Expression of β-catenin and γ-catenin in maxillary bone regeneration.

β- and γ-catenin are components of catenin family involved in cadherin adhesion function. Recently it has been shown that this family is involved in other functions such as signaling and activation of transcription factors. The final goal of this study was to evaluate the role of β- and γ-catenin in bone cell physiology and bone regeneration. Formalin-fixed-paraffin embedded specimens of 15 human bone specimens after sinus lift were collected and examined by immunohistochemstry using primary antibodies against β- and γ-catenin. Staining intensity and cellular localization were evaluated. β and γ-catenin showed a very high level of expression in human bone tissues. In particular catenins were expressed in cells with morphological findings of osteoblasts in the areas of new bone formation at the junction between mineralized and unmineralized tissue, between osteoid matrix and bone. Osteoclasts showed also positivity for catenins. Osteocytes, cells located in lacunae of mature mineralized bone with function of bone vitality maintenance, showed no expression for catenins. Specimens characterized by high amount of catenins in osteoblasts at 1° month showed high grade of bone maturation at 3° month. Data demonstrated an overall involvement of catenins in human bone tissues and in particular during bone regeneration process. The presence of staining for β- and γ-catenin particularly in osteoblasts demonstrates a significant role of catenins in functions, other than in cadherin interaction, such as signaling and activation of transcription factors during differentiation of bone tissues.