Blog
About

0
views
0
recommends
+1 Recommend
1 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found

      What Makes Cells Grow Larger and How Do They Do It? Renal Hypertrophy Revisited

      Cardiorenal Medicine

      S. Karger AG

      In vitro models, TGFβ, Ammonia, Kidney, Cell growth, Hypertrophy, Hyperplasia, Cell cycle, Growth factors, In vivo models

      Read this article at

      ScienceOpenPublisherPubMed
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Hypertrophy, defined as an increase in cell size without an increase in cell number, occurs in a number of conditions, including compensatory renal growth, diabetes mellitus, protein feeding, chronic metabolic acidosis, and chronic potassium deficiency. In vitro cell culture studies have been used to characterize the mechanisms involved in the development of hypertrophy. Two mechanisms have been identified and characterized. One mechanism involves regulation of processes that are also associated with the initial events of the hyperplastic growth process, and is referred as a cell cycle-dependent mechanism. The other mechanism occurs independently of these particular cell cycle processes, but involves regulation of protein degradation by lysosomal enzymes. This latter mechanism is referred to as a cell cycle-independent mechanism. In vivo studies suggest that both compensatory renal hypertrophy following uninephrectomy and diabetes mellitus-induced hypertrophy involve the cell cycle-dependent mechanism.

          Related collections

          Most cited references 3

          • Record: found
          • Abstract: found
          • Article: not found

          Retinoblastoma protein switches the E2F site from positive to negative element.

          Originally E2F sites were identified as elements in the promoters of adenovirus early genes that are necessary for activation of these genes by the early protein E1a (ref. 1). E2F promoter elements have been shown to be important for transcriptional activation of several genes critical for progression through the cell cycle. During the G1 phase of the cell cycle, the E2F protein forms a complex with the cell-cycle protein Rb (ref. 5) and it has been suggested that this binding of Rb to E2F inactivates E2F (ref. 5). Here we show that Rb-E2F is an active complex that, when bound to the E2F site, inhibits the activity of other promoter elements and thus silences transcription. We propose that the ability of this complex to inhibit transcription is integral to the function of Rb and provide evidence that E2F is a positive element in the absence of an active form of Rb. It has been shown that binding of Rb to E2F depends on the phosphorylation state of Rb (only the underphosphorylated form binds) and that the phosphorylation state of Rb changes during progression through the cell cycle. We therefore suggest that the E2F site alternates between a positive and negative element with the phosphorylation/dephosphorylation cycle of Rb. This cyclic activity may be responsible for activating and then inhibiting genes during the cell cycle.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Growth-dependent translation of IGF-II mRNA by a rapamycin-sensitive pathway.

            Insulin-like growth factor (IGF)-II is important for fetal growth and development. The human IGF-II gene generates multiple mature transcripts with different 5' untranslated regions (5'UTRs) but identical coding regions and 3'UTRs. We have previously shown that a minor 4.8-kilobase messenger RNA was engaged in the synthesis of preproIGF-II, and a major 6.0-kb mRNA was untranslated and stored in a 100S ribonucleoprotein particle. Here we demonstrate that the 6.0-kb mRNA is selectively mobilized and translated in dispersed exponentially growing cells. Translational activation is prevented by rapamycin and mimicked by anisomycin, which suggests that translation of the 6.0-kb mRNA is regulated by the p70S6k/85S6k kinase signalling pathway. Therefore, the minor 4.8-kb mRNA generates a constitutive production of prepro-IGF-II, whereas the major 6.0-kb mRNA provides a post-transcriptionally regulated species.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: found

              Regulation of the ROMK Potassium Channel in the Kidney

               H. Wald (1999)
              ROMK is a gene encoding inwardly rectifying adenosine triphosphate regulated K + channels. Alternative splicing of ROMK exons yields several different transcripts, ROMK 1–3, that are differentially expressed along the nephron. Cloned ROMK channels expressed in Xenopus oocytes exhibit properties similar to those of the native low-conductance K + secretory channels in cortical collecting duct and medullary thick ascending limb, as manifested by use of the patch-clamp technique. These similarities between the cloned and native channels suggest that ROMK represents the low-conductance secretory K + channels in the kidney. We studied the role of dietary K + and aldosterone in the regulation of ROMK mRNA expression in the rat kidney. K + deficiency downregulated ROMK mRNA in cortex and medulla. Adrenalectomy markedly downregulated cortical ROMK, while it increased it in the medulla. In adrenalectomized rats K + deficiency decreased ROMK mRNA in cortex and medulla similarly to intact rats. Na-K-ATPase subunits α 1 and β 1 were regulated in parallel to the regulation of ROMK. In the medulla ROMK mRNA correlated highly with serum K + and with the α 1 and β 1 subunits of Na-K-ATPase. These results show that cortical ROMK expression is regulated by aldosterone and K + , while the medullary ROMK mRNA is regulated by serum K + , irrespective of aldosterone.
                Bookmark

                Author and article information

                Journal
                EXN
                Nephron Exp Nephrol
                10.1159/issn.1660-2129
                Cardiorenal Medicine
                S. Karger AG
                1660-2129
                1999
                August 1999
                26 July 1999
                : 7
                : 4
                : 273-283
                Affiliations
                University of Texas Southwestern Medical Center, Dallas, Tex., USA
                Article
                20614 Exp Nephrol 1999;7:273–283
                10.1159/000020614
                10450014
                © 1999 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: 2, Tables: 1, References: 73, Pages: 11
                Product
                Self URI (application/pdf): https://www.karger.com/Article/Pdf/20614
                Categories
                Editorial Review

                Comments

                Comment on this article