title: The interrelationship between bone and fat: from cellular see-saw to endocrine reciprocity.
abstract: The number of mature osteoblasts and marrow adipocytes in bone is influenced by the differentiation of the common mesenchymal progenitor cell towards one phenotype and away from the other. Consequently, factors which promote adipogenesis not only lead to fatty marrow but also inhibit osteoblastogenesis, resulting in decreased osteoblast numbers, diminished bone formation and, potentially, inadequate bone mass and osteoporosis. In addition to osteoblast and bone adipocyte numbers being influenced by this skewing of progenitor cell differentiation towards one phenotype, mature osteoblasts and adipocytes secrete factors which may evoke changes in the cell fate and function of each other. This review examines the endogenous factors, such as PPAR-γ2, Wnt, IGF-1, GH, FGF-2, oestrogen, the GP130 signalling cytokines, vitamin D and glucocorticoids, which regulate the selection between osteoblastogenesis and adipogenesis and the interrelationship between fat and bone. The role of adipokines on bone, such as adiponectin and leptin, as well as adipose-derived oestrogen, is reviewed and the role of bone as an energy regulating endocrine organ is discussed.
authors.affiliation: Division of Endocrinology, Department of Medicine, Faculty of Medicine and Health Sciences, University of Stellenbosch, Francie van Zijl Drive, Tygerberg, 7505, South Africa.
authors.forename: H
authors.initials: H
authors.lastname: Sadie-Van Gijsen
authors.forename: N J
authors.initials: NJ
authors.lastname: Crowther
authors.forename: F S
authors.initials: FS
authors.lastname: Hough
authors.forename: W F
authors.initials: WF
authors.lastname: Ferris
mesh_terms: D017667:Adipocytes / Q000166:cytology*; D050156:Adipogenesis; D054392:Adipokines / Q000502:physiology; D001854:Bone Marrow Cells / Q000166:cytology*; D002454:Cell Differentiation; D050822:Cytokine Receptor gp130 / Q000502:physiology; D004703:Endocrine System / Q000502:physiology*; D004967:Estrogens / Q000502:physiology; D016222:Fibroblast Growth Factor 2 / Q000502:physiology; D005938:Glucocorticoids / Q000502:physiology; D013006:Growth Hormone / Q000502:physiology; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000502:physiology; D059630:Mesenchymal Stem Cells / Q000166:cytology; D010006:Osteoblasts / Q000166:cytology*; D047495:PPAR gamma / Q000502:physiology; D015398:Signal Transduction; D014807:Vitamin D / Q000502:physiology; D051153:Wnt Proteins / Q000502:physiology
chemical_list: D054392:Adipokines; D004967:Estrogens; D005938:Glucocorticoids; D047495:PPAR gamma; D051153:Wnt Proteins; D016222:Fibroblast Growth Factor 2; D050822:Cytokine Receptor gp130; D014807:Vitamin D; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone