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. 2002 Jun;13(6):2001–2015. doi: 10.1091/mboc.13.6.mk0602002001

Figure 8.

Figure 8

Figure 8

ARNT is necessary and sufficient for the recruitment of AhR to active transcription sites. ARNT mutant cells were either not transfected (A–C) or transfected with ARNT expression vector (D–F). Cells were treated for 1 h with 10 nM TCDD, and nascent RNA was labeled by BrUTP incorporation. Cells were fixed and endogenous AhR (A and D) and nascent RNA transcripts (B and E) were detected by indirect immunofluorescence combined with deconvolution microscopy by using anti-AhR and anti-BrU antibodies. Single optical sections from the middle of cells are shown. In the overlays (C and F), yellow indicates colocalizations. Areas marked by a rectangle are enlarged and shown as insets. The arrows point to the positions of the linescans. In contrast to the linescan in G, the linescan in H showed frequent overlaps between the fluorescence intensity peaks for endogenous AhR and nascent RNA, indicating that ARNT recruits AhR to active transcription sites. CCF analyses of endogenous AhR and nascent RNA distributions showed a strong drop around ΔX = 0, indicating a mutual exclusion between two distributions (I). A maximum Rp value and a peak around ΔX = 0 indicated a positively correlated, nonrandom colocalization between two distributions (J). Bars, 2 μm.