title: Bone sialoprotein keratan sulfate proteoglycan (BSP-KSPG) and FGF-23 are important physiological components of medullary bone.
abstract: Medullary bone is a specialized bone found in the marrow cavity of laying birds. It provides a significant contribution to the calcium supply for egg shell formation. Medullary bone is distinguished from cortical bone by the presence of large amounts of a keratan sulfate proteoglycan (KSPG). The aims of the present experiment are to confirm the identity of the core protein of KSPG, identify a marker of medullary bone metabolism, and determine whether changes in keratan sulfate (KS) concentration in blood are associated with the egg-laying cycle. Using two different isolation techniques- one specific for bone and another for blood- we have identified bone sialoprotein (BSP) to be the core protein of this KSPG. We also determined that the amount of keratan sulfate (KS) in laying hen blood fluctuates in synchrony with the egg-laying cycle, and thus can serve as a specific marker for medullary bone metabolism. During the course of this investigation, we also found FGF-23 (phosphatonin) to be expressed in medullary bone, in synchrony with the egg-laying cycle. Western blotting was used to demonstrate the presence of this peptide in both laying hen blood and medullary bone extracts. The importance of FGF-23 (phosphatonin) and parathyroid hormone in normalizing the dramatic changes in plasma calcium and phosphorus during the 24h egg-laying cycle is discussed.
authors.affiliation: Department of Animal Science, The Pennsylvania State University, University Park, PA, United States.
authors.forename: Jill A
authors.initials: JA
authors.lastname: Hadley
authors.affiliation: Department of Animal Science, The Pennsylvania State University, University Park, PA, United States.
authors.forename: Maria
authors.initials: M
authors.lastname: Horvat-Gordon
authors.affiliation: Department of Poultry Science, University of Georgia, Athens, GA, United States.
authors.forename: Woo-Kyun
authors.initials: WK
authors.lastname: Kim
authors.affiliation: The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, United States.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Praul
authors.affiliation: Department of Animal Science, The Pennsylvania State University, University Park, PA, United States.
authors.forename: Dennis
authors.initials: D
authors.lastname: Burns
authors.affiliation: Department of Animal Science, The Pennsylvania State University, University Park, PA, United States. Electronic address: lnr@psu.edu.
authors.forename: Roland M
authors.initials: RM
authors.lastname: Leach
mesh_terms: D000818:Animals; D002645:Chickens; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000502:physiology*; D058574:Integrin-Binding Sialoprotein / Q000502:physiology*; D007632:Keratan Sulfate / Q000502:physiology*; D011509:Proteoglycans / Q000502:physiology*
chemical_list: D058574:Integrin-Binding Sialoprotein; D011509:Proteoglycans; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; D007632:Keratan Sulfate
keywords: Blood calcium and phosphorus homeostasis; Bone sialoprotein; FGF-23; Keratan sulfate; Laying hen; Phosphatonin