Figure 8.

TGF-β1 promotes TAZ protein expression both in vivo and in vitro. A) Double-transgenic Pax8-rtTA-tet-o-TGF-β1 mice were generated by crossing Pax8-rtTA mice with tet-o-TGF-β1 single-transgenic animals to specifically express TGF-β1 in the tubular epithelium only when doxycycline (Dox) is administered. B) Immunohistochemical analysis was used to assess TAZ levels of kidney sections derived from Pax8-rtTA-tet-o-TGF-β1 double-transgenic mice, either noninduced (termed −Dox) or stimulated with Dox for 3 d (+Dox) to conditionally express TGF-β1 in the proximal tubular compartment. Scale bars, 90 μm. C) DAB signal quantitation demonstrating differences in TAZ expression between the 2 experimental groups is shown in the histogram, with the staining intensity of the −Dox kidney set at 1. D) Extracts of HK-2 cells, untreated or treated with TGF-β1 for various times, were processed by Western analysis for TAZ (D, E) and pSMAD3 and GAPDH (D) expression. E) Relative expression of TAZ at the indicated times, arbitrarily setting relative levels of TAZ in unstimulated control cells at 1. NS, not significant. Means ± sd (C, E). *P < 0.05, **P < 0.01.