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. Author manuscript; available in PMC: 2013 Jun 24.
Published in final edited form as: Mol Cell Endocrinol. 2011 Sep 21;357(1-2):30–36. doi: 10.1016/j.mce.2011.09.006

Figure 1. PR rapidly and dynamically interacts with the MMTV LTR.

Figure 1

(A) Relative position of regulatory elements in the MMTV LTR. DNA elements reported to bind PR Nfl and Oct are marked by blue, green and red respectively. (B) Relative position of nucelosmes at reconstituted MMTV LTR. (C and D) Array of two hundred copies head to tail MMTV LTR incorporated into chromosome four. Activated GFP tagged PR binds the MMTV array and give rise to an intense fluorescence signal (marked by yellow arrow) that can be detected in the nucleus above background. FRAP studies of GFP-PR bound MMTV array show that PR dynamically interacts with the MMTV array with on/off rates in a matter of seconds. (E) Integrative analysis of receptor occupancy of MMTV from single cells correlates with ChIP analysis on a population of cells. Model shows alleles with a single PR binding site from different cells in a cell population. After activation with hormone, interaction frequency of receptor and binding site increases in the majority of cells in the population. When a population of cells are analyzed by ChIP this dynamic interactions give rise to a signal above background. When a population of cells are synchronized waves spaced by minutes of receptor interaction with DNA can be detected. However at any time when focusing on single cells the receptor rapidly interacts (seconds) with chromatin.