caa a22 4500 397502478 CHVBK 20180308164535.0 cr unu---uuuuu 161202e19951001xx s 000 0 eng 10.1093/oxfordjournals.rpd.a082811 doi 0144-8420 pii (NATIONALLICENCE)oxford-10.1093/oxfordjournals.rpd.a082811 Repair-Modification of Radiodamaged Genes [Elektronische Daten] [P. Volpe, T. Eremenko] It is proposed that through repair-modification, the modified base 5mC may have facilitated the divergent evolution of coding (hypomethylated exon) and uncoding (hypermethylated promoter and intron) sequences in eukaryotic genes. The radioinduced repair patches appearing in regions lacking 5mC are fully reconstructed by excision-repair, whereas those appearing in regions containing 5mC are incompletely reconstructed by this conventional mechanism. Such a second class of repair patches may, however, become fully reconstructed, in the S phase, by repair-modification. In fact, while DNA polymerase ß - which is a key enzyme of excision-repair - is active through the whole interphase. DNA methylase - which is responsible for postsynthetic DNA modification - is essentially active in S. Uncoupling of these two enzyme systems, outside S, might explain why in unsynchronised cells repair patches of non-replicating strands are hypomethylated when compared with specific methylation of replicating strands. In other words, excision-repair would always be able to re-establish the primary ATGC language of both damaged unmethylated and methylated regions, while repair-modification would be able to re-establish the modified ATGC(5mC) language of the damaged methylated regions, only in S, but not in G1 or G2. In these two phases, when DNA methylation is inversely correlated with pre-mRNA transcription (as in the case of many tissue-specific genes), such demethylation might induce a silent transcriptional unit to become active. Radiation Protection Dosimetry Volpe P. aut Eremenko T. aut Radiation Protection Dosimetry Oxford University Press 62/1-2(1995-10-01), 19-22 0144-8420 62:1-2<19 1995 62 rpd https://doi.org/10.1093/oxfordjournals.rpd.a082811 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/oxfordjournals.rpd.a082811 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Volpe P. aut NATIONALLICENCE 700 1- Eremenko T. aut NATIONALLICENCE 773 0- Radiation Protection Dosimetry Oxford University Press 62/1-2(1995-10-01), 19-22 0144-8420 62:1-2<19 1995 62 rpd Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford