Transforming growth factor β signalling in vitro and in vivo:: activin ligand-receptor interaction, Smad5 in vasculogenesis, and repression of target genes by the δEF1/ZEB-related SIP1 in the vertebrate embryo

[摘要] The identification and characterization of components of the transforming growth factor beta (TGF beta) signalling pathway are proceeding at a very fast pace. To illustrate a number of our activities in this field, we first summarize our work aiming at the selection from a large collection of single residue substitution mutants of two activin A polypeptides in which D27 and K102, respectively, have been modified. This work has highlighted the importance of K102 and its positive charge for binding to activin type II receptors. Activin K102E, which did not bind to high-affinity receptor complexes, may be a valuable beta chain, when incorporated in recombinant inhibin to unambiguously detect novel inhibin binding sites at the cell surface. We then illustrate how Smad5 knockout mice and an overexpression approach with a truncated TGF beta type II receptor in the mouse embryo can contribute to the identification of a novel TGF beta --> T beta RII/ALK1 --> Smad5 pathway in endothelial cells in the embryo proper and the yolk sac vasculature. We conclude with a summary of our results with a Smad-interacting transcriptional repressor but focus on its biological significance in the vertebrate embryo. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.

[发布日期] 2001-06-30

[效力级别]  Proceedings Paper

[关键词] activin;angiogenesis;bone morphogenetic protein;Brachyury;Smad;Smad-interacting protein