Immunocytochemical and biochemical detection of EMMPRIN in the rat tooth germ: differentiation-dependent co-expression with MMPs and co-localization with caveolin-1 in membrane rafts of dental epithelial cells

Abstract

In tooth development matrix metalloproteinases (MMPs) are under the control of several regulatory mechanisms including the upregulation of expression by inducers and downregulation by inhibitors. The aim of the present study was to monitor the occurrence and distribution pattern of the extracellular matrix metalloproteinase inducer (EMMPRIN), the metalloproteinases MMP-2 and MT1-MMP and caveolin-1 during the cap and bell stage of rat molar tooth germs by means of immunocytochemistry. Strong EMMPRIN immunoreactivity was detected on the cell membranes of ameloblasts and cells of the stratum intermedium in the bell stage of the enamel organ. Differentiating odontoblasts exhibited intense EMMPRIN immunoreactivity, especially at their distal ends. Caveolin-1 immunoreactivity was evident in cells of the internal enamel epithelium and in ameloblasts. Double immunofluorescence studies revealed a focal co-localization between caveolin-1 and EMMPRIN in ameloblastic cells. Finally, western blotting experiments demonstrated the expression of EMMPRIN and caveolin-1 in dental epithelial cells (HAT-7 cells). A substantial part of EMMPRIN was detected in the detergent-insoluble caveolin-1-containing low-density raft membrane fraction of HAT-7 cells suggesting a partial localization within lipid rafts. The differentiation-dependent co-expression of MMPs with EMMPRIN in the enamel organ and in odontoblasts indicates that EMMPRIN takes part in the induction of proteolytic enzymes in the rat tooth germ. The localization of EMMPRIN in membrane rafts provides a basis for further investigations on the role of caveolin-1 in EMMPRIN-mediated signal transduction cascades in ameloblasts.

Regulation of invadopodia formation and activity by CD147

“…Independent studies have shown that CD147 (Schwab et al, 2007;Tang and Hemler, 2004) and MT1-MMP (Annabi et al, 2001;Yamaguchi et al, 2009) are at least in part localized in membrane compartments similar to lipid rafts. Thus, we examined whether CD147 influences MT1-MMP localization to lipid rafts.…”

EMMPRIN (basigin/CD147) is involved in the morphogenesis of tooth germ in mouse molars

“…A multi-step and complex process of the gene expressions are involved in the different stage of tooth development (for review see Cobourne 1999). Recently, a study reported the co-expression of EMMPRIN and MMPs in cells of rat enamel organ, suggesting that EMMPRIN signaling may be involved in cascades regulating the expression of MMPs in differentiating odontoblasts and ameloblasts (Schwab et al 2007). However, to our knowledge, no report has been made on the detail distribution of EMMPRIN in mouse tooth germ and the functions ascribed to EMMPRIN in odontogenesis are varied.…”

A novel functional site of extracellular matrix metalloproteinase inducer (EMMPRIN) that limits the migration of human uterine cervical carcinoma cells

“…Koga et al (12) have also reported similar findings, in that a synthetic peptide with 20 amino acids, including an EM1 sequence, abolishes the EMMPRINmediated proMMP-2 production. On the other hand, the loop II domain of EMMPRIN has been reported to form a complex with caveolin-1, which may be associated with the regulation of MMP production and the localization of EMMPRIN in lipid rafts (13)(14)(15). In addition, cyclophilin B-mediated isomerization of proline in the loop II domain of EMMPRIN has been reported to participate in the chemotactic activity of T lymphocytes (16 EMMPRIN may help with the understanding of its pathophysiological roles and the development of anti-metastatic strategies, they remain to be elucidated.…”