title: Estradiol-regulated transamidation of keratins by vaginal epithelial cell transglutaminase.
abstract: We have observed a marked increase in the activity of transglutaminase (EC 2.3.2.13) in rat vaginal epithelial cells in a time-dependent manner during estradiol-induced terminal differentiation. The increased transglutaminase activity facilitates a post-translational modification, transamidation of keratins by the formation of an isopeptide sigma (tau-glutamyl) lysine. This isopeptide was recovered from the urea-soluble and -insoluble fractions of keratins. The formation of sigma (tau-glutamyl) lysine was significantly reduced in rats primed with progesterone or tamoxifen-estradiol. These in vivo experiments were further confirmed by in vitro studies using the reconstituted keratin filaments, which demonstrated a remarkable acceleration in the formation of covalent cross-links mediated by vaginal epithelial cell transglutaminase obtained from rats primed with estradiol. By specifically modifying the lysine residues of the keratins with 2,4-pentanedione the aggregation of keratin filaments was inhibited. These findings reflect that the vaginal epithelial cell transglutaminase obtained from rats which is regulated by estradiol plays a key role in the process of terminal differentiation of rat vaginal epithelial cells.
authors.affiliation: Centre for Cellular & Molecular Biology, Hyderabad, India.
authors.forename: V
authors.initials: V
authors.lastname: Vijayalakshmi
authors.forename: P D
authors.initials: PD
authors.lastname: Gupta
mesh_terms: D000577:Amides / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D006868:Hydrolysis; D007633:Keratins / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D051381:Rats; D017208:Rats, Wistar; D012995:Solubility; D011503:Transglutaminases / Q000378:metabolism*; D014621:Vagina / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*
chemical_list: D000577:Amides; D005971:Glutamates; D018698:Glutamic Acid; D004958:Estradiol; D007633:Keratins; D011503:Transglutaminases; D008239:Lysine; D002118:Calcium