Lymphocyte enhancer-binding factor 1 (Lef1) inhibits terminal differentiation of osteoblasts
Article first published online: 2 NOV 2005
Copyright © 2005 Wiley-Liss, Inc.
Journal of Cellular Biochemistry
Volume 97, Issue 5, pages 969–983, 1 April 2006
How to Cite
Kahler, R. A., Galindo, M., Lian, J., Stein, G. S., van Wijnen, A. J. and Westendorf, J. J. (2006), Lymphocyte enhancer-binding factor 1 (Lef1) inhibits terminal differentiation of osteoblasts. J. Cell. Biochem., 97: 969–983. doi: 10.1002/jcb.20702
- Issue published online: 21 MAR 2006
- Article first published online: 2 NOV 2005
- Manuscript Accepted: 4 OCT 2005
- Manuscript Received: 29 AUG 2005
- NIH. Grant Numbers: RO1 AR050074, RO1 AR049069, R01 AR039588, T32 AR 050938
- matrix mineralization;
Lef1 is a transcriptional regulator of the Wnt/β-catenin signaling cascade. Wnts directly augment bone formation and osteoblast differentiation from mesenchymal stem cells by receptor-mediated pathways involving Lrp5 and Frizzled. We previously reported that Lef1 represses Runx2-dependent activation of the late osteoblast differentiation gene, osteocalcin. Lef1 is expressed in preosteoblasts but is undetectable in fully differentiated osteoblasts. To determine if downregulation of Lef1 is necessary for osteoblast maturation, we constitutively overexpressed Lef1 in MC3T3-E1 preosteoblasts. Lef1-overexpressing cells produced alkaline phosphatase (ALP) and osteocalcin later, and at lower levels than control cells. Moreover, the extracellular matrices of Lef1-overexpressing cell cultures never mineralized. To further examine the role of Lef1 in osteoblasts, we suppressed Lef1 expression in MC3T3-E1 cells by RNA interference. Transient expression of a Lef1 shRNA efficiently reduced murine Lef1 levels and transcriptional activity. Stable suppression of Lef1 in MC3T3 preosteoblasts did not affect proliferation or Runx2 levels; however, ALP production and matrix mineralization were accelerated by 3–4 days. Gene chip analyses identified 14 genes that are differentially regulated in Lef1-suppressed cells. These data outline a role for Lef1 in delaying osteoblast maturation and suggest that Lef1 controls the expression of multiple genes in osteoblasts. J. Cell. Biochem. 97: 969–983, 2006. © 2005 Wiley-Liss, Inc.