Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA.
Genes Dev. 2010 Aug 1;24(15):1620-33. doi: 10.1101/gad.1942110.
The bicistronic microRNA (miRNA) locus miR-144/451 is highly expressed during erythrocyte development, although its physiological roles are poorly understood. We show that miR-144/451 ablation in mice causes mild erythrocyte instability and increased susceptibility to damage after exposure to oxidant drugs. This phenotype is deeply conserved, as miR-451 depletion synergizes with oxidant stress to cause profound anemia in zebrafish embryos. At least some protective activities of miR-451 stem from its ability to directly suppress production of 14-3-3zeta, a phospho-serine/threonine-binding protein that inhibits nuclear accumulation of transcription factor FoxO3, a positive regulator of erythroid anti-oxidant genes. Thus, in miR-144/451(-/-) erythroblasts, 14-3-3zeta accumulates, causing partial relocalization of FoxO3 from nucleus to cytoplasm with dampening of its transcriptional program, including anti-oxidant-encoding genes Cat and Gpx1. Supporting this mechanism, overexpression of 14-3-3zeta in erythroid cells and fibroblasts inhibits nuclear localization and activity of FoxO3. Moreover, shRNA suppression of 14-3-3zeta protects miR-144/451(-/-) erythrocytes against peroxide-induced destruction, and restores catalase activity. Our findings define a novel miRNA-regulated pathway that protects erythrocytes against oxidant stress, and, more generally, illustrate how a miRNA can influence gene expression by altering the activity of a key transcription factor.
双顺反子 microRNA（miRNA）基因座 miR-144/451 在红细胞发育过程中高度表达，尽管其生理作用尚未完全了解。我们表明，miR-144/451 在小鼠中的缺失会导致红细胞轻微不稳定，并在暴露于氧化剂药物后增加损伤易感性。这种表型是深度保守的，因为 miR-451 的耗竭与氧化剂应激协同作用，导致斑马鱼胚胎发生严重贫血。miR-451 的至少一些保护活性源于其直接抑制 14-3-3zeta 产生的能力，14-3-3zeta 是一种磷酸丝氨酸/苏氨酸结合蛋白，可抑制转录因子 FoxO3 的核积累，FoxO3 是红细胞抗氧化基因的正调节剂。因此，在 miR-144/451(-/-) 红细胞中，14-3-3zeta 积累，导致 FoxO3 部分从细胞核重新定位到细胞质，其转录程序（包括抗氧化编码基因 Cat 和 Gpx1）受到抑制。支持这一机制，14-3-3zeta 在红细胞和成纤维细胞中的过表达抑制 FoxO3 的核定位和活性。此外，14-3-3zeta 的 shRNA 抑制可保护 miR-144/451(-/-) 红细胞免受过氧化物诱导的破坏，并恢复过氧化氢酶活性。我们的研究结果定义了一种新的 miRNA 调节途径，可保护红细胞免受氧化剂应激，更普遍地说明了 miRNA 如何通过改变关键转录因子的活性来影响基因表达。
