Abstract： Aurora A is one of the serine/threonine protein kinase who participates in a series of biological events such as centrosome replication, spindle assembly and cytokinesis. The purpose of this study was to explore the dynamic expression and function of Aurora A during oocyte-to-embryo transition in porcine (Sus scrofa). As Aurora A has an extremely close relationship with microtubules, our examination began with the expression and distribution of α-tubulin during the oocyte-to-embryo transition. Meanwhile, The dynamic expression and subcellular localization of Aurora A during oocyte-to-embryo transition were detected using indirect immunofluorescence method and laser confocal microscopy analysis. Then, the specific inhibition test was used to analyze the regulatory function of Aurora A in this particular transition stage. The results showed that Aurora A expressed in each period in the oocyte-to-embryo transition and had the similar subcellular localization with α-tubulin. At the metaphaseⅠ (MⅠ) and MⅡ stage, α-tubulin assembled a typical spindle in the cortex of oocyte, and a similar distribution presented in the same place where Aurora A was. During the prophase of mitosis, α-tubulin gradually gathered and reticulated, and Aurora A also had a net-like distribution. Following, α-tubulin was translated from the symmetric and barrel shaped spindle in the central of embryo to migration towards poles of embryo, at the same time Aurora A had a similar trend from mitosis metaphase to anaphase. When oocytes were treated with a highly selective inhibitor (MLN8054) of Aurora A, the extrusion rate of first polar body was significantly reduced with the increasing concentrations of MLN8054 (P＜0.05), and the percentage of abnormal spindle morphology, mainly including monopolar spindles and multipolar spindles, was significantly increased (P＜0.05). What's more, the high frequencies of abnormal spindle and chromosome alignment varied with the different exposure times. When oocytes at MⅡ stage which were treated with MLN8054 were parthenogenetic activation by electric pulse, the rate of embryo cleavage was decreased, but the difference was not significant (P＞0.05). The results showed that the expression of Aurora A was closely related to the α-tubulin distribution, with obvious stage characteristics during the transition of oocyte-to-embryo, and Aurora A might be involved in the regulation of oocyte maturation and embryo development via regulating the assembling and stability of spindle. The inhibition of Aurora A which were treated with MLN8054 had no significant effect on the transition of porcine MⅡ oocyte-to-embryo development, and the perhaps reasons might be the activity of Aurora A which was suppressed restored in the subsequent embryonic development and early embryo mitosis went through smoothly, when the competitive inhibition of MLN8054 was removed. This experiment mainly studied the expression of Aurora A and its effect on the structure of spindle during porcine oocyte-to-embryo transition, which provides an important experimental basis for porcine oocyte maturation and early embryo development as well as related signaling pathway in this process.
