MMP-13 is induced during chondrocyte hypertrophy.
During development, mRNA for matrix metalloproteinase-13 (MMP-13) is found associated with cartilage undergoing hypertrophy, suggesting that this collagenase plays a role in cell enlargement and/or cartilage calcification. Using chondrocytes from prehypertrophic cartilage of chick embryo sternae, we have examined the relationship between MMP-13 expression and the transition to hypertrophy. When hypertrophy was induced by serum-free culture with ascorbate and bone morphogenetic protein-2 (BMP-2), MMP-13 mRNA levels paralleled those for type X collagen. Chondrocytes from the caudal, nonhypertrophying portion of chick sternae expressed neither type X collagen nor MMP-13, confirming that MMP-13 mRNA is a marker for hypertrophy. Zymography with conditioned medium yielded a proteinase band at 59 kDa, which was absent in nonhypertrophic chondrocytes. A polyclonal antibody raised against chick MMP-13 reacted with the 59-kDa protein, confirming that it is MMP-13. Although mRNA for MMP-13 peaked at days 4-5 of culture, only low levels of MMP-13 activity were present, and the activity increased gradually in parallel with later increases in MMP-2. These results suggest that MMP-13 is activated by MMP-2 during chondrocyte maturation, and that the combination of both proteinases is required to prepare cartilage matrix for subsequent calcification, before endochondral ossification.
D'Angelo
M
M
Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Yan
Z
Z
Nooreyazdan
M
M
Pacifici
M
M
Sarment
D S
DS
Billings
P C
PC
Leboy
P S
PS
D000818:Animals; D015415:Biomarkers; D015152:Blotting, Northern; D015153:Blotting, Western; D002356:Cartilage / Q000196:embryology; D002642:Chick Embryo; D019902:Chondrocytes / Q000378:metabolism* / Q000473:pathology; D003094:Collagen / Q000096:biosynthesis; D017364:Collagenases / Q000096:biosynthesis*; D016895:Culture Media, Serum-Free / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006984:Hypertrophy / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D053509:Matrix Metalloproteinase 13; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis; D008954:Models, Biological; D012333:RNA, Messenger / Q000378:metabolism; D013249:Sternum / Q000196:embryology; D013997:Time Factors
D015415:Biomarkers; D016895:Culture Media, Serum-Free; D018076:DNA, Complementary; D012333:RNA, Messenger; D003094:Collagen; D017364:Collagenases; D053509:Matrix Metalloproteinase 13; D020778:Matrix Metalloproteinase 2