The thymidine synthetic nucleoside analogue bromodeoxyuridine (BrdU) has a long, colorful history of repeated use in molecular and cytokinetic studies, as detailed in reviews by Vanderlaan and Dolbeare (1,2). Because BrDU is only incorporated into newly synthesized DNA in actively replicating S-phase cells, it allows for accurate and comprehensive quantitation of the pattern, rate, and progression of cell proliferation. Data such as DNA-synthesis kinetics, cell fraction in S-phase, and the construction of dynamic proliferation profiles (with variables such as S-phase transit rate and potential doubling time) via bivariate BrdU/DNA flow cytometry analyses and/or microscopy can also be collected. Cells may be labeled in vitro or in vivo with this analogue, and is extremely valuable in detecting proliferation in tissues not easily accessible to other assay types (ie the brain).
BrdU is also commonly used to detect developmental progress in embryogenesis, as its concentration and pattern in tissues can be easily monitored give clues as DeNardo's group from UCSF used the BrdU antibody to study breast cancer survival rates in response to chemotherapy (3). They found that the tumor microenvironment – in this case the abundance of macrophages and T-cells – dictates survival and antitumor immunity. Okamoto et al employed the BrdU antibody in examining the role of the cell surface molecule transiently-expressed axonal glycoprotein 1 (TAG1) in migration and movement of neural progenitors to form proper brain structural architecture (4). Additionally, a recent aging publication from Mitchell’s lab at McMaster University highlights the link between telomeric repeat-binding factor 2 (TRF2) and ataxia telangiectasia mutated (ATM)-mediated structural changes in senescence, and relied upon immunohistochemistry with the BrdU antibody to add much needed knowledge to the cellular localization of methylated TRF25. Their data suggests that methylated TRF2 could be a potential biomarker for senescence triggered by factors such as dysfunctional telomeres and DNA damage.
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