Vol. 277, Issue 1, C132-C138, July 1999
Characterization of osteoblastic differentiation of stromal
cell line ST2 that is induced by ascorbic acid
Eri
Otsuka1,
Akira
Yamaguchi2,
Shigehisa
Hirose3, and
Hiromi
Hagiwara1
1 Research Center for
Experimental Biology and
3 Department of Biological
Sciences, Tokyo Institute of Technology, Yokohama 226-8501; and
2 Department of Oral
Pathology, Nagasaki University School of Dentistry, Nagasaki
852-8588, Japan
The stromal cell line ST2, derived from mouse bone marrow,
differentiated into osteoblast-like cells in response to ascorbic acid.
Ascorbic acid induced alkaline phosphatase (ALPase) activity, the
expression of mRNAs for proteins that are markers of osteoblastic differentiation, the deposition of calcium, and the formation of
mineralized nodules by ST2 cells. We investigated the mechanism whereby
ascorbic acid induced the differentiation of ST2 cells. Inhibitors of
the formation of collagen triple helices completely blocked the effects
of ascorbic acid on ST2 cells, an indication that matrix formation by
type I collagen is essential for the induction of osteoblastic
differentiation of ST2 cells by ascorbic acid. We furthermore examined
the effects of bone morphogenetic proteins (BMPs) on the
differentiation of ST2 cells induced by ascorbic acid. Ascorbic acid
had no effect on the expression of mRNAs for BMP-4 and the BMP
receptors. However, a soluble form of BMP receptor IA
inhibited the induction of ALPase activity by ascorbic acid. These
results suggest that ascorbic acid might promote the differentiation of
ST2 cells into osteoblast-like cells by inducing the formation of a
matrix of type I collagen, with subsequent activation of the signaling
pathways that involve BMPs.
ST2 cell; osteoblast; type I collagen; alkaline phosphatase; bone
morphogenetic protein
