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      Role of Connective Tissue Growth Factor in Mediating Hypertrophy of Human Proximal Tubular Cells Induced by Angiotensin II

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          Abstract

          Background/Aims: Cellular hypertrophy is an early important pathological feature of renal diseases such as diabetic nephropathy and remnant kidney. Recent studies have demonstrated that angiotensin II (Ang II) might be a major contributor in regulating cell hypertrophy. However, the exact mechanism is still unclear. The aim of our present work was to investigate the possible role of a newly clarified fibrogenic factor, connective tissue growth factor (CTGF), in mediating the effect of Ang II-induced tubular cell hypertrophy. Methods: The cell line HK2 was grown in Dulbecco’s modified Eagle’s medium containing 10% heat-inactivated fetal calf serum. After the cells were rested in serum-free medium for 24 h, the dose and time response of CTGF mRNA expression to Ang II stimulation was observed by RT-PCR, and protein synthesis was observed by Western blotting. The effect of anti-CTGF on Ang II (10<sup>–7</sup> M)-induced [<sup>3</sup>H]-leucine incorporation, total protein content (Coomassie brilliant blue G250 method) and change in cellular size [determined by a scanning electronic microscope (SEM)] was also observed. The influence of anti-CTGF antibody on the cell cycle was analyzed by using a fluorescence-activated cell sorter flow cytometer. Results: The results showed that Ang II induced expression of CTGF mRNA in a time- and dose-dependent manner (p < 0.05 and 0.01, respectively). Stimulation of cells with Ang II (10<sup>–7</sup> M) for 48 h resulted in a 92% increase in [<sup>3</sup>H]-leucine incorporation (5,584 cpm/10<sup>5</sup> cells at 0 h vs. 10,741 cpm/10<sup>5</sup> cells at 48 h; p = 0.01), which was significantly abolished by treatment with anti-CTGF antibody. Ang II (10<sup>–7</sup> M) significantly increased the total protein content in HK2 cells (control: 0.169 ± 0.011 mg/10<sup>5</sup> cells vs. Ang II: 0.202 ± 0.010 mg/10<sup>5</sup> cells; p = 0.03), which was markedly inhibited by cotreatment with anti-CTGF antibody. The average cellular diameter determined by SEM showed that the increase in cell size induced by Ang II could be significantly inhibited by anti-CTGF antibody (control: 11.92 ± 1.62 µm, Ang II group: 20.63 ± 3.83 µm, Ang II + anti-CTGF group: 16.43 ± 3.23 µm; p < 0.01, respectively). Furthermore, the flow cytometer study showed that Ang II arrested the cell cycle at G0–G1 phase, which was significantly reversed by treatment with anti-CTGF antibody (G0–G1 percentage: in Ang II group: 76 ± 1.8%, in Ang II + anti-CTGF group: 71 ± 1.78%; p = 0.04). Conclusion: Our data are the first to clearly demonstrate that CTGF might be an important mediator of Ang II-induced renal hypertrophy, which suggests that inhibiting the production of CTGF might be the new strategy in early prevention of renal fibrosis.

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          Most cited references 4

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          Connective tissue growth factor: a cysteine-rich mitogen secreted by human vascular endothelial cells is related to the SRC-induced immediate early gene product CEF-10

          Human umbilical vein endothelial (HUVE) cells have been previously reported to express the genes for the A and B chains of PDGF and to secrete PDGF-related factors into culture media. Antihuman PDGF IgG affinity chromatography was used to purify PDGF-related activity from HUVE cell-conditioned media. Immunoblot analysis of the affinity- purified proteins with anti-PDGF IgG and antibodies specific for the A or B chain peptides of PDGF combined with chemotactic and mitogenic assays revealed that the major PDGF immunorelated molecule secreted by HUVE cells is a monomer of approximately 36-38 kD and that less than 10% of the purified biologically active molecules are PDGF A or B chain peptides. Screening of an HUVE cell cDNA library in the expression vector lambda gtl 1 with the anti-PDGF antibody resulted in the cloning and sequencing of a cDNA with an open reading frame encoding a 38-kD cysteine-rich secreted protein which we show to be the major PDGF- related mitogen secreted by human vascular endothelial cells. The protein has a 45% overall homology to the translation product of the v- src-induced CEF-10 mRNA from chick embryo fibroblasts. We have termed this new mitogen connective tissue growth factor.
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            Proinflammatory actions of angiotensins.

            Many experimental data have suggested that the renin-angiotensin system participates in immune and inflammatory responses. Angiotensin II is involved in several steps of the inflammatory process: mononuclear cells respond to angiotensin II stimulation (cell proliferation and chemotaxis); angiotensin II regulates the recruitment of proinflammatory cells into the site of injury (mediated by the expression of vascular permeability factors, adhesion molecules and chemokines by resident cells); inflammatory cells can produce angiotensin II, and might therefore contribute to the perpetuation of tissue damage. In this review, we summarize the proinflammatory properties of angiotensin II, to demonstrate the novel role of this vasoactive peptide as a true cytokine. We will show the information obtained as a result of the pharmacological blockade of the renin angiotensin system, which has demonstrated that this system is involved in immune and inflammatory diseases. In this aspect, we discuss the molecular mechanism of angiotensin II-induced tissue damage, as well as its contribution to the pathogenesis of several diseases, including atherosclerosis, hypertension and renal damage, showing that angiotensin II plays an active role in the inflammatory response of these diseases.
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              Suppression Subtractive Hybridization Identifies High Glucose Levels as a Stimulus for Expression of Connective Tissue Growth Factor and Other Genes in Human Mesangial Cells

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                Author and article information

                Journal
                AJN
                Am J Nephrol
                10.1159/issn.0250-8095
                American Journal of Nephrology
                S. Karger AG
                0250-8095
                1421-9670
                2003
                December 2003
                21 November 2003
                : 23
                : 6
                : 429-437
                Affiliations
                aInstitute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, bPathophysiology Department, Nanjing Medical University, Nanjing, Jiangsu Province, China; cCenter for Nephrology, Royal Free and University College Medical School, London, dInstitute of Nephrology, University of Wales College of Medicine, Cardiff, UK
                Article
                74534 Am J Nephrol 2003;23:429–437
                10.1159/000074534
                14583661
                © 2003 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                Page count
                Figures: 10, Tables: 2, References: 25, Pages: 9
                Product
                Self URI (application/pdf): https://www.karger.com/Article/Pdf/74534
                Categories
                Original Report: Laboratory Investigation

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