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Title: Traf2 interacts with Smad4 and regulates BMP signaling pathway in MC3T3-E1 osteoblasts

Bone morphogenetic proteins (BMPs) play important roles in osteoblast differentiation and maturation. In mammals, the BMP-induced receptor-regulated Smads form complexes with Smad4. These complexes translocate and accumulate in the nucleus, where they regulate the transcription of various target genes. However, the function of Smad4 remains unclear. We performed a yeast two-hybrid screen using Smad4 as bait and a cDNA library derived from bone marrow, to indentify the proteins interacting with Smad4. cDNA clones for Tumor necrosis factor (TNF) receptor-associated factor 2 (Traf2) were identified, and the interaction between the endogenous proteins was confirmed in the mouse osteoblast cell line MC3T3-E1. To investigate the function of Traf2, we silenced it with siRNA. The level of BMP-2 protein in the medium, the expression levels of the Bmp2 gene and BMP-induced transcription factor genes, including Runx2, Dlx5, Msx2, and Sp7, and the phosphorylated-Smad1 protein level were increased in cells transfected with Traf2 siRNA. The nuclear accumulation of Smad1 increased with TNF-{alpha} stimulation for 30 min at Traf2 silencing. These results suggest that the TNF-{alpha}-stimulated nuclear accumulation of Smad1 may be dependent on Traf2. Thus, the interaction between Traf2 and Smad4 may play a role in the cross-talk between TNF-{alpha} and BMP signaling pathways.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [2]
  1. Department of Periodontology, Nihon University School of Dentistry, Tokyo (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
22199920
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 390; Journal Issue: 3; Other Information: Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; BONE MARROW; CONNECTIVE TISSUE CELLS; GENES; HYBRIDIZATION; MICE; RADIOPROTECTIVE SUBSTANCES; RECEPTORS; SKELETON; TRANSCRIPTION; TRANSCRIPTION FACTORS; YEASTS