FIGURE 4.

Ferulic acid induces HO-1 expression and its nuclear translocation. (A–D) Representative images from four independent immunofluorescence experiments in which we carried out a double-labeling with DAPI (A₁–D₁) and an anti-HO-1 antibody (A₂–D₂). Merged images are shown in A₃–D₃. XZ and YZ cross-sections in the boxes (referred to the dashed lines) from the confocal Z-stack acquisitions show cytosolic or nuclear fluorescence signal(s) (XZ and YZ boxes: a₁–d₁ refer to DAPI staining; a₂–d₂ refer to HO-1 fluorescence; a₃–d₃: Merge). In the Control group (A) a faint HO-1 fluorescence localized in the cytosol was detected (a₁–a₃). In TMT (10 μM) treated cells (B) HO-1 fluorescence was strong and primarily localized in the cytoplasm (b₁–b₃). In TMT (10 μM) + FA (10 μM) samples (C) a marked HO-1 activation both in cytoplasm and nucleus was observed, as indicated by Z-stack acquisitions (c₁–c₃). FA (10 μM) treatment induced a strong or moderate increase of HO-1 labeling, localized in the cytoplasm and nucleus, respectively (d₁–d₃ in D). Scale bar: 20 μm. For further information see text.