Molecular Genetics of Dosage Compensation in Drosophila

描述（由申请人提供） 这项研究将主要在俄罗斯进行，作为NIH资助的延伸# R01 GM45744。剂量补偿是一个引人注目的例子， 基因特异性调节和染色体结构。这一过程已经演变成 使具有一条X染色体的男性的X连锁基因表达等同， 女性有两个。在分子水平上检查的物种中， 补偿是由性别特异性因素介导的， 染色体调节染色质结构和基因表达。在果蝇中， 剂量补偿至少部分地通过位点特异性 组蛋白H4乙酰化，由男性特异性X特异性复合物调节 （由MSL蛋白和非编码roX RNA组成）。我们在这方面的重点 FIRCA的建议，由Zhimulev集团的细胞学专业知识， 将是分析果蝇的X染色体特异性 剂量补偿复合物 我们最近提出，在野生型雄性中，MSL复合物在 大约30个染色质进入位点，仅沿着X分布， 然后被顺式吸引到可能与 活跃的基因。这一显著的扩散特性 将通过绘制复合物在 内源性X染色体，以及在其中携带外源性X染色体的转基因 染色质进入位点异位插入常染色体。我们还将 研究影响MSL传播能力和位点特异性的条件， 包括热休克，限制MSL2亚基的水平，以及 X：A易位染色体。 在果蝇和人类中，调节分子通常以顺式限制， 但如果被带到常染色体上， 在剂量补偿之前。剖析这些现象背后的机制 表观遗传调控过程将提供洞察许多重要的 生物学问题，包括人类的正常和疾病状态。的高超 多线染色体的空间分辨率，一个确定的起始位点， 传播，以及蛋白质和RNA传播中突变体的可用性 组件使MSL复杂的一个理想的模型系统，以确定如何改变 染色质结构影响复杂生物体中的基因表达。

DESCRIPTION (provided by applicant) This research will be done primarily in Russia as an extension of NIH grant # R0l GM45744. Dosage compensation is a striking example of the interplay between gene-specific regulation and chromosomal architecture. This process has evolved to make X-linked gene expression equivalent in males with one X chromosome and females with two. In species examined at the molecular level, dosage compensation is mediated by sex-specific factors that decorate the X chromosomes to regulate chromatin structure and gene expression. In Drosophila, dosage compensation is achieved, at least in part, through site-specific histone H4 acetylation, modulated by a male-specific, X-specific complex (composed of the MSL proteins, and non-coding roX RNAs). Our focus in this FIRCA proposal, enabled by the cytological expertise of the Zhimulev group, will be to analyze the exquisite X chromosome-specificity of the Drosophila dosage compensation complex. We have recently proposed that in wild type males, the MSL complex forms at approximately 30 chromatin entry sites, distributed exclusively along the X, and is then attracted in cis to sequences or proteins that may be common to active genes throughout the genome. This remarkable property of spreading in cis will be examined by mapping the sites to which the complex spreads in the endogenous X chromosome, as well as in cases where a transgene carrying a chromatin entry site is inserted ectopically into an autosome. We will also study conditions that affect the ability and site-specificity of MSL spreading, including heat shock, limiting levels of the MSL2 subunit, and the behavior of X:A translocation chromosomes. In both flies and humans, regulatory molecules are normally restricted in cis to the X chromosome, but if brought to autosomes, can spread on genes never before dosage compensated. Dissecting the mechanisms underlying these epigenetic regulatory processes will provide insight into many important biological problems, including normal and disease states in humans. The superb spatial resolution of polytene chromosomes, a defined initiation site for spreading, and the availability of mutants in the protein and RNA spreading components make the MSL complex an ideal model system to determine how changes in chromatin architecture affect gene expression in complex organisms.