Expression of bone sialoprotein (BSP) in developing human tissues.
Bone sialoprotein (BSP) and its messenger RNA were localized in developing human skeletal and nonskeletal tissues by means of immunohistochemistry and in situ hybridization. Both protein and mRNA were found in mature, bone-forming cells but not in their immature precursors. In addition, osteoclasts displayed positive immunostaining and high densities of autoradiographic grains by in situ hybridization experiments. BSP was expressed in fetal epiphyseal cartilage cells, particularly in hypertrophic chondrocytes of growth plates. Though neither the protein nor the mRNA were identified in a variety of other connective and nonconnective tissues, an unexpected finding was the expression of BSP in the trophoblast cells of placenta. These findings show that BSP is primarily an osteoblast-derived component of the bone matrix expressed at late stages of differentiation. We have also found that osteoclasts produce BSP, possibly as a mediator of cell attachment to bone.
Bianco
P
P
Bone Research Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
Fisher
L W
LW
Young
M F
MF
Termine
J D
JD
Robey
P G
PG
D000818:Animals; D001842:Bone and Bones / Q000378:metabolism*; D002454:Cell Differentiation; D003238:Connective Tissue / Q000378:metabolism; D003239:Connective Tissue Cells; D005865:Gestational Age; D006132:Growth Plate / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D058574:Integrin-Binding Sialoprotein; D009693:Nucleic Acid Hybridization; D010006:Osteoblasts / Q000378:metabolism; D010010:Osteoclasts / Q000378:metabolism; D010011:Osteocytes / Q000378:metabolism; D015347:RNA Probes; D012333:RNA, Messenger / Q000032:analysis* / Q000235:genetics; D011817:Rabbits; D012795:Sialoglycoproteins / Q000032:analysis* / Q000235:genetics; D014327:Trophoblasts / Q000378:metabolism
C546871:IBSP protein, human; D058574:Integrin-Binding Sialoprotein; D015347:RNA Probes; D012333:RNA, Messenger; D012795:Sialoglycoproteins