Unexpected roles of phosphoinositides in the nucleus

项目总结/摘要 磷脂酰肌醇（PI）是一种次要的磷脂类，通常占细胞脂质的不到1%。 队列。尽管丰度低，PI对细胞生理和PI信号转导的改变有巨大影响 这些途径与包括神经变性疾病在内的许多人类疾病的发病机制有关， 代谢紊乱、自身免疫和癌症。这种病理生理学的重要性主要是由于 PI的信号传导作用取决于PI的亚细胞分布和PI之间的关键相互作用 PI效应器PI信号的一个扭曲是，与一般的信念相反， 在非膜核隔室中。核PI的性质和功能在很大程度上仍然未知 由于缺乏对核PI和PI效应物的系统研究，我们拥有专业知识， 表征参与关键信号传导途径包括囊泡运输的新型PI效应蛋白， 细胞骨架动力学和转录调节。由于PI激酶通常与PI效应物相关，因此 为了确保PI的产生与PI效应子的激活在时空上相关，我们进行了蛋白质组学分析， 以确定核PI生成激酶的相互作用组。在这些蛋白质组筛选中， 验证了与核PI激酶或PI本身相关的几种核复合物。经验证的 复合物包括转录因子和共激活因子、表观遗传酶和相关的共阻遏物， DNA修复机制和参与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 我们新发现的PI和PI激酶与细胞核中的效应物相互作用， 我的研究项目是破译核PI发出的信号通路。我们的整体 一种假设是，在适当的刺激下，在特定的亚核区室中，核PI激酶的激活 提高核PI的局部浓度，这些核PI灶作为平台调节PI 募集到焦点的效应物介导转录调节和调节的复合物的组装 表观遗传变化我未来五年研究计划的目标包括解剖自然， 核PI的亚核分布使用新的显微工具，这将使我们能够获得高分辨率 核PI的图像，定义了PI调节染色质定位到核斑点的新作用， 研究核PI在调控基因表达中的新作用，重点是转录调控 和表观遗传抑制与创新的细胞生物学，全基因组，和生化方法。于 研究计划的完成，我们将获得洞察意想不到的作用和分子机制 的PI在细胞核中，目标是确定新的战略，针对核PI信号通路 在多种人类疾病中失调。

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.