Society for Endocrinology Annual Meeting 2005
London, UK
07 November 2005 - 09 November 2005
Society for Endocrinology
Bone morphogenetic protein-2 and Smad signalling in clonal gonadotrophs
Queen Mary University of London, London, United Kingdom.
Bone morphogenetic protein-2 (BMP-2) signal transduction requires heterocomplexing between type II receptors and different type I (α or β) receptors resulting in the activation of different signalling pathways. Previously, we have used αT3-1 and Lβt-2 cell lines, which are representative of different stages of gonadotroph development, to demonstrate differential expression of the receptor isoforms during gonadotroph maturation. BMPR-Iα and II mRNA and protein were detected in both cell types but BMPR-Iβ was present only in the less differentiated αT3-1s.
To investigate activation of the Smad signalling pathway in these gonadotroph cell lines we have employed the Xvent2-luc plasmid. This plasmid contains a region of the BMP responsive Xenopus Vent2 promoter cloned into a luciferase reporter plasmid and has been demonstrated to respond to Smad activation following BMP treatment 1.
αT3-1 and LβT-2 cells were transiently transfected with Xvent2-luc and incubated with 10, 50, 100 and 200 ng/ml of BMP-2 for 4 h. αT3-1 cells showed fold increases of 1.35±0.19 (50 ng/ml) and 1.35±0.10 (100 ng/ml) in Xvent2-luc activity above basal. In contrast, transfected LβT-2 cells failed to respond to BMP-2 at any concentration. Thus, we have demonstrated transcriptional stimulation of Xvent2-luc to BMP-2 in αT3-1 s but not in the fully differentiated LβT-2 s. This may relate to the absence of the type Iβ? receptor in the LβT-2 cell line.
Acknowledgements: This project is supported by the BBSRC.
[1] Shimasaki et al. Journal of Biological Chemistry 3, 304 (2003).
Endocrine Abstracts (2005) 10 P60