Ctc1/Stn1/Ten1 complex is important for telomere maintenance.The essential role of hStn1 is in promoting efficient replication of lagging-strand telomeric DNA. Human Stn1 protects telomere integrity by promoting efficient lagging-strand synthesis at telomeres and mediating C-strand fill-in. Depletion of hStn1 induces catastrophic telomere shortening, DNA damage response, and early senescence in human somatic cells.
hStn1 deficiency leads to persistent and elevated association of DNA polymerase α (polα) to telomeres, suggesting that hStn1 may modulate the DNA synthesis activity of polα rather than controlling the loading of polα to telomeres. Additionally, data suggest that hStn1 is unlikely to be part of the telomere capping complex. The hStn1 assists DNA polymerases to efficiently duplicate lagging-strand telomeres in order to achieve complete synthesis of telomeric DNA, therefore preventing rapid telomere loss.