The Transcription Factor SP1 Regulates Centriole Function and Chromosomal Stability Through a Functional Interaction With the Mammalian Target of Rapamycin/Raptor Complex
The Transcription Factor SP1 Regulates Centriole Function and Chromosomal Stability Through a Functional Interaction With the Mammalian Target of Rapamycin/Raptor Complex
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DOI：
10.1002/gcc.20739
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发表时间：
2010-03-01
影响因子：
3.7
通讯作者：
Azizkhan-Clifford, Jane
中科院分区：
文献类型：
--
作者：
Astrinidis, Aristotelis;Kim, Jiyoon;Azizkhan-Clifford, Jane
特异性蛋白 1 (SP1) 是一种重要的转录因子，参与控制多种细胞过程（包括细胞周期、细胞凋亡和 DNA 损伤）的基因调节。迄今为止，关于 SP1 的非转录作用的报道还很少。使用共聚焦显微镜和中心体分级分离，我们将 SP1 鉴定为中心体蛋白。 Sp1缺陷的小鼠胚胎成纤维细胞和通过RNAi耗尽SP1的细胞会增加与中心粒分裂相关的中心体数量、减少微管成核、染色体错位、形成多极有丝分裂纺锤体和微核以及增加非整倍体的发生率。通过质谱分析，我们鉴定出 P70S6K（mTOR/raptor (mTORC1) 激酶复合物的效应子）是 SP1 的一种新型相互作用蛋白。我们发现SP1缺陷的细胞P70S6K效应核糖体蛋白S6的磷酸化增加，表明SP1参与mTORC1/P70S6K/S6信号通路的调节。我们之前报道过，异常的 mTORC1 激活会导致多余的中心体，这是一种由 mTORC1 抑制剂雷帕霉素拯救的表型。同样，雷帕霉素治疗挽救了 SP1 缺陷细胞的多重中心体表型。总而言之，这些数据有力地支持了这样的假设：SP1 通过调节 mTORC1 通路参与中心体数量的控制，并预测 SP1 功能的丧失可能导致中心粒分裂异常、mTORC1 信号传导失调和非整倍性，从而导致恶性转化。 (C) 2009 Wiley-Liss, Inc.
Specificity protein 1 (SP1) is an essential transcription factor implicated in the regulation of genes that control multiple cellular processes, including cell cycle, apoptosis, and DNA damage. Very few nontranscriptional roles for SP1 have been reported thus far. Using confocal microscopy and centrosome fractionation, we identified SP1 as a centrosomal protein. Sp1-deficient mouse embryonic fibroblasts and cells depleted of SP1 by RNAi have increased centrosome number associated with centriole splitting, decreased microtubule nucleation, chromosome misalignment, formation of multipolar mitotic spindles and micronuclei, and increased incidence of aneuploidy. Using mass spectrometry, we identified P70S6K, an effector of the mTOR/raptor (mTORC1) kinase complex, as a novel interacting protein of SP1. We found that SP1-deficient cells have increased phosphorylation of the P70S6K effector ribosomal protein S6, suggesting that SP1 participates in the regulation of the mTORC1/P70S6K/S6 signaling pathway. We previously reported that aberrant mTORC1 activation leads to supernumerary centrosomes, a phenotype rescued by the mTORC1 inhibitor rapamycin. Similarly, treatment with rapamycin rescued the multiple centrosome phenotype of SP1-deficient cells. Taken together, these data strongly support the hypothesis that SP1 is involved in the control of centrosome number via regulation of the mTORC1 pathway, and predict that loss of SP1 function can lead to aberrant centriole splitting, deregulated mTORC1 signaling, and aneuploidy, thereby contributing to malignant transformation. (C) 2009 Wiley-Liss, Inc.