Expression and localization of MGP in rat tooth cementum

Tooth cementum. a calcified hard tissue covering the root surfaces, is an i mportant component connecting the teeth to the collagenous fibres of the pe riodontal ligament. Although the overall composition of cementum may closel y resemble that of bent, each part has: not been fully characterized. Here, the localization of the matrix gamma -calboxyglutamic acid (Gla) protein ( MGP), one of the major cia-containing proteins in the body, in cementum was investigated using immunohistochemistry and in situ hybridization. (1) Str ong MGP antigenicity was observed in the acellular cementum, but was only m oderate in the cellular cementum, (2) polygonal periodontal ligament cells facing the acellular cementum and the uncalcified cellular cementum express ed MGP mRNA, indicating that these cells produced MGP and deposited it on t he cementum; (3) MGP accumulated at the junction between the uncalcified an d calcified cellular cementum; and (4) the distribution pattern of MGP anti genicity resembled that of osteopontin. As one function of MGP could be as a negative regulator for mineral apposition, the expression of MGP in the c ells adjacent to the cementum may be important to prevent hyperapposition o f minerals. (C) 2001 Elsevier Science Ltd. All rights reserved.