In contrast, adding exogenous GM3 or LacCer rescues selleck compound the phosphorylation of ERK1/2 repressed by pre-treatment with d-PDMP, suggesting that GM3 and LacCer are essential for the NT-4-mediated induction of AMBN expression and contribute to dental epithelial cells’ differentiation into ameloblasts [27]. Although first discovered in ameloblasts [28], AMBN is also expressed by osteoblasts [29], cementoblasts [30], and epithelial rests of Malassez in the periodontal

ligament [31]. The AMBN protein sequence features a fibronectin interaction site [32] and heparin-binding domains [33]. In rodents, there is a potential α2β1 integrin-binding domain and a thrombospondin cell adhesion motif in the AMBN protein [34]. The effect of AMBN on cell adhesion involves RhoA signaling and cell cycle progression through p27 [35]. AMBN is expressed in mouse calvarial bone and adjacent condensed mesenchyme, and an AMBN transgenic mouse model shows delayed posterior frontal suture fusion and incomplete suture closure. Furthermore, AMBN-overexpressing mice show reduced cell proliferation in suture blastemas and mesenchymal cells from posterior frontal sutures. In these mice, the expression of Msx2 in calvaria and suture mesenchymal cells is decreased. Finally, AMBN overexpression significantly reduces the expression of Msx2 downstream target molecules, including osteogenic transcription

factors Runx2 and Osterix. Together, these results suggest that AMBN plays a crucial role in the regulation of cranial bone growth and suture Cytoskeletal Signaling inhibitor closure via Msx2 suppression and proliferation inhibition [36]. Tooth root formation

begins after the completion of crown morphogenesis. At the edge of the tooth crown end, inner and outer enamel epithelia form the Hertwig’s epithelial root sheath (HERS), which extends along with dental follicular tissue for root formation. AMBN is a matrix protein secreted by ameloblasts and HERS-derived cells. In one study, AMBN siRNA treatment of 10-day-postnatal molars was found to inhibit root formation. Furthermore, HERS in these mice revealed a multilayered appearance, and BrdU-positive cells were increased in the Oxalosuccinic acid outer layers, indicating that AMBN regulates HERS cell proliferation and functions as a trigger for normal root formation [37]. Dental epithelial tumor formation has been observed in AMBN knockout mice [25], while AMBN has also been shown to be expressed in osteosarcoma cells. AMBN binds to CD63, a member of the transmembrane-4 glycoprotein superfamily, and promotes CD63 binding to integrin β1. Furthermore, the interaction between CD63 and integrin β1 induces Src kinase inactivation via the binding of CD63 to Src, indicating that AMBN is expressed in osteoblasts and functions as a promoting factor for osteogenic differentiation via a novel pathway through an interaction between CD63 and integrin β1 [38]. Enamelin (ENAM) is a secreted glycoprotein known to be critical for dental enamel formation.