Unexpected roles of phosphoinositides in the nucleus

项目摘要/摘要 磷脂酰肌醇(PI)是一类较小的磷脂，通常只占细胞脂的不到1% 一群人。尽管PI的丰度很低，但它对细胞生理和PI信号的改变有巨大的影响 通路与许多人类疾病的发病机制有关，包括神经退行性疾病， 代谢紊乱、自身免疫和癌症。这种病理生理学的重要性在很大程度上是由于 依赖于PI的亚细胞分布和PI之间的关键相互作用的PI的信号作用 和PI效应器。PI信号的一个转折是，与普遍认为的相反，发现了相当一部分PI 在非膜性核隔室中。核指标的性质和功能在很大程度上仍不为人所知。 由于缺乏对核PI和PI效应器的系统研究。我们拥有定义和定义 鉴定新的PI效应蛋白参与包括囊泡运输在内的关键信号通路， 细胞骨架动力学和转录调控。由于PI激酶通常与PI效应器相关联，因此 确保PI的产生在时空上与PI效应器的激活有关，我们进行了蛋白质组学分析 目的：确定核内PI生成蛋白的相互作用。在这些蛋白质组筛选中，我们有 验证了几个与核PI激酶或PI本身相关的核复合体。经过验证的 复合体包括转录因子和辅活化子，表观遗传酶和相关的辅阻遏子， DNA修复机制，以及参与RNA加工的因素。我们最近发现，核PI 聚集在不同的亚核区域，如核斑点和DNA双链断裂。基于 我们在核内与效应器相互作用的PI和PI激酶的新发现，主要目标是 我的研究计划是破译核PI发出的信号通路。我们的整体 假说是，在适当的刺激下，核内PI激酶在特定的亚核区被激活 提高核内PI的局部浓度，这些核内PI作为调节PI的平台 被招募到焦点的效应器介导转录调节和调节的复合体的组装 表观遗传变化。我未来五年的研究计划的目标包括解剖自然和 使用新的显微工具进行核内PI的亚核分布，这将使我们能够获得高分辨率 核PI的图像，定义了PI调节核斑点的染色质定位的新角色， 以及研究核PI在基因表达调控中的新作用，重点是转录调控 通过创新的细胞生物学、全基因组和生物化学方法进行表观遗传抑制。在此之前 完成研究计划，我们将深入了解意外的作用和分子机制 核内PI的研究，目的是确定针对核PI信号通路的新策略 在不同的人类疾病中调节失调。

PROJECT SUMMARY / ABSTRACT Phosphoinositides (PIs) are a minor class of phospholipids often comprising less than 1% of the cellular lipid cohort. Despite the low abundance, PIs have huge impacts on cell physiology and alterations of PI signaling pathways are associated with the pathogenesis of many human diseases including neurodegenerative diseases, metabolic disorders, autoimmunity, and cancer. This pathophysiological importance is largely due to the signaling roles of PIs which depend on the subcellular distribution of PIs and on key interactions between PIs and PI effectors. A twist in PI signaling is that in contrast to general belief, a substantial fraction of PIs is found in non-membranous nuclear compartments. The nature and functions of nuclear PIs remains largely unknown due to the lack of systematic studies of nuclear PIs and PI effectors. We have expertise in defining and characterizing novel PI effector proteins involved in key signaling pathways including vesicular trafficking, cytoskeleton dynamics, and transcription regulation. Since PI kinases are often associated with PI effectors thus ensuring PI generation is spatiotemporally linked to PI effector activation, we have performed proteomic analyses to identify the interactomes of the nuclear PI-generating kinases. Out of these proteomic screens, we have validated several nuclear complexes that associate with nuclear PI kinases or with PIs themselves. The validated complexes include transcription factors and coactivators, epigenetic enzymes and associated corepressors, the DNA repair machinery, and factors involved in RNA processing. We recently discovered that nuclear PIs accumulate at distinct subnuclear regions such as nuclear speckles and DNA double-strand breaks. Based on our novel discoveries of PIs and PI kinases interacting with effectors in the nucleus, the overarching goal of my research program is to decipher the signaling pathways emanating from the nuclear PIs. Our overall hypothesis is that upon suitable stimuli the activation of nuclear PI kinase at specific subnuclear compartments elevates the local concentration of nuclear PIs and these nuclear PI foci function as platforms to regulate PI effectors recruited to the foci mediating transcription regulation and assembly of complexes that regulate epigenetic changes. The goals of my research programs for the next five years include dissecting the nature and subnuclear distribution of nuclear PIs using novel microscopic tools which will enable us to obtain high resolution images of the nuclear PIs, defining the new roles of PIs regulating chromatin positioning to nuclear speckles, and investigating novel roles of nuclear PIs in regulating gene expression with focuses on transcription regulation and epigenetic repression with innovative cell biological, genome-wide, and biochemical approaches. Upon the completion of the research programs, we will obtain insight into the unexpected roles and molecular mechanism of PIs in the nucleus, with the goal of identifying novel strategies for targeting the nuclear PI signaling pathways dysregulated in diverse human disease.