Inactivation of the Odontogenic ameloblast-associated gene affects the integrity of the junctional epithelium and gingival healing

Abstract

Odontogenic ameloblast-associated (ODAM) belongs to the secretory calcium-binding phosphoprotein (SCPP) gene cluster. It is expressed by the epithelial ameloblasts during the accrued mineralisation of enamel and by cells of the junctional epithelium (JE), a specialised portion of the gingiva that plays a critical role in periodontal health. In both cases, ODAM localises at the interface between the cells and the tooth surface. It is also present among the cells of the JE, and is distinctively highly expressed in many epithelial tumours. ODAM has been proposed to be a matricellular protein implicated in the adhesion of epithelial cells to tooth surfaces, and possibly in mediating cell status. To gain further understanding of the role of ODAM, we have created an Odam knockout (KO) mouse by deleting coding exons 2-6. Inactivation of the gene was verified by Southern blot, PCR, real-time qPCR and loss of immunostaining for the protein. Young Odam KO mice showed no readily apparent phenotype. No significant differences were observed in enamel volume and density, rod-interrod organisation, and its attrition. However, in older animals, the JE presented some detachment, an increase in inflammatory infiltrate, and apical down-growth. In addition, its regeneration was delayed following a gingivectomy challenge. Our results indicate that inactivation of Odam expression has no dramatic consequence on enamel but the phenotype in older animals replicates some JE changes seen during human periodontal disease. Altogether, our results suggest that ODAM plays a role in maintaining integrity of the JE.

Odontogenic ameloblast-associated protein (ODAM) in gingival crevicular fluid for site-specific diagnostic value of periodontitis: A pilot study

“…The function of ODAM might be related to dentogingival attachment [5][6][7]. In this study, the value of ODAM in GCF was increased in deep periodontal pockets.…”

Expression of odontogenic ameloblast-associated protein in the dental follicle and its role in osteogenic differentiation of dental follicle stem cells

“…In a recent publication, Wazen et al (2015) reported that teeth were erupted in ODAM KO mice. However, this is not contradictory to our observations because our results indicated that ODAM is not an essential gene for osteogenesis; i.e., without ODAM, osteogenesis can still occur.…”

Absence of the dermatan sulfate chain of decorin does not affect mouse development

“…Tissues were post-fixed in 1% osmium tetroxide/1.5% potassium ferrocyanide for 2 h on ice, dehydrated through an increasing concentration of acetone, and infiltrated and embedded in Epon resin. Preparation of ultrathin sections and imaging were essentially as described previously [34]. Low magnification micrographs from wild type and knockin mice ( n  = 3) were visually inspected to have comparable tissue architecture.…”