Human articular chondrocytes express osteogenic protein-1.
This study demonstrates for the first time that human articular chondrocytes express osteogenic protein-1 (OP-1). OP-1 was originally purified from bone matrix and was shown to induce cartilage and bone formation. Both OP-1 protein and message were present in human normal and osteoarthritic (OA) cartilages. OP-1 mRNA was upregulated in OA cartilage compared with normal adult tissues. However, the level of mature OP-1 protein in the same OA tissues was downregulated, whereas the pro-OP-1 remained high. Moreover, these two forms of OP-1 were localized in an inverted manner. Mature OP-1 was primarily detected in the superficial layer, whereas the pro-form was mostly in the deep layer of cartilage. The presence of pro- and mature OP-1 in extracts of normal and OA cartilages was confirmed by Western blotting. These findings imply that articular chondrocytes continue to express and synthesize OP-1 throughout adulthood. The observed patterns of the distribution of pro- and mature OP-1 also suggest differences in the processing of this molecule by normal and OA chondrocytes and by the cells in the superficial and deep layers. Distinct distribution of OP-1 and its potential activation in deep zones and regions of cloning in OA cartilages may provide clues to the potential involvement of endogenous OP-1 in repair mechanisms. (J Histochem Cytochem 48:239-250, 2000)
Chubinskaya
S
S
Department of Biochemistry, Rush Medical College, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA.
Merrihew
C
C
Cs-Szabo
G
G
Mollenhauer
J
J
McCartney
J
J
Rueger
D C
DC
Kuettner
K E
KE
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis* / Q000235:genetics; D002358:Cartilage, Articular / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D019902:Chondrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta
C525819:BMP7 protein, human; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta