Immunohistochemical analysis of uroplakins, urothelial specific proteins, in ovarian Brenner tumors, normal tissues, and benign and neoplastic lesions of the female genital tract. (1/46)

Uroplakins are the characteristic integral membrane proteins in terminally differentiated, superficial urothelial asymmetric unit membrane. Brenner tumors of the ovary and Walthard cell nests of Fallopian tubes have been considered to represent urothelial differentiation in the female genital tract, but no definitive differentiation marker has been demonstrated supporting such a conclusion. An immunohistochemical analysis was performed to assess the expression of uroplakins in these lesions as well as in various benign and neoplastic lesions and normal tissues of the female genital tract. Focal expression of uroplakins was observed on the luminal surface of ovarian Brenner tumor cells forming microcysts in all 5 cases examined. In contrast, uroplakins were slightly expressed in only 1 of 12 cases of Walthard cell nests, even in the presence of microcyst formation. Uroplakins were not expressed in other benign or malignant lesions or normal tissues of the female genital tract. These results support the hypothesis that the Brenner tumor and possibly Walthard cell nests represent urothelial (transitional cell) differentiation.  (+info)

Comparison of uroplakin expression during urothelial carcinogenesis induced by N-butyl-N-(4-hydroxybutyl)nitrosamine in rats and mice. (2/46)

The expression of uroplakins, the tissue-specific and differentiation-dependent membrane proteins of the urothelium, was analyzed immunohistochemically in N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-treated rats and mice during bladder carcinogenesis. Male Fischer 344 rats were treated with 0.05% BBN in the drinking water for 10 wk and were euthanatized at week 20 of the experiment. BBN was administered to male B6D2F, mice; it was either provided at a rate of 0.05% in the drinking water (for 26 wk) or 5 mg BBN was administered by intragastric gavage twice weekly for 10 wk, followed by 20 wk without treatment. In rats, BBN-induced, noninvasive, low-grade, papillary, transitional cell carcinoma (TCC) showed decreased uroplakin-staining of cells lining the lumen but showed increased expression in some nonluminal cells. In mice, nonpapillary, high-grade dysplasia, carcinoma in situ, and invasive carcinoma were induced. There was a marked decrease in the number of uroplakin-positive cells lining the lumen and in nonluminal cells. This occurred in normal-appearing urothelium in BBN-treated mice and in dysplasic urothelium, in carcinoma in situ, and in invasive TCC. The percentage of uroplakin-positive nonluminal cells was higher in control mice than in rats, but it was lower in the mouse than in the rat after BBN treatment. Uroplakin expression was disorderly and focal in BBN-treated urothelium in both species. These results indicate that BBN treatment changed the expression of uroplakins during bladder carcinogenesis, with differences in rats and mice being related to degree of tumor differentiation.  (+info)

Uroplakin III is a highly specific and moderately sensitive immunohistochemical marker for primary and metastatic urothelial carcinomas. (3/46)

Uroplakins are specific differentiation products of terminally differentiated superficial urothelial cells. We tested the value of a new commercially available monoclonal antibody against uroplakin III (clone AU 1) as a paraffin-reactive immunohistochemical marker for primary and metastatic urothelial carcinomas. The study cases included 67 urothelial carcinomas of the urinary tract (35 primary tumors, 32 metastases) and 318 nonurothelial carcinomas, as well as 5 benign Brenner tumors and 2 transitional cell carcinomas of the ovaries. Uroplakin III was detected in 21 (60%) of the primary urothelial carcinomas and 17 (53%) of the metastases, resulting in an overall sensitivity of 0.57. The studied Brenner tumors also were immunoreactive for uroplakin III. All other studied carcinomas were consistently uroplakin III-negative (specificity 1.00). We found the new monoclonal antibody AU 1 against uroplakin III to be a highly specific paraffin-reactive immunohistochemical marker for urothelial tumors with a moderate sensitivity for the identification of primary and metastatic urothelial carcinomas.  (+info)

Terminal glycosylation of bovine uroplakin III, one of the major integral-membrane glycoproteins of mammalian bladder. (4/46)

Uroplakin III (UPIII) is one of the major transmembrane glycoproteins exposed at the luminal face of mammalian bladder. We investigated the terminal glycosylation of bovine UPIII in order to ascertain whether it contains the alpha 2,3-sialylated sequence thus potentially serving as a receptor for uropathogenic Escherichia coli expressing type S adhesins. We report the occurrence of sialic acid in alpha 2,3- and alpha 2,6-linkage to galactose in bovine UPIII glycans as evidenced by the sensitivity of UPIII to both Vibrio cholera and Newcastle disease virus neuraminidase and by the colocalization of UPIII antigen and material detected by lectins of Sambucus nigra and Maackia amurensis on the luminal face of the bladder. We also present evidence that UPIII glycans are capped by Gal-alpha 1,3-Gal epitope. Consistently, alpha 2,3- and alpha 2, 6-sialyltransferase, as well as alpha 1,3-galactosyltransferase were found to be present in the cells detached from the luminal side of bovine bladder, which are responsible for the UPIII biosynthesis. The putative role of UPIII sialylated glycans in enhancing the uropathogenicity of E. coli expressing type S adhesins is discussed.  (+info)

Human uroplakin Ib in ocular surface epithelium. (5/46)

PURPOSE: To investigate the expression and localization of the human gene encoding uroplakin Ib in ocular surface epithelium. METHODS: The full-length cDNA of human uroplakin Ib was isolated from a cDNA library of human corneal epithelium, and the expression of uroplakin Ib in various tissues was examined by reverse transcription-polymerase chain reaction (RT-PCR). In cornea and conjunctiva, the expressions of uroplakin Ia, II, and III were also examined by RT-PCR. Finally, the localization of uroplakin Ib in the ocular surface was analyzed by immunofluorescence confocal microscopy, by using an antiserum against a synthetic peptide. RESULTS: Two mRNA isoforms, arising through two polyadenylation sites, were isolated. RT-PCR detected uroplakin Ib in cornea, conjunctiva, bladder, placenta, and kidney. Among other uroplakins, uroplakin II was also faintly detected in cornea and conjunctiva. Immunofluorescence confocal microscopy documented uroplakin Ib protein in the cell membranes of superficial and wing cells in the corneal epithelium. It was not found, however, in the most apical corneal epithelial cells. In limbus and conjunctiva, uroplakin Ib was also localized in the cell membranes of all epithelial layers, apart from the most apical cells. CONCLUSIONS: Uroplakin Ib is highly expressed in ocular surface epithelia. As in bladder epithelium, uroplakin Ib may protect the ocular surface from bacterial infection.  (+info)

Ablation of uroplakin III gene results in small urothelial plaques, urothelial leakage, and vesicoureteral reflux. (6/46)

Urothelium synthesizes a group of integral membrane proteins called uroplakins, which form two-dimensional crystals (urothelial plaques) covering >90% of the apical urothelial surface. We show that the ablation of the mouse uroplakin III (UPIII) gene leads to overexpression, defective glycosylation, and abnormal targeting of uroplakin Ib, the presumed partner of UPIII. The UPIII-depleted urothelium features small plaques, becomes leaky, and has enlarged ureteral orifices resulting in the back flow of urine, hydronephrosis, and altered renal function indicators. Thus, UPIII is an integral subunit of the urothelial plaque and contributes to the permeability barrier function of the urothelium, and UPIII deficiency can lead to global anomalies in the urinary tract. The ablation of a single urothelial-specific gene can therefore cause primary vesicoureteral reflux (VUR), a hereditary disease affecting approximately 1% of pregnancies and representing a leading cause of renal failure in infants. The fact that VUR caused by UPIII deletion seems distinct from that caused by the deletion of angiotensin receptor II gene suggests the existence of VUR subtypes. Mutations in multiple gene, including some that are urothelial specific, may therefore cause different subtypes of primary reflux. Studies of VUR in animal models caused by well-defined genetic defects should lead to improved molecular classification, prenatal diagnosis, and therapy of this important hereditary problem.  (+info)

Stretch-regulated exocytosis/endocytosis in bladder umbrella cells. (7/46)

The epithelium of the urinary bladder must maintain a highly impermeable barrier despite large variations in urine volume during bladder filling and voiding. To study how the epithelium accommodates these volume changes, we mounted bladder tissue in modified Ussing chambers and subjected the tissue to mechanical stretch. Stretching the tissue for 5 h resulted in a 50% increase in lumenal surface area (from approximately 2900 to 4300 microm(2)), exocytosis of a population of discoidal vesicles located in the apical cytoplasm of the superficial umbrella cells, and release of secretory proteins. Surprisingly, stretch also induced endocytosis of apical membrane and 100% of biotin-labeled membrane was internalized within 5 min after stretch. The endocytosed membrane was delivered to lysosomes and degraded by a leupeptin-sensitive pathway. Last, we show that the exocytic events were mediated, in part, by a cyclic adenosine monophosphate, protein kinase A-dependent process. Our results indicate that stretch modulates mucosal surface area by coordinating both exocytosis and endocytosis at the apical membrane of umbrella cells and provide insight into the mechanism of how mechanical forces regulate membrane traffic in non-excitable cells.  (+info)

Role of membrane proteins in permeability barrier function: uroplakin ablation elevates urothelial permeability. (8/46)

Although water, small nonelectrolytes, and gases are freely permeable through most biological membranes, apical membranes of certain barrier epithelia exhibit extremely low permeabilities to these substances. The role of integral membrane proteins in this barrier function has been unclear. To study this problem, we have ablated the mouse gene encoding uroplakin III (UPIII), one of the major protein subunits in urothelial apical membranes, and measured the permeabilities of these membranes. Ablation of the UPIII gene greatly diminishes the amounts of uroplakins on the apical urothelial membrane (Hu P, Deng FM, Liang FX, Hu CM, Auerbach AB, Shapiro E, Wu XR, Kachar B, and Sun TT. J Cell Biol 151: 961-972, 2000). Our results indicate that normal mouse urothelium exhibits high transepithelial resistance and low urea and water permeabilities. The UPIII-deficient urothelium exhibits a normal transepithelial resistance (normal 2,024 +/- 122, knockout 2,322 +/- 114 Omega. cm(2); P > 0.5). However, the UPIII-deficient apical membrane has a significantly elevated water permeability (normal 0.91 +/- 0.06, knockout 1.83 +/- 0.14 cm/s x 10(-5); P < 0.05). The urea permeability of the UPIII-deficient membrane also increased, although to a lesser extent (normal 2.22 +/- 0.24, knockout 2.93 +/- 0.31 cm/s x 10(-6); P = 0.12). These results indicate that reduced targeting of uroplakins to the apical membrane does not significantly alter the tight junctional barrier but does double the water permeability. We provide the first demonstration that integral membrane proteins contribute to the apical membrane permeability barrier function of urothelium.  (+info)

• 1
• 2
• 3
• 4
• 5
• 6