Abstract
Transforming acidic coiled-coil (TACC) proteins are key players during mitosis via stabilization of the spindle. The roles of TACCs during meiosis are however less clear. We used bovine oocytes to study the expression and function of TACC3 during meiosis. TACC3 mRNA was detected in bovine oocytes during meiosis using qRT-PCR, and while it was also expressed in cleavage stage embryos, its expression was down-regulated at the morula and blastocyst stages. Immunofluorescence was used to demonstrate that TACC3 co-localized with tubulin in the metaphase I and II spindles. However, TACC3 was not detected at anaphase or telophase of the first meiotic division. Aurora A, which is known to phosphorylate and activate TACC3 in mitotic cells, showed a similar pattern of gene expression to that of TACC3 in meiotic oocytes and preimplantation embryos. Aurora A protein was however only very transiently associated to the meiotic spindle. Pharmaceutical inhibition of Aurora A activity inhibited TACC3 phosphorylation but did not prevent TACC3 appearance in the spindle. Inhibiting Aurora A activity did however lead to abnormal meiotic spindle formation and impaired maturation of bovine oocytes. Similar results were obtained by knock-down of TACC3 expression using siRNA injection. These results suggest that TACC3 is important for stabilizing the meiotic spindle, but phosphorylation of TACC3 by Aurora A is not required for its recruitment to the meiotic spindle although phosphorylation of TACC3 by other kinases cannot be excluded.
Highlights
During its preparation for fertilization, an oocyte reduces its DNA content to a haploid set of chromosomes via a process known as meiosis
Using conventional Reverse transcription (RT)-PCR, TACC3 mRNA expression was detected in all tissues examined (Fig 1B)
In order to examine the levels of TACC3 protein during oocyte maturation, lysates of germinal vesicle (GV) and meiotic division (MII) stage oocytes were examined by immunoblotting using a custom-made TACC3 antibody
Summary
During its preparation for fertilization, an oocyte reduces its DNA content to a haploid set of chromosomes via a process known as meiosis. Abnormal segregation of chromosomes can lead to numerical chromosome abnormalities, i.e. aneuploidy, which is generally incompatible with normal embryonic development. Whereas in fetal and adult tissues, abnormally dividing (mitotic) cells can be eliminated by for example apoptosis, abnormal chromosome segregation. TACC3 in Bovine Oocyte Meiosis study design, data collection and analysis, decision to publish, or preparation of the manuscript The Anistem Industry-Academia Partnerships and Pathways is a European FP7 IAPP project (non-commercial); EpiHealthNet Initial Training Networks is a European FP7 ITN project (non-commercial). The funding does not alter the authors' adherence to PLOS ONE policies on sharing our data and materials. There are no restrictions on sharing the authors' data and/or materials
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