Golubovsky M D, Konev A Y, Walter M F, Biessmann H, Mason J M
Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709-2233, USA.
Genetics. 2001 Jul;158(3):1111-23. doi: 10.1093/genetics/158.3.1111.
Genetically marked P elements inserted into the subtelomeric satellites of Drosophila show repression and variegation of the reporter gene. One such white+ reporter, inserted between the subtelomeric satellite and the terminal HeT-A array in the left arm of chromosome 2 (2L), is sensitive to its context; changes in the structure of the telomere region can be identified by changes in eye color. Addition of HeT-A or TART elements to the 2L terminus increases w+ expression, and loss of sequence from the end decreases expression. This indicates that the telomeric retrotransposons in Drosophila have an activating influence on the repressed subterminal reporter gene. Changes in eye color due to altered expression of the transgene also allow the detection of interactions between homologous telomeres. The 2L arms that terminate in long HeT-A/TART arrays showed increased expression of the subterminal w+ transgene when the terminal repeats on the homologue are absent or markedly shorter. We propose that the chromatin structure of the terminal HeT-A/TART array and the activity of a putative promoter/enhancer element on HeT-A are affected by telomeric interactions. Such trans-activation may reflect control over HeT-A transcription and, thus, transposition activity.
插入果蝇亚端粒卫星区域的基因标记P元件会导致报告基因的抑制和斑驳现象。其中一个这样的白色+报告基因插入在2号染色体左臂(2L)的亚端粒卫星和末端HeT - A阵列之间,对其所处环境敏感;端粒区域结构的变化可通过眼睛颜色的变化来识别。向2L末端添加HeT - A或TART元件会增加w +的表达,而末端序列的缺失则会降低表达。这表明果蝇中的端粒逆转座子对被抑制的亚末端报告基因具有激活作用。由于转基因表达改变导致的眼睛颜色变化也能检测到同源端粒之间的相互作用。当同源染色体上的末端重复序列缺失或明显缩短时,以长HeT - A/TART阵列结尾的2L臂显示出亚末端w +转基因的表达增加。我们推测,末端HeT - A/TART阵列的染色质结构以及HeT - A上一个假定的启动子/增强子元件的活性受端粒相互作用的影响。这种反式激活可能反映了对HeT - A转录的控制,进而反映了转座活性。