Table 2.
Post-translational modifications (PTM) at telomeres.
| Modification target | Org. | PTM type | Responsible enzyme | Function(s) | Reference |
|---|---|---|---|---|---|
| H3K9 | m | Methylation | SUV39H1, SUV39H2 | Chromatin compaction | Blasco (2007) |
| H4K20 | m | Methylation | SUV4-20H1, SUV4-20H2 | Chromatin compaction | Blasco (2007) |
| H3K79 | m | Methylation | Dot1L | Chromatin compaction | Jones et al. (2008) |
| H2BK5, H3K4 | h | Methylation | nd | nd | Rosenfeld et al. (2009) |
| H3K9 | At | Methylation | nd | nd | Vrbsky et al. (2010) |
| H3K27, H3K4 | At | Methylation | nd | nd | Vrbsky et al. (2010), Vaquero-Sedas et al. (2012) |
| H2AX | h | Phosphorylation | ATM, ATR, DNA-PKcs | DDR signaling | Takai et al. (2003) |
| H2A, H2AX | m | Ubiquitylation | RNF8 | DDR signaling | Peuscher and Jacobs (2011), Jacobs (2012) |
| H2A, H2AX | m, h | Ubiquitylation | RNF168 | Recruitment of 53BP1; NHEJ signaling | Doil et al. (2009), Okamoto et al. (2013) |
| H4K12 | Sc | Acetylation | NuA4 | Regulation of chromatin plasticity and accessibility | Zhou et al. (2011) |
| H3K9 | At | Acetylation | nd | nd | Vaquero-Sedas et al. (2012) |
| H3K9ac, H3K56ac | h | Deacetylation | SIRT6 | Chromatin compaction | Michishita et al. (2008), reviewed in Tennen and Chua (2011) |
| H3K9ac | m | Deacetylation | SIRT1 | Chromatin compaction | Palacios et al. (2010) |
| TRF1 | h | Ubiquitylation | Fbx4, RLIM | TRF1 turnover | Chang et al. (2003), Her and Chung (2009) |
| TPP1 | m, h | Ubiquitylation | RNF8 | TPP1 stabilization; A-NHEJ repression | Rai et al. (2011) |
| TRF2 | h | Ubiquitylation | Siah1 | TRF1 turnover, induced by p53 | Fujita et al. (2010) |
| TIN2* | h | Ubiquitylation | Siah2 | TIN2 depletion; possible role in shelterin remodeling | Bhanot and Smith (2012) |
| TRF1 | h | Poly-ADP-ribosylation | Tankyrase (1 and 2) | Decrease of TRF1 affinity for the DNA; TRF1 proteasomal degradation; TL | Smith and de Lange (2000), Cook et al. (2002), Dynek and Smith (2004) |
| Ub-TRF1 | m, h | Deubiquitylation | USP22 | TRF1 turnover; stabilization of WRN telomere association | Atanassov et al. (2009) |
| TRF1, TRF2 | m, h | Sumoylation | SMC5/6 | HR and TL (in ALT cells) | Potts and Yu (2007) |
| TRF2 | h | Methylation | PRMT1 | Telomere stability; telomere length regulation | Mitchell et al. (2009) |
| TRF2 | h | Phosphorylation | Aurora C*, ATM, CHK2 | Decrease of TRF2 binding to telomere | Tanaka et al. (2005), Spengler (2007), Buscemi et al. (2009) |
| TRF1 | h | Phosphorylation | Plk1, CK2 | Increase of telomere binding; role in TRF1 expression-induced apoptosis; TS | Kim et al. (2008), Wu et al. (2008) |
| TRF1 | h | Phosphorylation | ATM, Cdk1 | Decrease of TRF1 binding to telomere; TL | Wu et al. (2007a), McKerlie and Zhu (2011), McKerlie et al. (2012) |
| TRF1 | h | Phosphorylation | Akt* | TS | Chen et al. (2009) |
| Cdc13 | Sc | Sumoylation | Siz1, Siz2 | Telomerase inhibition | Hang et al. (2011) |
| Yku70/80, Sir4 | Sc | Sumoylation | Siz2 | Anchoring at NE, preventing TL | Ferreira et al. (2011) |
| TERT | h | Ubiquitylation | MKRN1, Hdm2, CHIP | TERT proteasomal degradation; TS | Kim et al. (2005), Lee et al. (2010), Oh et al. (2010) |
| TERT | h | Phosphorylation | Tyrosine kinase c-Abl | Inhibition of TERT activity; TS | Kharbanda et al. (2000) |
| Subtelomeric DNA | m | Methylation | DNMT1, DNMT3a, DNMT3b | Chromatin compaction; recombination repression; TS | Gonzalo et al. (2006) |
| nd | m | Phosphorylation | DNA-PKcs | Telomere protection | Bailey et al. (2004), Williams et al. (2009) |
| nd | Sc | Ubiquitylation | Cul8 | Transcriptional silencing | Mimura et al. (2010) |
org, organism; m, mouse; h, human; At, Arabidopsis thaliana; Sc, Saccharomyces cerevisiae; nd, not determined; *, in vitro evidences; DDR, DNA damage response; A-NHEJ, alternative non-homologous end-joining; TL, telomere lengthening; HR, homologous recombination; TS, telomere shortening; NE, nuclear envelope.