Pellegrini Matteo, Cheng Jerry C, Voutila Jon, Judelson Dejah, Taylor Julie, Nelson Stanley F, Sakamoto Kathleen M
Department of Molecular, Cellular, and Developmental Biology, University of California, Los Angeles, USA.
BMC Cancer. 2008 Sep 18;8:264. doi: 10.1186/1471-2407-8-264.
The cAMP Response Element Binding Protein, CREB, is a transcription factor that regulates cell proliferation, differentiation, and survival in several model systems, including neuronal and hematopoietic cells. We demonstrated that CREB is overexpressed in acute myeloid and leukemia cells compared to normal hematopoietic stem cells. CREB knockdown inhibits leukemic cell proliferation in vitro and in vivo, but does not affect long-term hematopoietic reconstitution.
To understand downstream pathways regulating CREB, we performed expression profiling with RNA from the K562 myeloid leukemia cell line transduced with CREB shRNA.
By combining our expression data from CREB knockdown cells with prior ChIP data on CREB binding we were able to identify a list of putative CREB regulated genes. We performed extensive analyses on the top genes in this list as high confidence CREB targets. We found that this list is enriched for genes involved in cancer, and unexpectedly, highly enriched for histone genes. Furthermore, histone genes regulated by CREB were more likely to be specifically expressed in hematopoietic lineages. Decreased expression of specific histone genes was validated in K562, TF-1, and primary AML cells transduced with CREB shRNA.
We have identified a high confidence list of CREB targets in K562 cells. These genes allow us to begin to understand the mechanisms by which CREB contributes to acute leukemia. We speculate that regulation of histone genes may play an important role by possibly altering the regulation of DNA replication during the cell cycle.
环磷酸腺苷反应元件结合蛋白（CREB）是一种转录因子，在包括神经元和造血细胞在内的多种模型系统中调节细胞增殖、分化和存活。我们证明，与正常造血干细胞相比，CREB在急性髓系白血病细胞中过表达。CREB敲低可在体外和体内抑制白血病细胞增殖，但不影响长期造血重建。
为了解调节CREB的下游途径，我们用转导了CREB短发夹RNA（shRNA）的K562髓系白血病细胞系的RNA进行了表达谱分析。
通过将来自CREB敲低细胞的表达数据与先前关于CREB结合的染色质免疫沉淀（ChIP）数据相结合，我们能够确定一份假定的CREB调控基因列表。我们对该列表中的顶级基因作为高可信度CREB靶点进行了广泛分析。我们发现该列表富含与癌症相关的基因，而且出乎意料的是，高度富含组蛋白基因。此外，由CREB调控的组蛋白基因更有可能在造血谱系中特异性表达。在用CREB shRNA转导的K562、TF-1和原发性急性髓系白血病（AML）细胞中验证了特定组蛋白基因表达的降低。
我们已经确定了K562细胞中高可信度的CREB靶点列表。这些基因使我们能够开始了解CREB促成急性白血病的机制。我们推测组蛋白基因的调控可能通过在细胞周期中改变DNA复制的调控发挥重要作用。
