Osthole-mediated cell differentiation through bone morphogenetic protein-2/p38 and extracellular signal-regulated kinase 1/2 pathway in human osteoblast cells.

Abstract

The survival of osteoblast cells is one of the determinants of the development of osteoporosis in patients. Osthole (7-methoxy-8-isopentenoxycoumarin) is a coumarin derivative present in many medicinal plants. By means of alkaline phosphatase (ALP) activity, osteocalcin, osteopontin, and type I collagen, enzyme-linked immunosorbent assay, we have shown that osthole exhibits a significant induction of differentiation in two human osteoblast-like cell lines, MG-63 and hFOB. Induction of differentiation by osthole was associated with increased bone morphogenetic protein (BMP)-2 production and the activations of SMAD1/5/8 and p38 and extracellular signal-regulated kinase (ERK) 1/2 kinases. Addition of purified BMP-2 protein did not increase the up-regulation of ALP activity and osteocalcin by osthole, whereas the BMP-2 antagonist noggin blocked both osthole and BMP-2-mediated ALP activity enhancement, indicating that BMP-2 production is required in osthole-mediated osteoblast maturation. Pretreatment of osteoblast cells with noggin abrogated p38 activation but only partially decreased ERK1/2 activation, suggesting that BMP-2 signaling is required in p38 activation and is partially involved in ERK1/2 activation in osthole-treated osteoblast cells. Cotreatment of p38 inhibitor SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-1H-imidazole] or p38 small interfering RNA (siRNA) expression inhibited osthole-mediated activation of ALP but only slightly affected osteocalcin production. In contrast, the production of osteocalcin induced by osthole was inhibited by the mitogen-activated protein kinase kinase inhibitor PD98059 (2'-amino-3'-methoxyflavone) or by expression of an ERK2 siRNA. These data suggest that BMP-2/p38 pathway links to the early phase, whereas ERK1/2 pathway is associated with the later phase in osthole-mediated differentiation of osteoblast cells. In this study, we demonstrate that osthole is a promising agent for treating osteoporosis.

• Authors: Po-Lin Kuo, Ya-Ling Hsu, Cheng-Hsiung Chang, Jiunn-Kae Chang
• Journal: The Journal of pharmacology and experimental therapeutics (J Pharmacol Exp Ther) Vol. 314 Issue 3 Pg. 1290-9 (Sep 2005) ISSN: 0022-3565 [Print] United States
• PMID: 15956019 (Publication Type: Journal Article)

Chemical References

• BMP2 protein, human
• Bone Morphogenetic Protein 2
• Bone Morphogenetic Proteins
• Coumarins
• DNA-Binding Proteins
• RNA, Small Interfering
• SMAD1 protein, human
• Smad Proteins
• Smad1 Protein
• Trans-Activators
• Transforming Growth Factor beta
• Mitogen-Activated Protein Kinase 1
• Mitogen-Activated Protein Kinase 3
• p38 Mitogen-Activated Protein Kinases
• osthol

Topics

• Bone Morphogenetic Protein 2
• Bone Morphogenetic Proteins (physiology)
• Cell Differentiation (drug effects)
• Cell Proliferation (drug effects)
• Cells, Cultured
• Coumarins (pharmacology)
• DNA-Binding Proteins (physiology)
• Humans
• MAP Kinase Signaling System (physiology)
• Mitogen-Activated Protein Kinase 1 (physiology)
• Mitogen-Activated Protein Kinase 3 (physiology)
• Osteoblasts (cytology, drug effects)
• Osteoporosis (drug therapy, etiology)
• RNA, Small Interfering (pharmacology)
• Smad Proteins
• Smad1 Protein
• Trans-Activators (physiology)
• Transforming Growth Factor beta (physiology)
• p38 Mitogen-Activated Protein Kinases (physiology)