G-protein Stimulatory α Subunit Is Involved in Osteogenic Activity in Osteoblastic Cell Line SaOS-2 Cells.
In an attempt to study the roles of G-protein stimulatory subunit α (Gsα) in osteoblasts, we introduced an expression vector encoding Gsα into human osteoblastic cell line SaOS-2, and established the clones stably overexpressing Gsα (SaOS-2-Gsα). In SaOS-2-Gsα, the intracellular content of cyclic AMP (cAMP) was increased compared with the parental SaOS-2 cells. In addition, when treated with PTH[1-34], SaOS-2-Gsα exhibited more accumulation of intracellular cAMP compared with the parental cells, suggesting an increased responsiveness to PTH. We evaluated the proliferation rates of SaOS-2-Gsα and the parental SaOS-2 cells, and found that the proliferation was accelerated in SaOS-2-Gsα cells. Reverse transcription-polymerase chain reaction (RT-PCR) analyses exhibited the increased expression of Runx2, a transcription factor involved in osteoblast differentiation, in SaOS-2-Gsα cells. Finally, to examine the osteoblastic function in vivo, we inoculated SaOS-2-Gsα or parental SaOS-2 cells subcutaneously to immunocompromised nude mice. Although tumors in nude mice were not formed after inoculation of parental SaOS-2 cells, SaOS-2-Gsα cells proliferated in host animals leading to the formation of tumors with mineralized bone-like tissues. Taken together, these results suggest that the signals via Gsα play critical roles in the proliferation and osteogenic functions of osteoblasts.
Department of Environmental Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan.
Miwa
M
Yamazaki
Department of Environmental Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan ; Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
Akira
A
Suzuki
Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan.
Keiichi
K
Ozono
Department of Environmental Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan.
Toshimi
T
Michigami
Gsα; Runx2; SaOS-2; osteoblast; osteogenic