The Key Laboratory for Mammalian Reproductive Biology and Biotechnology, Ministry of Education, Inner mongolia University, Hohhot, China.
PLoS One. 2013 Nov 14;8(11):e80039. doi: 10.1371/journal.pone.0080039. eCollection 2013.
TFIIB (transcription factor IIB) is a transcription factor that provides a bridge between promoter-bound TFIID and RNA polymerase II, and it is a target of various transcriptional activator proteins that stimulate the pre-initiation complex assembly. The localization and/or attachment matrix of TFIIB in the cytoplast is not well understood. This study focuses on the function of TFIIB and its interrelationship with α-tubulins in a mouse model. During oocyte maturation TFIIB distributes throughout the entire nucleus of the germinal vesicle (GV). After progression to GV breakdown (GVBD), TFIIB and α-tubulin co-localize and accumulate in the vicinity of the condensed chromosomes. During the MII stage, the TFIIB signals are more concentrated at the equatorial plate and the kinetochores. Colcemid treatment of oocytes disrupts the microtubule (MT) system, although the TFIIB signals are still present with the altered MT state. Injection of oocytes with TFIIB antibodies and siRNAs causes abnormal spindle formation and irregular chromosome alignment. These findings suggest that TFIIB dissociates from the condensed chromatids and then tightly binds to microtubules from GVBD to the MII phase. The assembly and disassembly of TFIIB may very well be associated with and driven by microtubules. TFIIB maintains its contact with the α-tubulins and its co-localization forms a unique distribution pattern. Depletion of Tf2b in oocytes results in a significant decrease in TFIIB expression, although polar body extrusion does not appear to be affected. Knockdown of Tf2b dramatically affects subsequent embryo development with more than 85% of the embryos arrested at the 2-cell stage. These arrested embryos still maintain apparently normal morphology for at least 96h without any obvious degeneration. Analysis of the effects of TFIIB in somatic cells by co-transfection of BiFC plasmids pHA-Tf2b and pFlag-Tuba1α further confirms a direct interaction between TFIIB and α-tubulins.
TFIIB（转录因子 IIB）是一种转录因子，它在启动子结合的 TFIID 和 RNA 聚合酶 II 之间提供了一个桥梁，并且是各种转录激活蛋白的靶标，这些蛋白可以刺激起始前复合物的组装。TFIIB 在胞质体中的定位和/或附着基质尚不清楚。本研究专注于 TFIIB 及其在小鼠模型中与α-微管蛋白的相互关系及其功能。在卵母细胞成熟过程中，TFIIB 分布在整个生发泡（GV）核中。在 GV 破裂（GVBD）后，TFIIB 和α-微管蛋白在浓缩染色体的附近共定位和积累。在 MII 期，TFIIB 信号在赤道板和动粒处更为集中。秋水仙素处理卵母细胞会破坏微管（MT）系统，尽管 TFIIB 信号仍存在于改变的 MT 状态下。向卵母细胞注射 TFIIB 抗体和 siRNA 会导致异常的纺锤体形成和染色体排列不规则。这些发现表明，TFIIB 从浓缩的染色质上解离，然后从 GVBD 到 MII 期紧密结合微管。TFIIB 的组装和拆卸很可能与微管相关，并由微管驱动。TFIIB 保持与α-微管蛋白的接触，其共定位形成独特的分布模式。卵母细胞中 Tf2b 的缺失导致 TFIIB 表达显著减少，尽管极体挤出似乎不受影响。Tf2b 的敲低显著影响随后的胚胎发育，超过 85%的胚胎停滞在 2 细胞期。这些停滞的胚胎在没有明显退化的情况下至少 96 小时保持明显正常的形态。通过共转染 BiFC 质粒 pHA-Tf2b 和 pFlag-Tuba1α 分析 TFIIB 在体细胞中的作用进一步证实了 TFIIB 和α-微管蛋白之间的直接相互作用。
