MEPE regulates growth plate mineralisation through its cleavage to the ASARM peptide

Abstract

Event Abstract Back to Event MEPE regulates growth plate mineralisation through its cleavage to the ASARM peptide KA Staines1*, VE Macrae1 and C Farquharson1 1 the University of Edinburgh, the Roslin Institute and Royal (Dick) School of Veterinary Studies, United Kingdom MEPE is mainly expressed in mineralising tissues, and has been implicated in osteoblast matrix mineralisation directly by releasing an ASARM peptide. Although the growth plates of MEPE transgenic mice display severe morphological disruption, the expression and function of MEPE in growth plate mineralisation remains largely undefined. {BR}Proximal tibiae from 3-week-old wild-type mice were analysed for Mepe expression by in situ hybridisation and growth plate microdissection. Gene expression by the ATDC5 chondrogenic cell line was examined by RT-qPCR over a 20-day culture period under calcifying conditions. 20µM phosphorylated (pASARM) and non-phosphorylated ASARM (npASARM) peptides were added to ATDC5 cultures, and to 17-day-old and 15-day-old embryonic metatarsal explants. {BR}Mepe expression was abundant throughout the growth plate as shown by in situ hybridisation. Microdissection of the growth plate confirmed an increased expression of Mepe in the hypertrophic chondrocytes (9-fold increase compared to proliferative chondrocytes, P<0.05). ATDC5 cells showed an initial decrease in Mepe expression at day-10 of culture, after which expression increased at day-15. Treatment of ATDC5 cells with pASARM peptide caused an inhibition of mineralisation, determined by alizarin red staining (P<0.01). Treatment with npASARM promoted mineralisation (P<0.01). The growth rate of 15 and 17-day-old embryonic metatarsals and the proliferation of chondrocytes within were not affected by treatment with 20µM pASARM or npASARM peptides. This indicates that the peptides were not toxic and the bones were still viable after 7 days of culture. However, in 17-day-old embryonic metatarsals, the growth of the central diaphyseal mineralisation zone was inhibited in bones treated with 20µM pASARM (P<0.001). This was further examined in 15-day-old embryonic metatarsals in which the central mineralised core only forms after 7 days in culture. Treatment with 20µM pASARM peptides completely prevented mineralisation. Alkaline phosphatase activity was unchanged between the treated and untreated bones, suggesting that the observed inhibition of mineralisation is not a result of decreased enzyme activity. {BR}Our findings indicate that MEPE is expressed by growth plate chondrocytes and that it is likely to have a developmental role in the inhibition of cartilage matrix mineralisation through its cleavage and subsequent phosphorylation of the ASARM peptide. Keywords: Bones, Bone Research Conference: 2011 joint meeting of the Bone Research Society & the British Orthopaedic Research Society, Cambridge, United Kingdom, 27 Jun - 29 Jun, 2011. Presentation Type: Oral Topic: Abstracts Citation: Staines K, Macrae V and Farquharson C (2011). MEPE regulates growth plate mineralisation through its cleavage to the ASARM peptide. Front. Endocrinol. Conference Abstract: 2011 joint meeting of the Bone Research Society & the British Orthopaedic Research Society. doi: 10.3389/conf.fendo.2011.02.00063 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: 30 Sep 2011; Published Online: 30 Sep 2011. * Correspondence: Prof. KA Staines, the University of Edinburgh, the Roslin Institute and Royal (Dick) School of Veterinary Studies, United Kingdom, k.staines@brighton.ac.uk 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 KA Staines VE Macrae C Farquharson Google KA Staines VE Macrae C Farquharson Google Scholar KA Staines VE Macrae C Farquharson PubMed KA Staines VE Macrae C Farquharson 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.