, St. Vincent's Hospital Melbourne, Fitzroy 3065, Australia
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26
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Al-Ayyoubi M, Gettins PGW, Volz K. Crystal Structure of Human Maspin, a Serpin with Antitumor Properties. J Biol Chem 2004; 279:55540-4. [PMID: 15501821 DOI: 10.1074/jbc.m409957200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Maspin, a member of the serpin superfamily, has tumor suppressing activity against breast and prostate cancer. Maspin inhibits tumor growth by blocking cell invasion, and its reactive center loop (RCL) is thought to mediate this activity. To understand this function on the molecular level, we have solved the three-dimensional structure of Maspin to 3.1 A resolution. The molecular structure shows the characteristic features of the serpin fold, but the RCL of Maspin is unique in length, composition, and placement. Although the RCL of Maspin is accessible and cleavable by some proteinases, it functions in the uncleaved, constrained conformation observed here. These structural results will contribute to our understanding of the mechanism by which Maspin suppresses tumors.
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Affiliation(s)
- Maher Al-Ayyoubi
- Department of Biochemistry and Molecular Biology, University of Illinois at Chicago, 835 S. Wolcott Avenue, Chicago, IL 60612-7334
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27
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Sawant S, Aparicio S, Tink AR, Lara N, Barnstable CJ, Tombran-Tink J. Regulation of factors controlling angiogenesis in liver development: a role for PEDF in the formation and maintenance of normal vasculature. Biochem Biophys Res Commun 2004; 325:408-13. [PMID: 15530407 DOI: 10.1016/j.bbrc.2004.10.041] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Indexed: 12/30/2022]
Abstract
PEDF and VEGF are important inhibitors and promoters of angiogenesis, and the ratio between the two is an important indicator in many neovascular diseases. In mouse liver PEDF and VEGF(165) were co-expressed at very early stages of liver development and their expression increased as liver embryogenesis progressed, suggesting that PEDF and VEGF are both crucial to vasculogenesis as well. VEGF(189) only appears at the P0 stage in liver organogenesis and is maintained at high levels thereafter. PEDF and the two VEGF isoforms are synthesized by fresh and cultured hepatocytes. Expression of VEGF(121) and overexpression of VEGF(165) were only seen in HepG2, a well-characterized hepatocellular carcinoma line. The results suggest that hepatic vascular architecture is under the control of both PEDF and VEGF, and that VEGF(165) and VEGF(189) have distinct functions in normal vascular development of the liver. The VEGF isoforms 121 and 189 may be key regulators of increased vascularity and progression of hepatocellular carcinoma, one of the most common malignant tumors, and may be of prognostic significance for this tumor.
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Affiliation(s)
- S Sawant
- Pharmaceutical Sciences, University of Missouri Kansas City, Kansas City, MO, USA
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28
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Halin S, Wikström P, Rudolfsson SH, Stattin P, Doll JA, Crawford SE, Bergh A. Decreased Pigment Epithelium-Derived Factor Is Associated with Metastatic Phenotype in Human and Rat Prostate Tumors. Cancer Res 2004; 64:5664-71. [PMID: 15313905 DOI: 10.1158/0008-5472.can-04-0835] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pigment epithelium-derived factor, a potent angiogenesis inhibitor in the eye, is also expressed in the prostate. Prostate size and angiogenesis is increased in pigment epithelium-derived factor knockout mice, and pigment epithelium-derived factor is down-regulated in some prostate cancers. To investigate whether pigment epithelium-derived factor expression correlates with tumor progression, we examined 5 Dunning rat prostate sublines with different growth rates, differentiation, androgen dependence, vascular density, and metastatic ability and 26 human prostate cancers of Gleason score 8-10 obtained from patients at transurethral resection selected to represent two groups, with and without metastases at diagnosis. By Western blot, real-time quantitative reverse transcription-PCR, and immunostaining, pigment epithelium-derived factor was detected in highly differentiated, nonmetastatic, androgen-sensitive Dunning tumors and in the anaplastic, androgen insensitive but nonmetastatic Dunning tumors. In contrast, the metastatic Dunning tumor sublines showed very low pigment epithelium-derived factor expression levels. In human cancer tissues, by immunohistochemistry and real-time quantitative reverse transcription-PCR, patients without metastases at diagnosis had higher tumor pigment epithelium-derived factor levels than tumors from patients with metastases at diagnosis. In both the rat model and in the human tumors, the proliferation index and vascular count, as determined by Ki-67 staining and endoglin and/or factor VIII-related antigen staining, inversely correlated with pigment epithelium-derived factor mRNA levels. These observations indicate that loss of pigment epithelium-derived factor expression could be associated with the progression toward a metastatic phenotype in prostate cancer.
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Affiliation(s)
- Sofia Halin
- Department of Medical Biosciences, Umeå University, Umeå, Sweden
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29
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Francis MK, Appel S, Meyer C, Balin SJ, Balin AK, Cristofalo VJ. Loss of EPC-1/PEDF expression during skin aging in vivo. J Invest Dermatol 2004; 122:1096-105. [PMID: 15140209 DOI: 10.1111/j.0022-202x.2004.22510.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
EPC-1/PEDF (early population doubling level cDNA-1/retinal pigmented epithelium-derived factor) is a single-copy, quiescence-specific gene that is transcribed into a 1.5 kb mRNA and then translated into a 50 kDa secreted protein that is a potent inhibitor of angiogenesis. EPC-1 expression has been detected in a number of cultured cell lines, including lung and skin fibroblasts, retinal pigmented epithelial cells, and endometrial stromal fibroblasts. Furthermore, its expression has been shown to decline during replicative aging of these cells in culture. In this report, we describe our examination of the age-related changes in EPC-1 expression in situ in skin sections from donors of different ages. EPC-1 mRNA is detected primarily in the dermal layer of the skin and its expression declines with increasing donor age. This decline is statistically significant between young (less than 31 years old) and middle-aged (between 30 and 60 years old) donors, with the decline becoming less dramatic at older ages. This age-related decline in the expression of an angiogenic inhibitor contributes to the imbalance of angiogenic modulators that is observed during aging. In fact, this decline may reflect a compensatory change to help reverse the decline of angiogenesis marked by reduced abundance of microvessels. This downregulation of an angiogenesis inhibitor may, in turn, play a critical role in the development of diseases caused by abnormal vascularization. The potential role of the age-associated decline in EPC-1 expression in tissue remodeling and in the development of skin diseases with excessive angiogenesis may provide new insights into disease prevention.
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Affiliation(s)
- Mary Kay Francis
- Lankenau Institute for Medical Research, Wynnewood, Pennsylvania, USA.
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30
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Tombran-Tink J, Lara N, Apricio SE, Potluri P, Gee S, Ma JX, Chader G, Barnstable CJ. Retinoic acid and dexamethasone regulate the expression of PEDF in retinal and endothelial cells. Exp Eye Res 2004; 78:945-55. [PMID: 15051476 DOI: 10.1016/j.exer.2003.12.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Indexed: 12/31/2022]
Abstract
Both all-trans-retinoic acid (ATRA) and pigment epithelial-derived factor (PEDF) regulate cell proliferation and differentiation. Treatment of human Y-79 retinoblastoma and A-RPE 19 pigment epithelial cells with ATRA increased the levels of PEDF protein and RNA. Endothelial cells from bovine retina and human umbilical cord expressed PEDF and the levels were also increased by ATRA. Mouse Müller glial cells and rat C6 glioma cells showed at least a 2.5 fold increase in PEDF RNA levels after ATRA treatment, as measured by quantitative PCR. The PEDF promoter contains a retinoic acid receptor element (RARE). Plasmids containing a PEDF promoter regulating a luciferase gene were transfected into D407 and C6 cells and the luciferase activity measured after incubation in the presence or absence of ATRA. In both cell types ATRA increased the level of luciferase activity suggesting the RARE is functional. Dexamethasone was also effective at increasing PEDF RNA levels in both mouse Muller glial cells and C6 rat glioma cells. To test the effects of PEDF on retinoic acid function, expression of retinoic acid receptors in Y-79 and A-RPE 19 cells was measured by PCR. In Y79 cells, PEDF treatment increased the expression levels of RARalpha and RXRgamma receptors and in the A-RPE 19 cells it resulted in a decrease in expression of the RARbeta and RXRbeta receptors. This study clearly indicates an interaction between PEDF and ATRA. The cell differentiation activities of PEDF may operate through mechanisms orchestrated by retinoids, and the converse may also be true. The differentiation, anti-mitotic, and apoptotic actions of PEDF and ATRA may utilize parallel pathways that converge at key junctional transduction molecules to coordinate cellular quiescence and maintain tissue mass in the presence of signals that stimulate abnormal cell proliferation. It will be an interesting therapeutic strategy to co-administer PEDF and retinoic acid in developing protocols for neovascular diseases in the eye and in cancer.
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Affiliation(s)
- J Tombran-Tink
- Division of Pharmaceutical Sciences, University of Missouri-Kansas City, Kansas City, MO, USA.
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31
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Tombran-Tink J, Barnstable CJ. Osteoblasts and osteoclasts express PEDF, VEGF-A isoforms, and VEGF receptors: possible mediators of angiogenesis and matrix remodeling in the bone. Biochem Biophys Res Commun 2004; 316:573-9. [PMID: 15020256 DOI: 10.1016/j.bbrc.2004.02.076] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2004] [Indexed: 01/05/2023]
Abstract
Pigment epithelial derived factor (PEDF) is one of the most effective inhibitors of angiogenesis described so far, especially in controlling the growth of blood vessels in the eye. We now describe the localization of PEDF in regions of active bone formation in the mid-gestation mouse embryo and its specific and high levels of secretion by osteoblasts. PEDF is detected to a lesser extent in osteoclasts as well. The proangiogenic factors, VEGF and its receptors VEGF-R1 and VEGF-R2, are also expressed by both osteoblasts and osteoclasts. These findings suggest that bone angiogenesis and matrix remodeling may be mediated both by PEDF and by VEGF.
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Affiliation(s)
- J Tombran-Tink
- Division of Pharmaceutical Sciences, University of Missouri-Kansas City, 5005 Rockhill Road, Kansas City, MO 64110, USA.
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32
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Quan GMY, Ojaimi J, Nadesapillai APW, Zhou H, Choong PFM. Resistance of epiphyseal cartilage to invasion by osteosarcoma is likely to be due to expression of antiangiogenic factors. Pathobiology 2004; 70:361-7. [PMID: 12865633 DOI: 10.1159/000071277] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2002] [Accepted: 03/07/2003] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES Epiphyseal cartilage is a barrier to osteosarcoma invasion, however the mechanisms behind this resistance remain unclear. The aim of this study was to examine the chronological and spatial patterns of osteosarcoma growth and invasion of local tissue structures including epiphyseal cartilage. METHODS We used an in vivomouse model of osteosarcoma to histologically examine tumors at different stages of disease progression. We compared the pattern of osteosarcoma penetration of epiphyseal cartilage with the expression pattern of two potent mediators of angiogenesis; proangiogenic vascular endothelial growth factor (VEGF) and antiangiogenic pigment epithelium-derived factor (PEDF). RESULTS Epiphyseal cartilage remained intact across its entire length in all sections examined, despite increasing tumor size as well as intra- and extraosseous destruction. In the most advanced cases, only the proangiogenic lowermost layers of the hypertrophic zone of the growth plate were eroded. This corresponded with the growth plate layers which highly expressed the angiogenic factor VEGF. In contrast, the resting, proliferative and upper hypertrophic layers were resistant to osteosarcoma invasion in all cases. This corresponded to the layers with the highest expression of the potent antiangiogenic factor PEDF. CONCLUSION Epiphyseal cartilage is resistant to local invasion by osteosarcoma. The balance of angiogenesis, influenced by pro- and antiangiogenic factors, is likely to play an important role in this resistance.
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Affiliation(s)
- Gerald M Y Quan
- Department of Orthopaedics, University of Melbourne, St. Vincent's Hospital Melbourne, Melbourne, Vic., Australia
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33
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Petersen SV, Valnickova Z, Enghild JJ. Pigment-epithelium-derived factor (PEDF) occurs at a physiologically relevant concentration in human blood: purification and characterization. Biochem J 2003; 374:199-206. [PMID: 12737624 PMCID: PMC1223568 DOI: 10.1042/bj20030313] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2003] [Revised: 05/01/2003] [Accepted: 05/09/2003] [Indexed: 11/17/2022]
Abstract
Pigment epithelium-derived factor (PEDF) inhibits the formation of blood vessels in the eye by inducing apotosis in actively dividing endothelial cells. The activity of PEDF equals or supersedes that of other anti-angiogenic factors, including angiostatin, endostatin and thrombospondin-1. In addition, PEDF has the potential to promote the survival of neurons and affect their differentiation. Here we show that PEDF is present in plasma at a concentration of approx. 100 nM (5 microg/ml) or twice the level required to inhibit aberrant blood-vessel growth in the eye. Thus the systemic delivery of PEDF has the potential to affect angiogenesis or neurotrophic processes throughout the body, significantly expanding the putative physiological role of the protein. A complete map of all post-translational modifications revealed that authentic plasma PEDF carries an N-terminal pyroglutamate blocking group and an N-linked glycan at position Asn266. The pyroglutamate residue may regulate the activity of PEDF analogously to the manner in which it regulates thyrotropin-releasing hormone.
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Affiliation(s)
- Steen V Petersen
- Department of Molecular Biology, University of Aarhus, DK-8000 Aarhus C, Denmark
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34
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Affiliation(s)
- Joyce Tombran-Tink
- Division of Pharmaceutical Sciences, University of Missouri-Kansas City, 5005 Rockhill Road, Kansas City, Missouri 64110, USA.
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35
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Miyagishi D, Ohno-Matsui K, Amagasa T, Morita I. Regulation of the expression of pigment epithelium-derived factor, an anti-angiogenic factor in human oral squamous cell carcinoma cell lines. Cancer Lett 2003; 196:77-85. [PMID: 12860293 DOI: 10.1016/s0304-3835(03)00185-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Angiogenesis plays an important role in tumor growth and metastasis and is regulated by a balance between angiogenic stimulators and inhibitors. We investigated the gene expression profile of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF), a potent endogenous anti-angiogenic factor, in human oral squamous cell carcinoma (SCC) cell lines. The treatment of SCC cells with hypoxia increased the expression of PEDF as well as VEGF. Moreover, the treatment of SCC cells with VEGF enhanced the expression of PEDF mRNA and secretion of PEDF. In LMF-4, a SCC clone producing abundant VEGF and PEDF, the addition of neutralizing VEGF antibody substantially blocked PEDF expression. These data suggest that human oral squamous cell carcinoma cells produce VEGF, which in turn regulates PEDF production, and this balance may be contributing to neovascularization in tumors.
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Affiliation(s)
- Daisuke Miyagishi
- Department of Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
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36
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Pignolo RJ, Francis MK, Rotenberg MO, Cristofalo VJ. Putative role for EPC-1/PEDF in the G0 growth arrest of human diploid fibroblasts. J Cell Physiol 2003; 195:12-20. [PMID: 12599204 DOI: 10.1002/jcp.10212] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
EPC-1/PEDF expression is closely associated with reversible growth arrest in normal human diploid fibroblast-like (HDF) cells and is diminished with proliferative senescence in vitro. EPC-1 expression in HDF cells is induced under conditions of density-dependent contact inhibition and growth factor deprivation. Antiserum generated against EPC-1 recognizes a secreted protein of approximately 50 kDa from medium conditioned by early passage HDF cells, but not from senescent cells. The addition of EPC-1 antiserum to early population doubling level (PDL) cultures near the plateau phase of growth significantly increases the number of cells entering DNA synthesis. Affinity purified EPC-1 antibodies alone enhance the ability of near plateau-phase early PDL WI-38 cells to synthesize DNA by as much as threefold. Further, the addition of recombinant EPC-1 (rEPC-1) to logarithmically growing cells resulted in a marked decrease in the ability of these cells to enter DNA synthesis. We also demonstrate the loss of EPC-1 expression in WI-38 and IMR-90 HDF cell lines with both senescence and simian virus 40 (SV40) transformation. The loss of EPC-1 expression with SV40 transformation occurs at the level of steady-state mRNA and protein accumulation with genomic EPC-1 sequences grossly intact. Taken together, these results suggest that EPC-1 may play a role in the entry of early passage fibroblasts into a G(0) state or the maintenance of such a state once reached.
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Affiliation(s)
- Robert J Pignolo
- Center for Gerontological Research, Medical College of Pennsylvania, Philadelphia, Pennsylvania, USA
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37
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Yasui N, Mori T, Morito D, Matsushita O, Kourai H, Nagata K, Koide T. Dual-site recognition of different extracellular matrix components by anti-angiogenic/neurotrophic serpin, PEDF. Biochemistry 2003; 42:3160-7. [PMID: 12641447 DOI: 10.1021/bi0206558] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pigment epithelium-derived factor (PEDF), a member of the serine protease inhibitor (serpin) superfamily, possesses anti-angiogenic and neurotrophic activities. PEDF has been reported to bind to extracellular matrix (ECM) components such as collagens and glycosaminoglycans (GAGs). In this study, to determine the binding sites for collagens and GAGs, we analyzed the interaction of recombinant mouse PEDF (rPEDF) with collagen I and heparin. By utilizing residue-specific chemical modification and site-directed mutagenesis techniques, we revealed that the acidic amino acid residues on PEDF (Asp(255), Asp(257), and Asp(299)) are critical to collagen binding, and three clustered basic amino acid residues (Arg(145), Lys(146), and Arg(148)) are necessary for heparin binding. Mapping of these residues on the crystal structure of human PEDF (Simonovic, M., Gettins, P. G. W., and Volz, K. (2001) Proc. Natl. Acad. Sci. U.S.A. 98, 11131-11135) demonstrated that the collagen-binding site is oriented toward the opposite side of the highly basic surface where the heparin-binding site is localized. These results indicate that PEDF possesses dual binding sites for different ECM components, and this unique localization of ECM-binding sites implies that the binding to ECM components could regulate PEDF activities.
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Affiliation(s)
- Norihisa Yasui
- Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima, Tokushima 770-8506, Japan
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38
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Affiliation(s)
- Peter G W Gettins
- Department of Biochemistry & Molecular Genetics, University of Illinois at Chicago, M/C 536, 1819-53 West Polk Street, Chicago, Illinois 60612, USA.
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39
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Meyer C, Notari L, Becerra SP. Mapping the type I collagen-binding site on pigment epithelium-derived factor. Implications for its antiangiogenic activity. J Biol Chem 2002; 277:45400-7. [PMID: 12237317 DOI: 10.1074/jbc.m208339200] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pigment epithelium-derived factor (PEDF), a neurotrophic and antiangiogenic serpin, is identified in tissues rich in collagen, e.g. cornea, vitreous, bone, and cartilage. We show that recombinant human PEDF formed complexes with collagens from the bovine cornea and vitreous. We have examined the direct binding of PEDF to collagen I and found that interactions were ionic in nature and occurred when PEDF and collagen I were both in solution, when either one was immobilized, or even when collagen I was denatured under reducing conditions. (125)I-PEDF bound to immobilized collagen I in a saturable fashion (K(D) = 123 nm). Compared with neurotrophic PEDF-derived peptides, ovalbumin and angiogenic inhibitors, only full-length PEDF competed efficiently with (125)I-PEDF for the binding to immobilized collagen I (EC(50) = 3 microg/ml). The collagen-binding region was analyzed using controlled proteolysis and chemically modified PEDF. Cleavage of the serpin exposed loop did not prevent binding to collagen I. Conjugation of lysines with fluorescein increased the collagen binding affinity. However, treatment of PEDF with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide abolished it, implicating the PEDF aspartic and/or glutamic acid residues in its interaction with collagen I. A negatively charged region on the surface of the PEDF molecule is rich in acidic residues (Glu(41), Glu(42), Glu(43), Asp(44), Asp(64), Asp(256), Asp(258), Glu(290), Glu(291), Glu(296), Asp(300), Glu(304)) available to interact directly with positively charged areas of collagen. This represents the first collagen-binding site described for a serpin, which in PEDF, is distinct from its heparin-binding region, neurotrophic active site, and its serpin exposed loop. The collagen-binding property of PEDF may play a role in surface localization and modulation of its antiangiogenic effects in the eye and bone.
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Affiliation(s)
- Christina Meyer
- Laboratory of Retinal Cell and Molecular Biology, NEI, National Institutes of Health, Bethesda, Maryland 20892-2740, USA
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40
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Gettins PGW, Simonovic M, Volz K. Pigment epithelium-derived factor (PEDF), a serpin with potent anti-angiogenic and neurite outgrowth-promoting properties. Biol Chem 2002; 383:1677-82. [PMID: 12530532 DOI: 10.1515/bc.2002.188] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Pigment epithelium-derived factor is a member of the serpin superfamily of proteins, but one that lacks inhibitory properties against either serine or cysteine proteinases. Nevertheless it possesses a number of physiological properties that make it a potentially important protein in regulation of angiogenesis, in neuronal cell survival and in protection of neurons from neurotoxic agents. It is also a protein that is highly up-regulated in the G0 phase of early-passage cells compared with rapidly proliferating cells or senescent cells, and so is also linked to both the cell cycle and cell senescence. The determination of a high resolution X-ray crystal structure of native PEDF provides insight into regions of the protein that may be involved in one or more of these functions.
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Affiliation(s)
- Peter G W Gettins
- Department of Biochemistry and Molecular Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
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41
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Mariani TJ, Reed JJ, Shapiro SD. Expression profiling of the developing mouse lung: insights into the establishment of the extracellular matrix. Am J Respir Cell Mol Biol 2002; 26:541-8. [PMID: 11970905 DOI: 10.1165/ajrcmb.26.5.2001-00080c] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We have undertaken a comprehensive gene expression profiling of the entire process of murine lung development using oligonucleotide-based microarrays. Our data reveals the expression pattern of approximately 11,000 genes throughout the morphologic stages of lung development. This includes known genes with unappreciated pulmonary expression and novel genes with undefined functions. Traditional gene expression analysis techniques verify a high degree of confidence in the microarray data. Examination of the data confirms previously known patterns of expression for extracellular matrix genes and provides new information regarding relationships in temporal expression among groups of these genes. Large-scale cluster analysis reveals associations in the expression profile of specific genes with defined developmental processes. For instance, we identify groups of genes, which are coordinately expressed with extracellular matrix genes during lung development. These data should serve as a resource for the pulmonary research community and assist in deciphering the molecular mechanisms governing normal lung development as well as those involved in aberrant developmental pathology.
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Affiliation(s)
- Thomas J Mariani
- Department of Pediatrics and the Program in Lung Development, Washington University School of Medicine and Saint Louis Children's Hospital, St. Louis, Missouri, USA.
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42
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Kuncl RW, Bilak MM, Bilak SR, Corse AM, Royal W, Becerra SP. Pigment epithelium-derived factor is elevated in CSF of patients with amyotrophic lateral sclerosis. J Neurochem 2002; 81:178-84. [PMID: 12067231 DOI: 10.1046/j.1471-4159.2002.00813.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pigment epithelium-derived factor (PEDF), a recently defined retinal trophic factor and anti-angiogenic factor for the eye, is also present in the CNS and is a motor neuron protectant. We asked whether PEDF levels in CSF are altered in patients with amyotrophic lateral sclerosis (ALS). Pigment epithelium-derived factor protein was detected by quantitative western blot analysis with a PEDF-specific antiserum. Levels of PEDF in CSF, expressed as a ratio to total CSF protein, were significantly elevated 3.4-fold in 15 patients with ALS compared with neurologic disease controls (p < 0.0003). This increase does not seem likely to reflect up-regulation of PEDF synthesis in muscle in response to denervation, as CSF PEDF was not elevated in severe denervating diseases other than ALS. Nor does the increase represent some non-specific release in neurodegeneration, as CSF PEDF was not elevated in other neurodegenerative diseases. While the mechanism of this presumably reactive increase is not known, the distinctive, surprisingly elevated level of PEDF in the CSF may be an autoprotective reaction in ALS.
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Affiliation(s)
- Ralph W Kuncl
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21218, USA.
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43
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Blacque OE, Worrall DM. Evidence for a direct interaction between the tumor suppressor serpin, maspin, and types I and III collagen. J Biol Chem 2002; 277:10783-8. [PMID: 11788595 DOI: 10.1074/jbc.m110992200] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Maspin (mammary serine protease inhibitor) was originally identified as a tumor suppressor protein in human breast epithelial cells and is a member of the serine proteases inhibitor (serpin) superfamily. It inhibits tumor cell motility and angiogenesis, and although predominantly cytoplasmic, it is also localized to the cell surface. In this study we have investigated the use of the yeast two-hybrid interaction trap to identify novel maspin targets. A target human fibroblast cDNA library was screened, and the alpha-2 chain of type I collagen was identified as a potential interactant. Binding studies with isolated proteins showed interaction between recombinant maspin and types I and III collagen but not other collagen subtypes, a profile strikingly similar to mouse pigment epithelium-derived factor (caspin), which is similarly down-regulated in murine adenocarcinoma tumors and is a potent inhibitor of angiogenesis. Kinetic analysis using an IAsys resonant mirror biosensor determined the dissociation constant of maspin for collagen type I to be 0.63 microm. Further two-hybrid interactions with maspin truncation constructs suggest that collagen binding is localized to amino acids 84-112 of maspin, which aligns with the collagen-binding region of colligin. A direct interaction between exogenous or cell surface maspin and extracellular matrix collagen may contribute to a cell adhesion role in the prevention of tumor cell migration and angiogenesis.
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Affiliation(s)
- Oliver E Blacque
- Department of Biochemistry and Conway Institute for Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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44
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Coljee VW, Rotenberg MO, Tresini M, Francis MK, Cristofalo VJ, Sell C. Regulation of EPC-1/PEDF in normal human fibroblasts is posttranscriptional. J Cell Biochem 2000; 79:442-52. [PMID: 10972981 DOI: 10.1002/1097-4644(20001201)79:3<442::aid-jcb90>3.0.co;2-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The EPC-1 (early population doubling level cDNA-1) gene, also known as pigment epithelium-derived factor, encodes a protein belonging to the serine protease inhibitor (serpin) superfamily that has been reported to inhibit angiogenesis and proliferation of several cell types. We have previously reported that the EPC-1 mRNA and the secreted EPC-1 protein are expressed at levels more than 100-fold higher in early passage, G(0), WI-38 cells compared to either proliferating or senescent WI-38 fibroblasts. To examine the molecular mechanisms that regulate changes in EPC-1 gene expression in WI-38 cells, we isolated and characterized the human EPC-1 gene and determined the mRNA cap site. Transcriptional assays showed no change in the transcription rates of EPC-1 between young proliferating, quiescent, and senescent WI-38 cells. These results suggest posttranscriptional regulation of the EPC-1 gene. Reverse transcriptase polymerase chain reaction measurements (of hnRNA) indicate regulation at the hnRNA level. The regulation of the EPC-1 gene at the level of hnRNA can explain the observed slow increase in the steady-state EPC-1 mRNA levels when cells become quiescent. The reduction of EPC-1 mRNA levels that occurs when cells exit G(0) and are induced to proliferate can be accounted for by a reduction of the EPC-1 mRNA stability in stimulated cells as compared to quiescent cells.
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Affiliation(s)
- V W Coljee
- Center for Gerontological Research, Allegheny University of the Health Sciences, Philadelphia, Pennsylvania 19129, USA
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45
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Abstract
The utilization of optical biosensors to study molecular interactions continues to expand. In 1998, 384 articles relating to the use of commercial biosensors were published in 130 different journals. While significant strides in new applications and methodology were made, a majority of the biosensor literature is of rather poor quality. Basic information about experimental conditions is often not presented and many publications fail to display the experimental data, bringing into question the credibility of the results. This review provides suggestions on how to collect, analyze and report biosensor data.
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Affiliation(s)
- D G Myszka
- University of Utah, Salt Lake City, UT 84132, USA.
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46
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Kato K, Ito H, Kamei K, Inaguma Y, Iwamoto I, Saga S. Phosphorylation of alphaB-crystallin in mitotic cells and identification of enzymatic activities responsible for phosphorylation. J Biol Chem 1998; 273:28346-54. [PMID: 9774459 DOI: 10.1074/jbc.273.43.28346] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The immunofluorescence localization of alphaB-crystallin in U373 MG human glioma cells with an antibody specific for alphaB-crystallin that had been phosphorylated at Ser-45 revealed an intense staining of cells in the mitotic phase of the cell cycle. Phosphorylated forms of alphaB-crystallin in mitotic cells were detected in all cell lines examined and in tissue sections of mouse embryos. Increases in the levels of alphaB-crystallin that had been phosphorylated at Ser-45 and Ser-19, but not at Ser-59, were detected biochemically by isoelectric focusing or SDS-polyacrylamide gel electrophoresis and a subsequent Western blot analysis of extracts of cells collected at the mitotic phase. When we estimated the phosphorylation activity specific for alphaB-crystallin in extracts of mitotic U373 MG cells, using the amino-terminal 72-amino acid peptide derived from unphosphorylated alphaB2-crystallin as the substrate, we found that the activities responsible for the phosphorylation of Ser-45 and Ser-19 were markedly enhanced but that the activity responsible for the phosphorylation of Ser-59 was suppressed. The protein kinases responsible for the phosphorylation of Ser-45 and Ser-59 in the amino-terminal 72-amino acid peptide were partially purified from extracts of cells that had been stimulated by exposure to H2O2 in the presence of calyculin A. The activities responsible for the phosphorylation of Ser-45 and Ser-59 were eluted separately from a column of Superdex 200 at fractions corresponding to about 40 and 60 kDa, respectively, while the kinase for Ser-19 was unstable. p44/42 mitogen-activated protein (MAP) kinase and MAP kinase-activated protein (MAPKAP) kinase-2 were concentrated in the Ser-45 kinase fraction and Ser-59 kinase fraction, respectively. Recombinant human p44 MAP kinase and MAPKAP kinase-2 purified from rabbit muscle selectively phosphorylated Ser-45 and -59, respectively. The Ser-45 kinase fraction and Ser-59 kinase fraction phosphorylated myelin basic protein and hsp27, respectively. These results suggest that the phosphorylations of Ser-45 and Ser-59 in alphaB-crystallin are catalyzed by p44/42 MAP kinase and MAPKAP kinase-2, respectively, in cells and that the phosphorylation of Ser-45 by p44/42 MAP kinase is enhanced while the phosphorylation of Ser-59 by MAPKAP kinase-2 is suppressed during cell division.
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Affiliation(s)
- K Kato
- Department of Biochemistry, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi 480-0392, Japan.
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