Keratinocyte Transglutaminase Promoter Analysis (original) (raw)
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The Journal of Cell Biology, 1978
When serially cultivated human epidermal keratinocytes are placed in suspension culture they stop growing and form, beneath the plasma membrane, an insoluble envelope consisting of protein cross-linked by ~-(y-glutamyl)lysine. The formation of envelopes in suspended cells is preceded by a sharp decline in the rate of protein synthesis, and most envelopes appear only after the average rate of protein synthesis has fallen to a very low level. If protein synthesis is reduced over 98% with cycloheximide or emetine at the time that surface-grown cells are placed in suspension culture, cross-linked envelopes form in most of the cells. This shows that the precursor of the envelope and the cross-linking enzyme are already in the cytoplasm in most cells of growing surface cultures. The process of envelope formation by suspension cultures is actually accelerated by the inhibitors of protein synthesis; an increased number of cells with cross-linked envelopes is observable within 4-6 h after the addition of cycloheximide. The inhibitor also induces a large fraction of the cells of surface cultures to form envelopes within a few days.
Induction of keratinocyte type-I transglutaminase in epithelial cells of the rat
Differentiation, 1986
Using immunogold-silver techniques, we have demonstrated that, in rats, type-I (keratinocyte) transglutaminase is expressed primarily in stratified squamous epithelia of the integument. the upper digestive tract, and the lower female genital tract. In these epithelia, the enzyme was found to be present predominantly in the granular layer, but was evident at low levcls even in the basal layer, especially in the genital tract. N o immunoreactivity was detected in glandular, columnar, or transitional epithelia or in soft tissues. However, considerable enzyme antigenicity was observed in the endometrium and in major ducts of the pancreas and mammary glands of near-term pregnant and early postpartum females. In cultures, substantial immunoreactivity was readily identifiable not only in epidermal, vaginal, and esophageal epithelial cells (immunopositive in vivo), but also in urinary bladder, seminal vesicle, and tracheal epithelial cells (immunonegative in vivo). Primary epithelial outgrowths from bladder and seminal vesicle tissue explants were immunopositive, demonstrating rapid adaptation to the culture environment. These results reveal three distinct levels of regulation of transglutaminase exprcssion in various cell types: (1) during the differentiation of keratinocytes, (2) during pregnancy, being evident principally in the endometrium but detectable elsewhere as well, and (3) during the cultivation of certain epithelia which do not normally express the cnzyme in vivo. We conclude that type-I transglutaminase may be a valuable marker for elucidating the regulation of normal epithelial differentiation and squamous metaplasia.
Organization and evolution of the human epidermal keratinocyte transglutaminase I gene
Proceedings of the National Academy of Sciences, 1992
Transglutaminases (TGases; protein-glutamine:amine 'glutamyltransferase, EC 2.3.2.13) are calcium-dependent crosslinking enzymes that modify proteins posttranslationally. Several distinct types of TGases have been identified, which appear to be encoded by a family of closely related genes. We isolated the gene encoding human keratinocyte-specific type I TGase (TGase I) and characterized its chromosomal organization. The TGase I gene consists of 15 exons separated by 14 introns and exhibits a restriction fragment length polymorphism. Exons appear to encode functional and/or structural domains: exon I and part of exon XV encode untranslated regions, whereas exons VII and XI contain the active site and a presumptive calcium-binding domain, respectively. Interestingly, exon VI of TGase I contains a consensus Arg-Gly-Asp tripeptide sequence whose presence suggests an intriguing extracellular function for the enzyme. We present a likely phylogenetic tree for seven known members of the TGase family based on amino acid sequence similarity. Arguments presented suggest that the active enzyme evolved first and the structural human erythrocyte membrane protein 4.2 (band 4.2) has undergone a rapid change in amino acid sequence. It follows that band 4.2 evolved from the type II TGases, whereas factor xm subunit a evolved from the type I group.
Primary structure of keratinocyte transglutaminase
Proceedings of the National Academy of Sciences, 1990
The nucleotide and deduced amino acid sequences of the coding regions of human and rat keratinocyte transglutaminases (protein-glutamine: amine y-glutamyltransferase; EC 2.3.2.13) have been determined. These yield proteins of -90 kDa that are 92% identical, indicative of the conservation of important structural features. Alignments of amino acid sequences show substantial similarity among the keratinocyte transglutaminase, human clotting factor XIII catalytic subunit, guinea pig liver tissue transglutaminase, and the human erythrocyte band-4.2 protein. The keratinocyte enzyme is most similar to factor XIII, whereas the band-4.2 protein is most similar to the tissue transglutaminase. A salient feature of the keratinocyte transglutaminase is its 105-residue extension beyond the N terminus of the tissue transglutaminase. This extension and the unrelated activation peptide of factor XIII (a 37-residue extension) appear to be added for specialized functions after divergence of the tissue transglutaminase from their common lineage.
Journal of Dermatological Science, 2003
Epidermal-type transglutaminase (TGase 3) is involved in the cross-linking of structural proteins in the epidermis, which results in the formation of the cornified envelope. TGase 3 is activated by limited proteolysis of a 77 kDa zymogen during keratinocyte differentiation. To characterize the expression of TGase 3 in human epidermis and cultured keratinocytes, we established specific monoclonal antibodies against the TGase 3. Recombinant proteins for human TGase 3 produced in bacteria and baculovirus-infected insect cells were purified as an antigen. Hybridomas are established and used for characterization of expression in epidermis and keratinocytes. Four antibodies were generated against recombinant human TGase 3, which reacted with the 77 kDa zymogen and in some cases either the 47 or 30 kDa active proteolytic fragments. In human epidermis and cultured keratinocytes, only the zymogen form of TGase 3 was detected. Immunohistochemical analysis of the skin revealed that the enzyme is present in the cells of the granular and cornified layers consistent with its role in cornified envelope formation. In cultured keratinocytes, TGase 3 was expressed in differentiating cells coincident with profilaggrin and keratin 10 expressions. Using monoclonal antibody against human TGase 3, we showed the expression of TGase 3 in upper layers of epidermis. TGase 3 displayed a diffuse cytoplasmic distribution in vitro consistent with its proposed role in the early phase of cornified cell envelope assembly in the cytoplasm.
The nucleotide and deduced amino acid sequences of the coding regions of human and rat keratinocyte transglutaminases (protein-glutamine: amine y-glutamyltrans-ferase; EC 2.3.2.13) have been determined. These yield proteins of-90 kDa that are 92% identical, indicative of the conservation of important structural features. Alignments of amino acid sequences show substantial similarity among the keratinocyte transglutaminase, human clotting factor XIII catalytic subunit, guinea pig liver tissue transglutaminase, and the human erythrocyte band-4.2 protein. The keratinocyte enzyme is most similar to factor XIII, whereas the band-4.2 protein is most similar to the tissue transglutaminase. A salient feature of the keratinocyte transglutaminase is its 105-residue extension beyond the N terminus of the tissue transglutami-nase. This extension and the unrelated activation peptide of factor XIII (a 37-residue extension) appear to be added for specialized functions after divergence of the tissue transglu-taminase from their common lineage.
Transglutaminase Function in Epidermis
Journal of Investigative Dermatology, 2005
Surface epithelial cells, such as the epidermal keratinocyte, undergo a process of terminal cell differentiation that results in the construction of a multilayered epithelium. This epithelium functions to protect the organism from the environment. Transglutaminases, enzymes that catalyze the formation of isopeptide protein-protein cross-links, are key enzymes involved in the construction of this structure. This brief review will focus on the role of these enzymes in constructing the epidermal surface.