engleski

The subcellular localization and oligomerization preferences of NME1/NME2 upon radiation-induced DNA damage

Nucleoside diphosphate kinases (NDPK/NME/Nm23) are housekeeping enzymes responsible for the maintenance of the cellular NTP pool by catalyzing the exchange of terminal phosphate from trinucleotides to dinucleotides through a high-energy phosphohistidine intermediate. At least 80 % of the cytoplasmic NDPK activity is being exerted by NME1/NDPK A and NME2/NDPK B which combine to form isoenzymes (A6, A5B1, …, B6). The NME1/NDPK A and NME2/NDPK B subunits have a variety of additional biological functions, from metastasis suppression and DNA damage repair to proliferation and development. Although eukaryotic NDPKs are active only as hexamers, it is unclear whether other NME functions require the hexameric form and how the isoenzyme composition varies in different cellular compartments. To investigate the effect of DNA damage on the intracellular localization of NME1 and NME2 and the composition of NME oligomers in the nucleus and cytoplasm, we used live-cell imaging and the FRET/FLIM technique. We demonstrated that exogenous NME1 and NME2 proteins colocalize in the cytoplasm of non-irradiated cells and move simultaneously to the nucleus after gamma irradiation. The FRET/FLIM experiments suggest that there is a slight shift in the homomer/heteromer balance between the nucleus and cytoplasm after DNA damage. Overall, our results suggest that NME1 and NME2 engage in mutual functions in the nucleus after irradiation, possibly performing specific functions in their homomeric state.

NME protein family ; NDPK ; DNA damage ; FRET/FLIM ; live-cell imaging

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