CONTEXT: The adipose tissue (AT), which is an endocrine organ, is linked to several metabolic abnormalities. Undercarboxylated osteocalcin (ucOCN) regulates insulin and adiponectin secretion. OBJECTIVE: Our objective was to investigate the involvement of OCN in obesity and to evaluate, in vitro and ex vivo, the role of AT in the modulation of this endocrine circuit. DESIGN, PATIENTS, AND SETTING: This transversal study involved 83 male subjects, divided according to the World Health Organization body mass index classification, evaluated at Padova's Obesity Outpatient Clinic. METHODS: OCN, both undercarboxylated (ucOCN) and carboxylated (cOCN) forms, was measured in serum by ELISA. OCN mRNA expression and protein production were measured by quantitative RT-PCR and immunohistochemistry during in vitro adipogenesis and in sc AT (SAT) and omental AT (OAT) from normal adult men. cOCN and ucOCN release by AT in a simple growth medium was verified by ELISA. RESULTS: Overweight and obese patients had a lower ucOCN and ucOC/OCN ratio. In the whole cohort, ucOCN/OCN ratio was negatively correlated to body mass index (rho = -0.233; P < 0.05). OCN mRNA was present in SAT and OAT and during all stages of adipogenesis, with higher expression in the first steps. Immunohistochemistry confirmed the expression of OCN protein. Both SAT and OAT were able to release cOCN and ucOCN. CONCLUSIONS: Our data support a pathophysiological link between ucOCN and cOCN balance and obesity. OCN is present in the first phases of adipogenesis but also in human AT ex vivo. AT releases, in vitro, both ucOCN and cOCN, suggesting a possible link between AT and OCN in the regulation of metabolism.
CONTEXT: The adipose tissue (AT), which is an endocrine organ, is linked to several metabolic abnormalities. Undercarboxylated osteocalcin (ucOCN) regulates insulin and adiponectin secretion. OBJECTIVE: Our objective was to investigate the involvement of OCN in obesity and to evaluate, in vitro and ex vivo, the role of AT in the modulation of this endocrine circuit. DESIGN, PATIENTS, AND SETTING: This transversal study involved 83 male subjects, divided according to the World Health Organization body mass index classification, evaluated at Padova's ObesityOutpatient Clinic. METHODS:OCN, both undercarboxylated (ucOCN) and carboxylated (cOCN) forms, was measured in serum by ELISA. OCN mRNA expression and protein production were measured by quantitative RT-PCR and immunohistochemistry during in vitro adipogenesis and in sc AT (SAT) and omental AT (OAT) from normal adult men. cOCN and ucOCN release by AT in a simple growth medium was verified by ELISA. RESULTS: Overweight and obesepatients had a lower ucOCN and ucOC/OCN ratio. In the whole cohort, ucOCN/OCN ratio was negatively correlated to body mass index (rho = -0.233; P < 0.05). OCN mRNA was present in SAT and OAT and during all stages of adipogenesis, with higher expression in the first steps. Immunohistochemistry confirmed the expression of OCN protein. Both SAT and OAT were able to release cOCN and ucOCN. CONCLUSIONS: Our data support a pathophysiological link between ucOCN and cOCN balance and obesity. OCN is present in the first phases of adipogenesis but also in human AT ex vivo. AT releases, in vitro, both ucOCN and cOCN, suggesting a possible link between AT and OCN in the regulation of metabolism.
Authors: A L Kuipers; C Gundberg; C M Kammerer; A S Dressen; C S Nestlerode; A L Patrick; V W Wheeler; C H Bunker; A B Newman; J M Zmuda Journal: Osteoporos Int Date: 2011-09-21 Impact factor: 4.507
Authors: Norman K Pollock; Paul J Bernard; Karl Wenger; Sudipta Misra; Barbara A Gower; Jerry D Allison; Haidong Zhu; Catherine L Davis Journal: J Bone Miner Res Date: 2010-07-16 Impact factor: 6.741
Authors: Claudia Boucher-Berry; Phyllis W Speiser; Dennis E Carey; Steven P Shelov; Siham Accacha; Ilene Fennoy; Robert Rapaport; Yomery Espinal; Michael Rosenbaum Journal: J Bone Miner Res Date: 2012-02 Impact factor: 6.741