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Transcriptional regulation restricting bone sialoprotein gene expression to both hypertrophic chondrocytes and osteoblasts
Author(s) -
Barnes George L.,
Torre Thomas Della,
Sommer Beatrice,
Young Marian F.,
Gerstenfeld Louis C.
Publication year - 2002
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.10351
Subject(s) - bone sialoprotein , enhancer , dlx5 , homeobox , microbiology and biotechnology , gene expression , regulation of gene expression , regulator , biology , runx2 , promoter , transcription factor , gene , chemistry , osteocalcin , genetics , biochemistry , alkaline phosphatase , enzyme
This study identifies a cis ‐acting element that confers tissue‐restricted expression to the bone sialoprotein ( BSP ) gene. Using both gain of function and loss‐of function studies, we demonstrate that this element acts as a tissue specific enhancer of BSP expression in osteoblasts and hypertrophic chondrocytes but does not function in non‐hypertrophic chondrocytes or fibroblasts. Furthermore, our data demonstrate that binding of this element occurs in correlation with active BSP expression. While Dlx5 has been implicated as the tissue‐specific regulator of BSP expression through direct DNA binding at an element with homology to the one under study here, our results demonstrate that Dlx5 does not act as a positive regulator of BSP expression. Finally, mutational analyses of this element demonstrate that while there is homology to putative homeodomain binding elements, this site is unlikely to bind homeodomain factors including Dlx5. Thus, these studies identify an important cis ‐acting element in the BSP promoter that acts as a tissue‐specific enhancer of BSP expression in both osteoblasts and hypertrophic chondrocytes. As such this is the first demonstration of a common regulatory mechanism utilized by both chondrocytes and osteoblasts for the tissue‐restricted expression of the BSP gene. J. Cell. Biochem. 87: 458–469, 2002. © 2002 Wiley‐Liss, Inc.