Depletion of TRF2 from chromosome ends causes telomeric fusions and genome instability in mammals, but in mouse neural stem cells (mNSCs), Trf2's role is non-telomeric. Although essential for mNSC proliferation and survival, Trf2 does not protect telomeres, aligning with findings that Trf2 is dispensable for telomere protection in pluripotent stem cells. In Trf2-deficient adult mNSCs (Trf2fl/fl; Nestin-Cre), proliferation decreased and neuronal differentiation was impaired, yet no telomere dysregulation or DNA damage response was observed. Similarly, TRF2 depletion in SH-SY5Y cells induced differentiation without telomere dysfunction. Mechanistically, non-telomeric TRF2 directly binds to the promoters of key genes that regulate differentiation, recruiting the polycomb repressor complex (PRC2) for H3K27 trimethylation, repressing differentiation genes to maintain NSC identity. G-quadruplex (G4) motifs are crucial for TRF2 binding; disrupting this interaction via G4-binding ligands or the G4-specific helicase DHX36 induces differentiation genes, promoting neurogenesis. These findings highlight TRF2's non-telomeric role in NSC survival, offering insights into neurogenesis and aging-related neurodegeneration.
Vinayagamurthy et al. (Wed,) studied this question.