Three-dimensional imaging reveals the spatial separation of 纬H2AX-MDC1-53BP1 and RNF8-RNF168-BRCA1-A complexes at ionizing radiation-induced foci

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• 作者：Myth T.S. Mok ; ^{mythmok@mythmok.com} ; Beric R. Henderson ^{beric.henderson@sydney.edu.au}
• 关键词：DNA damage ; Ionizing radiation ; Nuclear foci ; 纬H2AX ; MDC1 ; RNF8 ; RNF168 ; 53BP1 ; Abraxas (CCDC98) ; BRCA1 ; BRCC36 ; Merit40 (NBA1) ; RAP80
• 刊名：Radiotherapy and Oncology
• 出版年：2012
• 期刊代码：231_01678140
• 类别：med
• 出版时间：June, 2012
• 卷：103
• 期：3
• 页码：415-420
• 文件大小：1190 K

摘要

Background and purpose

Ionizing radiation (IR)-induced DNA damage causes the accumulation of DNA damage response (DDR) proteins as visible foci in cell nuclei. Despite the identified functional roles in DNA repair, the spatial relationships of different DDR proteins at foci have not been explicitly examined. This study aims to systematically compare the distribution of DDR proteins at IR-induced foci.

Materials and methods

MCF-7 cells were treated with IR, stained for 纬H2AX, MDC1, RNF8, RNF168, 53BP1, Abraxas (CCDC98), BRCA1, BRCC36, Merit40 (NBA1) and RAP80, and then imaged using high-resolution three-dimensional (3-D) confocal microscopy to assess the relative localization of proteins at foci.

Results

All BRCA1-A complex components displayed strong co-localization, which overlapped significantly with RNF8 and RNF168, but not with 纬H2AX and MDC1. Intriguingly, 53BP1 co-located well with 纬H2AX and MDC1, but remained separate from RNF8 and RNF168. These co-localization patterns were consistent for at least 3 h after IR.

Conclusions

The foci formations of 纬H2AX-MDC1-53BP1 and RNF8-RNF168-BRCA1-A complexes are spatially independent. Such divergence was not anticipated from prior studies on the recruitment of these proteins to foci. This information indicates that individual foci may represent distinct sites of DNA repair facilitated by a specific subset of DDR proteins.