The apical surface of mammalian bladder urothelium is highly specialized as it is almost completely covered by 2D crystals of hexagonally packed 16-nm uroplakin particles forming urothelial plaques. These plaques play important biological functions, in that they contribute to the formation of a strikingly effective permeability barrier. In addition, these plaques may strengthen the physical stability of the urothelial surface thus preventing it from rupturing during bladder distention, and one of the uroplakins, UPIa, may serve as the receptor for the uropathogenic E. coli that causes >85% of the urinary tract infections. Despite recent progress in the biochemical characterization of the uroplakin proteins, many important questions remain unanswered. For example, what are the mechanisms that control whether a uroplakin or a uroplakin heterodimer can exit from the ER? How are the protein machineries including MAL and Rab27b involved in targeting the uroplakins to the apical surface where they function? To answer these questions, we will pursue three specific Aims.
In Aim One, we will identify proteins that are associated with normal UPIb that can exit ER without a uroplakin partner vs. UPIb containing transmembrane domain mutations that is retained by ER, and we will study whether UPIIIa, which can bind to UPIb, can rescue mutated UPIb from being trapped in the ER.
In Aim Two, we will employ two genetically engineered mouse mutants that are defective in MAL or Rab27b to see whether they are necessary for the exocytosis of the uroplakin-delivering fusiform vesicles, and whether Rab27b functions upstream of MAL.
In Aim Three, we will study the functions of the conserved head domain vs. the variable tail domain of the Rab27b and its isoform Rab27a, by adenovirally delivering Rab27a, Rab27b and their domainexchanging chimeras into Rab27b-null umbrella cells. Together, these studies will yield new insights into the mechanism of urothelial membrane trafficking and pave the way for future studies on the possible role(s) of urothelial vesicular transport in bacterial invasion into and release from the urothelial cells.

Public Health Relevance

The apical surface of bladder urothelium forms a highly effective permeability barrier, and is specialized to endure mechanical stretch. Our studies will address how the uroplakin proteins are synthesized and delivered to the apical surface where they perform these functions, and they will shed light on how uropathogenic bacteria invade and later escape from the host urothelial cells, key events in recurrent urinary tract infections.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Program Projects (P01)
Project #
5P01DK052206-13
Application #
8566107
Study Section
Special Emphasis Panel (ZDK1-GRB-S (M2))
Project Start
1999-03-01
Project End
2015-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
13
Fiscal Year
2012
Total Cost
$414,509
Indirect Cost
$169,237
Name
New York University
Department
Type
DUNS #
121911077
City
New York
State
NY
Country
United States
Zip Code
10016
Schaffer, Jessica N; Norsworthy, Allison N; Sun, Tung-Tien et al. (2016) Proteus mirabilis fimbriae- and urease-dependent clusters assemble in an extracellular niche to initiate bladder stone formation. Proc Natl Acad Sci U S A 113:4494-9
Kisiela, Dagmara I; Avagyan, Hovhannes; Friend, Della et al. (2015) Inhibition and Reversal of Microbial Attachment by an Antibody with Parasteric Activity against the FimH Adhesin of Uropathogenic E. coli. PLoS Pathog 11:e1004857
Hickling, Duane R; Sun, Tung-Tien; Wu, Xue-Ru (2015) Anatomy and Physiology of the Urinary Tract: Relation to Host Defense and Microbial Infection. Microbiol Spectr 3:
Liu, Yan; Mémet, Sylvie; Saban, Ricardo et al. (2015) Dual ligand/receptor interactions activate urothelial defenses against uropathogenic E. coli. Sci Rep 5:16234
Desalle, Rob; Chicote, Javier U; Sun, Tung-Tien et al. (2014) Generation of divergent uroplakin tetraspanins and their partners during vertebrate evolution: identification of novel uroplakins. BMC Evol Biol 14:13
Mathai, John C; Zhou, Enhua H; Yu, Weiqun et al. (2014) Hypercompliant apical membranes of bladder umbrella cells. Biophys J 107:1273-9
Vieira, Neide; Deng, Fang-Ming; Liang, Feng-Xia et al. (2014) SNX31: a novel sorting nexin associated with the uroplakin-degrading multivesicular bodies in terminally differentiated urothelial cells. PLoS One 9:e99644
Gandhi, Devangini; Molotkov, Andrei; Batourina, Ekatherina et al. (2013) Retinoid signaling in progenitors controls specification and regeneration of the urothelium. Dev Cell 26:469-82
Zhou, Ge; Liang, Feng-Xia; Romih, Rok et al. (2012) MAL facilitates the incorporation of exocytic uroplakin-delivering vesicles into the apical membrane of urothelial umbrella cells. Mol Biol Cell 23:1354-66
Schnegelsberg, Birthe; Sun, Tung-Tien; Cain, Gary et al. (2010) Overexpression of NGF in mouse urothelium leads to neuronal hyperinnervation, pelvic sensitivity, and changes in urinary bladder function. Am J Physiol Regul Integr Comp Physiol 298:R534-47

Showing the most recent 10 out of 63 publications