Regulation of centromere localization of the Drosophila Shugoshin MEI-S332 and sister-chromatid cohesion in meiosis.
Bottom Line: These studies also suggested that MEI-S332 can be inactivated independently of delocalization, a conclusion supported here by localization and function studies in meiosis.Phosphoresistant and phosphomimetic mutants for the Aurora B and Polo phosphorylation sites were examined for effects on MEI-S332 localization and chromosome segregation in meiosis.Strikingly, MEI-S332 with a phosphomimetic mutation in the Aurora B phosphorylation site prematurely dissociates from the centromeres in meiosis I.
Affiliation: Whitehead Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142.Show MeSH
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Mentions: Two unexpected observations arose from anti-MEI-S332 staining of wild-type testes. First, although MEI-S332 is enriched at the centromere in early anaphase I, it is also detectable at lower levels throughout the chromosomes, revealing a redistribution at the metaphase I/anaphase I transition (Figure 1). Enhanced sensitivity of the anti-MEI-S332 antibody compared to the GFP signal used in previous studies likely accounts for our ability to observe the protein along the chromosome arms. The protein is not detectable on chromosomes in telophase I and prophase II but is localized to the centromeres in prometaphase II. The second new observation afforded by the antibody staining is that the protein is still present in the centromere region in some anaphase II cells. We do not observe it along chromosome arms as in early anaphase I cells. Because the protein does not delocalize completely at the metaphase II/anaphase II transition, there appears to be a mechanism to release cohesion without complete delocalization of MEI-S332, consistent with the cell culture studies.
Affiliation: Whitehead Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142.