Formation of acellular cementum-like layers, with and without extrinsic fiber insertion, along inert bone surfaces of aging c-Src gene knockout mice.
To investigate the long-term effects of c-src deficiency on skeletal and dental tissues, we examined the lower jaws and long bones of c-src gene knockout (c-src KO) mice by histological and histochemical methods. Numerous multinucleated osteoclasts were distributed throughout the mandible in 5-wk-old c-src KO mice, but by 14 wk they had almost completely disappeared from the alveolar bone, leaving tartrate-resistant acid phosphatase (TRAP)-positive layers along the bone surface. Deposition of osteopontin-positive mineralized tissue, reminiscent of acellular afibrillar cementum (AAC), was confirmed along the TRAP-positive bone surface at 14 wk. The layer progressively thickened up to 21 months. A comparable mineralized layer was noted along the trabeculae of long bones as thickened cement lines. In the periostin-rich areas of jaw bones, but not in the long bones, portions of AAC-like mineralized layers were often replaced with and/or covered by acellular extrinsic fiber cementum (AEFC)-like tissue. These data suggest that the deposition of AAC-like mineralized tissue is a general phenomenon that may occur along inert or slowly remodeling bone surfaces under conditions characterized by reduced bone-resorbing activity, whereas the induction of AEFC-like tissue seems to be associated with the expression of certain molecules that are particularly abundant in the microenvironment of the periodontal ligament.
Baba
Otto
O
Division of Biostructural Science, Tokyo Medical and Dental University Graduate School, Tokyo, Japan.
Miyata
Atsushi
A
Abe
Tatsuhiko
T
Shibata
Shunichi
S
Nakano
Yukiko
Y
Terashima
Tatsuo
T
Oda
Tsuyoshi
T
Kudo
Akira
A
Takano
Yoshiro
Y
D000375:Aging / Q000502:physiology; D000539:Alveolar Process / Q000378:metabolism*; D000818:Animals; D015815:Cell Adhesion Molecules / Q000378:metabolism; D025021:Cementogenesis / Q000502:physiology*; D003739:Dental Cementum / Q000378:metabolism*; D005269:Femur / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D016391:Genes, src / Q000502:physiology*; D006651:Histocytochemistry; D051379:Mice; D018345:Mice, Knockout / Q000378:metabolism; D010022:Osteopetrosis / Q000235:genetics / Q000378:metabolism; D053495:Osteopontin / Q000378:metabolism; D010513:Periodontal Ligament / Q000737:chemistry* / Q000378:metabolism; D014074:Tooth Calcification / Q000502:physiology
D015815:Cell Adhesion Molecules; C082838:Postn protein, mouse; D053495:Osteopontin