Insulin-like growth factor I regulates apoptosis in condylar cartilage.
Endogenous insulin-like growth factor-I (IGF-I) is known to affect the growth and development of condylar cartilage. However, the critical effect of IGF-I on cell survival is still unknown. We hypothesized that endogenous IGF-I could regulate the survival of cells of the mandibular condylar cartilage. Mandibular condyles dissected from 12-day-old rats were cultured for 1, 3, and 5 days in medium containing antisense oligodeoxynucleotide (AS-ODN) for IGF-I. Real-time RT-PCR analysis showed that the levels of IGF-I and IGF binding protein (IGFBP)3 mRNAs in the AS-ODN group were significantly decreased. After 3 days' culture, the number of necrotic cells was observed in the undifferentiated mesenchymal cell layer. These cells were TUNEL-positive and confirmed to be apoptotic by electron microscopic observation. Immunoblotting revealed that expression of cleaved caspase3 was increased with AS-ODN. These results may suggest that the cells in the undifferentiated mesenchymal cell layer of the mandibular condyle require IGF-I for survival.
Yokota
T
T
Department of Maxillofacial Restoration, Division of Maxillofacial/Neck Reconstruction, Graduate School, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
Shimokawa
H
H
Shibata
S
S
Itoh
K
K
Baba
Y
Y
Ohya
K
K
Ohyama
K
K
Suzuki
S
S
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002356:Cartilage / Q000166:cytology*; D053148:Caspase 3 / Q000032:analysis; D002454:Cell Differentiation; D002470:Cell Survival / Q000502:physiology; D015151:Immunoblotting; D020287:In Situ Nick-End Labeling; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000032:analysis; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000502:physiology*; D008335:Mandibular Condyle / Q000166:cytology*; D008648:Mesoderm / Q000166:cytology; D008854:Microscopy, Electron; D009336:Necrosis; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D009924:Organ Culture Techniques; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley
D018972:Insulin-Like Growth Factor Binding Protein 3; D020319:Oligodeoxyribonucleotides, Antisense; D007334:Insulin-Like Growth Factor I; D053148:Caspase 3