Hematopoietic expression of HOXB4 is regulated in normal and leukemic stem cells through transcriptional activation of the HOXB4 promoter by upstream stimulating factor (USF)-1 and USF-2
Hematopoietic expression of HOXB4 is regulated in normal and leukemic stem cells through transcriptional activation of the HOXB4 promoter by upstream stimulating factor (USF)-1 and USF-2
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DOI：
10.1084/jem.192.10.1479
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发表时间：
2000-11-20
影响因子：
15.3
通讯作者：
Emerson, SG
中科院分区：
文献类型：
--
作者：
Giannola, DM;Shlomchik, WD;Emerson, SG
同源盒基因编码一个转录因子家族，调节发育和出生后组织的稳态。由于HOXB 4在调节造血干细胞更新和分化之间的平衡中起关键作用，因此我们研究了人造血干细胞中HOXB 4表达的分子调控。在K562细胞中HOXB 4的表达在转录水平上被调节，并且瞬时转染在99-bp 5'启动子内限定了主要的HOXB 4调节序列。在血小板生成素/Flt-3配体/干细胞因子中培养高度纯化的人CD 34（+）骨髓细胞可诱导HOXB 4 3-10倍，而在粒细胞/巨噬细胞集落刺激因子中培养仅增加HOXB 4/荧光素酶表达20- 50%。HOXB 4启动子内的突变鉴定了一个潜在的E盒结合位点（HOX反应元件[HXRE]-2）作为最关键的调控序列，评估骨髓和K562文库中HXRE-2相互作用的酵母单杂交试验鉴定了上游刺激因子（USF）-2和小眼症转录因子（MITF）。用K562提取物进行的电泳迁移率变动测定证实，这些蛋白质与USF-1沿着在体外与HOXB 4启动子结合。在K562和CD 34（+）细胞中的共转染试验表明，USF-1和USF-2，而不是MITF，通过激活丝裂原活化蛋白激酶途径，诱导HOXB 4启动子响应刺激干细胞自我更新的信号。因此，人HOXB 4基因的造血表达受USF-1和USF-2的结合调节，并且该过程可能受到促进干细胞自我更新与分化的细胞因子的支持。
The homeobox genes encode a family of transcription factors that regulate development and postnatal tissue homeostasis. Since HOXB4 plays a key role in regulating the balance between hematopoietic stem cell renewal and differentiation, we studied the molecular regulation of HOXB4 expression in human hematopoietic stem cells. HOXB4 expression in K562 cells is recgulated at the level of transcription, and transient transfection defines primary HOXB4 regulatory sequences within a 99-bp 5' promoter. Culture of highly purified human CD34(+) bone marrow cells in thrombopoietin/Flt-3 ligand/stem cell factor induced HOXB4 3-10-fold, whereas culture in granulocyte/macrophage colony-stimulating factor, only increased HOXB4/luciferase expression 20-50%. Mutations within the HOXB4 promoter identified a potential E box binding site (HOX response element [HXRE]-2) as the most critical regulatory sequence, and yeast one hybrid assays evaluating bone marrow and K562 libraries for HXRE-2 interaction identified upstream stimulating factor (USF)-2 and micropthalmia transcription factor (MITF). Electrophoretic mobility shift assay with K562 extracts confirmed that these proteins, along with USF-1, bind to the HOXB4, promoter in vitro. Cotransfection assays in both K562 and CD34(+) cells showed that USF-1 and USF-2, but not MITF, induce the HOXB4 promoter in response to signals stimulating stem cell self-renewal, through activation of the mitogen-activated protein kinase pathway. Thus hematopoietic expression of the human HOXB4 gene is regulated by the binding of USF-1 and USF-2, and this process may be favored by cytokines promoting stem cell self-renewal versus differentiation.