The role of the poly(ADP-ribose) polymerase tankyrase1 in telomere length control by the TRF1 component of the shelterin complex

Authors:
Donigian JR, de Lange T
In:
Source: J Biol Chem
Publication Date: (2007)
Issue: 282(31): 22662-7
Research Area:
Cancer Research/Cell Biology
Cells used in publication:
NIH/3T3
Species: mouse
Tissue Origin: embryo
Embryonic fibroblast, mouse (MEF) immort
Species: mouse
Tissue Origin: embryo
Platform:
Nucleofectorâ„¢ I/II/2b
Abstract
Tankyrase1 is a multifunctional poly(ADP-ribose) polymerase (PARP) that can localize to telomeres through its interaction with the shelterin component TRF1. Tankyrase1 poly(ADP-ribosyl)ates (PARsylates) TRF1 in vitro and its nuclear overexpression leads to loss of TRF1 and telomere elongation, suggesting that tankyrase1 is a positive regulator of telomere length. In agreement with this proposal, we show that tankyrase1 RNAi results in telomere shortening proportional to the level of knockdown. Furthermore, we show that a tankyrase1 resistant form of TRF1 enforced normal telomere length control, indicating that tankyrase1 is not required downstream of TRF1 in this pathway. Thus, in human cells, tankyrase1 appears to act upstream of TRF1, promoting telomere elongation through the removal of TRF1. This pathway appears absent from mouse cells. We show that murine TRF1, which lacks the canonical tankyrase1 binding site, is not a substrate for tankyrase1 PARsylation in vitro. Furthermore, overexpression of tankyrase1 in mouse nuclei did not remove TRF1 from telomeres and had no detectable effect on other components of mouse shelterin. We propose that the tankyrase1-controlled telomere extension is a human specific elaboration that allows additional control over telomere length in telomerase positive cells.