TRF1 phosphorylation on T271 modulates telomerase-dependent telomere length maintenance as well as the formation of ALT-associated PML bodies

• Published in: Scientific reports 2016-11, Vol.6 (1), p.36913-36913, Article 36913
• Main Authors: Ho, Angus, Wilson, Florence R., Peragine, Stephanie L., Jeyanthan, Kajaparan, Mitchell, Taylor R. H., Zhu, Xu-Dong
• Format: Article
• Language: English
• Subjects: 13/106; 13/109; 13/44; 13/51; 13/89; 14/63; 631/337; 631/80; Cell Line, Tumor; Chromosomes; Deoxyribonucleic acid; DNA; Elongation; HeLa Cells; Homeostasis; Humanities and Social Sciences; Humans; Intranuclear Inclusion Bodies - metabolism; multidisciplinary; Mutation; Phosphorylation; Post-translation; Promyelocytic Leukemia Protein - metabolism; Protein Binding; Science; Telomerase; Telomerase - metabolism; Telomere - metabolism; Telomere Homeostasis; Telomeres; Telomeric Repeat Binding Protein 1 - chemistry; Telomeric Repeat Binding Protein 1 - genetics; Telomeric Repeat Binding Protein 1 - metabolism; Threonine; Tyrosine - chemistry
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep36913

TRF1, a component of the shelterin complex, plays a key role in both telomerase-dependent telomere maintenance and alternative lengthening of telomeres, the latter also known as ALT. Characteristics of ALT cells include C-circles and ALT-associated PML bodies, referred to as APBs. The function of TRF1 is tightly regulated by post-translational modification including phosphorylation, however TRF1 phosphorylation sites have yet to be fully characterized. Here we report a novel TRF1 phosphorylation site threonine 271. We show that a nonphosphorylatable mutation of T271A impairs TRF1 binding to telomeric DNA in vivo and renders TRF1 defective in inhibiting telomerase-dependent telomere elongation. On the other hand, TRF1 carrying a phosphomimic mutation of T271D is competent in not only binding to telomeric DNA but also inhibiting telomerase-mediated telomere lengthening. These results suggest that TRF1 phosphorylation on T271 negatively regulates telomerase-mediated telomere maintenance. We find that in telomerase-negative ALT cells, TRF1 carrying either a T271A or T271D mutation is able to promote C-circle production but fails to support APB formation. These results suggest that TRF1 phosphorylation on T271 is necessary for APB formation but dispensable for C-circle production. These results further imply that APB formation can be mechanistically separated from C-circle production.