Evidence for a dissimilarity of chicken oviducts differentiated by diethylstilboestrol and oestradiol-17 beta: a study of progesterone-induced egg-white protein (avidin) synthesis

Tissue specific expression and estrogen regulation of SERPINB3 in the chicken oviduct

Serine protease inhibitors (SERPINs) comprise the largest superfamily of protease inhibitors and appear to be ubiquitously expressed in a variety of species. Of these, squamous cell carcinoma antigen 1 (SCCA1), also known as a SERPINB3, was first identified in squamous cell carcinoma tissue from the cervix of women. However, there is little known about the expression and hormonal regulation of SERPINB3 in chickens. Therefore, the avian SERPINB3 gene was compared with those of other species with respect to structure, phylogenetic evolution and tissue- and cell-specific expression in hens. Chicken SERPINB3 has moderate homology to mammalian SERPINB3 proteins (36-47%). Of particular note, SERPINB3 mRNA was most abundant in the chicken oviduct and cell-specific expression was in glandular (GE) and luminal (LE) epithelial cells of the oviduct of laying hens. Treatment of young chicks with DES (diethylstilbestrol, a synthetic nonsteroidal estrogen) induced SERPINB3 mRNA and protein in GE and LE, but not in other cell types of the oviduct. Western blot analyses determined that immunoreactive SERPINB3 protein was also increased by DES in LE and GE of the oviduct of chicks. Collectively, these results indicate that SERPINB3 is an estrogen-induced gene expressed only in LE and GE of the chicken oviduct and implicate SERPINB3 in regulation of oviduct development and egg formation.

Avian SERPINB11 gene: characteristics, tissue-specific expression, and regulation of expression by estrogen

Serpins, a group of proteins with similar structural and functional properties, were first identified based on their unique mechanism of action: their inhibition of proteases. While most serpins have inhibitory roles, certain serpins are not involved in canonical proteolytic cascades but perform diverse functions including storage of ovalbumin in egg white, transport of hormones (thyroxine- and cortisol-binding globulin), and suppression of tumors. Of these, serpin peptidase inhibitor, clade B, member 11 (SERPINB11) is not an inhibitor of known proteases in humans and mice, and its function is unknown. In the present study, the SERPINB11 gene was cloned, and its expression profile was analyzed in various tissues from chickens. The chicken SERPINB11 gene has an open reading frame of 1346 nucleotides that encode a protein of 388 amino acids that has moderate homology (38.8%-42.3%) to mammalian SERPINB11 proteins. Importantly, SERPINB11 mRNA is most abundant in the chicken oviduct, specifically luminal and glandular epithelia, but it was not detected in any other chicken tissues of either sex. We then determined effects of diethylstilbestrol (DES; a synthetic nonsteroidal estrogen) on SERPINB11 expression in the chicken oviduct. Treatment of young chicks with DES induced SERPINB11 mRNA and protein only in luminal and glandular epithelial cells of the oviduct. Collectively, these results indicate that the novel estrogen-induced SERPINB11 gene is expressed only in epithelial cells of the chicken oviduct and implicate SERPINB11 in regulation of oviduct development and differentiated functions.

Inducibility of the avidin gene by progesterone is suppressed during estrogen-induced cytodifferentiation

We have studied epithelial differentiation of the chick oviduct as induced by diethylstilbestrol (DES) and 17 beta-estradiol (E2). The proportion of goblet cells in the oviduct was slightly higher after E2 than after DES treatment. Also avidin induction by progesterone was stronger following DES than E2 priming. In the estrogen pretreated oviduct epithelium, avidin expression was induced by progesterone in the surface epithelial cells, protodifferentiated gland cells and tubular gland cells, but not in goblet cells. During prolonged estrogen treatment, however, the inducibility of avidin by progesterone ceased in tubular gland cells but not in surface epithelial cells. The estrogen action on the expression of avidin could be explained by estrogen-induced terminal differentiation of the epithelial gland cells or by a direct effect of estrogen on the progesterone action, for instance interaction of estrogen receptor and progesterone receptor in the regulation of transcription.

The effect of dihydrotestosterone on the estrogen-induced cytodifferentiation of the chick oviduct

The androgenic effects on the estrogen-induced cytodifferentiation of the chick oviduct epithelium were investigated. Dihydrotestosterone was shown to have an effect on the organization of stromal cells. Since these cells contained androgen receptor (AR), it is reasonable to assume an involvement of androgens in the differentiation and functioning of these cells through a direct action. Immunohistochemical analysis revealed a wide distribution of AR. AR was shown to be expressed in both the endothelial and smooth muscle cells of blood vessels. In the immature oviduct AR was located in the epithelial, mesenchymal and mesothelial cells. In the differentiating oviduct, whether induced by exogenous estrogen or normally by endogenous hormones, AR was also expressed by the tubular gland cells. Dihydrotestosterone alone had no effect on the morphology of the immature oviduct, suggesting the involvement of the determinants of differentiation in the action of androgen together with estrogen.

Chick oviduct differentiation. The effect of estrogen and progesterone on the expression of progesterone receptor

Progesterone receptor (PR) is a marker of estrogen action. Its cellular appearance during estrogen (20 mg/kg i.m.)-induced differentiation of the immature chick oviduct was therefore studied by immunohistochemistry. PR was located in the epithelial, mesothelial, submucosal stromal and smooth muscle cells. Progesterone (20 mg/kg i.m.) caused an obvious decrease in PR immunoreactivity without inducing synthesis of progesterone-dependent avidin. Thus mere receptor occupation by ligand is not sufficient for this induction. This paper reports that the expression of PR in the mucosal stromal cell differs from that in other cell types. In the mucosal stromal cell PR was inducible, i.e., not shown without the action of estrogen. The formation of tubular glands did not commence before mucosal stromal cells expressed PR. It would seem that the mucosal stromal cells have a crucial role in mediating epithelial differentiation. The onset of differentiation was preceded by vascularization and invasion of mononuclear cells in the submucosa. It was conspicuous that the smooth muscle cells of arteries also contained PR.