title: KMUP-1 Promotes Osteoblast Differentiation Through cAMP and cGMP Pathways and Signaling of BMP-2/Smad1/5/8 and Wnt/β-Catenin.
abstract: 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.
authors.affiliation: Department of Pharmacy, Chia-Nan University of Pharmacy and Science, Tainan, Taiwan.
authors.forename: Shu-Fen
authors.initials: SF
authors.lastname: Liou
authors.affiliation: Department of Paediatrics, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.|Department of Paediatrics, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Jong-Hau
authors.initials: JH
authors.lastname: Hsu
authors.affiliation: Department and Graduate Institute of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Hsin-Chieh
authors.initials: HC
authors.lastname: Chu
authors.affiliation: Department of Pharmacy, Chia-Nan University of Pharmacy and Science, Tainan, Taiwan.
authors.forename: Hung-Hong
authors.initials: HH
authors.lastname: Lin
authors.affiliation: Department and Graduate Institute of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Ing-Jun
authors.initials: IJ
authors.lastname: Chen
authors.affiliation: Department and Graduate Institute of Pharmacology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Jwu-Lai
authors.initials: JL
authors.lastname: Yeh
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000096:biosynthesis* / Q000235:genetics; D002113:Calcification, Physiologic; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects; D010880:Piperidines / Q000008:administration & dosage*; D012333:RNA, Messenger / Q000096:biosynthesis; D051898:Smad1 Protein / Q000096:biosynthesis* / Q000235:genetics; D051902:Smad5 Protein / Q000096:biosynthesis* / Q000235:genetics; D051904:Smad8 Protein / Q000096:biosynthesis* / Q000235:genetics; D060449:Wnt Signaling Pathway; D014970:Xanthines / Q000008:administration & dosage*
chemical_list: C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D010880:Piperidines; D012333:RNA, Messenger; D051898:Smad1 Protein; C497401:Smad1 protein, mouse; D051902:Smad5 Protein; C497798:Smad5 protein, mouse; D051904:Smad8 Protein; C491621:Smad9 protein, mouse; D014970:Xanthines; C439304:KMUP 1; D000242:Cyclic AMP; D006152:Cyclic GMP