Department of Reproductive Medicine and Gynaecology, University Medical Center Utrecht, Utrecht, The Netherlands.
Hum Reprod. 2011 Jul;26(7):1868-81. doi: 10.1093/humrep/der111. Epub 2011 Apr 14.
Human embryos generated by IVF demonstrate a high incidence of chromosomal segregation errors during the cleavage divisions. To analyse underlying molecular mechanisms, we investigated the behaviour of the chromosomal passenger complex (CPC) in human oocytes and embryos. This important mitotic regulatory complex comprises the inner centromere protein (INCENP), survivin, borealin and Aurora B, or the meiotic kinase Aurora C.
We analysed mRNA expression by quantitative RT-PCR of all CPC members in human oocytes, tripronuclear (3PN) zygotes, 2-cell and 4-cell embryos developed from 3PN zygotes, plus good-quality cryopreserved 8-cell, morula and blastocyst stage embryos. Protein expression and localization of CPC members were investigated by immunofluorescence in oocytes and embryos arrested at prometaphase. Histone H3S10 phosphorylation was investigated as an indicator of a functional CPC.
INCENP, survivin and borealin were detected at the inner centromere of prometaphase chromosomes in all stages investigated. Whereas Aurora B and C are both present in oocytes, Aurora C becomes the most prominent kinase in the CPC during the first three embryonic cell cycles. Moreover, Aurora C mRNA was up-regulated with Aurora B after activation of the embryonic genome and both proteins were detected in early Day 4 embryos. Subsequently, only Aurora B was detected in blastocysts.
In contrast to somatic cells, our results point to a specific role for Aurora C in the CPC during human preimplantation embryo development. Although, the presence of Aurora C in itself may not explain the high chromosome segregation error rate, the data presented here provide novel information regarding possible mechanisms.
体外受精（IVF）产生的人类胚胎在卵裂过程中表现出很高的染色体分离错误率。为了分析潜在的分子机制，我们研究了人类卵母细胞和胚胎中染色体乘客复合物（CPC）的行为。这个重要的有丝分裂调节复合物包括着丝粒内蛋白（INCENP）、survivin、borealin 和 Aurora B，或减数分裂激酶 Aurora C。
我们通过定量 RT-PCR 分析了所有 CPC 成员在人类卵母细胞、三原核（3PN）受精卵、由 3PN 受精卵发育而来的 2-细胞和 4-细胞胚胎，以及优质冷冻保存的 8-细胞、桑椹胚和囊胚阶段胚胎中的 mRNA 表达。通过免疫荧光在卵母细胞和停滞在前期的胚胎中研究了 CPC 成员的蛋白表达和定位。组蛋白 H3S10 磷酸化被作为 CPC 功能的指标进行研究。
INCENP、survivin 和 borealin 在所有研究阶段的前期染色体着丝粒内均有检测到。虽然 Aurora B 和 C 都存在于卵母细胞中，但在胚胎的前三个细胞周期中，Aurora C 成为 CPC 中最主要的激酶。此外，在胚胎基因组激活后，Aurora B 的表达上调，并在第 4 天的早期胚胎中检测到两种蛋白。随后，只有 Aurora B 在囊胚中被检测到。
与体细胞不同，我们的结果表明 Aurora C 在人类植入前胚胎发育中的 CPC 中具有特定的作用。尽管 Aurora C 的存在本身可能并不能解释高染色体分离错误率，但这里提供的新数据提供了关于可能的机制的新信息。
