Browsing by keyword "*Activin Receptors, Type I"

Now showing items 1-2 of 2

    • CBFa(AML/PEBP2)-related elements in the TGF-beta type I receptor promoter and expression with osteoblast differentiation
      Ji, Changhua; Casinghino, Sandra; Chang, David J.; Chen, Yun; Javed, Amjad; Ito, Yoshiaki; Hiebert, Scott W.; Lian, Jane B.; Stein, Gary S.; McCarthy, Thomas L.; et al. (1998-05-15)
      Organization of the transforming growth factor-beta (TGF-beta) type I receptor (TRI) promoter predicts constitutive transcription, although its activity increases with differentiation status in cultured osteoblasts. Several sequences in the rat TRI promoter comprise cis-acting elements for CBFa (AML/PEBP2alpha) transcription factors. By gel mobility shift and immunological analyses, a principal osteoblast-derived nuclear factor that binds to these sites is CBFa1 (AML-3/PEBP2alphaA). Rat CBFa1 levels parallel expression of the osteoblast phenotype and increase under conditions that promote mineralized bone nodule formation in vitro. Fusion of CBFa binding sequence from the TRI promoter to enhancer-free transfection vector increases reporter gene expression in cells that possess abundant CBFa1, and overexpression of CBFa increase the activity of transfected native TRI promoter/reporter plasmid. Consequently, phenotype-restricted use of cis-acting elements for CBFa transcription factors can contribute to the high levels of TRI that parallel osteoblast differentiation and to the potent effects of TGF-beta on osteoblast function.

    • Interaction and functional cooperation of PEBP2/CBF with Smads. Synergistic induction of the immunoglobulin germline Calpha promoter
      Hanai, J.; Chen, L. F.; Kanno, T.; Ohtani-Fujita, N.; Kim, W. Y.; Guo, W. H.; Imamura, T.; Ishidou, Y.; Fukuchi, M.; Shi, M. J.; et al. (1999-10-29)
      Smads are signal transducers for members of the transforming growth factor-beta (TGF-beta) superfamily. Upon ligand stimulation, receptor-regulated Smads (R-Smads) are phosphorylated by serine/threonine kinase receptors, form complexes with common-partner Smad, and translocate into the nucleus, where they regulate the transcription of target genes together with other transcription factors. Polyomavirus enhancer binding protein 2/core binding factor (PEBP2/CBF) is a transcription factor complex composed of alpha and beta subunits. The alpha subunits of PEBP2/CBF, which contain the highly conserved Runt domain, play essential roles in hematopoiesis and osteogenesis. Here we show that three mammalian alpha subunits of PEBP2/CBF form complexes with R-Smads that act in TGF-beta/activin pathways as well as those acting in bone morphogenetic protein (BMP) pathways. Among them, PEBP2alphaC/CBFA3/AML2 forms a complex with Smad3 and stimulates transcription of the germline Ig Calpha promoter in a cooperative manner, for which binding of both factors to their specific binding sites is essential. PEBP2 may thus be a nuclear target of TGF-beta/BMP signaling.