Octamer independent activation of transcription from the kappa immunoglobulin germline promoter.
Octamer independent activation of transcription from the kappa immunoglobulin germline promoter.
复制标题
八聚体独立激活来自 kappa 免疫球蛋白种系启动子的转录。
DOI：
10.1093/nar/24.23.4805
复制
发表时间：
1996
影响因子：
14.9
通讯作者：
VanNess,B
中科院分区：
文献类型：
--
作者：
Prabhu,A;O'Brien,DP;Weisner,GL;Fulton,R;VanNess,B
免疫球蛋白V区启动子的先前分析已经导致发现了在免疫球蛋白基因的组织特异性和发育调节转录激活中功能重要的共同八聚体基序。位于κ基因座的J区基因片段上游的生殖系启动子（Ko）还含有八聚体基序（含有单碱基对突变，称为变体八聚体），其先前已显示在体外结合Oct-1和Oct-2转录因子。为了进一步阐明这种变体八聚体基序在调控未重排κ基因座的种系转录中的作用，我们定量了Oct-1和Oct-2对变体八聚体基序的相对结合亲和力，并确定了这种八聚体基序在转录激活中的功能作用。我们发现，尽管变异八聚体基序在体外与Oct-1和Oct-2结合的亲和力比共有八聚体基序低5倍，但变异八聚体基序突变为共有八聚体或非八聚体基序对生殖系启动子的转录激活没有影响。我们还发现kappa增强子对生殖系和V区启动子的激活存在显着差异。我们的研究结果表明，生殖细胞启动子和V区启动子不同，在他们的依赖八聚体激活和增强子激活的反应不同。这些发现在调节生殖系转录以及伴随的κ轻链基因座的V-J重组激活方面具有重要意义。
Previous analyses of immunoglobulin V region promoters has led to the discovery of a common octamer motif which is functionally important in the tissue-specific and developmentally regulated transcriptional activation of immunoglobulin genes. The germline promoters (Ko) located upstream of the J region gene segments of the kappa locus also contain an octamer motif (containing a single base pair mutation and referred to as the variant octamer) which has been shown previously to bind Oct-1 and Oct-2 transcription factorsin vitro. To further elucidate the role of this variant octamer motif in the regulation of germline transcription from the unrearranged kappa locus, we have quantitated the relative binding affinity of Oct-1 and Oct-2 for the variant octamer motif and determined the functional role of this octamer motif in transcriptional activation. We find that, although the variant octamer motif binds Oct-1 and Oct-2in vitrowith 5-fold lower affinity than the consensus octamer motif, mutation of the variant octamer motif to either a consensus octamer or non-octamer motif has no effect on transcriptional activation from the germline promoter. We also find significant differences in activation of germline and V region promoters by kappa enhancers. Our results suggest that the germline promoters and V region promoters differ in their dependence on octamer for activation and respond differently to enhancer activation. These findings have important implications in regulation of germline transcription as well as concomitant activation of the V-J recombination of the kappa light chain locus.