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Constitutive expression of thrombospondin 1 in MC3T3‐E1 osteoblastic cells inhibits mineralization
Author(s) -
Ueno Akemichi,
Miwa Yoshihiro,
Miyoshi Keiko,
Horiguchi Taigo,
Inoue Hideo,
Ruspita Intan,
Abe Kaori,
Yamashita Kikuji,
Hayashi Eiji,
Noma Takafumi
Publication year - 2006
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.20735
Subject(s) - extracellular matrix , microbiology and biotechnology , thrombospondin , mineralization (soil science) , extracellular , chemistry , cell culture , thrombospondins , cell growth , osteoblast , thrombospondin 1 , biology , in vitro , biochemistry , matrix metalloproteinase , angiogenesis , cancer research , genetics , organic chemistry , metalloproteinase , nitrogen
Thrombospondin 1 (TSP1) is a multifunctional extracellular glycoprotein present mainly in the fetal and adult skeleton. Although an inhibitory effect of TSP1 against pathological mineralization in cultured vascular pericytes has been shown, its involvement in physiological mineralization by osteoblasts is still unknown. To determine the role of TSP1 in biomineralization, mouse osteoblastic MC3T3‐E1 cells were cultured in the presence of antisense phosphorothioate oligodeoxynucleotides complementary to the TSP1 sequence. The 18‐ and 24‐mer antisense oligonucleotides caused concentration‐dependent increases in the number of mineralized nodules, acid‐soluble calcium deposition in the cell/matrix layer, and alkaline phosphatase activity within 9 days, without affecting cell proliferation. The corresponding sense or scrambled oligonucleotides did not affect these parameters. In the antisense oligonucleotide‐treated MC3T3‐E1 cells, thickened extracellular matrix, well‐developed cell processes, increased intracellular organelles, and collagen fibril bundles were observed. On the other hand, the addition of TSP1 to the culture decreased the production of a mineralized matrix by MC3T3‐E1 cells. Furthermore, MC3T3‐E1 clones overexpressing mouse TSP1 were established and assayed for TSP1 protein and their capacity to mineralize. TSP1 dose‐dependently inhibited mineralization by these cells both in vitro and in vivo. These results indicate that TSP1 functions as an inhibitory regulator of bone mineralization and matrix production by osteoblasts to sustain bone homeostasis. J. Cell. Physiol. 209: 322–332, 2006. © 2006 Wiley‐Liss, Inc.