Visualization by BiFC of different C/EBPβ dimers and their interaction with HP1α reveals a differential subnuclear distribution of complexes in living cells.
Visualization by BiFC of different C/EBPβ dimers and their interaction with HP1α reveals a differential subnuclear distribution of complexes in living cells.
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BiFC 的不同 C/EBPβ 二聚体的可视化及其与 HP1α 的相互作用揭示了活细胞中复合物的差异亚核分布。
DOI：
10.1016/j.yexcr.2010.11.008
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发表时间：
2011
影响因子：
3.7
通讯作者：
Piwien-Pilipuk,Graciela
中科院分区：
文献类型：
--
作者：
Susperreguy,Sebastián;Prendes,LucianaP;Desbats,MaríaA;Charó,NancyL;Brown,Karen;MacDougald,OrmondA;Kerppola,Tom;Schwartz,Jessica;Piwien-Pilipuk,Graciela
细胞分化过程中基因激活和沉默的协调事件如何受到细胞核空间组织的影响仍然知之甚少。关于控制转录因子亚核分布的分子机制，以及它们与塑造染色质结构的核蛋白的相互作用知之甚少。在这里，我们表明C/EBPβ不仅与着丝粒周围异染色质结合，而且在诱导3 T3-L1细胞脂肪细胞分化时与核骨架相互作用。不同的C/EBPβ二聚体定位于不同的核结构域。在活细胞中使用BiFC，我们表明，肝脏激活蛋白（Liver Activating Protein）同源二聚体定位于常染色质和异染色质中。相反，LIP（肝抑制蛋白）同源二聚体只定位于异染色质。重要的是，它们的差异亚核分布反映了与HP 1 α相互作用的位点。HP 1 α抑制3 T3-L1前脂肪细胞中C/EBPβ依赖基因c/ebpα的转录能力并占据其启动子。当诱导脂肪形成时，c/ebpα启动子的HP 1 α结合减少，允许转录。因此，C/EBPβ与染色质或核骨架相互作用的平衡以及与HP 1 α相互作用的动态变化，在脂肪形成过程中对C/EBP靶基因的调控起着关键作用。
How the co-ordinated events of gene activation and silencing during cellular differentiation are influenced by spatial organization of the cell nucleus is still poorly understood. Little is known about the molecular mechanisms controlling subnuclear distribution of transcription factors, and their interplay with nuclear proteins that shape chromatin structure. Here we show that C/EBPβ not only associates with pericentromeric heterochromatin but also interacts with the nucleoskeleton upon induction of adipocyte differentiation of 3T3-L1 cells. Different C/EBPβ dimers localize in different nuclear domains. Using BiFC in living cells, we show that LAP (Liver Activating Protein) homodimers localize in euchromatin and heterochromatin. In contrast, LIP (Liver Inhibitory Protein) homodimers localize exclusively in heterochromatin. Importantly, their differential subnuclear distribution mirrors the site for interaction with HP1α. HP1α inhibits LAP transcriptional capacity and occupies the promoter of the C/EBPβ-dependent gene c/ebpα in 3T3-L1 preadipocytes. When adipogenesis is induced, HP1α binding decreases from c/ebpα promoter, allowing transcription. Thus, the equilibrium among different pools of C/EBPβ associated with chromatin or nucleoskeleton, and dynamic changes in their interaction with HP1α, play key roles in the regulation of C/EBP target genes during adipogenesis.