The influence of parathyroid hormone-related protein (PTHrP) on tooth-germ development and osteoclastogenesis in alveolar bone of PTHrP-knock out and wild-type mice in vitro.
In a previous study, it was shown that tooth germs of neonatal homozygous parathyroid hormone-related protein (PTHrP)-knockout mice are penetrated or compressed by the surrounding alveolar bone, suggesting an important role for PTHrP in the formation and activation of osteoclasts around growing tooth germs. In order to elucidate the role of PTHrP during the development of the tooth germ and related structures, mandibular explants containing cap stage tooth germs of embryonic day 14, homozygous mice were here cultured with or without surrounding alveolar bone. There was no difference in the number of tartrate-resistant acid phosphatase-positive multinucleated osteoclastic cells around the first molars of homozygous and wild-type mice. After 10 days of culture, osteoclastic cells were rarely present in explants from homozygous mice and penetration of alveolar bone into the dental papilla was observed. The decline in osteoclast number was partly restored by the addition of PTHrP to the culture. Tooth germs of both wild-type and homozygous mice cultured without alveolar bone developed well, with no apparent structural abnormality; dentine formation was evident after 10 days. These data suggest that PTHrP is not required for the development of the tooth germ proper but is indispensable in promoting the osteoclast formation required to accommodate that development.
Mekaapiruk
Kongkwan
K
Maxillofacial Orthognathics, Division of Maxillofacial/Neck Reconstruction, Department of Maxillofacial Reconstruction and Function, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, 113-8549, Tokyo, Japan.
Suda
Naoto
N
Hammond
Vicki E
VE
Beck
Felix
F
Kuroda
Takayuki
T
Takano
Yoshiro
Y
Terashima
Tatsuo
T
D000135:Acid Phosphatase / Q000032:analysis; D000539:Alveolar Process / Q000196:embryology*; D000818:Animals; D002455:Cell Division / Q000502:physiology; D005260:Female; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009924:Organ Culture Techniques; D010010:Osteoclasts / Q000166:cytology*; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones / Q000235:genetics / Q000502:physiology*; D000071681:Tartrate-Resistant Acid Phosphatase; D014083:Tooth Germ / Q000502:physiology*
D007527:Isoenzymes; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase