MicroRNA-34a Inhibits Cell Proliferation by Repressing Mitogen-Activated Protein Kinase Kinase 1 during Megakaryocytic Differentiation of K562 Cells
MicroRNA-34a Inhibits Cell Proliferation by Repressing Mitogen-Activated Protein Kinase Kinase 1 during Megakaryocytic Differentiation of K562 Cells
复制标题
DOI：
10.1124/mol.109.063321
复制
发表时间：
2010-06-01
影响因子：
3.6
通讯作者：
Tsujimoto, Gozoh
中科院分区：
文献类型：
--
作者：
Ichimura, Atsuhiko;Ruike, Yoshinao;Tsujimoto, Gozoh
佛波酯(PMA)诱导人慢性粒细胞白血病K562细胞系的巨核细胞分化。我们研究了microRNAs(MiRNAs)在这一过程中的潜在调控作用。全基因组表达谱鉴定出21个miRNAs(MiRs)是由PMA处理K562细胞诱导的。其中miR-34a、miR-221和miR-222在分化早期即被诱导表达，并在分化后期维持表达。细胞信号分析表明，PMA激活细胞外信号调节蛋白激酶(ERK)可通过miR-34a基因上游区域的激活蛋白-1结合位点反式激活miR-34a的表达。报告基因分析表明，丝裂原活化蛋白激酶1(MEK1)是miR-34a的直接靶点，c-fos是miR-221/222的直接靶点。虽然三种miRNAs的过表达对细胞分化的影响不大，但miR-34a的过表达显著抑制了K562细胞的增殖，并伴随着MEK1蛋白表达的降低。相反，针对miR-34a的锁定核酸探针显著促进了PMA处理的K562细胞的增殖。综上所述，结果表明，PMA激活了MEK-ERK通路，强烈诱导了miRNA-34a的表达，进而通过抑制MEK1的表达抑制了细胞的增殖。因此，这些结果突显了miR-34a在巨核细胞分化过程中的重要调节作用，特别是在阻止细胞生长的过程中，这是细胞进入分化的先决条件。
Phorbol 12-myristate 13-acetate (PMA) induces megakaryocytic differentiation of the human chronic myelocytic leukemia cell line K562. We examined the potential regulatory role of microRNAs (miRNAs) in this process. Genome-wide expression profiling identified 21 miRNAs (miRs) that were induced by the treatment of K562 cells with PMA. Among them, the expression of miR-34a, miR-221, and miR-222 was induced in the early stages and maintained throughout the late stages of differentiation. Cell signaling analysis showed that the activation of extracellular signal-regulated protein kinase (ERK) in response to PMA strongly induced miR-34a expression by transactivation via the activator protein-1 binding site in the upstream region of the miR-34a gene. Reporter gene assays identified mitogen-activated protein kinase kinase 1 (MEK1) as a direct target of miR-34a and c-fos as a direct target of miR-221/222. Although overexpression of the three miRNAs had little effect on cell differentiation, overexpression of miR-34a significantly repressed the proliferation of K562 cells with a concomitant reduction in MEK1 protein expression. Conversely, a locked nucleic acid probe against miR-34a significantly enhanced the proliferation of PMA-treated K562 cells. Taken together, the results show that PMA activates the MEK-ERK pathway and strongly induces miRNA-34a expression, which in turn inhibits cell proliferation by repressing the expression of MEK1. Thus, the results highlight an important regulatory role for miR-34a in the process of megakaryocytic differentiation, especially in the arrest of cell growth, which is a prerequisite for cells to enter differentiation.