The role of lipid homeostasis in nuclear shape and function

脂质稳态在核形状和功能中的作用

• 批准号: 7734249
• 负责人: Orna Cohen-Fix
• 金额: $ 23.51万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7734249
• 关键词: Affect; Aging; Anabolism; Architecture; Biological Models; Candidate Disease Gene; Cell Nucleolus; Cell Nucleus; Cellular biology; Centrosome; Chromosome Segregation; Code; Defect; Electron Microscopy; Elements; Exhibits; Fatty acid glycerol esters; Genes; Genetic; Genetic Screening; Growth; Homeostasis; Homologous Gene; Homologous Protein; Human; Link; Lipids; Malignant Neoplasms; Membrane; Methodology; Microtubules; Morphology; Movement; Mutation; Nature; Nuclear; Nuclear Envelope; Nuclear Pore Complex; Nuclear Structure; Obesity; Pathway interactions; Peripheral; Phospholipids; Play; Process; Proteins; Role; Saccharomycetales; Shapes; Structure; Tissue Differentiation; Yeasts; base; cell type; genetic analysis; lipid biosynthesis; lipine; mutant; spindle pole body

Alterations in nuclear structure are associated with aging and cancer, and yet the functional link between nuclear architecture and nuclear functions is not well understood. We have been using budding yeast as a model system to study nuclear architecture. In an earlier study from our lab (Campbell et al, 2006), we showed that the shape of the yeast nucleus is affected by processes that regulate lipid biosynthesis. In particular, inactivating the yeast homolog of lipin leads to expansion of the nuclear membrane in a particular nuclear compartment. To further understand the link between lipid homeostasis and nuclear function we embarked on a genetic screen for mutations that render the lipin pathway essential for viability. To this end, we combined mutations in candidate genes with the spo7 mutation, looking for reduced growth in the double mutant. The candidate genes were selected based on their function and localization; most were involved in processes that take place near or at the nuclear membrane and most mutations were in genes coding for proteins that exhibit a peripheral localization. Through this screen we found a mutant that was known to affect spindle pole body function. The yeast spindle pole body is equivalent to the metazoan centrosome and it acts in nucleating spindle microtubules during chromosome segregation and in nucleating cytoplasmic microtubules that are needed for nuclear movement. The mechanism by which the spindle pole body is inserted and maintained in the nuclear membrane is not known, but this is a question of immense importance because the mechanism of nuclear membrane insertion could apply to other nuclear membrane structures, such as nuclear pore complexes. We found that additional mutations known to abrogate spindle pole body assembly also relay on the lipin pathway for viability. These findings suggest that the composition of the nuclear membrane affects the function of nuclear membrane associated structures. Our studies are now focused on understanding the nature of this defect, using cell biology and genetic methodologies. We are also collaborating with Dr. Sue Jaspersen in order to look at spindle pole bodies by electron microscopy and to determine the relationship between nuclear membrane composition and the assembly of integral membrane structures.

核结构的改变与衰老和癌症有关，但核结构和核功能之间的功能联系尚未得到很好的理解。我们一直使用芽殖酵母作为模型系统来研究核结构。在我们实验室的早期研究中（坎贝尔等人，2006），我们发现酵母细胞核的形状受到调节脂质生物合成过程的影响。特别是，失活的酵母同系物脂蛋白导致扩张的核膜在一个特定的核隔室。为了进一步了解脂质体内平衡和核功能之间的联系，我们着手进行基因筛选，以寻找使脂蛋白途径对生存力至关重要的突变。 为此，我们将候选基因中的突变与spo 7突变相结合，寻找双突变体中生长减少的情况。候选基因的选择是基于它们的功能和定位;大多数参与核膜附近或核膜上发生的过程，大多数突变发生在编码表现出外周定位的蛋白质的基因中。通过这个筛选，我们发现了一个已知影响纺锤体极体功能的突变体。酵母纺锤体极体相当于后生动物的中心体，它在染色体分离过程中起着使纺锤体微管成核的作用，并在细胞核运动所需的细胞质微管成核中起作用。纺锤体极体插入并保持在核膜中的机制尚不清楚，但这是一个非常重要的问题，因为核膜插入的机制可以应用于其他核膜结构，如核孔复合物。我们发现，其他已知的突变废除纺锤体极体组装也接力的脂蛋白途径的活力。这些发现表明，核膜的组成影响核膜相关结构的功能。我们的研究现在集中在利用细胞生物学和遗传学方法来了解这种缺陷的性质。我们还与Sue Jaspersen博士合作，通过电子显微镜观察纺锤体极体，并确定核膜组成与整体膜结构组装之间的关系。