Department of Medicine and Human Genetics and Department of Biology, Bioinformatics Centre, McGill University, McGill University Health Centre, Montreal General Hospital Research Institute, Montreal, QC, Canada.
Mol Biol Cell. 2010 Mar 1;21(5):811-20. doi: 10.1091/mbc.e09-06-0534. Epub 2010 Jan 6.
Studies have shown that nuclear translocation of actin occurs under certain conditions of cellular stress; however, the functional significance of actin import remains unclear. Here, we demonstrate that during the phorbol 12-myristate 13-acetate (PMA)-induced differentiation of HL-60 cells toward macrophages, beta-actin translocates from the cytoplasm to the nucleus and that this process is dramatically inhibited by pretreatment with p38 mitogen-activated protein kinase inhibitors. Using chromatin immunoprecipitation-on-chip assays, the genome-wide maps of beta-actin binding to gene promoters in response to PMA treatment is analyzed in HL-60 cells. A gene ontology-based analysis shows that the identified genes belong to a broad spectrum of functional categories such as cell growth and differentiation, signal transduction, response to external stimulus, ion channel activity, and immune response. We also demonstrate a correlation between beta-actin occupancy and the recruitment of RNA polymerase II at six selected target genes, and beta-actin knockdown decreases the mRNA expression levels of these target genes induced by PMA. We further show that nuclear beta-actin is required for PMA-induced transactivation of one target gene, solute carrier family 11 member 1, which is important for macrophage activation. Our data provide novel evidence that nuclear accumulation of beta-actin is involved in transcriptional regulation during macrophage-like differentiation of HL-60 cells.
研究表明，细胞应激的某些条件下核易位肌动蛋白的发生;然而，肌动蛋白导入的功能意义仍不清楚。在这里，我们证明在佛波醇 12-肉豆蔻酸 13-醋酸盐 (PMA)诱导 HL-60 细胞向巨噬细胞分化过程中，β-肌动蛋白从细胞质易位到细胞核，这个过程是通过预处理 p38 有丝分裂原活化蛋白激酶抑制剂显著抑制。使用染色质免疫沉淀芯片分析，在 HL-60 细胞中分析了β-肌动蛋白与基因启动子结合的全基因组图谱，以响应 PMA 处理。基于基因本体论的分析表明，所鉴定的基因属于广泛的功能类别，如细胞生长和分化、信号转导、对外界刺激的反应、离子通道活性和免疫反应。我们还证明了β-肌动蛋白占据与六种选定靶基因的 RNA 聚合酶 II 募集之间的相关性，并且β-肌动蛋白敲低降低了 PMA 诱导的这些靶基因的 mRNA 表达水平。我们进一步表明，核β-肌动蛋白是 PMA 诱导的一个靶基因溶质载体家族 11 成员 1 的转录激活所必需的，这对巨噬细胞激活很重要。我们的数据提供了新的证据表明，核积累的β-肌动蛋白参与 HL-60 细胞向巨噬细胞样分化过程中的转录调控。
