Dept. of Biochemistry and Molecular Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Dev Biol. 2012 Feb 15;362(2):309-19. doi: 10.1016/j.ydbio.2011.12.001. Epub 2011 Dec 9.
In order to investigate regulation and redundancy within the sloppy paired (slp) locus, we analyzed 30 kilobases of DNA encompassing the tandem, coordinately regulated slp1 and slp2 transcription units. We found a remarkable array of stripe enhancers with overlapping activities surrounding the slp1 transcription unit, and, unexpectedly, glial cell enhancers surrounding slp2. The slp stripe regulatory region generates 7 stripes at blastoderm, and later 14 stripes that persist throughout embryogenesis. Phylogenetic analysis among drosophilids suggests that the multiplicity of stripe enhancers did not evolve through recent duplication. Most of the direct integration among cis-regulatory modules appears to be simply additive, with one notable exception. Despite the apparent redundancy among stripe enhancers, transgenic rescue suggests that most are required for full function, to maintain wingless expression and parasegment boundaries throughout embryogenesis. Transgenic rescue also reveals indirect positive autoregulation by the 7 early stripes, without which alternate stripes within the 14-stripe pattern are lost, leading to embryos with a pair-rule phenotype.
为了研究 sloopy paired（slp）基因座中的调控和冗余性，我们分析了包含串联、协调调控的 slp1 和 slp2 转录单元的 30 千碱基 DNA。我们发现了一个显著的条纹增强子阵列，其围绕着 slp1 转录单元具有重叠的活性，并且出人意料的是，还有围绕着 slp2 的神经胶质细胞增强子。slp 条纹调控区在原肠胚期产生 7 条条纹，然后在胚胎发生过程中持续产生 14 条条纹。果蝇属间的系统发育分析表明，条纹增强子的多样性不是通过最近的复制而进化的。大多数顺式调控模块之间的直接整合似乎只是简单的累加，只有一个显著的例外。尽管条纹增强子之间存在明显的冗余性，但转基因拯救表明，大多数增强子对于维持 wingless 表达和副节边界的完整功能是必需的，在整个胚胎发生过程中。转基因拯救还揭示了 7 个早期条纹的间接正自调节作用，如果没有这种作用，14 个条纹模式中的其他条纹就会丢失，导致具有成对规则表型的胚胎。
