REGULATION OF ERYTHROID GENE EXPRESSION

GATA转录因子家族在造血中的作用仍然是我们研究的主要焦点。几个实验室在小鼠身上进行的基因靶向实验已经证实，GATA-1、-2和-3对血液发育至关重要。虽然这些因子识别相同的DNA位点，有时在同一细胞中共存，但有趣的是，它们并不补偿彼此的损失。GATA-1和GATA -2可以与一组双GATA结合位点相互作用，这些位点存在于许多关键基因的调控区域和β -珠蛋白基因座控制区。虽然大多数GATA/DNA相互作用是通过c端锌指介导的，但这些双位点相互作用涉及两个锌指，并且这些蛋白的活性以结合位点依赖的方式变化，提示变构调节。我们已经证明，这些活性差异不是由于DNA弯曲的差异，因为GATA-1的n指并不参与这一过程。由于GATA-1的n指提供了几个关键辅因子的相互作用表面，我们怀疑活性的差异可能是通过蛋白质中改变其与这些辅因子相互作用的位点依赖性构象变化来介导的。我们正在试图解决GATA-1的锌指结合到几个双DNA位点的结构，并正在研究突变GATA蛋白的活性来测试这种可能性。其他研究表明，鸡叶酸受体基因和邻近β -珠蛋白位点的基因都受GATA因子的调控，但这些基因在红细胞发育过程中表达的时间模式不同；目前正在调查造成这种差异的原因。分离这些基因座的鸡β -珠蛋白绝缘体元件可能负责，和/或单个基因座中可能存在对GATA蛋白的存在有不同反应的顺式元件。- GATA家族基因表达发育造血细胞GATA-1染色质位点控制区GATA-2

The role of the GATA transcription factor family in hematopoiesiscontinues to be a major focus of our research. Gene targeting experiments in mice by several laboratories have established that GATA-1, -2, and -3, are critical to blood development. While these factors recognize the same DNA site and sometimes coexist in the same cells, interestingly they do not compensate for the loss of one another. GATA-1 and -2 can interact with a group ofdouble GATA binding sites which exist in the regulatory regions of many critical genes, and in the beta-globin locus control region. While most GATA/DNA interactions are mediated through the C-terminal zinc finger,these double site interactions involve both zinc fingers, and the activity of these proteins varies in a binding site dependent manner,suggesting allosteric regulation. We have shown that these activity differences are not due to differential DNA bending, since the N-finger of GATA-1 does not contribute to that process. Because the N-finger of GATA-1 supplies the interaction surface for several critical cofactors,we suspect that the differences in activity may be mediated through site dependent conformational changes in the proteins that alter their interactions with these cofactors. We are attempting to solve the structure of the zinc fingers of GATA-1 bound to several double DNA sites, and are studying the activity of mutant GATA proteins to test this possibility. Other studies have shown that the chicken folate receptor gene andthe genes in the adjacent beta-globin locus are all regulated by GATA factors,but these genes are not expressed in the same temporal pattern during red cell development; the basis for this discrepancy is under investigation. The chicken beta-globin insulator element, which separates these loci maybe responsible, and/or there may be cis-elements in the individual loci which respond differently to the presence of GATA proteins. - GATA family gene expression development hematopoietic cells GATA-1 chromatin locus control region GATA-2