FIGURE 9.

A model for PinX1 as a link between TRF1 and telomerase inhibition. As telomeres are elongated by telomerase, increased TRF1 molecules bind, recruiting more PinX1 for telomerase inhibition. Once telomerase activity is inhibited, telomeres begin to shorten with each round of DNA replication, resulting in fewer TRF1 binding sites, less recruitment of PinX1 to inhibit telomerase, and therefore, re-entry of telomerase. This leads to telomere elongation and the start of another round of this cycle.