Tenomodulin expression in the periodontal ligament enhances cellular adhesion.

Tenomodulin (Tnmd) is a type II transmembrane protein
characteristically expressed in dense connective tissues such as
tendons and ligaments. Its expression in the periodontal ligament
(PDL) has also been demonstrated, though the timing and function
remain unclear. We investigated the expression of Tnmd during
murine tooth eruption and explored its biological functions in
vitro. Tnmd expression was related to the time of eruption when
occlusal force was transferred to the teeth and surrounding
tissues. Tnmd overexpression enhanced cell adhesion in NIH3T3 and
human PDL cells. In addition, Tnmd-knockout fibroblasts showed
decreased cell adhesion. In the extracellular portions of Tnmd, the
BRICHOS domain or CS region was found to be responsible for
Tnmd-mediated enhancement of cell adhesion. These results suggest
that Tnmd acts on the maturation or maintenance of the PDL by
positively regulating cell adhesion via its BRICHOS domain.