Differences in the Origins of Kinetochore-positive and Kinetochore-negative Micronuclei: A Live Cell Imaging Study

Publication date: Available online 23 February 2016 Source:Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis Author(s): Erkang Jiang Micronuclei (MNi) are extensively used to evaluate genotoxicity and chromosomal instability. Classification of kinetochore-negative (K-MNi) and kinetochore-positive micronuclei (K+MNi) improves the specificity and sensitivity of the micronucleus (MN) test; however, the fundamental differences in the origins of K-MNi and K+MNi have not been addressed due to the limitations of traditional methods. In the current study, HeLa CENP B-GFP H2B-mCherry cells were constructed in which histone 2B (H2B) and centromere protein B (CENP B) were expressed as fusion proteins to monomeric Cherry (mCherry) and EGFP, respectively. MNi were identified using H2B-mCherry; K+MN contained CENP B-GFP, while K-MN did not. Long-term live cell imaging was conducted to examine MN formation in the dual-color fluorescent HeLa cells. The results suggested that K-MNi were derived from kinetochore-negative displaced chromosomes (K-DCs), kinetochore-negative lagging chromosomes (K-LCs) and fragments of broken chromosome bridges (CBs) during late mitotic stages. The results also indicated that K+MNi are derived from kinetochore-positive displaced chromosomes (K+DCs), kinetochore-positive lagging chromosomes (K+LCs), and fragments of broken CBs. Different aberrant chromosomes emerged during mitosis at different frequencies and developed into K-MNi and/or K...

Source: Mutation Research Fundamental and Molecular Mechanisms of Mutagenesis - February 23, 2016 Category: Cytology Source Type: research