Functional analysis of candidate phosphorylation sites of telomere repeat binding factor 2 (TRF2)

Abstract

TRF2 is a multifunctional protein implicated in telomere length maintenance, DNA double strand break repair and telomere protection. TRF2 undergoes extensive post-translational modification including phosphorylation. Mass spectrometry analysis has identified two candidate TRF2 phosphorylation sites: T317 and S323. In this study, the roles of these two potential phosphorylation sites were examined for their role in cell growth, telomere length maintenance and DNA damage response. Through retroviral infection, HT1080, HeLaII and GM847 cell lines stably expressing the vector alone, Myc-tagged wild type TRF2, Myc-tagged TRF2 carrying a nonphosphorylatable mutation of either T317A or S323A and Myc-tagged TRF2 carrying a phosphomimic mutation of either T317D or S323D were generated. Overexpression of TRF2 mutant alleles has no effect on cell growth and proliferation as well as TRF2 association with ALT-associated PML bodies. On the other hand, the effect of TRF2 mutant alleles on DNA damage response and telomere length maintenance is inconclusive and requires further investigation.