Abstract
Human telomerase RNA component hTERC comprises multiple motifs that contribute to hTERC biogenesis, holoenzyme activity, and enzyme recruitment to telomeres. hTERC contains several guanine tracts (G-tracts) at its 5'-end, but its associated proteins and potential roles in telomerase function are still poorly understood. The heterogeneous nuclear ribonucleoproteins F, H1, and H2 (hnRNP F/H) are splicing factors that preferentially bind to poly(G)-rich sequences RNA. Here, we demonstrate that hnRNP F/H associate with both hTERC and telomerase holoenzyme to regulate telomerase activity. We reveal hnRNP F/H bind to the 5'-end region of hTERC in vitro and in vivo, and identify the first three G-tracts of hTERC and qRRM1 domain of hnRNP F/H are required for their interaction. Furthermore, hnRNP F/H also directly interact with telomerase holoenzyme. Functionally, we show that hnRNP F/H plays important roles in modulating telomerase activity and telomere length. Moreover, hnRNP F/H deletion greatly impair cancer and stem cell proliferation, and induce stem cell senescence, while hnRNP F/H overexpression delay stem cell senescence. Collectively, our findings unveil a novel role of hnRNP F/H as the binding partners of hTERC and telomerase holoenzyme to regulate telomerase function.