Telomeric repeat-containing RNA structure in living cells.

Telomeric repeat-containing RNA (referred to as TERRA), a noncoding RNA molecule, has recently been found in mammalian cells. The detailed structural features and function of the TERRA RNA at human chromosome ends remain unclear, although this RNA molecule may be a key component of the telomere machinery. In the present studies, we investigated the structural features of human TERRA RNA in living cells. Using a light-switching pyrene probe, we found that human TERRA RNA forms a parallel G-quadruplex structure in living cells, providing the in vivo evidence for the presence of the G-quadruplex in human TERRA RNA. Furthermore, imaging experiments clearly show that TERRA RNA G-quadruplex localizes to telomere DNA at cell nuclei. These results provide valuable information to allow understanding of the structure and function of human TERRA RNA.