The Dosage Compensation Machinery of C. elegans

描述（由申请人提供）：凝聚素复合物在有丝分裂期间起作用，以形成凝聚的有丝分裂染色体，并在间期期间调节基因的表达。这两个目标都被认为是通过改变染色体的高级结构来实现的。在线虫中，C.两种不同的凝聚素复合物执行这两种功能。有丝分裂凝聚素复合体在染色体分离中起作用，而剂量补偿复合体调节两性X染色体上的基因表达，以平衡两性之间的X连锁基因剂量。我们的长期目标是破译蠕虫剂量补偿的分子机制，并确定它如何与染色体凝聚的机制。剂量补偿复合物的生化纯化导致了CPG-1的发现，CPG-1是一种新的剂量补偿复合物亚基，它也在染色体分离中起作用。为了揭示剂量补偿和染色体分离之间的机制相似性，我们将使用遗传，生物化学和显微镜工具来分析CPG-1在这两个过程中发挥作用的方式。第二部分将分析剂量补偿染色体的染色质纤维。我们发现，HTZ-1，H2 A的组蛋白变体，是消耗剂量补偿X染色体相比，常染色体。我们提出的实验的目标是破译这种消耗如何有助于剂量补偿。为此，我们将在低分辨率（免疫荧光）和高分辨率（染色质免疫沉淀）下研究剂量补偿复合物和HTZ-1与X染色体之间的关系。任何有机体的健康发育都取决于向每个细胞提供正确数量的染色体，然后打开正确的基因组。将错误数量的染色体传递给细胞，或者不适当地打开或关闭基因，会导致发育障碍或癌症。染色体的这些功能在很大程度上取决于它们所含的DMA的结构和组织。更好地了解染色体结构如何决定基因活性水平并确保适当的染色体分离的基本生物学原理，对于理解健康发育和疾病的发展都很重要。

DESCRIPTION (provided by applicant): The condensin complex functions both during mitosis, to form condensed mitotic chromosomes, and during interphase, to regulate expression of genes. Both of these goals are thought to be accomplished by altering the higher order of structure of chromosomes. In the nematode, C. elegans, two distinct condensin complexes perform these two functions. The mitotic condensin complex plays a role in chromosome segregation, while the dosage compensation complex regulates expression of genes on hermaphrodite X chromosomes to equalize X-linked gene dosage between the sexes. Our long-term goal is to decipher the molecular mechanism of worm dosage compensation and to determine how it relates to the mechanism of chromosome condensation. Biochemical purification of the dosage compensation complex led to the discovery of CPG-1, a new dosage compensation complex subunit, which also functions in chromosome segregation. To reveal mechanistic similarities between dosage compensation and chromosome segregation, we will use genetic, biochemical, and microscopic tools to analyze the ways in which CPG-1 can function during both processes. The second part of our proposed study will analyze the chromatin fiber of dosage compensated chromosomes. We found that HTZ-1, a histone variant of H2A, is depleted on dosage compensated X chromosomes as compared to autosomes. The goal of our proposed experiments is to decipher how this depletion contributes to dosage compensation. To do that we will study the relationship between the association of dosage compensation complex and HTZ-1 with the X chromosome, both at low resolution (immunofluorescence) and high resolution (chromatin immunoprecipitation). Healthy development of any organism depends on delivering the correct number of chromosomes to each cell and on each cell then turning on the right set of genes. Delivering the wrong number of chromosomes to cells, or inappropriately turning genes on or off, leads to developmental disorders or cancer. These functions of chromosomes depend largely on the structure and organization of DMA contained in them. A better knowledge of the basic biological principals of how chromosome structure determines gene activity levels and ensures proper chromosome segregation will be important to understanding both healthy development and the development of disease.