Both alpha and beta isoforms of mammalian DNA topoisomerase II associate with chromosomes in mitosis.
Two isoforms of DNA topoisomerase II, alpha and beta, coded by separate genes, are expressed in actively cycling vertebrate cells. Some previous studies have suggested that only topoisomerase II alpha remains associated with chromosomes at mitosis. Here, the distributions of topoisomerase II alpha and beta in mitosis were studied by subcellular fractionation and by immunolocalization. Both isoforms of topoisomerase II were found to remain associated with mitotic chromatin. Topoisomerase II alpha was distributed along chromosome arms throughout mitosis and was highly concentrated at centromeres until mid-anaphase, particularly in some cell types. Topoisomerase II beta showed weak concentration at centromeres in early mitosis in some cell types and was distributed along chromosome arms at every stage of mitosis through telophase. These studies suggest that in most cells both the major topoisomerase II isoforms may play roles in chromatin remodeling during M phase.
Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA.
Allison P
AP
Null
Joanna
J
Hudson
Gary J
GJ
Gorbsky
D000818:Animals; D000906:Antibodies; D000918:Antibody Specificity / Q000276:immunology; D000951:Antigens, Neoplasm; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002875:Chromosomes / Q000235:genetics*; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D004268:DNA-Binding Proteins; D004173:Dipodomys; D005057:Eukaryotic Cells / Q000166:cytology / Q000201:enzymology*; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics / Q000276:immunology / Q000378:metabolism
D000906:Antibodies; D000951:Antigens, Neoplasm; D004268:DNA-Binding Proteins; D020033:Protein Isoforms; D004247:DNA; D004250:DNA Topoisomerases, Type II