Cortical bone maturation in mice requires SOCS3 suppression of gp130/STAT3 signalling in osteocytes
Emma C Walker,
Kim Truong,
Narelle E McGregor,
Ingrid J Poulton,
Tsuyoshi Isojima,
Jonathan H Gooi,
T John Martin,
Natalie A Sims
Affiliations
Emma C Walker
St. Vincent’s Institute of Medical Research, Fitzroy, Australia
Kim Truong
St. Vincent’s Institute of Medical Research, Fitzroy, Australia; University of Melbourne, Department of Medicine at St. Vincent’s Hospital, Fitzroy, Australia
Narelle E McGregor
St. Vincent’s Institute of Medical Research, Fitzroy, Australia
Ingrid J Poulton
St. Vincent’s Institute of Medical Research, Fitzroy, Australia
Tsuyoshi Isojima
St. Vincent’s Institute of Medical Research, Fitzroy, Australia; Department of Pediatrics, Teikyo University School of Medicine, Tokyo, Japan
Jonathan H Gooi
St. Vincent’s Institute of Medical Research, Fitzroy, Australia; Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Australia
T John Martin
St. Vincent’s Institute of Medical Research, Fitzroy, Australia; University of Melbourne, Department of Medicine at St. Vincent’s Hospital, Fitzroy, Australia
St. Vincent’s Institute of Medical Research, Fitzroy, Australia; University of Melbourne, Department of Medicine at St. Vincent’s Hospital, Fitzroy, Australia
Bone strength is determined by its dense cortical shell, generated by unknown mechanisms. Here we use the Dmp1Cre:Socs3f/f mouse, with delayed cortical bone consolidation, to characterise cortical maturation and identify control signals. We show that cortical maturation requires a reduction in cortical porosity, and a transition from low to high density bone, which continues even after cortical shape is established. Both processes were delayed in Dmp1Cre:Socs3f/f mice. SOCS3 (suppressor of cytokine signalling 3) inhibits signalling by leptin, G-CSF, and IL-6 family cytokines (gp130). In Dmp1Cre:Socs3f/f bone, STAT3 phosphorylation was prolonged in response to gp130-signalling cytokines, but not G-CSF or leptin. Deletion of gp130 in Dmp1Cre:Socs3f/f mice suppressed STAT3 phosphorylation in osteocytes and osteoclastic resorption within cortical bone, leading to rescue of the corticalisation defect, and restoration of compromised bone strength. We conclude that cortical bone development includes both pore closure and accumulation of high density bone, and that these processes require suppression of gp130-STAT3 signalling in osteocytes.
