Journal: Cell reports
Article Title: TRF2 Mediates Replication Initiation within Human Telomeres to Prevent Telomere Dysfunction
doi: 10.1016/j.celrep.2020.108379
Figure Lengend Snippet: (A) Immunoblot of cell lysates of LOX cell lines stably expressing Dox-inducible SNF2H shRNA or Luc control shRNA. (B) ChIP analysis of LOX cells stably expressing Dox-inducible SNF2H shRNA grown in the absence+ (−) or presence (+) of 1 μg/mL Dox for 10 days using antibodies against ORC2, MCM3, or IgG (control). Blots were probed by hybridization with 32 P-labeled TelG or Alu probes. (C) Quantification of four independent experiments represented in (B). The ChIP data were first normalized to input, and the percent input for Dox (+) is shown as relative to Dox (−), which was set as 1. Student’s t test was used for statistical analysis. Error bars indicate SD. **p < 0.002; ns, p > 0.05. (D) Telomere length analysis of LOX cell lines stably expressing Dox-inducible SNF2H shRNA or Luc control shRNA. Cells were grown in the absence (−) or presence (+) of 1 μg/mL Dox for 10 days. Telomere length and relative amount of telomeric DNA were determined by restriction digestion of genomic DNA with AluI/MboI, followed by PFGE and Southern hybridization with a 32 P-labeled (CCCTAA) 4 probe. Ethidium bromide staining of the total DNA digest was used to normalize for DNA loading (bottom). Fragment size (in kilobases) is indicated on the left of the blot. The relative intensity of telomeric DNA signals (− Dox versus + Dox) is indicated below the blot. (E) Model of telomeric origin function in telomere replication. The repetitive sequence of telomeric DNA impedes and stalls replication forks. Failure to restart replication (i) leads to incomplete replication, telomere repeat loss, and dysfunction. Restart of replication from telomeric origins (ii) results in completion of telomere replication and proper telomere maintenance. (F) Model of telomeric origin assembly and firing. (i) SNF2H remodels telomere chromatin to allow ORC loading. (ii) TRF2 recruits the ORC. (iii) The ORC recruits cdc6 and cdt1, followed by double-hexamer MCM replicative helicase loading, resulting in pre-RC formation (origin licensing). (iv) Telomeric origin fires.
Article Snippet: Antibodies used in ChIP assays include rabbit polyclonal antibodies ORC2 (Bethyl), MCM3 (Abcam), histone H3K9me3 (Diagenode) or IgG (Cell Signaling).
Techniques: Western Blot, Stable Transfection, Expressing, shRNA, Control, Hybridization, Labeling, Staining, Sequencing