Figure 5.

Uroplakin III localization and stretch-induced increases in cell surface uroplakin III expression and metabolically labeled protein secretion. (A) Ultrathin cryosections of 5-h control tissue labeled with anti-uroplakin III antibody and secondary antibody conjugated to 5-nm gold. Asterisks denote examples of uroplakin III-positive vesicles. (B) Representative Western blots of total and cell surface uroplakin III expression in control or stretched samples. The bottom panel is exposed longer to allow the total cell signal in stretched samples to be visible. (C) Quantification of relative expression of cell-associated uroplakin III at the apical surface for each condition. Shown is mean ± SEM (n = 5). (D) Samples were stretched for 5 h and labeled with anti-uroplakin III antibody and secondary antibody conjugated to 5-nm gold. (E) Cells were pulsed with [³⁵S]cysteine/methionine, chased for 1 h, and stretched or incubated without stretch for 5, 15, 120, or 300 min. Shown is average cpm present in apical medium at each time point ± SEM (n = 3). (F) Percentage of basally added [¹⁴C]urea that appeared in the apical medium after 0, 15, 120, or 300 min of stretch or incubation without stretch. Shown is mean ± SEM (n = 3).