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At least 19 recordsLinked to original sources
PubMed1979

Hormonal control of uteroglobin secretion in rabbit uterus: inhibition of uteroglobin synthesis and messenger ribonucleic acid accumulation by oestrogen and anti-oestrogen administration.

Investigations were conducted to quantify activity of uteroglobin mRNA and secretion of uteroglobin in rabbit uterus after administration of progesterone and 5alpha-dihydrotestosterone, either alone or concomitantly with oestradiol-17beta and tamoxifen, a non-steroidal anti-oestrogen. Poly(A)-containing mRNA was isolated from the uterine tissue by extraction with phenol/chloroform, precipitation with ethanol and chromatography on oligo(dT)-cellulose. Cell-free translation in vitro of the poly(A)-containing mRNA was carried out in a wheat-germ lysate, and the product isolated by specific immuno-precipitation with anti-uteroglobin antiserum purified by affinity chromatography. Radioimmunoassay was utilized to determine uteroglobin content in the uterine flushings and tissue preparations. When given for 5 days, both progesterone (1mg/kg per day) and 5alpha-dihydrotestosterone (25mg/kg per day) elicited a marked induction of uteroglobin secretion, which was accompanied with accumulation of uteroglobin mRNA in the tissue. Concomitant administration of oestradiol-17beta (50mug/kg per day) or tamoxifen (12.5mg/kg per day) significantly decreased both progesterone- and 5alpha-dihydrotestosterone-induced uteroglobin secretion, with a parallel decrease in the uteroglobin-mRNA activity. The decline in the uteroglobin content of the uterine flushes brought about by oestradiol-17beta or tamoxifen administration was not due to inhibition of secretion of this protein by the endometrial cells, since a simultaneous decrease occurred in the tissue uteroglobin content. After a 5-day pretreatment with progesterone (1mg/kg per day), administration of oestradiol-17beta (50mug/kg per day) during the ensuing 4 days greatly accelerated the decay of the uteroglobin content in the uterine fluid.

Animals↗
PubMed1991

Cell-specific, developmentally and hormonally regulated expression of the rabbit uteroglobin transgene and the endogenous mouse uteroglobin gene in transgenic mice.

We have generated a transgenic mouse line by introducing the rabbit uteroglobin gene with 4 kb of 5'-flanking DNA and 1 kb of 3'-flanking DNA into the mouse germ line via microinjection into fertilized oocytes. Expression of the rabbit uteroglobin transgene was examined and compared with the endogenous mouse uteroglobin gene. Both genes are expressed in the lung, male genital tract and uterus. In the lung, mRNA expression is enhanced by glucocorticoids and restricted to the Clara cells that line terminal and respiratory bronchioli. During embryonic lung development, transcripts are first detected at day 17. Expression in the uterus is restricted to the glandular epithelium and can be induced by sequential treatment with estrogens and progesterone. In the uterus of these pseudopregnant mice the level of rabbit uteroglobin transcripts is higher than that of the mouse endogenous uteroglobin transcripts. In the male genital tract, expression of both genes is restricted to the epithelial layers of the vesicular gland, vas deferens and epididymis. Our results indicate that the rabbit uteroglobin gene together with 4 kb of 5'-flanking DNA and 1 kb of 3'-flanking DNA contains the information required for cell type-specific, developmentally, and hormonally regulated expression.

Animals↗
PubMed1989

Preliminary assignments of the aromatic and some methyl group resonances of the 1H-NMR spectrum of the oxidized form of uteroglobin. Application to the interaction of oxidized uteroglobin with progesterone.

Two-dimensional NMR methods have been used to assign aromatic and methyl group resonances in the 1H-NMR spectrum of oxidized uteroglobin. Assignments to specific amino acids are based on X-ray-determined structures of two crystal forms (C222(1) and P2(1] and on an energy-minimized X-ray structure of the C222(1) form of uteroglobin. These preliminary assignments are sufficient to probe the interaction of oxidized uteroglobin with progesterone in solution. The protein global structure is unmodified but some direct or indirect conformational changes are induced in the H1H4(H1'H4') pockets and close to Phe28 by progesterone.

Binding Sites↗
PubMed1987

Uteroglobin production in the pseudopregnant rabbit uterus. Immunohistochemical studies.

Uteroglobin, a secretory protein of rabbit uterine epithelium, was localized by the direct immunoperoxidase method in control and hCG-induced pseudopregnant rabbits. In control rabbits, uteroglobin was confined to the apical cytoplasm of nearly all cells of the endometrial epithelium. The induction of pseudopregnancy resulted in a pronounced continuing increase, through 4 days post-hCG administration, in the absolute number of epithelial cells engaged in uteroglobin synthesis. Furthermore, the endoplasmic reticulum was more intensely stained for uteroglobin than in the epithelial cells of control rabbit endometrium. Thus, the increased production of uteroglobin, in response to hormonal stimulation, appears to be achieved both through an increase in the amount of uteroglobin synthesized by a given cell as well as by an increase in the number of cells involved in uteroglobin synthesis. Concurrent with the increase in the number of cells synthesizing uteroglobin, an increase in the number of unstained cells first appeared at the second day of pseudopregnancy, during the period of maximal epithelial proliferation. However, within those cells containing uteroglobin on the second day following injection with hCG, most staining was limited to the perinuclear membrane. At various times following hCG administration, a number of scattered cells, intensely stained for uteroglobin, were observed in the uterine epithelium. Based upon ultrastructural studies, failure to exclude trypan blue, and the presence of intra-mitochondrial uteroglobin, they were identified as either dead or dying cells.

Animals↗
PubMed1978

Uterine and lung uteroglobins in the rabbit. Two similar proteins with differential hormonal regulation.

Previous studies have shown that several rabbit tissues contain proteins which cross-react in the radioimmunoassay for uteroglobin, a progestin-regulated protein in rabbit uterus (Torkkeli et al. (1977) Mol. Cell. Endocrinol. 9, 101-118). In the present study, a uteroglobin-like protein was purified to an apparent homogeneity from an extra-uterine tissue, rabbit lung, by successive chromatographies on hydroxyapatite, Sephadex G-75, SP-Sephadex, DEAE-cellulose and CM-cellulose. The final preparation behaved homogeneously in various polyacrylamide gel electrophoretic systems and in isoelectric focusing. The uteroglobin-like protein isolated from the lung had very similar physicochemical and immunological properties to those of uteroglobin present in the rabbit uterine fluid. The two proteins had: (i) the same molecular weight, of approx. 13 000, with a two subunit structure (each approx. Mr 7000); (ii) identical behavior in polyacrylamide gel electrophoresis under non-denaturing and denaturing conditions; (iii) the same isoelectric point at pH 5.4; (iv) absence of carbohydrate in the molecule; (v) very similar amino acid compositions; (vi) lack of tryptophan among the amino acids; (vii) the same N-terminal amino acid (glycine), and (viii) indistinguishable immunological characteristics. Collectively, these data strongly suggest that uterine and lung uteroglobins are identical proteins. In contrast to the induction of the uterine uteroglobin by steroids with progestational activity, the synthesis of extra-uterine uteroglobins was no affected by these steroid hormones to any major extent. In keeping with the concept that lung is a target tissue for glucocorticoid action, cortisol and dexamethasone were capable of increasing the concentration of lung uteroglobin 3-fold (from 3 to 9 microgram/mg soluble protein). These compounds did not, however, alter the secretion of the uterine protein. Administration of high doses of testosterone and 5alpha-dihydrotestosterone elevated significantly the content of both uterine and lung uteroglobin. Only approx. one-fifth of the adult pulmonary uteroglobin levels were present in lungs of newborn rabbits indicating that developmental changes occur in the lung uteroglobin content.

Adrenal Cortex Hormones↗
PubMed1976

Factors in diminution of uteroglobin secretion in the rabbit.

Uteroglobin was measured under various hormonal conditions: pregnancy, pseudopregnancy, pseudopregnancy with exogenous progesterone, pseudopregnancy with exogenous 20alpha-hydroxyprogesterone, ovariectomy with exogenous progesterone, ovariectomy with exogenous estrogen, ovariectomy with exogenous estrogen and progesterone, and ovariectomy with either exogenous progesterone or estrogen and progesterone, plus uterine trauma. In pregnant females, uteroglobin levels diminished sharply after day 9. In pseudopregnancy, high concentrations were maintained through day 14. Although exogenous progesterone did not prevent this decrease in pseudopregnant females, re-elevation occurred in the continued presence of progesterone. A similar pattern of decline and re-elevation was found in ovariectomized females that received injections of estrogen and progesterone. With an increase in estrogen dosage, the period of uteroglobin secretion was shorter and the magnitude lower. Ovariectomized females receiving only progesterone did not manifest a clear uteroglobin diminution. Uterine trauma on day 7 of exogenous steroid administration to ovariectomized females was followed by a diminution in uteroglobin. At the dosage level used, administration of 20alpha-hydroxyprogesterone did not affect the peak uteroglobin secretion occurring on day 5 of pseudopregnancy. Ovariectomized females receiving estrogen or sesame oil vehicle had barely detectable levels of uteroglobin. A uteroglobin-estrogen complex is suggested as a possible inhibitor of uteroglobin synthesis by a feedback inhibition pathway in pseudopregnant females and in ovariectomized females treated with progesterone plus estrogen. In pregnant females, a uteroglobin-estrogen complex and/or the uterine decidual response to implantation could control uteroglobin synthesis.

20-alpha-Dihydroprogesterone↗
PubMed1991

Effect of in vitro culture on the dynamics of uteroglobin distribution in rabbit blastocysts.

The purpose of this study was to investigate the localization and transport of uteroglobin in normal rabbit blastocysts (day 4-day 6 p.c.) and in those cultured for 6-48 h in vitro, using a specific radioimmunoassay and immunocytochemistry. The results of the radioimmunoassay showed that in day 4 p.c. blastocyst tissue (based on homogenate measurements) a significant decrease of the uteroglobin content started after only 6 h of culture in vitro. A significant concomitant rise of uteroglobin was observed in the culture medium after 12 h of in vitro culture. Using immunocytochemistry it was not possible to detect uteroglobin in any compartment of the non-cultured or in vitro cultured day 4 p.c. blastocysts. The efflux of uteroglobin down a concentration gradient was confirmed by the immunocytochemistry in non-cultured and in vitro cultured day 5 p.c. and day 6 p.c. blastocysts. Uteroglobin immunoreactions were mainly detected in non-cultured blastocysts (day 5 and 6 p.c.) in large vesicles of the trophoblast cells. In addition endocytotic vesicles at the inside of the apical membrane of trophoblast cells, some cell debris within the perivitelline space and the neozona were labelled. During in vitro culture of day 5 and 6 p.c. blastocysts, uteroglobin labelling in the coverings did not change. In non-cultured and cultured day 5 and 6 p.c. blastocysts neither the compartments of the embryoblast, the endoderm cells nor the blastocyst cavity showed any uteroglobin immunoreactions. After only 6 h of in vitro culture, uteroglobin immunoreactions were no longer found within the trophoblast cells. The reaction did not reappear during the course of in vitro culture up to 48 h, suggesting a complete lack of de novo synthesis of uteroglobin by blastocysts.

Animals↗
PubMed1976

Translation of the mRNA for rabbit uteroglobin in cell-free systems. Evidence for a precursor protein.

Uteroglobin, an hormonally induced protein composed of two similar subunits, represents around 50% of the proteins synthesized and secreted into the uterine lumen of rabbits treated sequentially with estradiol and progesterone. The endometrium of these animals was used as a source for the isolation of the mRNA for uteroglobin. Poly(A)-rich RNA, extracted from purified polysomes with phenol chloroform and isolated on oligo(dT)-cellulose columns, contains one fourth of the total protein coding activity of the endometrium. Between 20--25% of the polypeptides synthesized by this RNA in cell-free systems derived from Krebs II ascites cells or wheat germs react with a monospecific antiserum prepared in guinea pigs against uteroglobin. The material bound to the antibody was identified as a precursor of uteroglobin according to the following criteria. 1. The product synthesized in vitro can be displaced from the complex with the specific immunoglobulin by purified uteroglobin. 2. Analysis of the immunoprecipitate on polyacrylamide gels containing urea and dodecylsulfate demonstrate the existence of a single labelled polypeptide with an apparent molecular weight larger than the uteroglobin subunits. 3. The tryptic digest of this polypeptide, labelled in vitro with [3H]lysine, shares seven peptides with mature uteroglobin labelled with the same amino acid in perfused uteri, and exhibits and additional peptide not present in uteroglobin. 4. Injection of the same mRNA preparation into Xenopus oocytes results in the production of uteroglobin. The endometrium of intact animals treated with estradiol alone also contains the same mRNA bound to polysomes but in a smaller proportion, indicating that the progesterone-induced synthesis of uteroglobin is accompanied by an accumulation of the specific mRNA in the polysomes.

Animals↗
PubMed1987

Estradiol-17 beta and progesterone regulate secretion of uteroglobin through different pathways.

Uteroglobin, the primary secretory protein of rabbit uterine epithelium, was localized by the direct immunoperoxidase method in uteri of control ovariectomized rabbits and of ovariectomized rabbits injected with progesterone or estradiol-17 beta. In control rabbits, staining for uteroglobin was almost entirely abolished six weeks after bilateral ovariectomy. Two days following progesterone injection of ovariectomized rabbits, intense staining for uteroglobin could be detected within the endoplasmic reticulum, Golgi complexes, and compact secretory vesicles of most endometrial epithelial cells. Estradiol-17 beta injection resulted in a different intracellular pattern of uteroglobin distribution. Two days following treatment with that steroid hormone, intense staining for uteroglobin was localized within large apical mucous droplets and moderate staining was present in the endoplasmic reticulum and Golgi complexes of these cells. The increased mucin content of the endometrial epithelium following treatment with estradiol-17 beta was confirmed by a periodic acid-Schiff histochemical reaction in the presence of diastase. Quantitation by radioimmunoassay of uteroglobin production in vitro by uterine fragment confirmed that progesterone had a greater effect on enhancing uteroglobin production than estradiol-17 beta and that both steroid hormones did not have any effect after 30 min of incubation in vitro. We suggest that progesterone not only regulates uteroglobin production at the transcriptional level, but that it also regulates the mode of uteroglobin secretion by the induction of a different pathway, compared with the one used when estradiol-17 beta is administered alone.

Animals↗
PubMed1979

Synthesis and characterization of a DNA complementary to pre-uteroglobin mRNA.

Uteroglobin, a progesterone-induced uterine protein of the rabbit, is synthesized in cell-free systems as a precursor containing 21 additional amino-acids at its N-terminal end. The mRNA for pre-uteroglobin has been purified from the membrane-bound polysomes of induced endometrium and used as template for the synthesis of a full copy complementary DNA. Final purification of the cDNA was based on hybridization to the template mRNA up to a low value of r0t (0.01 M . s) and digestion of the non-hybridized cDNA by S1 nuclease. A comparison of the hybridization kinetics of the pre-uteroglobin cDNA and rabbit globin cDNA to their respective templates indicates a nucleotide sequence complexity of 650 for pre-uteroglobin mRNA, in agreement with the values obtained by sucrose gradient centrifugation and polyacrylamide gel electrophoresis in formamaide. The melting temperature of the hybrids of pre-uteroglobin cDNA to its template reflects the absence of mismatched sequences. This cDNA has been used to quantify pre-uteroglobin mRNA sequences in the endometrial RNA from control animals and from animals treated sequentially with estradiol and progesterone. In agreement with the induction of uteroglobin-synthesizing activity, there is a dramatic increase in the uterine content of pre-uteroglobin mRNA after hormonal treatment. Part of this effect can be accounted for by hormonally induced cell proliferation. When expressed on a DNA basis there is a 50--100-fold increase in the cellular content of pre-uteroglobin mRNA following hormonal treatment.

Animals↗
PubMed1985

Immunocytochemical localization of uteroglobin in the rabbit endometrium.

Uteroglobin, the progesterone dependent pregnancy-characteristic endometrial protein in the rabbit, is found within the endometrial epithelium on the fourth and sixth day of pregnancy at the electron-microscopic level by use of the immunoperoxidase technique and a specific anti-uteroglobin serum from the sheep. As known from earlier studies, uteroglobin is the predominant protein synthesized of the endometrial secretion. In the present study, it is localized exclusively in the non-ciliated epithelial cells. A common route of secretory proteins within these cells is observed by uteroglobin labelling: rough endoplasmatic reticulum----Golgi complex----condensing vesicles----secretory products. Uteroglobin occurs in small vesicles on the trans-face of the Golgi complex, and in addition beneath the apical plasma membrane where it appears in membrane-bound vesicles, which apparently are extruded into the uterine lumen. Most of the uteroglobin is located in the luminal secretion. The distribution of intracellular uteroglobin is found only in cells of the basal endometrial gland, adjacent to the myometrium. The cytoplasm of uterine epithelial cells facing the cavum does not show uteroglobin reaction products.

Animals↗
PubMed1990

Variable expression of the uteroglobin gene following the administration of norethisterone and its A-ring reduced metabolites.

Enzyme-mediated A-ring reduction of norethisterone (NET) results in the transformation of a molecule with potent intrinsic progestational activity into neutral derivatives with estrogen-like effects. To ascertain whether these structural modifications of NET are able to modify the uteroglobin (U) gene (G) expression, a series of experiments assessing the UG products after the administration of NET and its reduced A-ring metabolites were conducted in prepubertal female rabbits. Synthesis of endometrial uteroglobin and its specific mRNA were studied in animals following the administration of NET, 5 alpha-dihydro NET,3 beta,5 alpha-tetrahydro NET and progesterone. Animals treated with either estradiol or vehicle alone served as controls. The uteroglobin content in uterine flushings and cytosols was determined by immunodiffusion and polyacrilamide gel electrophoresis techniques and by a specific double-antibody radioimmunoassay, while the U mRNA synthesis was assessed by its molecular hybridization to [alpha 32P]d-ATP uteroglobin cDNA. NET induced a significant increase of the uterine content of uteroglobin similar to that observed with progesterone with a simultaneous increase on U mRNA synthesis. On the contrary, 5 alpha-NET and 3 beta,5 alpha-NET induced very little, if any uteroglobin synthesis with a concomitantly low U mRNA production as compared with NET; thus exhibiting a similar effect to that observed in estradiol-treated animals. The overall results were interpreted as demonstrating that the enzyme mediated structural changes of NET which occur at the target organs induce variable expression of the uteroglobin gene. The data indicate that the rabbit uteroglobin gene products are suitable molecular markers to evaluate the hormonal potency of contraceptive synthetic progestins and their derivatives.

Animals↗
PubMed1990

Clara cell 10 kDa protein (CC10): comparison of structure and function to uteroglobin.

The cellular localization, functional activities and structures of rat and human Clara cell 10 kDa proteins (CC10) are compared to rabbit uteroglobin. CC10 is present exclusively in the non-ciliated cells of the surface epithelium of the pulmonary airways, whereas uteroglobin is reported to be present in the lung and reproductive organs. There is about 55% identity between the amino acid sequences of rat CC10 and either rabbit uteroglobin or human CC10. The latter two have 61% identity. Using the known structure of uteroglobin as the model, correlations between the structure and function for this group of proteins are made. Substitution of the residues for the rat and human CC10 into the structure of uteroglobin suggests that these proteins may be members of a structurally homologous family. Some of the functional differences may be due to distortion of the hydrophobic pocket in the dimeric protein and a surface hypervariability located on one contiguous helix and beta turn. Rat CC10 and rabbit uteroglobin both, nearly equally, inhibit papain and bind progesterone. Human CC10 does not inhibit papain and has markedly lower progesterone binding (4.6% of rabbit uteroglobin). Antiinflammatory activity of synthetic peptides corresponding to a homologous sequence region of uteroglobin and the two Clara cell proteins was tested. The region chosen has sequence similarity to lipocortin I. The peptides not only failed to inhibit carrageenan-induced foot pad swelling but exacerbated it. All three proteins inhibit pancreatic phospholipase A2. The phospholipase A2 inhibitory effect of CC10 may be important in regulating the inflammatory responses in the lung.

Amino Acid Sequence↗
PubMed1979

Progesterone-induced secretory protein. NH2-Terminal sequence of pre-uteroglobin.

Uteroglobin is a protein secreted by the rabbit uterus in response to progesterone. In cell-free translation systems, the mRNA for uteroglobin codes for a protein larger in size than the secreted protein. To investigate the relationship between these two forms, the NH2-terminal sequences of pre-uteroglobin and of uteroglobin have been determined. Uteroglobin was purified from rabbit uterine flushings and pre-uteroglobin was obtained by immunoprecipitation of the products of translation of poly(A)-rich endometrial RNA in the wheat germ system in the presence of single or multiple radioactive amino acids. Sequencing was performed by automated Edman degradation and the residue at each cycle was identified by chromatography. The larger size of pre-uteroglobin is accounted for by a 21-amino-acid leader sequence, containing 15 hydrophobic residues, at the NH2 terminus. The sequence Thr-Leu-Ala-Leu occurs twice in the leader region. In common with other secretory proteins, the transient hydrophobic extension at the NH2 terminus of pre-uteroglobin may function to assist transfer of the nascent peptide into the lumen of the endoplasmic reticulum, as proposed in the "signal" hypothesis.

Amino Acid Sequence↗
PubMed1988

Expression of a uteroglobin-like protein in human prostate.

Phospholipase A2 (PLA2) is a key enzyme that initiates the arachidonic acid cascade responsible for the synthesis of prostaglandins and leukotrienes, compounds well known for their inflammatory properties. Inhibition of this enzyme may modulate prostaglandin and leukotriene tissue levels. Uteroglobin is a potent PLA2 inhibitor found in rabbit uterus, prostate, seminal vesicle, and tracheobronchial tree. Tissue from ten human patients undergoing prostatectomy was examined for presence of a uteroglobin-like protein. Seven patients underwent transurethral resection and three had an open prostatectomy. Preoperative diagnosis in nine of the 10 patients was benign prostatic hypertrophy. One suspected, poorly differentiated, adenocarcinoma was confirmed and one unsuspected, well differentiated, adenocarcinoma was discovered. Specimens were submitted for Western blot, electron microscopy with immunogold staining, radioimmunoassay, and immunofluorescence. Six patients had evidence of uteroglobin-like protein, three with high levels (greater than or equal to 1000 pg./mg. protein), two with moderate levels (75 to 250 pg.), one with a low level (less than or equal to 75 pg.). Uteroglobin-like protein was present in all three patients who underwent open prostatectomy and in three of the seven patients with transurethral resections. The uteroglobin-like protein level was 2.5 to five times greater in both prostatic utricle specimens. All four assays corroborated these results. Because rabbit uteroglobin coats sperm and masks spermatic antigenicity in the rabbit female genital tract, this report of biochemical and immunological evidence for uteroglobin-like protein in the human prostate may have implications for human male fertility.

Adenocarcinoma↗
PubMed1992

Human CC10, the homologue of rabbit uteroglobin: genomic cloning, chromosomal localization and expression in endometrial cell lines.

Human and rat cDNAs to Clara Cell 10 kDa protein (CC10) have been previously isolated. Comparison of the amino acid sequences showed that CC10 is homologous to rabbit uteroglobin. Here we present further evidence that human CC10 is the human counterpart of rabbit uteroglobin. We have isolated the gene and have mapped its genomic localization to chromosome 11q11-qter. Sequence analysis of the 5'-flanking region reveals that the homology between the human and the rabbit gene starts at the first exon/intron boundary and extends up to -1.4 kb. A second region of 0.74 kb from -1.77 to -2.51 kb in the human 5'-flanking gene region is homologous to rabbit sequences that include four progesterone receptor binding sites which have been implicated in progesterone regulation of rabbit uteroglobin gene expression in endometrium. Sequence alignment of this region on the nucleotide level shows that only two weak progesterone receptor binding sites are partially conserved. In addition, close inspection of the human and rabbit promoters reveals that the estrogen responsive element and two recently identified cis elements of the rabbit promoter located between -177 and -258 bp are also absent in the human uteroglobin promoter. Despite these differences in the 5'-flanking regions of the genes, we report that the human uteroglobin mRNA is expressed in a human cell line of endometrial origin indicating that human uteroglobin is expressed in the uterus like its rabbit homologue. Thus, it appears that human uteroglobin is not only a marker for lung Clara cells but also an endometrial differentiation marker.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1986

Uteroglobin messenger ribonucleic acid: localization in rabbit uterus and lung by in situ hybridization.

The messenger RNA (mRNA) coding for uteroglobin has been localized in the rabbit uterus and lung by in situ hybridization. Tissue sections fixed in ethanol-acetic acid were hybridized to the cloned complementary DNA probe labeled with tritium. The hybridization sites were detected by radioautography. Control experiments using [3H]pBR322 DNA demonstrated the specificity of the observed labeling. In the lung, uteroglobin mRNA, present in small concentrations, could be clearly visualized only after background was decreased by incubation of sections with S1 nuclease. In pregnant rabbit uterine horns, uteroglobin mRNA, visualized by silver grains, was found in the endometrial epithelium. The concentration was greater in the cells of glandular epithelium than in the cells of surface epithelium. Specific and intense labeling was spread through the cytoplasm. Practically all epithelial cells contained uteroglobin mRNA. Hybridization was very weak in the uterine epithelial cells of the nonpregnant rabbit. In the lung, a high degree of labeling occurred on the ciliated and bronchiolar cells of the epithelium of bronchi and bronchioles whereas the goblet cells remained unlabeled. Certain cells lining alveolar ducts and alveoli in the pulmonary parenchyma also showed a slight labeling. No differences in the labeling were observed in the lung of either pregnant or non-pregnant animals. There are several differences in the intensity and distribution of labeling between our hybridization experiments and previous studies involving immunocytochemical detection of uteroglobin protein. The latter technique thus probably not only reflects the pattern of synthesis of the protein but also depends on uteroglobin retention in the cells. Moreover, no evidence was found to bear out the hypothesis that some endometrial cells which contain uteroglobin do not synthesize this protein but take it up from endometrial fluid.

Animals↗