ROLE OF TRANSGLUTAMINASE IN KERATINIZATION OF VAGINAL EPITHELIAL-CELLS IN ESTROUS CYCLING RATS

Aspects of the regulation of calcium dependent transglutaminase (TGase ) enzyme in the terminally differentiating vaginal epithelial cells (V EC) from cycling and oestradiol primed ovariectomized (OVX) rats are d escribed. There is a significant increase in the TGase activity and a quantitative rise. in its cross-linked Sigma(tau-glutamyl)lysine coval ent product in the VEC of oestrus rats. A similar phenomena was also e vident in the oestradiol primed OVX rats. However, in the VEC of the d iestrus/unprimed OVX rats, the enzyme activity and its cross-linked pr oduct tend to be at its basal level. An increase of TGase activity in the keratinized layers of the oestrus VEC was observed. Immunohistoche mical localization data parallel the biochemical measurements. These f indings suggest that TGase activity may be associated with the differe ntial status of the cell and primarily aids in the conferring structur al stability and integrity to the stratified VEC. Aggregates of the ke ratin tonofilament bundles which are covalently cross-linked by the fo rmation of Sigma(tau-glutamyl)lysine in the oestrus vagina renders the m resistant to denaturant and proteolytic treatments.