urochordate ascidians possess a single isoform of aurora kinase that localizes to the midbody via tpx2 in eggs and cleavage stage embryos有尾索的海鞘类具有一个同种型极光激酶所在的中间体通过tpx2鸡蛋和卵裂胚胎阶段.pdf
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Urochordate Ascidians Possess a Single Isoform of
Aurora Kinase That Localizes to the Midbody via TPX2 in
Eggs and Cleavage Stage Embryos
Celine Hebras, Alex McDougall*
´
Universite Pierre et Marie Curie and CNRS, Developmental Biology Unit, Villefranche-sur-Mer, France
Abstract
Aurora kinases are key proteins found throughout the eukaryotes that control mitotic progression. Vertebrate Aurora-A and
B kinases are thought to have evolved from a single Aurora-kinase isoform closest to that found in present day
urochordates. In urochordate ascidians Aurora binds both TPX2 (a vertebrate AURKA partner) and INCENP (a vertebrate
AURKB partner) and localizes to centrosomes and spindle microtubules as well as chromosomes and midbody during both
meiosis and mitosis. Ascidian Aurora also displays this localization pattern during mitosis in echinoderms, strengthening the
idea that non-vertebrate deuterostomes such as the urochordates and echinoderms possess a single form of Aurora kinase
that has properties of vertebrate Aurora-kinase A and B. In the ascidian, TPX2 localizes to the centrosome and the spindle
poles also as in vertebrates. However, we were surprised to find that TPX2 also localized strongly to the midbody in ascidian
eggs and embryos. We thus examined more closely Aurora localization to the midbody by creating two separate point
mutations of ascidian Aurora predicted to perturb binding to TPX2. Both forms of mutated Aurora behaved as predicted:
neither localized to spindle poles where TPX2 is enriched. Interestingly, neither form of mutated Aurora localized to the
midbody where TPX2 is also enriched, suggesting that ascidian Aurora midbody localization required TPX2 binding in
ascidians. Functional analysis revealed that inhibition of Aurora kinase with a pharmacological inhibi
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