Transcription Factor GATA1 Is Dispensable for Mast Cell Differentiation in Adult Mice

Although previous studies have shown that GATA1 is required for mast cell differentiation, the effects of the complete ablation of GATA1 in mast cells have not been examined. Using conditional Gata1 knockout mice (Gata1^−/y), we demonstrate here that the complete ablation of GATA1 has a minimal effect on the number and distribution of peripheral tissue mast cells in adult mice. The Gata1^−/y bone marrow cells were capable of differentiating into mast cells ex vivo. Microarray analyses showed that the repression of GATA1 in bone marrow mast cells (BMMCs) has a small impact on the mast cell-specific gene expression in most cases. Interestingly, however, the expression levels of mast cell tryptases in the mouse chromosome 17A3.3 were uniformly reduced in the GATA1 knockdown cells, and GATA1 was found to bind to a 500-bp region at the 5′ end of this locus. Revealing a sharp contrast to that observed in the Gata1-null BMMCs, GATA2 deficiency resulted in a significant loss of the c-Kit⁺ FcεRIα⁺ mast cell fraction and a reduced expression of several mast cell-specific genes. Collectively, GATA2 plays a more important role than GATA1 in the regulation of most mast cell-specific genes, while GATA1 might play specific roles in mast cell functions.     

JAB1与糖皮质激素受体的相互作用及对其转录活性的影响

应用酵母双杂交方法筛选到与糖皮质激素受体(GR)结合的蛋白JAB1,进一步验证JAB1与GR的结合作用并证明其对GR的影响.构建与Gal4-BD融合表达的载体pGBKT7-GR LBD,与构建于pACT2载体上的人骨髓cDNA文库杂交,在SD/-Ade/-His/-Leu/-Trp选择培养板上培养,经X-α-gal检测,阳性克隆片段插入pGEM^®-T Vector 载体,测序,再经酵母双杂交和GST pull down蛋白质结合实验验证其结合作用,应用反映GR转录活性的CAT报告基因检测JAB1对GR的调节活性.结果在人骨髓cDNA文库中,筛选到42个X-α-gal检测变蓝且含有pACT2质粒序列的克隆,其中有5个克隆的序列皆为Jun活性区结合蛋白JAB1的一部分.酵母双杂交和蛋白质结合实验表明,JAB1与COS7真核表达的GR-LBD在体外有结合作用.JAB1加强GR转录激活的能力.