Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy.
Nucleic Acids Res. 2011 Jan;39(2):486-501. doi: 10.1093/nar/gkq819. Epub 2010 Sep 17.
The Sox6 transcription factor plays critical roles in various cell types, including erythroid cells. Sox6-deficient mice are anemic due to impaired red cell maturation and show inappropriate globin gene expression in definitive erythrocytes. To identify new Sox6 target genes in erythroid cells, we used the known repressive double Sox6 consensus within the εy-globin promoter to perform a bioinformatic genome-wide search for similar, evolutionarily conserved motifs located within genes whose expression changes during erythropoiesis. We found a highly conserved Sox6 consensus within the Sox6 human gene promoter itself. This sequence is bound by Sox6 in vitro and in vivo, and mediates transcriptional repression in transient transfections in human erythroleukemic K562 cells and in primary erythroblasts. The binding of a lentiviral transduced Sox6FLAG protein to the endogenous Sox6 promoter is accompanied, in erythroid cells, by strong downregulation of the endogenous Sox6 transcript and by decreased in vivo chromatin accessibility of this region to the PstI restriction enzyme. These observations suggest that the negative Sox6 autoregulation, mediated by the double Sox6 binding site within its own promoter, may be relevant to control the Sox6 transcriptional downregulation that we observe in human erythroid cultures and in mouse bone marrow cells in late erythroid maturation.
Sox6 转录因子在各种细胞类型中发挥着关键作用，包括红细胞。Sox6 缺陷小鼠由于红细胞成熟受损而贫血，并在定型红细胞中表现出异常的珠蛋白基因表达。为了在红细胞中鉴定新的 Sox6 靶基因，我们使用已知的εy-珠蛋白启动子中的抑制性双 Sox6 共识序列，在基因组范围内进行生物信息学搜索，寻找在红细胞生成过程中表达变化的基因中具有相似的、进化上保守的基序。我们在 Sox6 人类基因启动子本身内发现了一个高度保守的 Sox6 共识序列。该序列在体外和体内被 Sox6 结合，并在人红白血病 K562 细胞和原代红细胞中的瞬时转染中介导转录抑制。慢病毒转导的 Sox6FLAG 蛋白与内源性 Sox6 启动子的结合伴随着内源性 Sox6 转录本的强烈下调，以及该区域在体内对 PstI 限制酶的染色质可及性降低。这些观察结果表明，由其自身启动子内的双 Sox6 结合位点介导的负性 Sox6 自身调节可能与我们在人红细胞培养物和小鼠骨髓细胞晚期红细胞成熟中观察到的 Sox6 转录下调有关。
