Differential effects of sumoylation on the activities of CCAAT enhancer binding protein alpha (C/EBPα) p42 versus p30 may contribute in part, to aberrant C/EBPα activity in acute leukemias.
Differential effects of sumoylation on the activities of CCAAT enhancer binding protein alpha (C/EBPα) p42 versus p30 may contribute in part, to aberrant C/EBPα activity in acute leukemias.
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DOI：
10.4081/hr.2011.e5
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发表时间：
2011-01-13
影响因子：
0.9
通讯作者：
Khanna-Gupta A
中科院分区：
文献类型：
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作者：
Hankey W;Silver M;Sun BS;Zibello T;Berliner N;Khanna-Gupta A
在这项研究中，我们研究了小泛素相关修饰物（SUMO）对髓系主调节因子C/EBPα的翻译后修饰的作用。我们已经使用了瞬时转染分析，寡核苷酸下拉分析和染色质免疫沉淀在全反式维甲酸（ATRA）诱导的早幼粒细胞系MPRO和NB 4。我们证明了类小泛素化野生型p42-C/EBPα与早期髓样细胞中髓样特异性乳铁蛋白（LF）基因的负调控相关，并且p42-C/EBPα类小泛素化的减少与成熟髓样细胞中LF基因的表达一致。然而，在急性早幼粒细胞白血病细胞系NB 4中，类小泛素化的p42在ATRA诱导后仍然持续与LF启动子结合。这与这些细胞中缺乏乳铁蛋白表达相关。因此，C/EBPα类小泛素化状态的变化似乎有助于在正常中性粒细胞发育过程中调节这一主调节因子转录活性的开关。我们还证明AML相关显性阴性p30-C/EBPα亚型的SUMO化并不改变LF启动子的反式激活活性。这可能是因为p30 C/EBPα亚型与LF启动子的结合效率远低于其全长对应物。我们的数据表明，p42-C/EBPα在发育中的中性粒细胞的活性是更敏感的sumo化的变化比p30亚型。这种差异可能与p30-C/EBPα的致白血病潜能有关。
In this study, we have examined the role of post-translational modification of the myeloid master regulator C/EBPα by small ubiquitin-related modifier (SUMO). We have used transient transfection analysis, oligonucleotide pulldown assays and chromatin immuno-precititation in all-trans retinoic acid (ATRA)-inducible promyelocytic cell lines MPRO and NB4. We demonstrate that sumoylated wild-type p42-C/EBPα is associated with negative regulation of the myeloid specific lactoferrin (LF) gene in early myeloid cells and that a reduction in p42-C/EBPα sumoylation coincides with expression of the LF gene in maturing myeloid cells. In the acute promyelocytic leukemia cell line NB4 however, sumoylated p42 remains persistently bound to the LF promoter following ATRA-induction. This correlates with lack of lactoferrin expression in these cells. Changes in sumoylation status of C/EBPα thus appear to contribute to a switch that regulates transcriptional activity of this master regulator during normal neutrophil development. We also demonstrate that sumoylation of the AML associated dominant negative p30-C/EBPα isoform does not alter transactivation activity of the LF promoter. This may be because the p30 C/EBPα isoform binds to the LF promoter much less efficiently than its full length counterpart. Our data suggest that the activity of p42-C/EBPα in the developing neutrophil is more sensitive to changes in sumoylation than the p30 isoform. This difference may contribute to the leukemogenic potential of p30-C/EBPα.