Expression of the cadherin-11 gene is a discriminative factor between articular and growth plate chondrocytes.
OBJECTIVE
Calcification of hypertrophic chondrocytes is the final step in the differentiation of growth plates, although the precise mechanism is not known. We have established two growth plate-derived chondrocyte cell lines, MMR14 and MMR17, from p53-/- mice (Nakamata T, Aoyama T, Okamoto T, Hosaka T, Nishijo K, Nakayama T, et al. In vitro demonstration of cell-to-cell interaction in growth plate cartilage using chondrocytes established from p53-/- mice. J Bone Miner Res 2003;18:97-107). Prolonged in vitro culture produced calcified nodules in MMR14, but not in MMR17. Factors responsible for the difference in calcification between the two cell lines may also be involved in the physiological calcification in growth plate.


METHODS
Gene expression profiles of MMR14 and MMR17 were compared using a cDNA microarray to identify candidate genes involved in the calcification process.


RESULTS
Forty-five genes were identified as upregulated in MMR14, including the cadherin-11 (Cdh-11) gene. The expression of Cdh-11 in MMR14 was detected in cell-cell junctions, while no expression was observed in MMR17. Primary cultured chondrocytes from growth plate (GC) also expressed the Cdh-11, and the staining of Cdh-11 was observed in the late hypertrophic zone of growth plate. Cell aggregation assays showed that chondrocytes required Ca2+ to form nodules, and knockdown of the Cdh-11 gene expression using short interfering RNA inhibited the formation of calcified nodules in MMR14. The introduction of Cdh-11 into MMR17 failed to produce calcified nodules indicating that Cdh-11 is one, but not the sole, factor responsible for the production of calcified nodules.


CONCLUSIONS
Although the physiological role is still unclear, Cdh-11 is a discriminative factor between articular and growth plate chondrocytes.
Matsusaki
T
T
Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.
Aoyama
T
T
Nishijo
K
K
Okamoto
T
T
Nakayama
T
T
Nakamura
T
T
Toguchida
J
J
D000818:Animals; D015820:Cadherins / Q000096:biosynthesis*; D002113:Calcification, Physiologic / Q000235:genetics*; D002358:Cartilage, Articular / Q000166:cytology*; D002460:Cell Line; D019902:Chondrocytes / Q000166:cytology*; D015870:Gene Expression; D006132:Growth Plate / Q000166:cytology*; D051379:Mice
D015820:Cadherins; C086960:osteoblast cadherin