Controlled light exposure microscopy reveals dynamic telomere microterritories throughout the cell cycle

Area of Science:

• Cell Biology
• Genetics
• Microscopy

Background:

• Telomeres are crucial for chromosome stability but their organization in cycling human cells remains unclear.
• Understanding telomere dynamics is essential for insights into genome instability.

Purpose of the Study:

• To investigate the spatiotemporal organization and dynamic behavior of telomeres throughout the cell cycle in living human cells.
• To elucidate the role of telomere-binding proteins TRF1 and TRF2 in telomere organization.

Main Methods:

• Utilized four-dimensional microscopy in living human ECV-304 cells stably expressing TRF1 and TRF2 fused to mCitrine.
• Employed controlled light exposure microscopy (CLEM) to minimize photodamage.
• Combined stable cell lines, CLEM, and cytometry for nuclear organization studies.

Main Results:

• Identified dynamic telomere association within small territories, often at chromatin domain interfaces.
• TRF1 and TRF2 proteins are present in these territories but not rigidly bound.
• Observed dissociation of TRF proteins and disintegration of telomere territories at mitosis onset, rendering individual telomeres faintly visible.

Conclusions:

• Novel insights into compartment-based nuclear organization and telomere dynamics were provided.
• The study offers a model approach for investigating telomere-driven genome instability and long-term nuclear dynamics.