Distribution of u.v.-induced repair events in higher-order chromatin loops in human and hamster fibroblasts.
The repair of u.v.-induced damage in human and rodent cells was investigated at the level of DNA loops attached to the nuclear matrix. After 2 h post-u.v. incubation, DNase I digestion studies revealed a 3- to 4-fold enrichment of repair-labeled DNA at the nuclear matrix in four xeroderma pigmentosum cell strains belonging to complementation group C. This non-random distribution was not affected by treatment with sodium butyrate. In other cells with limited excision repair, i.e. two xeroderma pigmentosum cell strains of complementation group D and Syrian hamster embryonic cells, as well as in HeLa cells and normal human fibroblasts, no enrichment of repair-labeled DNA at the nuclear matrix was observed. Visualization of repair events in DNA loops by autoradiography of DNA halo-matrix structures confirmed the biochemical observations. The presence or absence of preferential repair of nuclear matrix-associated DNA paralleled the presence or absence of inhomogeneity in the distribution of T4 endonuclease-V-sensitive sites. A detailed analysis of repair events in xeroderma pigmentosum cells of complementation group C showed that after 2 h post-u.v. incubation, repair events were found at both attachment sites in a limited number of loops and that large domains of loops were not subjected to repair.
Mullenders
L H
LH
van Kesteren
A C
AC
Bussmann
C J
CJ
van Zeeland
A A
AA
Natarajan
A T
AT
D000818:Animals; D001345:Autoradiography; D002087:Butyrates / Q000494:pharmacology; D020148:Butyric Acid; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism*; D006224:Cricetinae; D004247:DNA / Q000528:radiation effects*; D004260:DNA Repair; D043224:Deoxyribonuclease (Pyrimidine Dimer); D003850:Deoxyribonuclease I / Q000494:pharmacology; D004706:Endodeoxyribonucleases / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D008647:Mesocricetus; D013936:Thymidine / Q000378:metabolism; D014316:Tritium; D014466:Ultraviolet Rays; D014764:Viral Proteins; D014983:Xeroderma Pigmentosum / Q000378:metabolism
D002087:Butyrates; D002250:Carbon Radioisotopes; D002843:Chromatin; D014764:Viral Proteins; D014316:Tritium; D020148:Butyric Acid; D004247:DNA; D004706:Endodeoxyribonucleases; D003850:Deoxyribonuclease I; C470698:endonuclease V, phage T4; D043224:Deoxyribonuclease (Pyrimidine Dimer); D013936:Thymidine