Gsα Controls Cortical Bone Quality by Regulating Osteoclast Differentiation via cAMP/PKA and β-Catenin Pathways

• Published in: Scientific reports Vol. 7; no. 1; p. 45140
• Main Authors: Ramaswamy, Girish, Kim, Hyunsoo, Zhang, Deyu, Lounev, Vitali, Wu, Joy Y., Choi, Yongwon, Kaplan, Frederick S., Pignolo, Robert J., Shore, Eileen M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24-03-2017; Nature Publishing Group
• Subjects: 13/106; 14/63; 38/77; 631/208; 631/80; 64/110; 82; 82/29; 82/80; Animals; beta Catenin - metabolism; Cell Differentiation; Cells, Cultured; Chromogranins - genetics; Chromogranins - metabolism; Cortical Bone - cytology; Cortical Bone - metabolism; Cyclic AMP - metabolism; Cyclic AMP Response Element-Binding Protein - metabolism; Cyclic AMP-Dependent Protein Kinases - metabolism; Cyclin D1 - metabolism; Female; GTP-Binding Protein alpha Subunits, Gs - genetics; GTP-Binding Protein alpha Subunits, Gs - metabolism; Humanities and Social Sciences; Male; Mice; Mice, Inbred C57BL; multidisciplinary; NFATC Transcription Factors - metabolism; Osteoclasts - cytology; Osteoclasts - metabolism; Science; Signal Transduction; Wnt Proteins - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep45140

Skeletal bone formation and maintenance requires coordinate functions of several cell types, including bone forming osteoblasts and bone resorbing osteoclasts. Gsα, the stimulatory subunit of heterotrimeric G proteins, activates downstream signaling through cAMP and plays important roles in skeletal development by regulating osteoblast differentiation. Here, we demonstrate that Gsα signaling also regulates osteoclast differentiation during bone modeling and remodeling.
Gnas
, the gene encoding Gsα, is imprinted. Mice with paternal allele deletion of
Gnas (Gnas
+/p−
) have defects in cortical bone quality and strength during early development (bone modeling) that persist during adult bone remodeling. Reduced bone quality in
Gnas
+/p−
mice was associated with increased endosteal osteoclast numbers, with no significant effects on osteoblast number and function. Osteoclast differentiation and resorption activity was enhanced in
Gnas
+/p−
cells. During differentiation,
Gnas
+/p−
cells showed diminished pCREB, β-catenin and cyclin D1, and enhanced Nfatc1 levels, conditions favoring osteoclastogenesis. Forskolin treatment increased pCREB and rescued osteoclast differentiation in
Gnas
+/p−
by reducing Nfatc1 levels. Cortical bone of
Gnas
+/p−
mice showed elevated expression of Wnt inhibitors sclerostin and Sfrp4 consistent with reduced Wnt/β-catenin signaling. Our data identify a new role for Gsα signaling in maintaining bone quality by regulating osteoclast differentiation and function through cAMP/PKA and Wnt/β-catenin pathways.