CROSS-LINKING OF THE DERMO-EPIDERMAL JUNCTION OF SKIN REGENERATING FROM KERATINOCYTE AUTOGRAFTS - ANCHORING FIBRILS ARE A TARGET FOR TISSUETRANSGLUTAMINASE

Since transglutaminases create covalent gamma-glutamyl-epsilon-lysine cross-links between extracellular matrix proteins they are prime candi dates for stabilizing tissue during wound healing. Therefore, we studi ed the temporo-spatial expression of transglutaminase activity in skin regenerating from cultured epithelial autografts in severely burned c hildren by the specific incorporation of monodansylcadaverine into cry ostat sections from skin biopsies obtained between 5 d to 17 mo after grafting. The dansyl label was subsequently immunolocalized in the epi dermis, dermal connective tissue, and along the basement membrane, Inc ubation of cryosections of normal and regenerating skin with purified tissue transglutaminase confirmed the dermo-epidermal junction and the papillary dermis as targets for this enzyme and revealed that in rege nerating skin transamidation of the basement membrane zone was complet ed only 4-5 mo after grafting. Immunoelectron microscopy revealed that three distinct regions on the central portion of anchoring fibrils we re positive for monodansylcadaverine in normal skin which were negativ e during the initial phase of de novo formation of anchoring fibrils i n regenerating skin. Biochemically, we identified collagen VII as pote ntial substrate for tissue transglutaminase. Thus, tissue transglutami nase appears to play an important role not only in cross-linking of th e papillary dermis but also of the dermo-epidermal junction in particu lar.