Visualization of formation of chromosome translocations in living cells

Wednesday, October 10, 2012 — Poster Session II
Noon – 2:00 p.m	Natcher Conference Center, Building 45	NCI	CELLBIO-13

Authors

• V. Roukos
• T. Voss
• T. Misteli

Abstract

Chromosomal translocations play an important role in tumorigenesis. The molecular mechanisms leading to the formation of translocations are poorly characterized. We developed an experimental system to directly visualize the formation of chromosomal translocations in living cells. In this system, we induce DNA breaks at engineered IsceI restriction sites in a controlled fashion to mimic endogenous DSBs. The broken ends are fluorescently marked and can be visualized and tracked in space and time. To capture the low frequency event of a translocation forming in a living cell, we utilized high-throughput microscopy and automated image analysis. We find that upon induction of DSBs repair factors are rapidly recruited to breaks sites and translocations form. Timelapse imaging revealed that translocations were generated by proximal chromosomes confirming a model in which spatial genome organization predisposes chromosomes for translocation. Translocating DSBs exhibited distinct motion properties from non-translocating loci. Moreover, we show that the chromosomal breaks translocate with the similar efficiency in different cell cycle phases. Pharmacological inhibition of key players of the DNA damage response differentially affected the formation of translocations. The experimental system developed here allows for the first time to visualize and probe the cell biological properties of cancer translocations in living cells.

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