DIFFERENTIAL EFFECTS OF GROWTH HORMONE FAMILY PEPTIDES ON THE EXPRESSION OF INSULIN-LIKE GROWTH FACTOR 1 AND 2 mRNAs

Abstract

Event Abstract Back to Event DIFFERENTIAL EFFECTS OF GROWTH HORMONE FAMILY PEPTIDES ON THE EXPRESSION OF INSULIN-LIKE GROWTH FACTOR 1 AND 2 mRNAs Chad Walock1*, Lincoln Martin2, Jeffrey Kittilson2 and Mark Sheridan1, 2 1 North Dakota State University, Cell and Molecular Biology, United States 2 North Dakota State University, Biological Sciences, United States The growth of vertebrates is primarily controlled by the growth hormone (GH)-insulin-like growth factor (IGF) system. In mammals, postembryonic growth is mediated by IGF-1 produced under the influence of GH, whereas embryonic growth is mediated by IGF-2, the production of which is not influenced by GH. Recent reports of IGF-2 expression in tissues of juvenile and adult fish suggest that it may play a role in regulating post-embryonic growth in this group. In this study, we used juvenile (postembryonic) rainbow trout to examine the influence of GH family peptides on the expression of IGF-1 and IGF-2 mRNAs and to assess the mechanism(s) through which GH exerts its actions. Fish were implanted with mini osmotic pumps containing GH or saline for 21 days. GH significantly increased mRNA levels of IGF-1 and IGF-2 in both liver and muscle of levels observed in saline-implanted fish. The direct effects of GH, prolactin (PRL), and somatolactin (SL) were assessed on isolated hepatocytes incubated in vitro. GH stimulated expression of IGF-1 and IGF-2 mRNAs in a concentration- and time-related manner; GH was more potent and more efficacious in stimulating IGF-2 expression than IGF-1 expression. The extracellualar signal-regulated kinase (ERK) pathways inhibitor, U0126, and the phosphatidylinositol 3-kinase (PI3K)/Akt pathway inhibitor, LY294002, blocked GH-stimulated IGF-1 and IGF-2 expression. PRL had slight but significant effects on the expression of IGF-1 and IGF-2; PRL-stimulated expression of IGF mRNAs also was blocked by U0126 and LY294002. SL had no effect on the expression of either IGF-1 or IGF-2 mRNA. These findings indicate that GH stimulates IGF-2 expression to a greater extent than IGF-1 expression and support a role of IGF-2 in postembryonic growth of fish. These findings also indicate that GH-stimulated IGF-1 and IGF-2 expressed involve activation of the ERK and PI3K/Akt signaling pathways. (Supported by NSF IOS 0920116) Acknowledgements We would like to thank Heather Bergan, Mike Caruso, Andrea Hanson, Elle Kvam, Dillon Marquart, and Lindsey Norbeck for their assistance. Prof. Akiyosi Takahasi and Dr. Shiunsuke Moriyama generously provided salmonid GH, PRL, and SL. Supported by NSF grant IOS 0920116 to M. A. Sheridan. Keywords: Akt, ERK, Growth Hormone, insulin-like growth factors, PI3K, Prolactin, Somatolactin Conference: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011. Presentation Type: Poster Topic: Metabolism and feeding Citation: Walock C, Martin L, Kittilson J and Sheridan M (2011). DIFFERENTIAL EFFECTS OF GROWTH HORMONE FAMILY PEPTIDES ON THE EXPRESSION OF INSULIN-LIKE GROWTH FACTOR 1 AND 2 mRNAs. Front. Endocrinol. Conference Abstract: NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology. doi: 10.3389/conf.fendo.2011.04.00059 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 22 Jul 2011; Published Online: 09 Aug 2011. * Correspondence: Mr. Chad Walock, North Dakota State University, Cell and Molecular Biology, Fargo, North Dakota, United States, chad.walock@my.ndsu.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Chad Walock Lincoln Martin Jeffrey Kittilson Mark Sheridan Google Chad Walock Lincoln Martin Jeffrey Kittilson Mark Sheridan Google Scholar Chad Walock Lincoln Martin Jeffrey Kittilson Mark Sheridan PubMed Chad Walock Lincoln Martin Jeffrey Kittilson Mark Sheridan Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.