Expression of superficial zone protein in mandibular condyle cartilage.
OBJECTIVE
Superficial zone protein (SZP) has been shown to function in the boundary lubrication of articular cartilages of the extremities. However, the expression of SZP has not been clarified in mandibular cartilage which is a tissue that includes a thick fibrous layer on the surface. This study was conducted to clarify the distribution of SZP on the mandibular condyle and the regulatory effects of humoral factors on the expression in both explants and fibroblasts derived from mandibular condyle.


METHODS
The distribution of SZP was determined in bovine mandibular condyle cartilage, and the effects of interleukin-1beta (IL-1beta) and transforming growth factor-beta (TGF-beta) on SZP expression were examined in condyle explants and fibroblasts derived from the fibrous zone of condyle cartilage.


RESULTS
SZP was highly distributed in the superficial zone of intact condyle cartilage. The SZP expression was up-regulated by TGF-beta in both explants and cultured fibroblasts, whereas the expression was slightly down-regulated by IL-1beta. A significant increase in accumulation of SZP protein was also observed in the culture medium of the fibroblasts treated with TGF-beta.


CONCLUSIONS
These results suggest that SZP plays an important role in boundary lubrication of mandible condylar cartilage, is synthesized locally within the condyle itself, and exhibits differential regulation by cell mediators relevant to mandibular condyle repairing and pathologies.
Ohno
S
S
Department of Orthodontics and Craniofacial Developmental Biology, Division of Cervico-Gnathostomatology, Hiroshima University Graduate School of Biomedical Sciences, Minami-ku, Hiroshima 734-8553, Japan.
Schmid
T
T
Tanne
Y
Y
Kamiya
T
T
Honda
K
K
Ohno-Nakahara
M
M
Swentko
N
N
Desai
T A
TA
Tanne
K
K
Knudson
C B
CB
Knudson
W
W
D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism*; D002417:Cattle; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D007150:Immunohistochemistry / Q000379:methods; D053583:Interleukin-1beta / Q000494:pharmacology; D008297:Male; D008335:Mandibular Condyle; D011509:Proteoglycans / Q000032:analysis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013704:Temporomandibular Joint; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D000099158:Proteoglycan 4
D053583:Interleukin-1beta; D011509:Proteoglycans; D016212:Transforming Growth Factor beta; C498836:PRG4 protein, Bos taurus; D000099158:Proteoglycan 4