Involvement of Prolyl Hydroxylase Domain Protein in the Rosiglitazone-Induced Suppression of Osteoblast Differentiation

• Published in: PloS one Vol. 10; no. 9; p. e0139093
• Main Authors: Kang, Ju-Hee, Kwak, Hyun Jeong, Choi, Hye-Eun, Kim, Juyoung, Hong, Sangmee, Kim, Ok-Hee, Oh, Byung Chul, Cheon, Hyae Gyeong
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 29-09-2015; Public Library of Science (PLoS)
• Subjects: Activation; Adipocytes; Alkaline phosphatase; Animals; Antagonists; Apoptosis; Biocompatibility; Biomedical materials; Blotting, Western; Bone density; Bone loss; Bone marrow; Cbfa-1 protein; Cell differentiation; Cell Differentiation - drug effects; Cells, Cultured; Complications and side effects; Degradation; Diabetes mellitus; Differentiation; Dosage and administration; Endocrinology; Female; Femur; Genetic aspects; Homeostasis; Hypoglycemic Agents - pharmacology; Hypoxia; Hypoxia-Inducible Factor-Proline Dioxygenases - genetics; Hypoxia-Inducible Factor-Proline Dioxygenases - metabolism; Immunoenzyme Techniques; Insulin; Isoforms; Laboratory animals; Medicine; Mice; Mice, Inbred ICR; Oral administration; Osteoblastogenesis; Osteoblasts; Osteoblasts - cytology; Osteoblasts - drug effects; Osteoblasts - enzymology; Osteogenesis - drug effects; Osteogenesis - physiology; Pharmacology; Physiological aspects; PPAR gamma - agonists; Procollagen-Proline Dioxygenase - genetics; Procollagen-Proline Dioxygenase - metabolism; Prolyl hydroxylase; Proteasomes; Proteins; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; Rosiglitazone; Rosiglitazone maleate; Thiazolidinediones - pharmacology; Transcription factors; Ubiquitination; South Korea
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0139093

Rosiglitazone is a well-known anti-diabetic drug that increases insulin sensitivity via peroxisome proliferator-activated receptor γ (PPARγ) activation, but unfortunately it causes bone loss in animals and humans. A previous study showed that prolyl hydroxylase domain protein (PHD) plays a role in rosiglitazone-induced adipocyte differentiation. Based on the inverse relationship between adipocyte and osteoblast differentiation, we investigated whether PHD is involved in the effects of rosiglitazone on osteoblast differentiation. Rosiglitazone inhibited osteoblast differentiation in a concentration-dependent manner, and in parallel induced three PHD isoforms (PHD1, 2, and 3). PHD inhibitors and knockdown of each isoform prevented the inhibitory effects of rosiglitazone on osteoblast differentiation and increased the expression of Runx2, a transcription factor essential for osteoblastogenesis. MG-132, a proteasomal inhibitor also prevented the rosiglitazone-induced degradation of Runx2. Furthermore, both increased PHD isoform expressions and reduced osteoblast differentiation by rosiglitazone were prevented by PPARγ antagonists, indicating these effects were mediated via PPARγ activation. In vivo oral administration of rosiglitazone to female ICR mice for 8 weeks reduced bone mineral densities and plasma alkaline phosphatase (ALP) activity, and increased PHD expression in femoral primary bone marrow cells and the ubiquitination of Runx2. Together, this suggests that the rosiglitazone-induced suppression of osteoblast differentiation is at least partly induced via PPARγ-mediated PHD induction and subsequent promotion of the ubiquitination and degradation of Runx2.