• P D Gupta

      Articles written in Journal of Biosciences

    • Effect of steroid hormones on vaginal epithelial cells: Anin vitro model for steroid hormone action

      S Vijayasaradhi A Khar P D Gupta

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      Conditions have been standardized to maintain rat vaginal epithelial cellsin vitro with more than 95% viability. Cultured epithelial cells were used to study the effects of normal fetal calf scrum, estradiol and progesterone on the incorporation of [3H]-uridine in RNA and incorporation of [14C]-aminoacids in proteins. While fetal calf serum and estradiol stimulate the incorporation of both uridine and afno acids, progesterone did not show any effect. Estradiol treated vaginal cells show typical fcroridges (indicative of keratinization of cells) in contrast to estradiol deprived cells, which show microvilli on cell surface when examined in scanning electron microscope.

    • Keratinization of rat vaginal epithelium. II. Immunofluorescence study on keratin filaments in cycling and estrogen primed rats

      S Vijayasaradhi P D Gupta

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      Rat vaginal epithelial layers from animals in different phases of the estrous cycle showed positive immunofluorescence when treated with either monoclonal antibody to intermediate filaments or immunoglobulin G fraction of antiserum raised against epidermal keratin filaments. During estrus, the intensity of fluorescence observed was maximum in the keratinized cellular layers. In estradiol-primed immature and ovariectomized rats the maximum fluorescence intensity was observed in the layers immediately lining the lumen. However, basal layers in ovariectomized rats also showed some fluorescence. Data presented in this communication indicate that the abundance of keratin filaments in vaginal epithelial cells can be modulated by altering the level of estradiol in the system.

    • Keratinization of rat vaginal epithelium IV. Modulation of transglutaminase activity by oestradiol

      S Vijayasaradhi P D Gupta

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      Calcium-dependent transglutaminase activity was found to be present in vaginal homogenates from adult cycling rats. Treatment of immature or adult ovariectomized rats with oestradiol (0.1 μg/g body weight) resulted in 1.5–2-fold enhancement in the enzyme activity. Progesterone treatment (0.1 μg/g body weight) decreased the enzyme activity. Analysis of amino acids produced by proteolytic enzyme digestion of insoluble keratins from rat vaginal tissue indicated the presence of γ-glutamyl-ε-⥿sine dipeptide (4 μmol/g protein) in this protein. These results suggest that oestradiol acts on vaginal tissue and induces the activity of transglutaminase. This enzyme catalyses the formation of γ-glutamyl-ε-lysine crosslinks between keratin polypeptides and thus leads to kerartization of the tissue.

    • Oestradiol regulated keratin gene expression in rat vaginal epithelial cells

      K Sridhar Rao A G Reddy P D Gupta

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      Oestradiol acts both as a mitogen and as an inducer of differentiation of target cells. The cellular responses to oestradiol are generally mediated through the regulation of gene expression, although nongenomic modes of action are also documented. The present observations show that the regulation of keratin gene expression in rat vaginal epithelial cells is under the influence of oestradiol. It is observed that oestradiol regulates both the qualitative and quantitative expressions of keratin polypeptides in a time dependent and sequence specific manner. These regulatory effects are the result of modulations in transcriptional, post-transcriptional and translational processes of these genes, brought about by the hormone in vaginal epithelial cells.

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