Expression of the transcriptional repressor Gfi-1 is regulated by C/EBP{alpha} and is involved in its proliferation and colony formation-inhibitory effects in p210BCR/ABL-expressing cells.
Expression of the transcriptional repressor Gfi-1 is regulated by C/EBP{alpha} and is involved in its proliferation and colony formation-inhibitory effects in p210BCR/ABL-expressing cells.
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DOI：
10.1158/0008-5472.can-10-1667
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发表时间：
2010-10-15
期刊：
影响因子：
11.2
通讯作者：
Calabretta B
中科院分区：
文献类型：
--
作者：
Lidonnici MR;Audia A;Soliera AR;Prisco M;Ferrari-Amorotti G;Waldron T;Donato N;Zhang Y;Martinez RV;Holyoake TL;Calabretta B
C/eBPα在p210BCR/abl表达细胞中的异位表达可诱导粒细胞分化，抑制细胞增殖，抑制白血病的发生。为了分析这些生物学效应的分子机制，我们在32D-p210bcr/abl细胞中通过芯片分析鉴定了C/eBPα调控基因。在bcr/abl表达细胞中，C/eBPα以结合依赖的方式激活其表达的基因之一是转录抑制因子GFI-1。我们发现C/EBPα与GfI-1 5‘侧翼区的功能C/EBP结合部位相互作用，增强了GfI-1的启动子活性。此外，在K562细胞中，RNAi介导的GFI1表达下调部分挽救了C/EBPα的增殖抑制作用，而不是诱导分化作用。野生型GFI-1的异位表达而转录抑制突变体(GFI-1P2A)不能抑制bcr/abl表达细胞的增殖和集落形成，但不能诱导粒细胞分化。相比之下，GFI-1 shRNA转导的CD34+CML细胞的克隆形成能力明显高于Scrble转导的CML细胞。综上所述，这些研究表明，GFI-1是C/EBPα的直接靶点，在表达bcr/abl的细胞中，它的增殖和生存抑制作用是必需的。
Ectopic expression of C/EBPα in p210BCR/ABL-expressing cells induces granulocytic differentiation, inhibits proliferation and suppresses leukemogenesis. To dissect the molecular mechanisms underlying these biological effects, C/EBPα-regulated genes were identified by microarray analysis in 32D-p210BCR/ABL cells. One of the genes whose expression was activated by C/EBPα in a DNA binding-dependent manner in BCR/ABL-expressing cells is the transcriptional repressor Gfi-1. We show here that C/EBPα interacts with a functional C/EBP binding site in the Gfi-1 5′ flanking region and enhances the promoter activity of Gfi-1. Moreover, in K562 cells, RNAi-mediated downregulation of Gfi-1 expression partially rescued the proliferation inhibitory but not the differentiation inducing effect of C/EBPα. Ectopic expression of wild type Gfi-1 but not of a transcriptional repressor mutant (Gfi-1P2A) inhibited proliferation and markedly suppressed colony formation but did not induce granulocytic differentiation of BCR/ABL-expressing cells. By contrast, Gfi-1 shRNA-tranduced CD34+ CML cells were markedly more clonogenic than the scramble-transduced counterpart. Together, these studies indicate that Gfi-1 is a direct target of C/EBPα required for its proliferation and survival inhibitory effects in BCR/ABL-expressing cells.