Telomeres Diffusion Study Implies on A Self-Organization Mechanism of the Genome in the Nucleus

The human genome contains tens of thousands of genes that are organized in chromosomes and packed in the nucleus of the cell. How can the chromosomes and DNA stay organized in territories without any compartmentalization? This order is sustained throughout the life cycle of a cell, a property that emerges as a key contributor to genome function, though its full extent is not yet known.To address this question, we studied fluorescently-labeled telomeres diffusion in a broad time range of 10−2 - 104 seconds by combining a few microscopy methods followed by comprehensive diffusion analysis [1]. We found that the telomeres follow a complex diffusion pattern never reported before. The diffusion of the telomeres was found to be anomalous (subdiffusive) at short time scales and it changes to normal diffusion at longer times.The transient diffusion indicates that telomeres are subject to a local binding mechanism with a wide but finite time distribution.We therefore suggest that local temporal binding mechanism leads to the maintenance of structures and positions in the nucleus without the need for actual compartments. Such a mechanism has another advantage by providing flexibility. If telomere binding is switched off (e.g., by shortening the binding time), this will allow the nucleus to undergo architectural changes.[1] I. Bronstein, Y. Israel, E. Kepten, S. Mai, Y. Shav-Tal, E. Barkai and Y. Garini, Transient anomalous diffusion of telomeres in the nucleus of mammalian cells. Physical Review Letters 103, 018102 (2009).