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X R Wu

Publications and source records attributed to X R Wu.

At least 19 recordsLinked to original sources
PubMed2001

Role of Ha-ras activation in superficial papillary pathway of urothelial tumor formation.

Urothelial tumors develop along two distinctive phenotypic pathways (superficial papillary non-invasive tumors versus flat carcinoma in situ lesions), with markedly different biological behavior and prognosis. Although multiple genetic alterations have been identified in human bladder cancer, their cause-effect relationship with the two pathways has not been firmly established. Using a urothelium-specific promoter of the uroplakin II gene, we showed earlier in transgenic mice that the urothelial expression of SV40T antigen, which inactivates p53 and pRb, induced carcinoma in situ and invasive and metastatic bladder cancer. In striking contrast, we demonstrate here that the urothelial expression of an activated Ha-ras in transgenic mice caused urothelial hyperplasia and superficial papillary non-invasive bladder tumors. These results provide strong, direct experimental evidence that the two phenotypical pathways of bladder tumorigenesis are caused by distinctive genetic defects. Our results indicate that Ha-ras activation can induce urothelial proliferation in vivo; and that urothelial hyperplasia is a precursor of low-grade, superficial papillary bladder tumors. Our transgenic models provide unique opportunities to study the detailed molecular events underlying different types of bladder neoplasms, and can serve as useful preclinical models for evaluating the in vivo efficacy of preventive and therapeutic agents that act on various signaling pathways in bladder cancer.

Animals↗
PubMed2001

Organization of uroplakin subunits: transmembrane topology, pair formation and plaque composition.

The apical surfaces of urothelial cells are almost entirely covered with plaques consisting of crystalline, hexagonal arrays of 16 nm uroplakin particles. Although all four uroplakins, when SDS-denatured, can be digested by chymotrypsin, most uroplakin domains in native urothelial plaques are resistant to the enzyme, suggesting a tightly packed structure. The only exception is the C-terminal, cytoplasmic tail of UPIII (UPIII) which is highly susceptible to proteolysis, suggesting a loose configuration. When uroplakins are solubilized with 2% octylglucoside and fractionated with ion exchangers, UPIa and UPII were bound as a complex by a cation exchanger, whereas UPIb and UPIII were bound by an anion exchanger. This result is consistent with the fact that UPIa and UPIb are cross-linked to UPII and UPIII, respectively, and suggests that the four uroplakins form two pairs consisting of UPIa/II and UPIb/III. Immunogold labelling using a new mouse monoclonal antibody, AU1, revealed that UPIII is present in all urothelial plaques, indicating that the two uroplakin pairs are not segregated into two different types of urothelial plaque and that all plaques must have a similar uroplakin composition. Taken together, these results indicate that uroplakins form a tightly packed structure, that the four uroplakins interact specifically forming two pairs, and that both uroplakin pairs are required for normal urothelial plaque formation.

Amino Acid Sequence↗
PubMed2001

Brenner tumors but not transitional cell carcinomas of the ovary show urothelial differentiation: immunohistochemical staining of urothelial markers, including cytokeratins and uroplakins.

To determine whether Brenner tumors and transitional cell carcinomas (TCCs) of the ovary are urothelial in type, the immunoprofiles of 14 Brenner tumors, including three malignant examples, and eight ovarian TCCs were compared with those of Walthard nests, urothelium, 12 urinary bladder TCCs and 17 ovarian adenocarcinomas (serous, endometrioid, mucinous, and undifferentiated type). The immunohistochemical stains used included those for cytokeratins CKs 5/6, CK7, CK8, CK13, and CK20, vimentin, CA125, and the specific urothelial differentiation marker uroplakin III. CK7 and CK8 were broadly expressed in most tumors of ovary and bladder examined, while vimentin was focally present in some ovarian TCCs and adenocarcinomas. As in normal and neoplastic bladder urothelium, urothelial markers, including uroplakin III, CK13, and CK20, were detected in the epithelial nests of Brenner tumors. Brenner tumor cells also expressed uroplakins Ia and II. CA125 was observed focally in some Brenner tumors. In contrast, TCCs of the ovary and Walthard nests lacked uroplakins and were essentially negative for CK20 and CK13 but quite strongly expressed CA125. This immunophenotype closely resembled that found in ovarian adenocarcinomas. Thus, it appears that the only true urothelial-type ovarian neoplasm is the Brenner tumor, whereas ovarian TCC most likely represents a poorly differentiated adenocarcinoma with a morphologic transitional cell pattern. These results may explain the controversies as expressed in the recent literature concerning TCC of the ovary and establish its place among the ovarian adenocarcinomas of müllerian type.

Adenocarcinoma↗
PubMed2001

Uroplakin Ia is the urothelial receptor for uropathogenic Escherichia coli: evidence from in vitro FimH binding.

The binding of uropathogenic Escherichia coli to the urothelial surface is a crucial initial event for establishing urinary tract infection because it allows the bacteria to gain a foothold on the urothelial surface, thus preventing them from being removed by micturition. In addition, it triggers bacterial invasion as well as host urothelial defense. This binding is mediated by the FimH adhesin located at the tip of the bacterial type 1-fimbrium, a filamentous attachment apparatus, and its urothelial receptor. We have prepared a biotinylated, recombinant FimH-FimC adhesin:chaperone complex and used it to identify its mouse urothelial receptor. The FimH-FimC complex binds specifically to a single 24 kDa major mouse urothelial plaque protein, which we identified as uroplakin Ia by mass spectrometry, cDNA cloning and immunoreactivity. The terminal mannosyl moieties on Asn-169 of uroplakin Ia are responsible for FimH as well as concanavalin A binding. Although FimH binds to uroplakin Ia with only moderate strength (K(d) approximately 100 nM between pH 4 and 9), the binding between multiple fimbriae of a bacterium and the crystalline array of polymerized uroplakin receptors should achieve high avidity and stable bacterial attachment. The FimH-FimC complex binds preferentially to the mouse urothelial umbrella cells in a pattern similar to uroplakin staining. Our results indicate that the structurally related uroplakins Ia and Ib are glycosylated differently, that uroplakin Ia serves as the urothelial receptor for the type 1-fimbriated E. coli, and that the binding of uropathogenic bacteria to uroplakin Ia may play a key role in mediating the urothelial responses to bacterial attachment.

Adhesins, Bacterial↗
PubMed2001

[Cantonese population data of the tetranucleotide repeat locus D7S809 and its application in paternity test].

The tetranucleotide repeat locus D7S809 was investigated in Cantonese population by polymerase chain reaction (PCR) amplification, subsequent polyacryramide gel electrophoresis and silver staining. 14 alleles and 50 genotypes were detected in 190 sample individuals. All alleles differed in size by 4 bp repeat. No interalleles were found. The heterozygosity, power of discrimination and chance of non-paternal exclusion were 0.8613, 0.9645 and 0.7184 respectively. No significant deviations from Hardy-Weinberg equilibrium were found. The D7S809 was a highly polymorphic, stable and accurate type locus and had been successfully applied to 100 paternity test cases.

Alleles↗
PubMed2000

Tamm-Horsfall protein binds to type 1 fimbriated Escherichia coli and prevents E. coli from binding to uroplakin Ia and Ib receptors.

The adherence of uropathogenic Escherichia coli to the urothelial surface, a critical first step in the pathogenesis of urinary tract infection (UTI), is controlled by three key elements: E. coli adhesins, host receptors, and host defense mechanisms. Although much has been learned about E. coli adhesins and their urothelial receptors, little is known about the role of host defense in the adherence process. Here we show that Tamm-Horsfall protein (THP) is the principal urinary protein that binds specifically to type 1 fimbriated E. coli, the main cause of UTI. The binding was highly specific and saturable and could be inhibited by d-mannose and abolished by endoglycosidase H treatment of THP, suggesting that the binding is mediated by the high-mannose moieties of THP. It is species-conserved, occurring in both human and mouse THPs. In addition, the binding to THP was much greater with an E. coli strain bearing a phenotypic variant of the type 1 fimbrial FimH adhesin characteristic of those prevalent in UTI isolates compared with the one prevalent in isolates from the large intestine of healthy individuals. Finally, a physiological concentration of THP completely abolished the binding of type 1 fimbriated E. coli to uroplakins Ia and Ib, two putative urothelial receptors for type 1 fimbriae. These results establish, on a functional level, that THP contains conserved high-mannose moieties capable of specific interaction with type 1 fimbriae and strongly suggest that this major urinary glycoprotein is a key urinary anti-adherence factor serving to prevent type 1 fimbriated E. coli from binding to the urothelial receptors.

Animals↗
PubMed2000

Ablation of uroplakin III gene results in small urothelial plaques, urothelial leakage, and vesicoureteral reflux.

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.

Animals↗
PubMed2000

Terminal glycosylation of bovine uroplakin III, one of the major integral-membrane glycoproteins of mammalian bladder.

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.

Adhesins, Escherichia coli↗
PubMed2000

Brain distribution and efficacy of carbamazepine in kainic acid induced seizure in rats.

To investigate the relationships between carbamazepine (CBZ) concentrations in serum and the brain, and the anticonvulsive efficacy in kainic acid (KA) induced seizures in rats, adult Wistar rats (n=25) were intraperitoneally given 40 mg/kg CBZ, followed by 15 mg/kg KA (n=20) or saline (control, n=5). At 90 min after the injection, CBZ concentrations in 5 rats without seizures (CBZ effective group), 5 rats with seizures (CBZ no-effective group) and five control rats were measured. Serum and brain tissues from six areas (cortex, brain stem, cerebellum, thalamus, hippocampus and striatum) were used for CBZ assay. CBZ was measured using a EMIT immunoassay kit. In blood, CBZ was higher in rats treated with CBZ+KA than in a control group (CBZ+saline). In the brain, the effective group demonstrated significantly high CBZ concentration in the hippocampus. KA appeared to raise serum CBZ level when it was given in combination with CBZ. This was probably caused by the accelerated absorption of CBZ from local site as the results of an increased metabolic rate and the more demands for blood supply after KA treatment. The positive correlation between efficacy of CBZ and the concentration in the hippocampus suggests that CBZ levels in the hippocampus is closely correlated with the efficacy of CBZ against KA induced seizures.

Animals↗
PubMed2000

Uroplakin and androgen receptor expression in the human fetal genital tract: insights into the development of the vagina.

PURPOSE: Although a dual origin of the vagina has been popularized, other theories support a müllerian or wolffian duct origin or various combinations of these structures and the urogenital sinus. Uroplakins are specialized membrane proteins of the urothelial plaque, constituting the asymmetrical unit membrane of the bladder, and represent specific molecular markers of urothelial differentiation. We hypothesize that the epithelium of the dorsal wall of the urogenital sinus is involved in the formation of the sinovaginal bulbs and will express uroplakins. In addition, localization of the androgen receptor and its temporal expression during development may in part explain the varied effects of androgens on the lower female genital tract in congenital adrenal hyperplasia. MATERIALS AND METHODS: Lower genitourinary tracts from 4 human female fetuses (9 to 18 weeks) were serially sagittally sectioned. Representative sections were stained with hematoxylin and eosin, rabbit antibodies against panuroplakin and antibodies to the androgen receptor. RESULTS: At 9 weeks of gestation the urogenital sinus showed evidence of evagination and the formation of the sinovaginal bulbs. The urothelium of the entire urogenital sinus expressed uroplakins including the region of the dorsal wall involved in evagination and formation of the sinovaginal bulbs. The müllerian ducts were in direct contact with the area of urogenital sinus evagination but were not in continuity with the sinus. Androgen receptors were expressed in the epithelium and the stroma of the urogenital sinus, sinovaginal bulbs, and müllerian and wolffian ducts. By 14 weeks androgen receptor expression was almost absent in the urothelium of the urogenital sinus, and the epithelium and surrounding stroma of the lower vagina and müllerian ducts. CONCLUSIONS: The area of evagination of the urogenital sinus expresses uroplakins, is involved in the formation of the sinovaginal bulbs and further substantiates the urogenital sinus origin of the lower vagina. Since testosterone inhibits formation of the lower vagina, the timing of exposure to systemic testosterone in congenital adrenal hyperplasia will determine the phenotypic appearance of the external genitalia and effect of testosterone on the development of the lower genital tract. If exposure to testosterone occurs after 12 weeks only clitoromegaly occurs. Androgen receptor is absent in the urogenital sinus urothelium, vaginal epithelium and müllerian ducts by 14 weeks, suggesting that these tissues become androgen insensitive and vaginal development will proceed normally after that critical time.

Embryonic and Fetal Development↗
PubMed2000

[Pathophysiological alterations in cultured astrocytes exposed to hypoxia/reoxygenation].

While the research of hypoxic-ischemic injury to the central nervous system has been focused on neurons, astrocytes are also critically involved in and contribute to the hypoxic-ischemic process. The role these cells play appears to be more and more important. There are considerable progress in characterizing the pathophysiological alterations of these cells during hypoxic-ischemic brain damage.

Animals↗
PubMed1999

Urothelium-specific expression of an oncogene in transgenic mice induced the formation of carcinoma in situ and invasive transitional cell carcinoma.

Although many genetic alterations are known to be associated with human transitional cell carcinoma (TCC) of the urinary bladder, relatively little is known about the roles of these molecular defects, singular or in combination, in bladder tumorigenesis. We have developed a transgenic mouse model of bladder tumorigenesis using a 3.6-kb promoter of uroplakin II gene to drive the urotheliums-specific expression of oncogenes. In this study, we demonstrate that transgenic mice bearing a low copy number of SV40T transgene developed bladder carcinoma in situ (CIS), whereas those bearing high copies developed CIS as well as invasive and metastatic TCCs. These results indicate that the SV40T inactivation of p53 and retinoblastoma gene products, defects frequently found in human bladder CIS and invasive TCCs, can cause the aggressive form of TCC. Our results also provide experimental proof that CIS is a precursor of invasive TCCs, thus supporting the concept of two distinct pathways of bladder tumorigenesis (papillary versus CIS/invasive TCC). This transgenic system can be used for the systematic dissection of the roles of individual or combinations of specific molecular events in bladder tumorigenesis.

Animals↗
PubMed1999

Three-dimensional analysis of the 16 nm urothelial plaque particle: luminal surface exposure, preferential head-to-head interaction, and hinge formation.

The luminal surface of mouse urothelium in contact with the urine is almost entirely covered with plaques consisting of uroplakin-containing particles that form p6 hexagonal crystals with a center-to-center distance of 16 nm. A combination of quick-freeze/deep-etch images and our previous negative staining data indicate that the head domain of the uroplakin particle, which is exposed without an extensive glycocalyx shield, interacts closely with the head domains of the neighboring particles, while the membrane-embedded tail domains are farther apart; and that urothelial particles and plaques are not rigid structures as they can change their configuration in response to mechanical perturbations. Based on these data, we have constructed three-dimensional models depicting the structural organization of urothelial particles and plaques. Our models suggest that the head-to-head interaction may play a key role in determining the shape and size of the urothelial plaques. These models can explain many properties of urothelial plaques including their unique shape, detergent-insolubility, and morphological changes during vesicle maturation.

Animals↗
PubMed1999

New concepts of histological changes in experimental augmentation cystoplasty: insights into the development of neoplastic transformation at the enterovesical and gastrovesical anastomosis.

PURPOSE: To our knowledge the pathogenesis of malignancy associated with ileal cystoplasty, ureterosigmoidostomy and ileal conduits is currently unknown. To gain further insights into the mechanism of neoplastic transformation we studied histological changes in a canine augmentation cystoplasty model. MATERIALS AND METHODS: Enterocystoplasty and gastrocystoplasty were performed using a 5 to 7 cm. patch of ileum in 8 dogs and gastric antrum in 6. Specimens were harvested 4 months postoperatively. Representative 3 microm sections of the enterovesical and gastrovesical junctions were stained with hematoxylin and eosin. Uroplakin expression was assessed using an indirect peroxidase method subjected to double staining with alcian blue and periodic acid-Schiffreagent. RESULTS: The bladder portion of the augmentation cystoplasty had 3 to 4 stratified cell layers covered with a distinctive umbrella cell layer. Strong uroplakin staining was visible in all cell layers except the basal layer. At the enterovesical and gastrovesical junctions 6 to 10 layers of hyperplastic, urothelial appearing cells covered the glandular epithelium of the ileal and gastric segments. These cells expressed uroplakins. At this junction zone there was a marked decrease of underlying enteric glands, which had atrophied in proportion to the degree of urothelial hyperplasia. Double staining of uroplakin stained sections with alcian blue and periodic acid-Schiff reagent revealed mucosubstances in hyperplastic urothelial cells covering the enteral segments, indicating that the cells co-expressed uroplakins and mucins. CONCLUSIONS: Histological changes in this experimental canine model of augmentation cystoplasty indicated that the overgrowth of hyperplastic transitional epithelium develops at the enterovesical and gastrovesical junctions. These cells express not only uroplakins, but also mucosubstances. Our results suggest that the migrated hyperplastic urothelial cells have undergone changes characteristic of the enteric and gastric epithelium, which may have important implications in the pathogenesis of malignancy in bladder augmentations.

Anastomosis, Surgical↗
PubMed1999

Urothelial hinge as a highly specialized membrane: detergent-insolubility, urohingin association, and in vitro formation.

Urothelial surface is covered by numerous plaques (consisting of asymmetric unit membranes or AUM) that are interconnected by ordinary looking hinge membranes. We describe an improved method for purifying bovine urothelial plaques using 2% sarkosyl and 25 mM NaOH to remove contaminating membrane and peripheral proteins selectively. Highly purified plaques interconnected by intact hinge areas were obtained, indicating that the hinges are as detergent-insoluble as the plaques. These plaque/hinge preparations contained uroplakins, an as yet uncharacterized 18-kDa plaque-associated protein, plus an 85-kDa glycoprotein that is known to be hinge-associated in situ. Examination of the isolated, in vitro-resealed bovine AUM vesicles by quick-freeze deep-etch showed that each AUM particle consists of a 16-nm, luminally exposed "head" anchored to the lipid bilayer via a 9-mm transmembranous "tail", and that an AUM plaque can break forming several smaller plaques separated by newly formed particle-free, hinge-like areas. These data lend support to our recently proposed three-dimensional model of mouse urothelial plaques. In addition, our findings suggest that urothelial plaques are dynamic structures that can rearrange giving rise to new plaques with intervening hinges; that the entire urothelial apical surface (both plaque and hinge areas) is highly specialized; and that these two membrane domains may be equally important in fulfilling some of the urothelial functions.

Animals↗
PubMed1999

Detection of circulating uroplakin-positive cells in patients with transitional cell carcinoma of the bladder.

PURPOSE: Although transitional cell carcinoma of the bladder (TCC) metastasizes frequently with devastating consequences, no marker has been available to monitor this process. Uroplakins are a group of specific markers for normal urothelium and are continuously expressed by the majority of TCCs. Detection of uroplakin-positive cells in the circulation would be a strong indication of hematogenous dissemination of tumor cells in patients with TCC. MATERIALS AND METHODS: Total RNAs were extracted from peripheral blood of 60 patients with TCC (50 non-metastatic and 10 metastatic) and 10 healthy controls, reverse-transcribed and subjected to polymerase chain reaction amplification (RT-PCR) using oligonucleotide primers of human uroplakin II gene. A uroplakin-expressing human bladder cancer cell line (RT4) was used as a positive control to establish the sensitivity of the RT-PCR assay. RESULTS: We showed that the PCR-amplification of the mRNA encoding uroplakin II (UPII), a 15-kDa urothelium-specific marker, constitutes a highly sensitive and specific assay for detecting 100% of transitional cell carcinoma tissue, and that this assay can detect a single bladder cancer cell in a 5-ml. blood sample. UPII mRNA was detected in the blood samples of 2 patients with metastatic bladder cancer without chemotherapy and 1 out of 8 such patients with chemotherapy, but not in those of 50 non-metastatic patients or normal controls. CONCLUSIONS: Uroplakin II is a highly specific marker for human TCC and the detection of uroplakin II in the peripheral blood is associated with metastatic spread of bladder cancer cells. The specific and sensitive detection of uroplakin II provides a useful adjunct for detecting bladder cancer metastasis, staging, and monitoring chemotherapeutic response.

Biomarkers, Tumor↗