Immunohistochemical localization of fibroblast growth factor receptors in the rat mandibular condylar cartilage and tibial cartilage.
The fibroblast growth factor receptors (FGFRs), members of the tyrosine-kinase receptor family, are known to play a crucial role in the growth and development of cartilaginous tissues. The mandibular condylar cartilage has been suggested to have a characteristic growth pattern compared with the tibial growth plate cartilage, e.g., cell alignment, mode of proliferation and differentiation, and response to humoral and mechanical factors. To examine the mRNA expression and localization of fibroblast growth factor receptor (FGFR)-1, -2, and -3 in the condylar and tibial growth plate cartilages, reversed transcribed polymerase chain reaction (RT-PCR) assay and immunohistochemistry were carried out using growing rats. The enzymatically isolated rat condylar and tibial chondrocytes expressed mRNA of aggrecan and type II collagen, which are together known as the major cartilaginous extracellular matrices. Both types of cells expressed mRNA of FGFR-1, -2, and -3 by RT-PCR. In the neonatal rat, immunolocalization of FGFR-1, -2, and -3 was found in the middle of the condylar cartilage, mainly in the hypertrophic zone of the tibial cartilage. At 3 weeks old, the three FGFRs were broadly observed in both cartilages. At 8 weeks old, localization of FGFR-3 was absent in the hypertrophic cell layer of the condyle, whereas it was still broadly observed in the tibial growth plate cartilage. In the same stage, FGFR-1 and FGFR-2 showed similar localization in both cartilages to that at 3 weeks of age. All these observations suggest that FGFRs play an important role in the differential growth pattern of the condylar cartilage.
Hamada
T
T
Second Department of Orthodontics, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
Suda
N
N
Kuroda
T
T
D000818:Animals; D002358:Cartilage, Articular / Q000737:chemistry*; D019902:Chondrocytes / Q000737:chemistry; D015870:Gene Expression; D006132:Growth Plate / Q000737:chemistry*; D008335:Mandibular Condyle / Q000737:chemistry*; D011505:Protein-Tyrosine Kinases; D012333:RNA, Messenger; D051381:Rats; D017208:Rats, Wistar; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis* / Q000235:genetics; D051496:Receptor, Fibroblast Growth Factor, Type 1; D051497:Receptor, Fibroblast Growth Factor, Type 2; D051498:Receptor, Fibroblast Growth Factor, Type 3; D017468:Receptors, Fibroblast Growth Factor / Q000032:analysis* / Q000235:genetics; D013977:Tibia / Q000737:chemistry*
D012333:RNA, Messenger; D017468:Receptors, Fibroblast Growth Factor; C496350:Fgfr1 protein, rat; C496356:Fgfr2 protein, rat; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D051496:Receptor, Fibroblast Growth Factor, Type 1; D051497:Receptor, Fibroblast Growth Factor, Type 2; D051498:Receptor, Fibroblast Growth Factor, Type 3