Shelterin complex (Shelterin)

The Shelterin complex, also known as the telosome, is a specialized six-protein assembly consisting of TRF1, TRF2, POT1, TIN2, TPP1, and RAP1 that binds specifically to telomeric DNA to maintain genomic integrity. Its primary biological function is to cap the ends of chromosomes, sequestering the 3' single-stranded telomeric overhang into a protective T-loop structure that prevents the DNA damage response (DDR) machinery from recognizing chromosome ends as double-strand breaks. By inhibiting ATM and ATR kinase signaling and repressing repair pathways like non-homologous end joining (NHEJ) and homology-directed repair (HDR), the complex prevents chromosomal fusions and instability. In many cancers, the shelterin complex is dysregulated to facilitate telomere maintenance and cellular immortality, making it a high-priority therapeutic target. Pharmacological interventions include G-quadruplex stabilizers that displace shelterin proteins and small molecules designed to disrupt critical protein-protein interactions within the complex. Such treatments aim to induce telomere uncapping, triggering senescence or apoptosis specifically in malignant cells. However, a significant therapeutic challenge remains the potential for off-target effects on healthy stem cells and the risk of inducing widespread genomic instability.

Other names

TelosomeTelomere-binding protein complexShelterinTelomere-specific protein complex

Disruption of telomere capping to induce DNA damage response (ATM/ATR activation), inhibition of telomerase access to the 3' overhang, and stabilization of G-quadruplex structures to displace shelterin components.