Protein sequences were downloaded from the reviewed section of the UniProt database

phosphorylation, undermining the process of chromatin condensation.24 However there is still debate over whether Thr3 phosphorylation is a prerequisite for Ser10 PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19836572 modification. When Thr3 phosphorylation is strongly inhibited in mammalian cells using multiple Haspin inhibitors, including 5ITu, both the protein level and the subcellular localization of H3S10-P is not distinguishably changed,19 this is in line with our data that H3S10-P is not affected, both in amount and spatial distribution, in 5-ITu-treated oocytes, in spite of the significantly-blocked Thr3 phosphorylation. A growing body of research indicates that H3 Thr3 phosphorylation is indispensable for the full activity of 169939-93-9 Aurora B toward centromeric targets, such as mitotic centromere-associated kinesin and centromere protein A, which regulating kinetochore-microtubule attachments and spindle checkpoint signaling, but significantly less essential for Aurora B activity on chromosome arms, which putatively required for H3S10 phosphorylation.19,27,28 There is also other signal pathway that contributes to Aurora B kinase activity across chromosome arms.28 In the current study, we found that the meiotic resumption and chromatin condensation are significantly delayed in 5-ITutreated oocytes, despite undisturbed H3S10-P expression, this demonstrates that Ser10 phosphorylation is not a sufficient condition for chromatin condensation, and that other factors must be involved, with Thr3 phosphorylation as a prerequisite. The condensin complex is required for chromatin fiber packaging into compact rod-like chromosome, and importantly, this complex uploading to chromatin is dependent on phosphorylated Thr3 in H3 tail.10,24 It is gradually assumed that the properly uploaded condensins, together with H4 K16 deacetylation, a step promoted by H3 Ser10 phosphorylation, is responsible for shaping chromosome structure.24 In mitotic cells, H3T3-P is restricted to centromeres and serves as a ligand for Survivin, a component of the chromosomal passenger complex, mediating the kinase subunit of CPC Aurora B localization on chromosome, particulay at the centromere.20 Dysregulation of H3T3-P expression can affect Aurora B positioning, thus disturb several crucial mitotic events, especially the attachment between microtubules and kinetochores, as well as the functional setup of the spindle checkpoint, leading to severe abnormallity in cell cycle progression and chromosome separation.19,27 Mammalian oocytes contain both Aurora B and Aurora C, and in distinct difference, CELL CYCLE 221 Aurora C localizes to kinetochores and the inter-chromatid axis, whereas Aurora B localizes to the spindle, in spite of their high similarity in sequence. In a great extent, Aurora C is the homolog of mitotic Aurora B in oocytes.2931 The pattern of Aurora C subcellular localization resembles that of Survivin in mouse oocytes during meiotic division.29,32,33 Inhibition of Aurora C activity during meiosis has previously been shown to accelerate the completion of meiosis I by inactivating SAC,29,32 phenocopying the depletion of Survivin.33 The linear distribution of H3T3-P along ICA is similar with that of both Aurora C and Survivin, and inhibition of H3T3-P specially affects the localization of Aurora C at the ICA, but not at the kinetochore, partially due to the absence of H3T3-P aggregation in the centromeric area.19 Given that H2A with phosphorylated T120 at 222 Q. WANG ET AL. centromeres has been reported to regulate the ki