Involvement of vps33a in the fusion of uroplakin-degrading multivesicular bodies with lysosomes

The apical surface of the terminally differentiated mouse bladder urothelium is largely covered by urothelial plaques, consisting of hexagonally packed 16-nm uroplakin particles. These plaques are delivered to the cell surface by fusiform vesicles (FVs) that are the most abundant cytoplasmic organelles. We have analyzed the functional involvement of several proteins in the apical delivery and endocytic degradation of uroplakin proteins. Although FVs have an acidified lumen and Rab27b, which localizes to these organelles, is known to be involved in the targeting of lysosome-related organelles (LROs), FVs are CD63 negative and are therefore not typical LROs. Vps33a is a Sec1-related protein that plays a role in vesicular transport to the lysosomal compartment. A point mutation in mouse Vps33a (Buff mouse) causes albinism and bleeding (Hermansky-Pudlak syndrome) because of abnormalities in the trafficking of melanosomes and platelets. These Buff mice showed a novel phenotype observed in urothelial umbrella cells, where the uroplakin-delivering FVs were almost completely replaced by Rab27b-negative multivesicular bodies (MVBs) involved in uroplakin degradation. MVB accumulation leads to an increase in the amounts of uroplakins, Lysosomal-associated membrane protein (LAMP)-1/2, and the activities of beta-hexosaminidase and beta-glucocerebrosidase. These results suggest that FVs can be regarded as specialized secretory granules that deliver crystalline arrays of uroplakins to the cell surface, and that the Vps33a mutation interferes with the fusion of MVBs with mature lysosomes thus blocking uroplakin degradation.

Susceptibility of rodent cell lines to rat coronaviruses and differential enhancement by trypsin or DEAE-dextran

Cell lines of rodent origin were tested for susceptibility to infection with rat coronavirus (RCV), including sialodacryoadenitis virus (SDAV) and Parker's rat coronavirus (PRCV). LBC rat mammary adenocarcinoma cells were susceptible only if the cells were treated with diethylaminoethyl-dextran (DEAE-D). A recent report that RCVs grow well in L2 mouse fibroblast cells was confirmed and expanded. RCV infection of L2 cells was substantially enhanced by treatment of cells with trypsin but not by treatment with DEAE-D. Primary isolation of SDAV from experimentally infected rats was accomplished using trypsin-treated L2 cells. One of 13 additional cell lines tested (rat urinary bladder epithelium, RBL-02) supported growth of RCVs, and growth was slightly enhanced by DEAE-D, but not by trypsin. These refinements of in vitro growth conditions for RCVs should facilitate further studies of their basic biology and improve options for primary isolation.

Non-histone nuclear protein HMGN2 differently regulates the urothelium barrier function by altering expression of antimicrobial peptides and tight junction protein genes in UPEC J96-infected bladder epithelial cell monolayer

The urinary tract is vulnerable to frequent challenges from environmental microflora. Uropathogenic Escherichia coli (UPEC) makes a major contribution to urinary tract infection (UTI). Previous studies have characterized positive roles of non-histone nuclear protein HMGN2 in lung epithelial innate immune response. In the study presented here, we found HMGN2 expression was up-regulated in UPEC J96-infected urothelium. Surprisingly, over-expression of HMGN2 promoted disruption of BECs 5637 cells' intercellular junctions by down-regulating tight junction (TJs) components' expression and physical structure under J96 infection. Further investigation showed that BECs 5637 monolayer, in which HMGN2 was over-expressed, had significantly increased permeability to J96. Our study systemically explored the regulatory roles of HMGN2 in BECs barrier function during UPEC infection and suggested different modulations of intracellular and paracellular routes through which UPEC invades the bladder epithelium.

Diagnosing the bladder as the source of pelvic pain: successful treatment for adults and children

The key to successful therapy of interstitial cystitis (IC) is to correctly diagnose it. The significant majority of patients with IC have a dysfunctional bladder epithelium that allows urinary solutes (primarily potassium) to leak into the bladder wall, causing symptoms and tissue damage. Drugs that correct this dysfunction and suppress symptoms are important to achieve successful outcomes in patients. Today over 95% of females with IC are misdiagnosed as having gynecologic chronic pelvic pain, vulvodynia, vaginitis, endometriosis, overactive bladder or urinary tract infection. Men are misdiagnosed as having prostatitis. Often children are not diagnosed at all. Multimodal drug therapy may be required and can achieve successful resolution of IC in over 90% of patients. IC in children can be treated successfully with pentosan polysulfate.

The role of pentosan polysulfate in treatment approaches for interstitial cystitis

Studies of the mechanisms and causes of interstitial cystitis (IC) and of the properties of pentosan polysulfate have provided a scientific rationale for using pentosan polysulfate to treat IC. In randomized, double-blind studies, patient and investigator evaluations of pentosan polysulfate in the treatment of IC resulted in favorable assessments of the drug. In addition, IC patients in two out of four randomized, prospective trials improved significantly in most variables with treatment by oral pentosan polysulfate; in the two other studies, the IC patients improved in some domains with pentosan therapy, although not significantly. Importantly, two longer-term, patient-evaluation studies showed that a longer duration of treatment with pentosan polysulfate resulted in greater improvements in patients' response rates and outcomes. The results indicate that treatment should be continued for 6 months or longer in order to show significant improvement. Of particular interest are studies suggesting that a potassium test may possibly predict the response of IC patients to treatment with pentosan polysulfate.

Human urogenital sinus mesenchyme is an inducer of prostatic epithelial development

OBJECTIVE

To determine whether human fetal urogenital sinus mesenchyme (UGM) can induce prostatic development in a responsive mouse epithelium.

METHOD

Male and female human fetal UGM was combined with mouse urinary bladder epithelium (BLE), and the resultant human UGM + mouse BLE tissue recombinants were grown under renal capsules of male athymic mice. Human male and female UGM was derived from reproductive tracts 9 and 14 weeks of gestation obtained following elective termination of pregnancy. At these ages prostatic ducts had already emerged from the urogenital sinus epithelium, and the human UGM remained contaminated with human prostatic epithelium. This unavoidable problem was tolerated because the induced mouse prostatic epithelium could be distinguished from contaminating human prostatic epithelium.

RESULTS

The simple columnar epithelium induced from mouse bladder epithelium by human male and female UGM resembled mouse prostatic epithelium by: (a) histology, (b) the pattern of basal cell distribution, (c) Hoechst dye nuclear staining, (d) expression of NKX3.1, (e) the pattern of androgen receptor expression and (f) the expression of probasin, a mouse prostatic secretory protein. Summary/Interpretation: These findings provide validation for mouse as a model of human prostatic development as the molecular dialogue involved in mesenchymal-epithelial interactions are sufficiently conserved that human UGM can induce mouse bladder epithelium to undergo prostatic development.