Please use this identifier to cite or link to this item:
https://hdl.handle.net/2440/40008
Type: | Conference paper |
Title: | Mouse oocyte-secreted factors and gdf-9 stimulate granulosa cell proliferation via bmpr-ii and activate the smad2/3 pathway |
Author: | Gilchrist, R. Ritter, L. Myllymaa, S. Kaivo-Oja, N. Amato, F. Ritvos, O. Mottershead, D. |
Citation: | Biology of Reproduction, 2004, pp.223-223 |
Publisher: | Allen Press Inc |
Publisher Place: | online |
Issue Date: | 2004 |
ISSN: | 0006-3363 |
Conference Name: | Society for the Study of Reproduction. Conference (37th : 2004 : Vancouver, Canada) |
Abstract: | Oocytes regulate follicle growth and development by secreting paracrine growth factors that act on granulosa cells (GC). We have recently determined that growth differentiation factor-9 (GDF-9) accounts for ∼50% of the total mitogenic activity of oocytes, the remaining portion is as yet uncharacterized. This study was conducted to identify the receptor/signalling system utilized by oocytes to promote GC proliferation. We used an established oocyte-secreted mitogen bioassay, where denuded oocytes are co-cultured with primed-mouse mural GC. In this system, oocytes, GDF-9, TGF-b1 and activin-A all promoted GC DNA synthesis in a dose-dependent manner, but bone-morphogenic protein-6 (BMP-6) and BMP-7 did not. The type-II receptor for GDF-9 is BMPRII and using real-time RT-PCR, cumulus cells (CC) and mural GC were found to express equivalent levels of BMPRII mRNA. We tested the capacity of the receptor ectodomain (ECD) to neutralize oocyte-stimulated mural GC proliferation. The BMPRII ECD antagonised both oocyte and GDF-9 bioactivity in a dose-dependent manner, completely abolishing activity of both mitogens at 1 ug/ml. The BMPRII ECD did not antagonize TGF-b and partially antagonized activin-A bioactivity, demonstrating its specificity. The TGFbR-II ECD, ActR-II ECD and ActR-IIB ECD all failed to neutralize oocyte- or GDF-9-stimulated GC DNA synthesis, whereas they did antagonize the activity of their respective ligands. The BMPRII ECD also completely antagonized oocyte-stimulated CC DNA synthesis. Using this oocyte-factor bioassay with mural GC transfected with Smad luciferase reporter constructs, we found that oocytes, GDF-9 and TGF-b (but not BMP-6) activated the Smad2/3 pathway. Consistent with this, oocytes and GDF-9 led to phosphorylation of GC Smad2 molecules as detected by Western blot. Conversely the Smad1/5/8 pathway was activated by BMP-6, but not by GDF-9, TGF-b nor surprisingly by oocytes. This study provides evidence that BMPRII is a key receptor for transmitting the paracrine actions of oocytes in GC. However, oocyte-secreted factors do not activate the BMP intracellular signalling pathway but rather the TGF-b/activin intracellular pathway. Thus oocytes utilize an unusual interaction of the two TGF-b superfamily receptor/signalling systems that are generally considered distinct. |
Description: | Abstract only |
Description (link): | http://abstracts.co.allenpress.com/pweb/ssr2004/document/?ID=38518 |
Appears in Collections: | Aurora harvest Obstetrics and Gynaecology publications |
Files in This Item:
There are no files associated with this item.
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.