PinX1 Localizes to Telomeres and Stabilizes TRF1 at Mitosis

Abstract

Human telomeres are DNA-protein complexes that cap and protect the ends of chromosomes. The protein PinX1 associates with telomeres through an interaction with the resident double-stranded telomere-binding protein TRF1. PinX1 also binds to and inhibits telomerase, the enzyme responsible for complete replication of telomeric DNA. We now report that endogenous PinX1 associates with telomeres primarily at mitosis. Moreover, knockdown of PinX1 caused delayed mitotic entry and reduced the accumulation of TRF1 on telomeres during this stage of the cell cycle. Taking these findings together, we suggest that one function of PinX1 is to stabilize TRF1 during mitosis, perhaps to promote transition into M phase of the cell cycle.

ACKNOWLEDGMENTS

We thank J. Linger for TRF1 cDNA and S. Smith and D. Broccoli for anti-TRF1 antibodies.

This research was supported by NIH grants CA082481 and CA123031 (to C.M.C.).