title: Altered hematopoiesis in glypican-3-deficient mice results in decreased osteoclast differentiation and a delay in endochondral ossification.
abstract: Loss of function mutations in the gene encoding the heparan sulfate proteoglycan Glypican-3 (GPC3) causes an X-linked disorder in humans known as Simpson-Golabi-Behmel Syndrome (SGBS). This disorder includes both pre- and postnatal overgrowth, a predisposition to certain childhood cancers, and a complex assortment of congenital defects including skeletal abnormalities. In this study, we have identified a previously unrecognized delay in endochondral ossification associated with the loss of Gpc3 function. Gpc3 knockout animals show a marked reduction in calcified trabecular bone, and an abnormal persistence of hypertrophic chondrocytes at embryonic day 16.5 (E16.5). These hypertrophic chondrocytes down-regulate Type X collagen mRNA expression and undergo apoptosis, suggesting a normal progression of hypertrophic chondrocyte cell fate. However, replacement of these cells by mineralized bone is delayed in association with a marked delay in the appearance of osteoclasts in the bone in vivo. This delay in vivo correlates with a significant reduction in the capacity to form osteoclasts from bone marrow macrophage precursors in vitro in response to M-CSF and RANKL, and with a reduction in the numbers of bone-marrow-derived cells expressing the markers CD11b and Gr-1. Together, these results indicate selective impairment in the development of the common hematopoietic lineage from which monocyte/macrophages and PMNs are derived. This is the first report of a requirement for heparan sulfate, and specifically Gpc3, in the lineage-specific differentiation of these cell types in vivo.
authors.affiliation: Department of Pediatrics, Washington University School of Medicine and St. Louis Children's Hospital, St. Louis, MO 63110, USA.
authors.forename: Beth L
authors.initials: BL
authors.lastname: Viviano
authors.forename: Laura
authors.initials: L
authors.lastname: Silverstein
authors.forename: Camila
authors.initials: C
authors.lastname: Pflederer
authors.forename: Stephenie
authors.initials: S
authors.lastname: Paine-Saunders
authors.forename: Kathy
authors.initials: K
authors.lastname: Mills
authors.forename: Scott
authors.initials: S
authors.lastname: Saunders
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001854:Bone Marrow Cells / Q000378:metabolism / Q000502:physiology*; D001973:Bromodeoxyuridine; D002352:Carrier Proteins / Q000494:pharmacology; D002454:Cell Differentiation / Q000502:physiology*; D019902:Chondrocytes / Q000378:metabolism; D024121:Collagen Type X / Q000378:metabolism; D005434:Flow Cytometry; D005697:Galactosides; D053673:Glypicans; D006410:Hematopoiesis / Q000235:genetics / Q000502:physiology*; D019812:Heparan Sulfate Proteoglycans / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007211:Indoles; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation / Q000235:genetics; D010010:Osteoclasts / Q000166:cytology* / Q000502:physiology; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B
chemical_list: D002352:Carrier Proteins; D024121:Collagen Type X; D005697:Galactosides; D053673:Glypicans; D019812:Heparan Sulfate Proteoglycans; D007211:Indoles; D008562:Membrane Glycoproteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D016173:Macrophage Colony-Stimulating Factor; D001973:Bromodeoxyuridine; C044888:5-bromo-4-chloro-3-indolyl beta-galactoside