Transforming growth factor-beta 1, -beta 2 and -beta 3 in cartilage and bone cells during endochondral ossification in the chick.
The localization of TGF-beta 1, -beta 2 and -beta 3 was studied in the growth plate, epiphysis and metaphysis of the tibiotarsus of three-week-old chicks. The different TGF-beta isoforms were localized to hypertrophic chondrocytes, chondroclasts, osteoblasts and osteoclasts using immunohistochemical staining analysis with specific TGF-beta antibodies. TGF-betas in osteoclasts and chondroclasts were restricted to those cells located on the respective matrices. TGF-beta 3 localization was mainly cytoplasmic in the transitional (early hypertrophic) chondrocytes, but nuclear staining was also detected in some proliferating chondrocytes. The cell-specific localization of these TGF-beta isoforms supports the hypothesis that TGF-beta has a role in the coupling of new bone formation to bone and cartilage matrix resorption during osteochondral development and suggests that TGF-beta may be a marker of chondrocyte differentiation. TGF-beta localization preceded a marked increase in type II collagen mRNA expression in transitional chondrocytes, suggesting a role for TGF-beta in the induction of synthesis of extracellular matrix.
Thorp
B H
BH
AFRC Institute of Animal Physiology and Genetics, Edinburgh Research Station, Roslin, Midlothian, Scotland.
Anderson
I
I
Jakowlew
S B
SB
D000818:Animals; D001842:Bone and Bones / Q000378:metabolism*; D002356:Cartilage / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D002645:Chickens / Q000378:metabolism*; D007150:Immunohistochemistry; D010006:Osteoblasts / Q000378:metabolism; D010010:Osteoclasts / Q000378:metabolism; D010012:Osteogenesis / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D016212:Transforming Growth Factor beta