Girton Jack, Wang Chao, Johansen Jørgen, Johansen Kristen M
Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, USA.
Fly (Austin). 2013 Apr-Jun;7(2):129-33. doi: 10.4161/fly.24266. Epub 2013 Apr 1.
In this study we have taken advantage of recent whole genome sequencing studies that have determined the DNA content in the heterochromatic regions of each Drosophila chromosome to directly correlate the effect on position-effect variegation of a pericentric insertion reporter line, 118E-10 with the total amount of heterochromatic DNA. Heterochromatic DNA levels were manipulated by adding or subtracting a Y chromosome as well as by the difference in the amount of pericentric heterochromatin between the X and Y chromosome. The results showed a direct, linear relationship between the amount of heterochromatic DNA in the genome and the expression of the w marker gene in the 118E-10 pericentric reporter line and that increasing amounts of heterochromatic DNA resulted in increasing amounts of pigment/gene activity. In Drosophila heterochromatic spreading and gene silencing is counteracted by H3S10 phosphorylation by the JIL-1 kinase, and we further demonstrate that the haplo-enhancer effect of JIL-1 is proportional to the amount of total heterochomatin, suggesting that JIL-1's activity is dynamically modulated to achieve a more or less constant balance depending on the levels of heterochromatic factors present.
在本研究中，我们利用了最近的全基因组测序研究，这些研究确定了每条果蝇染色体异染色质区域的DNA含量，以直接关联一个着丝粒插入报告系118E - 10对位置效应斑驳的影响与异染色质DNA的总量。通过添加或减去一条Y染色体以及利用X和Y染色体之间着丝粒异染色质数量的差异来操纵异染色质DNA水平。结果表明，基因组中异染色质DNA的量与118E - 10着丝粒报告系中w标记基因的表达之间存在直接的线性关系，并且异染色质DNA量的增加导致色素/基因活性量的增加。在果蝇中，异染色质扩展和基因沉默被JIL - 1激酶介导的H3S10磷酸化所抵消，并且我们进一步证明JIL - 1的单倍体增强子效应与总异染色质的量成比例，这表明JIL - 1的活性被动态调节，以根据存在的异染色质因子水平实现或多或少恒定的平衡。
