Topoisomerase II alpha is required for embryonic development and liver regeneration in zebrafish.
Topoisomerases solve the topological problems encountered by DNA throughout the lifetime of a cell. Topoisomerase II alpha, which is highly conserved among eukaryotes, untangles replicated chromosomes during mitosis and is absolutely required for cell viability. A homozygous lethal mutant, can4, was identified in a screen to identify genes important for cell proliferation in zebrafish by utilizing an antibody against a mitosis-specific marker, phospho-histone H3. Mutant embryos have a decrease in the number of proliferating cells and display increases in DNA content and apoptosis, as well as mitotic spindle defects. Positional cloning revealed that the genetic defect underlying these phenotypes was the result of a mutation in the zebrafish topoisomerase II alpha (top2a) gene. top2a was found to be required for decatenation but not for condensation in embryonic mitoses. In addition to being required for development, top2a was found to be a haploinsufficient regulator of adult liver regrowth in zebrafish. Regeneration analysis of other adult tissues, including fins, revealed no heterozygous phenotype. Our results confirm a conserved role for TOP2A in vertebrates as well as a dose-sensitive requirement for top2a in adults.
Dovey
Michael
M
Children's Hospital and Dana-Farber Cancer Institute, Boston, MA, USA.
Patton
E Elizabeth
EE
Bowman
Teresa
T
North
Trista
T
Goessling
Wolfram
W
Zhou
Yi
Y
Zon
Leonard I
LI
D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002875:Chromosomes / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008115:Liver Regeneration / Q000502:physiology*; D008297:Male; D008938:Mitosis / Q000502:physiology; D008969:Molecular Sequence Data; D000075223:Poly-ADP-Ribose Binding Proteins; D015027:Zebrafish / Q000033:anatomy & histology / Q000196:embryology / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
D000951:Antigens, Neoplasm; D004268:DNA-Binding Proteins; D007527:Isoenzymes; D000075223:Poly-ADP-Ribose Binding Proteins; D029961:Zebrafish Proteins; D004250:DNA Topoisomerases, Type II; C000618811:TOP2A protein, human