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Sheibani N, Wang S, Darjatmoko SR, Fisk DL, Shahi PK, Pattnaik BR, Sorenson CM, Bhowmick R, Volpert OV, Albert DM, Melgar-Asensio I, Henkin J. Novel anti-angiogenic PEDF-derived small peptides mitigate choroidal neovascularization. Exp Eye Res 2019; 188:107798. [PMID: 31520600 PMCID: PMC7032632 DOI: 10.1016/j.exer.2019.107798] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/07/2019] [Accepted: 09/10/2019] [Indexed: 12/12/2022]
Abstract
Abnormal migration and proliferation of endothelial cells (EC) drive neovascular retinopathies. While anti-VEGF treatment slows progression, pathology is often supported by decrease in intraocular pigment epithelium-derived factor (PEDF), an endogenous inhibitor of angiogenesis. A surface helical 34-mer peptide of PEDF, comprising this activity, is efficacious in animal models of neovascular retina disease but remains impractically large for therapeutic use. We sought smaller fragments within this sequence that mitigate choroidal neovascularization (CNV). Expecting rapid intravitreal (IVT) clearance, we also developed a method to reversibly attach peptides to nano-carriers for extended delivery. Synthetic fragments of 34-mer yielded smaller anti-angiogenic peptides, and N-terminal capping with dicarboxylic acids did not diminish activity. Charge restoration via substitution of an internal aspartate by asparagine improved potency, achieving low nM apoptotic response in VEGF-activated EC. Two optimized peptides (PEDF 335, 8-mer and PEDF 336, 9-mer) were tested in a mouse model of laser-induced CNV. IVT injection of either peptide, 2-5 days before laser treatment, gave significant CNV decrease at day +14 post laser treatment. The 8-mer also decreased CNV, when administered as eye drops. Also examined was a nanoparticle-conjugate (NPC) prodrug of the 9-mer, having positive zeta potential, expected to display longer intraocular residence. This NPC showed extended efficacy, even when injected 14 days before laser treatment. Neither inflammatory cells nor other histopathologic abnormalities were seen in rabbit eyes harvested 14 days following IVT injection of PEDF 336 (>200 μg). No rabbit or mouse eye irritation was observed over 12-17 days of PEDF 335 eye drops (10 mM). Viability was unaffected in 3 retinal and 2 choroidal cell types by PEDF 335 up to 100 μM, PEDF 336 (100 μM) gave slight growth inhibition only in choroidal EC. A small anti-angiogenic PEDF epitope (G-Y-D-L-Y-R-V) was identified, variants (adipic-Sar-Y-N-L-Y-R-V) mitigate CNV, with clinical potential in treating neovascular retinopathy. Their shared active motif, Y - - - R, is found in laminin (Ln) peptide YIGSR, which binds Ln receptor 67LR, a known high-affinity ligand of PEDF 34-mer.
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Affiliation(s)
- Nader Sheibani
- Department of Ophthalmology and Visual Sciences, Biomedical Engineering, and Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Shoujian Wang
- Department of Ophthalmology and Visual Sciences, Biomedical Engineering, and Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Soesiawati R Darjatmoko
- Department of Ophthalmology and Visual Sciences, Biomedical Engineering, and Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Debra L Fisk
- Department of Ophthalmology and Visual Sciences, Biomedical Engineering, and Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Pawan K Shahi
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Bikash R Pattnaik
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Christine M Sorenson
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Reshma Bhowmick
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Olga V Volpert
- Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Daniel M Albert
- Department of Ophthalmology and Visual Sciences, Biomedical Engineering, and Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | | | - Jack Henkin
- Center for Developmental Therapeutics, Northwestern University, Evanston, IL, USA.
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Lukas K, Thomas U, Gessner A, Wehner D, Schmid T, Schmid C, Lehle K. Plasma functionalization of polycarbonaturethane to improve endothelialization—Effect of shear stress as a critical factor for biocompatibility control. J Biomater Appl 2016; 30:1417-28. [DOI: 10.1177/0885328215626072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Medical devices made of polycarbonaturethane (PCU) combine excellent mechanical properties and little biological degradation, but restricted hemocompatibility. Modifications of PCU might reduce platelet adhesion and promote stable endothelialization. PCU was modified using gas plasma treatment, binding of hydrogels, and coupling of cell-active molecules (modified heparin, anti-thrombin III (ATIII), argatroban, fibronectin, laminin-nonapeptide, peptides with integrin-binding arginine-glycine-aspartic acid (RGD) motif). Biocompatibility was verified with static and dynamic cell culture techniques. Blinded analysis focused on improvement in endothelial cell (EC) adhesion/proliferation, anti-thrombogenicity, reproducible manufacturing process, and shear stress tolerance of ECs. EC adhesion and antithrombogenicity were achieved with 9/35 modifications. Additionally, 6/9 stimulated EC proliferation and 3/6 modification processes were highly reproducible for endothelialization. The latter modifications comprised immobilization of ATIII (A), polyethyleneglycole-diamine-hydrogel (E) and polyethylenimine-hydrogel connected with modified heparin (IH). Under sheer stress, only the IH modification improved EC adhesion within the graft. However, ECs did not arrange in flow direction and cell anchorage was restricted. Despite large variation in surface modification chemistry and improved EC adhesion under static culture conditions, additional introduction of shear stress foiled promising preliminary data. Therefore, biocompatibility testing required not only static tests but also usage of physiological conditions such as shear stress in the case of vascular grafts.
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Affiliation(s)
- Karin Lukas
- IMHR, Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
| | | | - André Gessner
- IMHR, Institute for Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
| | | | | | - Christof Schmid
- Department of Cardiothoracic Surgery, University Hospital Regensburg, Regensburg, Germany
| | - Karla Lehle
- Department of Cardiothoracic Surgery, University Hospital Regensburg, Regensburg, Germany
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Chavan SS, Hudson LK, Li JH, Ochani M, Harris Y, Patel NB, Katz D, Scheinerman JA, Pavlov VA, Tracey KJ. Identification of pigment epithelium-derived factor as an adipocyte-derived inflammatory factor. Mol Med 2012; 18:1161-8. [PMID: 22714715 DOI: 10.2119/molmed.2012.00156] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 06/14/2012] [Indexed: 12/31/2022] Open
Abstract
Obesity is a major risk factor for insulin resistance, type 2 diabetes mellitus and cardiovascular disease. The pathophysiology of obesity is associated with chronic low-grade inflammation. Adipose tissue in obesity is significantly infiltrated by macrophages that secrete cytokines. The mechanisms of interaction between macrophages and adipocytes, leading to macrophage activation and increased cytokine release, remain to be elucidated. We reasoned that an adipocyte-derived factor might stimulate activation of macrophages. We have identified pigment epithelium-derived factor (PEDF) as a mediator of inflammation that is secreted by adipocytes and mediates macrophage activation. Recombinant PEDF activates macrophages to release tumor necrosis factor (TNF) and interleukin-1 (IL-1). The PEDF receptor adipose triglyceride lipase (ATGL) is required for PEDF-mediated macrophage activation. Selective inhibition of ATGL on macrophages attenuates PEDF-induced TNF production, and PEDF enhances the phosphorylation of p38 and extracellular signal-regulated kinase 1/2 mitogen-activated protein kinases. PEDF administration to rats results in increased serum TNF levels, and insulin resistance. Together, these findings suggest that PEDF secreted by adipocytes contributes to the onset and maintenance of chronic inflammation in obesity, and may be a therapeutic target in ameliorating insulin resistance.
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Affiliation(s)
- Sangeeta S Chavan
- Laboratory of Biomedical Science, The Feinstein Institute for Medical Research, Manhasset, New York 11030, United States of America.
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Abstract
The 67LR (67 kDa laminin receptor) enables cells to interact with components of the extracellular matrix. The molecule is derived from the 37LRP (37 kDa laminin receptor precursor); however, the precise molecular mechanism of this conversion is unknown. Recombinant 37LRP, expressed in and purified from Escherichia coli, bound to human laminin in a SPR (surface plasmon resonance) experiment. 67LR isolated from human breast-cancer-derived cells in culture was also shown to bind to laminin by SPR. However, the kinetics of association are qualitatively different. 37LRP, but not 67LR, binds to heparan sulfate. The binding of 37LRP to heparan sulfate did not affect the interaction of 37LRP with laminin. In contrast, heparan sulfate reduces the extent of binding of laminin to 67LR. Taken together, these results show that 37LRP has some of the biological activities of 67LR, even prior to the conversion event. However, the conversion affects the sites of interaction with both laminin and heparan sulfate.
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Abstract
The 67LR (67 kDa laminin receptor) is a cell-surface receptor with high affinity for its primary ligand. Its role as a laminin receptor makes it an important molecule both in cell adhesion to the basement membrane and in signalling transduction following this binding event. The protein also plays critical roles in the metastasis of tumour cells. Isolation of the protein from either normal or cancerous cells results in a product with an approx. molecular mass of 67 kDa. This protein is believed to be derived from a smaller precursor, the 37LRP (37 kDa laminin receptor precursor). However, the precise mechanism by which cytoplasmic 37LRP becomes cell-membrane-embedded 67LR is unclear. The process may involve post-translational fatty acylation of the protein combined with either homo- or hetero-dimerization, possibly with a galectin-3-epitope-containing partner. Furthermore, it has become clear that acting as a receptor for laminin is not the only function of this protein. 67LR also acts as a receptor for viruses, such as Sindbis virus and dengue virus, and is involved with internalization of the prion protein. Interestingly, unmodified 37LRP is a ribosomal component and homologues of this protein are found in all five kingdoms. In addition, it appears to be strongly associated with histones in the eukaryotic cell nucleus, although the precise role of these interactions is not clear. Here we review the current understanding of the structure and function of this molecule, as well as highlighting areas requiring further research.
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Yang Q, Liu Y, Cheng J, Wang JJ, Yang YJ, Zhang SL. Up-regulating effect of hepatitis C virus core protein on laminin B1 chain gene promoter. Shijie Huaren Xiaohua Zazhi 2003; 11:955-958. [DOI: 10.11569/wcjd.v11.i7.955] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM HCV core protein is a potential transactivator for a broad spectrum of hepatocellular genes. To investigate activity of HCV core protein on laminin B1 chain promoter, we use co-transfection methods and reporter gene expression in hepatoblastoma cell.
METHODS LAMB-p sequence was identified in GenBank by bioinformatics and amplified from HepG2 genome by polymerase chain reaction (PCR). The amplified product was cloned into pCAT3 vector. The NIH 3T3 and COS-7 cell line were transfected by pCAT3-LAMB-p, the NIH 3T3 cell line was co-transfected by pCAT3-LAMB-p and pcDNA3.1(-)-core. The choloraphenical acetyltransferase (CAT) activity was detected by enzyme-linked immunosorbent assay (ELISA) kit.
RESULTS In all cell lines, we found pCAT3-LAMB-p had higher activity of CAT than pCAT3-basic by ELISA kit. The expression of CAT in co-transfection was 3.3 times as higher as that of pCAT3-LAMB-p plasmid.
CONCLUSION HCV-core protein has transactivity on LAMB promoter, and this result is implicating in the pathogenesis of fibrosis related to HCV infection
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Affiliation(s)
- Qian Yang
- Gene Therapy Research Center, Institute of Infectious Diseases, 302 Hospital of PLA, Beijing 100039, China
| | - Yan Liu
- Gene Therapy Research Center, Institute of Infectious Diseases, 302 Hospital of PLA, Beijing 100039, China
| | - Jun Cheng
- Gene Therapy Research Center, Institute of Infectious Diseases, 302 Hospital of PLA, Beijing 100039, China
| | - Jian-Jun Wang
- Gene Therapy Research Center, Institute of Infectious Diseases, 302 Hospital of PLA, Beijing 100039, China
| | - Yan-Jie Yang
- Gene Therapy Research Center, Institute of Infectious Diseases, 302 Hospital of PLA, Beijing 100039, China
| | - Shu-Lin Zhang
- Gene Therapy Research Center, Institute of Infectious Diseases, 302 Hospital of PLA, Beijing 100039, China
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Jaseja M, Copié V, Starkey J. Conformational studies of antimetastatic laminin-1 derived peptides in different solvent systems, using solution NMR spectroscopy. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2003; 61:24-39. [PMID: 12472846 DOI: 10.1034/j.1399-3011.2003.21040.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Due to its critical role in cancer progression, interactions between laminin-1 and the 67 kDa Laminin-Binding Protein (the 67 kDa LBP) have been the focus of a number of structural and biological studies. As laminin-1 is such a large and complex molecule, research interests have turned to the investigation of bioactive peptides derived from binding domains of laminin-1. Two peptides of interest, CDPGYIGSR (peptide 11) and YIGSR, both derived from the beta1 chain of laminin-1, have been shown to block invasion of basement membranes by tumor cells. Substituting the C-terminal arginine to lysine, a conservative substitution, results in a loss of peptide antimetastatic activity. This difference in bioactivity has been attributed, based on numerous modeling studies of free peptide conformations, to structural differences between YIGSR and YIGSK. Yet the nature of the 'active' free peptide backbone conformation has been a matter of debate and controversy. In order to test the validity of the structural modeling claims, we have undertaken detailed conformational studies of the two laminin-1 derived peptides YIGSR and CDPGYIGSR along with the biologically inactive YIGSK analog by two-dimensional solution 1H NMR spectroscopy in three different solvent systems. Herein we report that although both the active (YIGSR, CDPGYIGSR) and the inactive (YIGSK) peptides can adopt several closely related conformations in solution, the two peptides share similar conformational preferences, and there are no significant structural differences between the active and inactive peptides, contrary to previously reported modeling data. We conclude that the basis of the peptide biological activity, in contrast to published models, cannot be attributed to well-defined structural preferences of the free peptides. We infer that the difference in bioactivity observed between YIGSR and YIGSK originates primarily from the chemical nature of the arginine versus lysine sidechain substitution, rather than being due to a structural change in the free peptide conformations.
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Affiliation(s)
- M Jaseja
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Massachusetts 59717, USA
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Abstract
Cellular regulatory mechanisms normally maintain a delicate balance between cell proliferation, quiescence and death. The imbalance between these functions resulting from molecular intracellular changes is a key factor in tumorigenesis. Tumor cells detaching from the primary tumor possess a propension for invasion and metastasis formation. These tumor cells can attach, migrate, proliferate and grow in host tissue. The surrounding extracellular matrix (ECM) modulates these functions. It is now widely accepted that cell-matrix interactions play an important role in these processes. Most investigators concentrated their attention on the role of integrins in the above processes. There are, however, only scant data on the role of elastin and its receptors in tumor invasion. Nevertheless, experimental evidence indicates that the 67 kDa elastin-laminin receptor (ELR) subunit plays an important role in tumor invasion by mediating essential tumor cell functions leading to metastases. In this review we will concentrate on the putative role of the 67 kDa ELR subunit in tumor invasion.
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Affiliation(s)
- Tamas Fülöp
- Département de Médecine, Center de recherché sur le vieillissement, Service de Gériatrie, Institut Universitaire de Gériatrie de Sherbrooke, 1036 rue Belvedere sud, Sherbrooke, Que., Canada J1H 4C4.
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9
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Gebarowska D, Stitt AW, Gardiner TA, Harriott P, Greer B, Nelson J. Synthetic peptides interacting with the 67-kd laminin receptor can reduce retinal ischemia and inhibit hypoxia-induced retinal neovascularization. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 160:307-13. [PMID: 11786424 PMCID: PMC1867145 DOI: 10.1016/s0002-9440(10)64374-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The high-affinity 67-kd laminin receptor (67LR) is expressed by proliferating endothelial cells during retinal neovascularization. The role of 67LR has been further examined experimentally by administration of selective 67LR agonists and antagonists in a murine model of proliferative retinopathy. These synthetic 67LR ligands have been previously shown to stimulate or inhibit endothelial cell motility in vitro without any direct effect on proliferation. In the present study, a fluorescently labeled 67LR antagonist (EGF(33-42)) was injected intraperitoneally into mice and its distribution in the retina was assessed by confocal scanning laser microscopy. Within 2 hours this peptide was localized to the retinal vasculature, including preretinal neovascular complexes, and a significant amount had crossed the blood retinal barrier. For up to 24 hours postinjection, the peptide was still present in the retinal vascular walls and, to a lesser extent, in the neural retina. Non-labeled EGF(33-42) significantly inhibited pre-retinal neovascularization in comparison to controls treated with phosphate-buffered saline or scrambled peptide (P < 0.0001). The agonist peptide (Lam beta 1(925-933)) also significantly inhibited proliferative retinopathy; however, it caused a concomitant reduction in retinal ischemia in this model by promoting significant revascularization of the central retina (P < 0.001). Thus, 67LR appears to be an important target receptor for the modulation of retinal neovascularization. Agonism of this receptor may be valuable in reducing the hypoxia-stimulated release of angiogenic growth factors which drives retinal angiogenesis.
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Affiliation(s)
- Dorota Gebarowska
- Centre of Ophthalmology and Vision Science and the School of Biology and Biochemistry, The Queen's University of Belfast, Royal Victoria Hospital, Belfast, Northern Ireland, United Kingdom
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McKenna DJ, Simpson DA, Feeney S, Gardiner TA, Boyle C, Nelson J, Stitt AW. Expression of the 67 kDa laminin receptor (67LR) during retinal development: correlations with angiogenesis. Exp Eye Res 2001; 73:81-92. [PMID: 11428865 DOI: 10.1006/exer.2001.1013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Interaction of vascular cells with the laminin component of basement membranes is important for normal cell function. Likewise, abnormal interactions may have a critical role in vascular pathology. It has been previously demonstrated that the 67 kDa laminin receptor (67LR) is expressed at high levels during proliferative retinopathy in a mouse model and in the current study we have examined 67LR in the neonatal mouse to determine if this receptor plays a role in aspects of developmental angiogenesis in the developing murine retina. Groups of C57/BL6 mice were killed at postnatal day P1, P3, P5, P7, P9 and P11 to assess the retinal vasculature. A number of mice were perfused with FITC-dextran and the eyes removed, fixed in 4% paraformaldehyde (PFA) and flat-mounted for confocal scanning laser microscopy. The eyes from the remaining mice were either placed in 4% PFA and embedded in paraffin-wax, or had the neural retina dissected off and total RNA or protein extracted. Immunofluorescence, in situ hybridization, quantitative reverse transcriptase polymerase chain reaction and Western blotting analysis were employed to locate and determine expression levels of 67LR. Both 67LR mRNA and protein expression showed a characteristic bi-phasic expression pattern which correlated with key stages of retinal vascular development in the murine retina. 67LR showed high expression levels at P1 (P < 0.05) (correlating with superficial vascular plexus formation) and at P7 (P < 0.05) (correlating with deep vascular plexus formation). Conversely, 67LR expression was decreased when active angiogenic activity was lowest. Significantly, optical sectioning of retinal flat-mounts revealed high levels of 67LR expression in developing segments of both superficial and deep capillary plexi, a pattern which co-localized strongly with laminin. 67LR is regulated during post-natal development of the retinal vasculature. High levels of 67LR during the two well-defined phases of retinal capillary plexus formation suggests that this receptor may play an important role in retinal angiogenesis.
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Affiliation(s)
- D J McKenna
- Department of Ophthalmology, The Queen's University of Belfast, The Royal Victoria Hospital, Belfast BT12 6BA, Northern Ireland, U.K
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Bernardini N, Bianchi F, Dolfi A. Laminin and beta1 integrin distribution in the early stages of human kidney development. Nephron Clin Pract 2000; 81:289-95. [PMID: 10050083 DOI: 10.1159/000045295] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Laminin, an extracellular matrix molecule (EMM) widely expressed in the basal laminae, interacts with specific membrane receptors among which the integrin molecules are the best known. During embryo development laminin is the first synthesized EMM and plays a significant role in the morphogenesis of organs in which epithelial-mesenchymal interactions and branching take place. The present study describes the distribution of laminin and of beta1 integrin receptors during the very early stages of human kidney development. The observations were carried out on paraffin sections of human embryos ranging between the 4th and the 7th gestational week. Laminin was detected within the basement membranes of mesonephric duct, vesicles, glomerular vessels and celomic epithelium. The metanephric anlage reacted with anti-laminin immunoglobulins in the basement membrane underlying the ampullae and in few blastemic cap cells. Low levels of beta1 integrin reactivity were found in both the mesonephric and metanephric structures. This study provides for the first time data about the distribution of laminin and beta1 integrin in the early stages of human renal organogenesis suggesting a key role for these molecules in the epithelial-mesenchymal interactions necessary for kidney development.
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Affiliation(s)
- N Bernardini
- Chair of Histology and General Embryology, Faculty of Medicine and Surgery, Pisa University, Pisa, Italy
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Shmakov AN, Bode J, Kilshaw PJ, Ghosh S. Diverse patterns of expression of the 67-kD laminin receptor in human small intestinal mucosa: potential binding sites for prion proteins? J Pathol 2000; 191:318-22. [PMID: 10878555 DOI: 10.1002/1096-9896(2000)9999:9999<::aid-path640>3.0.co;2-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
It has been shown that the 67-kD laminin receptor (LR) may function as a receptor for Sindbis and tick-born encephalitis viruses. Recent data indicate that the 37-kD precursor (LRP) for this molecule acts as a receptor for prion proteins (PrP), self-proteins implicated in the pathogenesis of transmissible spongiform encephalopathies including new variant Creutzfeldt-Jakob disease (nvCJD). Laminin and PrP share the same binding site on LRP, which is incorporated into the mature LR as a functional binding domain. To localize PrP binding sites potentially relevant to oral infection, the expression of the LR in human small intestinal mucosa was studied. Expression of the LR was determined by immunohistochemistry in duodenal and jejunal biopsies using a monoclonal antibody (MLuC5) which specifically recognizes the 67-kD LR. Biopsy material was obtained from 39 control patients, 15 patients with ulcerative colitis, 15 patients with Crohn's disease and uninvolved small bowel, and 28 patients with active coeliac disease. Two distinctive patterns of LR expression were found within each group of patients. One pattern was characterized by LR expression in the brush border and Golgi apparatus region of villus and crypt enterocytes. Paneth cell secretory granules were positive for LR in these samples. Brush border expression of LR was found in approximately 40% of samples, with the exception of Crohn's disease (6.7% of samples were positive). Another pattern of LR expression was characterized by positively stained endothelium, while the epithelium was generally negative (45 of 97). The use of two polyclonal antibodies which recognize both the LRP and the LR confirmed brush border and paranuclear expression of the LR, but also showed varying cytoplasmic and apical surface immunoreactivity in MLuC5-negative epithelium, reflecting the distribution of LRP as opposed to the mature receptor. In conclusion, expression of the LR in the brush border and in Paneth cell secretory granules suggests that this molecule might be involved in both secretory and endocytotic functions. The major implication of intestinal epithelial/brush border expression of the LR may be an increased susceptibility to oral infection with prion proteins.
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Affiliation(s)
- A N Shmakov
- Gastrointestinal Laboratory, Department of Medical Sciences, University of Edinburgh, UK
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Donaldson EA, McKenna DJ, McMullen CB, Scott WN, Stitt AW, Nelson J. The expression of membrane-associated 67-kDa laminin receptor (67LR) is modulated in vitro by cell-contact inhibition. MOLECULAR CELL BIOLOGY RESEARCH COMMUNICATIONS : MCBRC 2000; 3:53-9. [PMID: 10683318 DOI: 10.1006/mcbr.2000.0191] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interaction of cells with their substratum is an important determinant of cell behaviour, influencing attachment, proliferation, and motility. Such interactions are mediated by cell surface receptors which bind to attachment factors, like the glycoprotein laminin in basement membranes. We have previously shown that expression of the 67-kDa laminin receptor (67LR) is elevated in proliferating retinal microvasculature compared with mature, quiescent vessels. Here, we examined 67LR mRNA and protein expression in primary cultures of retinal microvascular endothelial cells (RMEC) and in the breast cancer cell-line T47D during stages of contact inhibition. In both cell types, the expression levels of 67LR mRNA and membrane-associated 67LR protein were significantly increased during the proliferative phases of monolayer formation. As the cells achieved contact inhibition, 67LR expression was reduced to comparatively low levels. Thus, the differential expression of 67LR between dividing and contact-inhibited cells may indicate a role for this receptor during proliferative processes.
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Affiliation(s)
- E A Donaldson
- School of Biology and Biochemistry, Queen's University of Belfast, Belfast, BT9 7BL, Northern Ireland
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