53BP1 - DNA damage is no fun

Wed, 05/07/2014 - 09:20

The 53BP1 (p53 binding protein 1) was initially believed to be a p53 transcriptional enhancing partner, but it has now been established as an ataxia telangiectasia mutated (ATM) substrate. As a late DNA damage response (DDR) marker, 53BP1 appears during the telophase and cytokinesis phase of mitotic mammalian cells1. This was discovered when a 53BP1 antibody was applied to mitotic cells to demonstrate the absence of a full DDR response that was also sensitive to suppression by high levels of cyclin-dependent kinase1 (CDK1) activation. Additionally, the ubiquitination cascade was known to be involved in 53BP1 recruitment to DNA damage sites within cells, but Mallette’s group used a 53BP1 antibody to pinpoint the degradation of the JMJD2A/KDM4A tandem tumor domain via an E3 ubiquitin ligase RNF8 pathway2.

Immunocytochemistry/Immunofluorescence: 53BP1 Antibody Immunocytochemistry/Immunofluorescence: 53BP1 Antibody

More DNA damage experiments were performed using a 53BP1 antibody in rat embryos with damaged paternal genomes that were exposed to cyclophosphamide, an anticancer alkylating agent3. In those studies, the DNA damage repair response appears to be helpful for assessing embryo viability and developmental competence. Another cell cycle study involving a 53BP1 antibody focused on characterizing competitive differences between 53BP1 and BRCA1 regulation in both cycling and non-cycling cells4. There, Croke’s group found that breast cancer cells exhibit an endogenous means of balancing both of these systems. Immunofluorescent and immunohistochemical studies with 53BP1 antibodies that were published in Nature Cell Biology by Naim’s group demonstrated the proteins ERCC1 and MUS81-EME1 co-localize to chromosomal instability areas known as common fragile sites (CFSs) within mitotic chromosomes5.

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