Coen D
Mécanismes Moléculaires de la Spéciation, Université Pierre et Marie Curie, Paris, France.
Genetics. 1990 Dec;126(4):949-60. doi: 10.1093/genetics/126.4.949.
Drosophila P element mobilization is subject to a complex array of regulatory mechanisms. A fruitful approach to study them is the use of insertion mutations whose expression is influenced by P regulation. In the present report, it is shown that P element somatic products may influence the expression of an unrelated gene inserted in a P transposon. The P[wdl9.3]19De transgene carriers an in vitro modified white gene harboring a duplication of the 5' regulatory sequences. Expression of this transgene is repressed in a P background. No maternal effect is detected and repression can be relieved as soon as P chromosomes are replaced by M ones. The amplitude of repression is correlated to the P transposase activity of the individuals examined. Repression appears to be exerted by somatic products of complete autonomous P elements or of in vitro modified P elements lacking the capacity to express the fourth P exon. The P repression of P[wdl9.3]19DE is strongly dependent on the insertion site of this transgene. This P repression effect occurs only in the presence of the zeste allele and is suppressed by Su(z)2 mutations. No qualitative differences of transcription pattern are observed between white+ and P[wdl9.3]19DE in any backgrounds. P repression acts to reduce the amount of the major white transcript. This suggests that P regulatory products may act through cis-interactions at a distance of over 3 kb.
果蝇P因子的转座受一系列复杂调控机制的影响。研究这些机制的一个有效方法是利用插入突变，其表达受P因子调控的影响。在本报告中，表明P因子的体细胞产物可能影响插入P转座子中的一个不相关基因的表达。转基因P[wdl9.3]19De携带一个体外修饰的白色基因，该基因含有5'调控序列的重复序列。在P背景下，该转基因的表达受到抑制。未检测到母体效应，一旦用M染色体取代P染色体，抑制作用即可解除。抑制幅度与所检测个体的P转座酶活性相关。抑制作用似乎是由完全自主的P因子或缺乏表达P因子第四外显子能力的体外修饰P因子的体细胞产物施加的。P[wdl9.3]19DE的P抑制作用强烈依赖于该转基因的插入位点。这种P抑制效应仅在存在zeste等位基因时发生，并被Su(z)2突变所抑制。在任何背景下，白色基因野生型和P[wdl9.3]19DE之间均未观察到转录模式的定性差异。P抑制作用可减少主要白色转录本的数量。这表明P调控产物可能通过3 kb以上距离的顺式相互作用发挥作用。
