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Two- and Three-Dimensional Live Cell Imaging of DNA Damage Response Proteins
Published on: September 28, 2012
Active dissociation of Hoechst 33342 from DNA in living mammalian cells
M V Filatov1, E Y Varfolomeeva
1St. Petersburg Nuclear Physics Institute, Russia.
Abstract:
The fluorescent dye Hoechst 33342, which binds tightly to DNA in the minor groove, can be effectively extracted from the DNA in vivo due to an energy-dependent process. It is the dissociation of the dye from DNA rather than its removal from a cell that has a critical role in this process. The dissociation can be suppressed by the topoisomerase-2 inhibitors novobiocin, ellipticine and etoposide. Breaks in the DNA also inhibit the process. The dissociation of the dye requires that DNA remain intact along a region of at least several thousand base pairs. It is proposed that DNA in mammalian cells is a dynamic, conformationally nonstable system and that topologically closed loops consisting of several thousand base pairs constantly appear and disappear in chromatin.
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