XB-IMG-176225
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Fig. 2. OGRE/G4 deletion strongly decreases the DNA replication activity of an endogenous origin. a The OGRE/G4 sequence of an endogenous origin (Ori1) was deleted and the deletion was confirmed using a restriction site close to the targeted sequence (see “Methods” section). b G4 formation propensity profiling of the Ori1 sequence targeted for deletion. The Ori1 sequence is located on chromosome 11 and presents a strong peak in the G4-Hunter score profile (red line). Such peak is not present upon OGRE/G4 deletion (alleles 1 and 2, blue and green dotted lines, respectively), and no point above 1 or below −1 is observed. This argues against the probability of G4 formation at this mutated locus. The striped lines on the top indicate the extent of the deletion in allele 1 (red and blue) and allele 2 (green and blue). c Nascent strand enrichment of Ori1 in parental NIH 3T3 cell line (black) and in mutant clones with the deletion (grey). Replication activity was strongly decreased after deletion of the OGRE/G4 sequence, whereas the activity of the external origin (Ori 2) did not vary. The background control regions Bcgd1 and 2 are located in origin-free regions. Results are the mean ± SD of 3 independent experiments; p values were obtained using the two-tailed Student’s t test; *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001, p > 0.05. d Deletion of the OGRE/G4 did not affect the transcription level of the Rai1 gene, associated with Ori1. As a control, the housekeeping genes Actb and Gapdh were used. Results are the mean ± SD of 3 independent experiments; p values were obtained using the two-tailed Student’s t test; p > 0.05. Primer sequences are in Supplementary Table 2. e DNA replication activity was assessed as in Fig. 1c with the EBV origin, or with the 500 bp OGRE/G4 element of Ori2, or after scrambling or deletion of the same OGRE/G4 sequence. Results are the mean ± SD of 4–5 independent experiments; p values were obtained using the two-tailed Student’s t test; *p ≤ 0.05; **p ≤ 0.01; p > 0.05. Note that data presented for episome containing delta oriP and OGRE/G4-containing origin were performed independently from results presented in the Fig. 1; ns not significant: p > 0.05 Image published in: Prorok P et al. (2019) © The Author(s) 2019. This image is reproduced with permission of the journal and the copyright holder. This is an open-access article distributed under the terms of the Creative Commons Attribution license Larger Image Printer Friendly View |