PIN2 Interacting Protein 1 (PINX1)

PINX1, was found to inhibit telomerase activity and affect tumorigenicity. The predicted 328-amino acid PINX1 protein has a gly-rich region in its N terminus and a telomerase inhibitory domain (TID) in its C terminus.PINX1 encodes a 45-kD protein in cells.Overexpression of PINX1 or its TID inhibited telomerase activity, shortened telomeres, and induced crisis, whereas depletion of endogenous PINX1 increased telomerase activity and elongated telomeres. Depletion of PINX1 also increased tumorigenicity in nude mice, consistent with its localization at 8p23, a region with frequent loss of heterozygosity in a number of human cancers. The authors concluded that PINX1 is a potent telomerase inhibitor and a putative tumor suppressor.