PLAP-1/asporin, a novel negative regulator of periodontal ligament mineralization.
Periodontal ligament-associated protein-1 (PLAP-1)/asporin is a recently identified novel member of the small leucine-rich repeat proteoglycan family. PLAP-1/asporin is involved in chondrogenesis, and its involvement in the pathogenesis of osteoarthritis has been suggested. We report that PLAP-1/asporin is also expressed specifically and predominantly in the periodontal ligament (PDL) and that it negatively regulates the mineralization of PDL cells. In situ hybridization analysis revealed that PLAP-1/asporin was expressed specifically not only in the PDL of an erupted tooth but also in the dental follicle, which is the progenitor tissue of the PDL during tooth development. Overexpression of PLAP-1/asporin in mouse PDL-derived clone cells interfered with both naturally and bone morphogenetic protein 2 (BMP-2)-induced mineralization of the PDL cells. On the other hand, knockdown of PLAP-1/asporin transcript levels by RNA interference enhanced BMP-2-induced differentiation of PDL cells. Furthermore co-immunoprecipitation assays showed a direct interaction between PLAP-1/asporin and BMP-2 in vitro, and immunohistochemistry staining revealed the co-localization of PLAP-1/asporin and BMP-2 at the cellular level. These results suggest that PLAP-1/asporin plays a specific role(s) in the periodontal ligament as a negative regulator of cytodifferentiation and mineralization probably by regulating BMP-2 activity to prevent the periodontal ligament from developing non-physiological mineralization such as ankylosis.
Yamada
Satoru
S
Department of Periodontology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
Tomoeda
Miki
M
Ozawa
Yasuhiro
Y
Yoneda
Shinya
S
Terashima
Yoshimitsu
Y
Ikezawa
Kazuhiko
K
Ikegawa
Shiro
S
Saito
Masahiro
M
Toyosawa
Satoru
S
Murakami
Shinya
S
D000818:Animals; D002113:Calcification, Physiologic; D002454:Cell Differentiation; D002460:Cell Line; D003001:Cloning, Molecular; D003795:Dental Sac / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000502:physiology*; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D008807:Mice, Inbred BALB C; D010006:Osteoblasts / Q000378:metabolism; D010513:Periodontal Ligament / Q000254:growth & development / Q000378:metabolism*; D014070:Tooth / Q000254:growth & development / Q000378:metabolism
C511592:Aspn protein, mouse; D016326:Extracellular Matrix Proteins