REGULATION OF ERYTHROID GENE EXPRESSION

加塔转录因子家族在造血中的作用仍然是我们研究的一个主要焦点。几个实验室在小鼠中进行的基因靶向实验已经确定加塔-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，有时在相同的细胞中共存，但有趣的是，它们并不补偿彼此的损失。加塔-1和-2可与一组双加塔结合位点相互作用，这些结合位点存在于许多关键基因的调控区和β-珠蛋白基因座控制区。虽然大多数加塔/DNA相互作用是通过C-末端锌指介导的，但这些双位点相互作用涉及两个锌指，并且这些蛋白质的活性以结合位点依赖性方式变化，表明变构调节。我们已经表明，这些活性差异不是由于差异DNA弯曲，因为加塔-1的N-指不有助于该过程。由于加塔-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改变蛋白质与这些辅因子的相互作用的位点依赖性构象变化介导的。我们正试图解决与几个双DNA位点结合的加塔-1的锌指结构，并正在研究突变加塔蛋白的活性以测试这种可能性。其他研究表明，鸡叶酸受体基因和邻近β-珠蛋白基因座的基因都受加塔因子的调控，但这些基因在红细胞发育过程中的表达时间模式不同;这种差异的基础正在调查中。分离这些基因座的鸡β-珠蛋白绝缘子元件可能起作用，和/或在单个基因座中可能存在对加塔蛋白的存在有不同反应的顺式元件。- 加塔家族基因表达发育造血细胞加塔-1染色质位点控制区加塔-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