Morphometric analysis of the translocation of lumenal membrane between cytoplasm and cell surface of transitional epithelial cells during the expansion-contraction cycles of mammalian urinary bladder

Minsky, Bruce D.; Chlapowski, Francis J.

doi:10.1083/jcb.77.3.685

Cited by 122 publications

(106 citation statements)

References 8 publications

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“…During expansion cycles the bladder accommodates an increase in volume by first eliminating membrane infolding and, during extended stretch an incorporation of cytoplasmic vesicles Minsky & Chlapowski, 1978). Recent measurements indicate that the selectivity of the amiloride-sensitive channels in the cytoplasmic vesicles after apical fusion were not different between control and diet animals, however, the selectivity of these channels was at least, 30: 1 (PNa: PK) and was not dependent upon dietary conditions (Lewis & de Moura, 1982).…”

Section: Apical Selectivitymentioning

confidence: 99%

Apical membrane permeability and kinetic properties of the sodium pump in rabbit urinary bladder.

Lewis¹,

Wills²

1983

The Journal of Physiology

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SUMMARY1. Previous studies have shown that aldosterone stimulates the rate of Na+ transport across the rabbit urinary bladder epithelium by increasing the apical membrane permeability to Na+. Paradoxically, ion-sensitive and conventional micro-electrode measurements demonstrated that intracellular Na+ activity aNa+ was essentially unchanged by aldosterone, i.e. aka+ was constant regardless of the rate of Na+ transport. The present study was designed to resolve this apparent contradiction.2. The effects of elevated, endogenous aldosterone levels produced by low-Na+ diet (Lewis & Diamond, 1976) on urinary bladder Na+ transport were investigated in vitro using Ussing-type chambers and intracellular conventional and ion-sensitive microelectrodes. Apical membrane selectivity and the kinetics of the Na+ pump were assessed as a function of hormone stimulation.3. The aldosterone-stimulated increase in Na+ transport was accounted for by increases in both the relative selective permeability of the apical membrane to Na+ and an increase in its absolute Na+ permeability.4. The kinetics of the Na+ pump were evaluated electrically by loading the cells with Na+ (monitored with Na+-sensitive micro-electrodes) or alternatively by manipulating serosal solution K+ concentration and measuring changes in the basolateral membrane electromotive forces and resistance. From these measurements the current generated by the pump was calculated as a function of intracellular Na+ or extracellular K+. The kinetics of the pump were not altered by aldosterone. A model of highly co-operative binding estimated Km for Na+ as 14-2 mm and 2-3 mm for K+. Hill coefficients for these ions were 2-8 and 1-8, respectively, consistent with a pump stoichiometry of 3 Na+ to 2 K+. The kinetic properties of the Na-K pump indicate that physiological levels of aka+ are poised at the foot of a step kinetic curve which energetically favours Na+ extrusion.

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Section: Apical Selectivitymentioning

confidence: 99%

Apical membrane permeability and kinetic properties of the sodium pump in rabbit urinary bladder.

Lewis¹,

Wills²

1983

The Journal of Physiology

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“…These crystalline uroplakin arrays expand and cover almost the entire surface of mature fusiform vesicles, which ultimately fuse with the apical plasma membrane of umbrella cells (10,11,(13)(14)(15). Uroplakin plaques at the cell surface are thought to undergo a dynamic process of internalization and reinsertion that modulates the surface area of the urothelium during the micturition cycle (11,(16)(17)(18)(19)(20)(21). However, it has recently been reported that the retrieval of uroplakins from the plasma membrane is an endocytic process not followed by temporary storage for future recycling, but rather by the degradation of uroplakins in lysosomal compartments (21).…”

mentioning

confidence: 99%

Rab27b is associated with fusiform vesicles and may be involved in targeting uroplakins to urothelial apical membranes

Chen

Guo

Deng

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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The terminally differentiated umbrella cells of bladder epithelium contain unique cytoplasmic organelles, the fusiform vesicles, which deliver preassembled crystalline arrays of uroplakin proteins to the apical cell surface of urothelial umbrella cells. We have investigated the possible role of Rab proteins in this delivery process, and found Rab27b to be expressed at an extraordinary high level (0.1% of total protein) in urothelium, whereas Rab27b levels were greatly reduced (to <5% of normal urothelium) in cultured urothelial cells, which synthesized only small amounts of uroplakins and failed to form fusiform vesicles. Immuno-electron microscopy showed that Rab27b was associated with the cytoplasmic face of the fusiform vesicles, but not with that of the apical plasma membrane. The association of Rab27b with fusiform vesicles and its differentiation-dependent expression suggest that this Rab protein plays a role in regulating the delivery of fusiform vesicles to the apical plasma membrane of umbrella cells.

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“…The tight junction may also function as a barrier to diffusion of membrane constituents between the apical and basolateral membranes (3,19). Cytoskeletons such as microfilaments, observed mostly in the apical cytoplasm, may join and serve as a machinery for the delivery of the fusiform vesicles to the cell surface (16,18). Due to these mechanisms, the superficial cell might maintain its plasma membrane polarity after dissociation.…”

Section: Discussionmentioning

confidence: 99%

Regional differences in lectin binding pattern on the plasma membrane of dissociated rat bladder epithelial cells ad revealed by the ferritin-labeling method.

Nishiyama

Yokoyama

Honda³

1992

Acta Histochem. Cytochem

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The transitional epithelium of the rat urinary bladder was successfully dissociated to single cells and/or clumps of several attached cells, and the morphological features were well preserved in most of the cells. After tissue dissociation, therefore, three cell types, i. e., superficial, intermediate and basal cells, from the epithelium could be clearly and easily identified under the electron microscope. Ferritin-conjugated concanavalin A (Fer-ConA) and Ricinus communis agglutinin (Fer-RCA) binding sites on the surface of the dissociated cells were examined and compared by transmission electron microscopy.In the dissociated superficial cell, Fer-ConA binding sites were essentially negative on the apical plasma membrane except for on its ridge regions, while they were numerous and continuous on the basolateral plasma membrane. Thus, between the apical and the basolateral portions of the plasma membrane, there were obvious regional differences in ConA binding pattern as well as differences in morphological features. On the plasma membrane of the dissociated intermediate cell, Fer-ConA binding sites were distributed irregularly; and on the entire surface of the basal cell, they displayed an even and continuous distribution.In other words, the particular regions of the plasma membrane of the cell types that contained the asymmetric unit membrane lacked Fer-ConA, while the remaining regions with the ordinary unit membrane had numerous sites of Fer-ConA labeling. The basal cell showed the highest density of FerConA binding sites on the plasma membrane among all the cell types.Fer-RCA binding sites on the surface of the plasma membrane were numerous and continuous on the entire cell surface of all three epithelial cell types. In contrast to Fer-ConA, no differences were found in Fer-RCA binding pattern on the cell surfaces among three cell types except that the binding sites were somewhat more numerous in the basal cell.The apical plasma membrane of the superficial cell in the transitional epithelium of the rat urinary bladder is thus a specialized membrane in terms of morphology and composition of membrane surface carbohydrates. The cellular polarity of the superficial cell can be readily appreciated by the ferritin-labeled lectin binding technique.The transitional epithelium of the mammalian urinary bladder is composed of three cell layers, i. e., superficial, intermediate, and basal cell layers. The apical plasma membrane of the superficial cell is a highly specialized membrane with concave plaques of the asymmetric unit membrane (AUM), which have hexagonal lattice of sub-units and are separated by narrow ridge regions of the ordinary unit membrane (UM) (7). Ultrastructural features of the AUM are probably related to its functional properties, i. e., this membrane acts as a barrier to flow of water and ions between the hypertonic urine and the isotonic tissue fluids. It can be presumed that the ultrastructural and functional characteristics of the AUM reflect its unusual chemical composition of lipids and proteins...

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Morphometric analysis of the translocation of lumenal membrane between cytoplasm and cell surface of transitional epithelial cells during the expansion-contraction cycles of mammalian urinary bladder

Cited by 122 publications

References 8 publications

Apical membrane permeability and kinetic properties of the sodium pump in rabbit urinary bladder.

Apical membrane permeability and kinetic properties of the sodium pump in rabbit urinary bladder.

Rab27b is associated with fusiform vesicles and may be involved in targeting uroplakins to urothelial apical membranes

Regional differences in lectin binding pattern on the plasma membrane of dissociated rat bladder epithelial cells ad revealed by the ferritin-labeling method.

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