Immunohistochemical localization of a proto‐cadherin fat tumour‐suppressor homolog in the regenerating tail of lizard suggests a role in apical growth control

Abstract

AbstractThe present immunohistochemical and western blotting study evaluates the localization of a proto‐cadherin which gene is overexpressed in the regenerating blastema of the lizard Podarcis muralis. Bioinformatic analysis suggests that the antibody recognizes FAT1/2 proteins. Western blot indicates a main band around 50 kDa, a likely fragment derived from the original membrane‐bound large protein. Immunofluorescence shows main labelling in differentiating wound keratinocytes, lower in ependyma, mesenchyme and extracellular matrix of the blastema. The apical epidermal peg contains keratinocytes with labelled peripheral cytoplasm, as confirmed using ultrastructural immunogold that also reveals most labelling located along the cell surface of mesenchymal cells. Myoblasts and differentiating myotubes of regenerating muscles are less intensely labelled. The regenerating cartilaginous tube contains sparse labelled chondroblasts, especially in external and internal perichondria. In regenerating scales, differentiating beta‐cells appear immunofluorescent mainly along the cell perimeter. In more differentiated muscle, cartilage and connective tissues of the new tail, the labelling lowers or disappears. The observations indicate that FAT1/2 proto‐cadherins are present in the apical blastema where an intense remodelling takes place for the growth of the new tail but where also a tight control of cell division and migration is active and may regulate potential tumorigenic process.