involucrin and Vitamin-A-Deficiency

To determine the role played by keratinocyte transglutaminase (TG1, TG(K)) in the abnormal keratinization of the cornea.. Vitamin A-deficient rats were produced as a model of severe dry eyes, and the expression of the mRNA and the enzyme activity of TG1 were examined in the corneas. The envelope proteins and keratins of cornified cells were also examined immunohistochemically.. The expression and enzyme activity of TG1 mRNA on the ocular surface were significantly upregulated as the vitamin A deficiency developed. As the TG1 expression was upregulated, involucrin, loricrin, and keratin 10 began to be expressed on the epithelial cells of the cornea.. Upregulation of TG1 expression followed by the appearance of the envelope proteins and keratin10 in cornified cells indicated that TG1 is involved in the abnormal keratinization of the cornea.

Topics: Animals; Blotting, Northern; Cornea; Disease Models, Animal; Dry Eye Syndromes; Epithelial Cells; Gene Expression Regulation, Enzymologic; Immunoenzyme Techniques; Keratin-10; Keratins; Membrane Proteins; Protein Precursors; Rats; Rats, Sprague-Dawley; Retinaldehyde; RNA, Messenger; Transglutaminases; Up-Regulation; Vitamin A; Vitamin A Deficiency

The expression of cornifin, a putative cross-linked envelope precursor, was investigated in several squamous differentiating tissues by in situ hybridization and immunohistochemical analysis. Cornifin mRNA and protein, which are absent in the normal mucociliary tracheal epithelium, are induced in the suprabasal layers of the squamous metaplastic tracheal epithelium of vitamin A-deficient hamsters. Similar to the induction of squamous metaplasia in vivo, culture of rabbit tracheal cells in the absence of retinoids results in squamous differentiation and expression of cornifin. This induction of cornifin expression is suppressed by retinoic acid and several of its analogs. Cornifin mRNA and protein are also detected in the suprabasal layers of the squamous epithelium of rabbit esophagus and tongue. The distribution of cornifin in human epidermis was compared with that of two other crosslinked envelope precursor proteins, involucrin and loricrin. The localization of cornifin and involucrin is very similar. Both are induced in the spinous layer and appear at an earlier stage during epidermal differentiation than loricrin. The expression of cornifin is greatly increased in psoriatic skin. Cornifin mRNA is barely detectable in normal epidermis, whereas it is present at relatively high levels in the suprabasal layers of psoriatic epidermis. Topical treatment with RA results in thickening of the skin and increases the level of cornifin mRNA and protein in the upper spinous layers of mouse skin. Cornifin expression correlates generally with squamous differentiation in a variety of tissues and is abnormally regulated in psoriatic skin and in skin treated topically with retinoic acid.

Topics: Administration, Topical; Animals; Cells, Cultured; Cornified Envelope Proline-Rich Proteins; Cricetinae; Esophagus; Gene Expression; Humans; Male; Membrane Proteins; Mice; Protein Precursors; Psoriasis; Rabbits; RNA, Messenger; Skin; Trachea; Tracheal Neoplasms; Tretinoin; Vitamin A Deficiency