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KMUP‐1 Promotes Osteoblast Differentiation Through cAMP and cGMP Pathways and Signaling of BMP‐2/Smad1/5/8 and Wnt/β‐Catenin
Author(s) -
Liou ShuFen,
Hsu JongHau,
Chu HsinChieh,
Lin HungHong,
Chen IngJun,
Yeh JwuLai
Publication year - 2015
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.24904
Subject(s) - osteoblast , runx2 , alkaline phosphatase , wnt signaling pathway , noggin , bone morphogenetic protein 2 , microbiology and biotechnology , chemistry , phosphodiesterase , signal transduction , biology , bone morphogenetic protein , biochemistry , in vitro , enzyme , gene
Phosphodiesterase (PDE) inhibitors have been suggested as a possible candidate for the treatment of osteopenia, including osteoporosis. KMUP‐1 is a novel xanthine derivative with inhibitory activities on the PDE 3, 4, and 5 iso‐enzymes to suppress the degradation of cAMP and cGMP. This study aimed to investigate the effect of KMUP‐1 on osteoblast differentiation and the underlying cellular and molecular mechanisms. Primary osteoblasts and osteoblastic MC3T3‐E1 cells were examined. KMUP‐1 enhanced alkaline phosphatase (ALP) activity and mineralization compared to untreated controls in primary osteoblasts and MC3T3‐E1 cells. KMUP‐1 also increased the mRNA expression of the osteoblastic differentiation markers, including collagen type 1a, ALP, osteocalcin, osteoprotegerin, BMP‐2, and Runx2, a key transcription regulator for osteoblastic differentiation. The osteogenic effect of KMUP‐1 was abolished by BMP signaling inhibitor, noggin. Furthermore, we found that KMUP‐1 upregulated Smad1/5/8 phosphorylations with subsequent BRE‐Luc activation confirmed by transient transfection assay. In addition, KMUP‐1 inactivated glycogen synthase kinase‐3β (GSK‐3β), with associated nuclear translocation of β‐catenin. Co‐treatment with H89 and KT5823, cAMP and cGMP pathway inhibitors, respectively, reversed the KMUP‐1‐induced activations of Smad1/5/8, β‐catenin, and Runx2. The findings demonstrate for the first time that KMUP‐1 can promote osteoblast maturation and differentiation in vitro via BMP‐2/Smad1/5/8 and Wnt/β‐catenin pathways. These effects are mediated, in part, by the cAMP and cGMP signaling. Thus, KMUP‐1 may be a novel osteoblast activator and a potential new therapy for osteoporosis. J. Cell. Physiol. 230: 2038–2048, 2015. © 2014 Wiley Periodicals, Inc.