Osteoblast expression of an engineered Gs-coupled receptor dramatically increases bone mass

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 105; no. 4; pp. 1209 - 1214
• Main Authors: Hsiao, Edward C, Boudignon, Benjamin M, Chang, Wei C, Bencsik, Margaret, Peng, Jeffrey, Nguyen, Trieu D, Manalac, Carlota, Halloran, Bernard P, Conklin, Bruce R, Nissenson, Robert A
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 29.01.2008; National Acad Sciences
• Series: From the Cover
• Subjects: Amino Acid Sequence; Animals; Biological Sciences; Bone Density - physiology; Cell Line; Female; GTP-Binding Protein alpha Subunits, Gs - biosynthesis; GTP-Binding Protein alpha Subunits, Gs - genetics; GTP-Binding Protein alpha Subunits, Gs - metabolism; GTP-Binding Protein alpha Subunits, Gs - physiology; Humans; Ligands; Male; Mice; Mice, Transgenic; Molecular Sequence Data; Osteoblasts - chemistry; Osteoblasts - metabolism; Protein Engineering - methods; Receptors, Serotonin, 5-HT4 - biosynthesis; Receptors, Serotonin, 5-HT4 - genetics; Serotonin 5-HT4 Receptor Agonists; Signal Transduction - genetics; Signal Transduction - physiology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0707457105

Osteoblasts are essential for maintaining bone mass, avoiding osteoporosis, and repairing injured bone. Activation of osteoblast G protein-coupled receptors (GPCRs), such as the parathyroid hormone receptor, can increase bone mass; however, the anabolic mechanisms are poorly understood. Here we use "Rs1," an engineered GPCR with constitutive Gs signaling, to evaluate the temporal and skeletal effects of Gs signaling in murine osteoblasts. In vivo, Rs1 expression induces a dramatic anabolic skeletal response, with midfemur girth increasing 1,200% and femur mass increasing 380% in 9-week-old mice. Bone volume, cellularity, areal bone mineral density, osteoblast gene markers, and serum bone turnover markers were also elevated. No such phenotype developed when Rs1 was expressed after the first 4 weeks of postnatal life, indicating an exquisite temporal sensitivity of osteoblasts to Rs1 expression. This pathway may represent an important determinant of bone mass and may open future avenues for enhancing bone repair and treating metabolic bone diseases.