'How is PtdIns(4,5)P2, a membrane lipid messenger, localised and regulated in splicing speckles, a membrane less compartment within the nucleus?

“PtdIns(4,5)P2（一种膜脂信使）如何在剪接斑点（细胞核内的无膜区室）中定位和调节？

• 批准号: BB/Y001648/1
• 负责人: Nullin Divecha
• 金额: $ 110.7万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FY001648%2F1
• 关键词: How; PtdIns; P2; membrane; lipid

DNA is the code for human life that makes up genes that are used to produce proteins. Proteins are the molecular workhorses that are used by cells to carry out specific functions. Cells in our bodies are constantly under attack from stressors which lead to their damage and demise. For example, many different environmental exposures lead to damage of our DNA. This can include sunlight or harmful chemicals in the air. DNA is the building blocks of our cells, and if it becomes damaged the cell cannot function properly and this can either lead to the cell dying, or often can lead to the development of diseases such as cancer. DNA is contained in a specialised compartment of the cells called the nucleus. To respond to these stressors that damage our DNA, cells have to be made aware of, or sense, the damage and then have to initiate an appropriate response. There is a highly sophisticated machinery in cells that can sense damaged DNA, and when it does so sends an appropriate signal to inform the cell to change its behaviour and respond to it. One of these signals is made up of a family of lipids or fat molecules collectively called phosphoinositides or PPIns for short. Because of their chemical composition these fat molecules like to stay together with other fat molecules which normally forms a membrane, rather like a soap bubble. In fact, the membrane is what forms the outside of a cell. However, in the nucleus surprisingly, these PPIns molecules sit in a specialised place called a splicing speckle which are known not to have any membranes. How PPIns arrive at the speckles and how they are kept there is a mystery which we are now beginning to understand. In the nucleus these speckles are involved in a rather special function, called splicing, that helps the cell to use the DNA to produce proteins. The DNA instruction manual has a peculiar structure. It contains regions called genes which code for proteins. These genes are made up of smaller blocks of DNA; some of which code for part of the protein and are called exons, and other parts between the exons that contain nonsense code called introns. The instructions to make a protein rely on piecing together the coding exons of the DNA while removing the introns. To do this without losing the cells copy of DNA, it is first copied into a similar molecule called RNA, which contains the exons and introns. The nonsense introns are then removed and this process is called splicing. Once the introns have been removed, the RNA can be used to make proteins to help the cell to respond to the stressors. We think that these PPIns are a key part of the whole process. In response to stressors it seems that the amount of these PPIns at the speckle goes up. Remarkably these PPIns have an ability to be able to attract and talk to special proteins and change where they are in the cell and how well they carry out their functions. It turns out that in fact, they bind and talk to many of the proteins that are involved in splicing. Part of this study will work out exactly how DNA damage changes the amount of PPIns at the speckle, and which splicing proteins respond to the increase in PPIns. What this leaves out is the mystery about how the PPIns arrive and stay in the speckle. In a beautifully coordinated manner, we have found that one of the proteins that is involved in splicing, called SRSF2, is able to bind to PPIns and is critical for bringing the PPIns to the speckle and holding them there. How SRSF2 does this will form a major part of this study.How well splicing works is fundamental to life itself and during human life splicing ability changes, Moreover, SRSF2 is often mutated in blood cancers. PPIns are made and removed by a family of proteins called enzymes and we hope to make drug like molecules that inhibit them. These could be used to specifically control the levels of PPIns in the nucleus; which could then be used to treat several diseases such as cancer and perhaps help during ageing.

DNA是人类生命的密码，它构成了用于生产蛋白质的基因。蛋白质是细胞用来执行特定功能的分子工具。我们体内的细胞不断受到压力源的攻击，导致它们的损伤和死亡。例如，许多不同的环境暴露导致我们的DNA受损。这可能包括阳光或空气中的有害化学物质。DNA是我们细胞的基石，如果它受损，细胞就不能正常工作，这可能导致细胞死亡，或者经常导致癌症等疾病的发展。DNA被包含在细胞的一个专门的隔间中，称为细胞核。为了应对这些损害我们DNA的压力，细胞必须意识到或感觉到这种损害，然后必须启动适当的反应。细胞中有一种高度复杂的机制，可以感知受损的DNA，并在此过程中发出适当的信号，通知细胞改变其行为并做出反应，其中一种信号由统称为磷酸肌醇或PPIns的脂质或脂肪分子家族组成。由于它们的化学成分，这些脂肪分子喜欢与其他脂肪分子呆在一起，通常形成一层膜，而不是像肥皂泡。事实上，细胞膜是构成细胞外部的物质。然而，令人惊讶的是，在细胞核中，这些PPIns分子位于一个称为剪接斑点的专门位置，已知它没有任何膜。PPIn如何到达斑点以及它们如何保持在那里是一个谜，我们现在开始了解这个谜。在细胞核中，这些斑点参与了一种相当特殊的功能，称为剪接，帮助细胞利用DNA产生蛋白质。DNA指令手册有一个特殊的结构。它包含了一个叫做基因的区域，这个区域编码蛋白质。这些基因由较小的DNA块组成;其中一些编码蛋白质的一部分，称为外显子，而外显子之间包含无意义代码的其他部分称为内含子。制造蛋白质的指令依赖于将DNA的编码外显子拼凑在一起，同时去除内含子。为了做到这一点，而不丢失细胞的DNA拷贝，它首先被复制到一个类似的分子称为RNA，其中包含外显子和内含子。然后无义内含子被移除，这个过程称为剪接。一旦内含子被移除，RNA就可以用来制造蛋白质，帮助细胞对压力源做出反应。我们认为这些PPins是整个过程的关键部分。在对压力源的反应中，这些PPIn在斑点处的量似乎上升。值得注意的是，这些PPIns能够吸引和与特殊蛋白质交谈，并改变它们在细胞中的位置以及它们执行功能的方式。事实上，它们与许多参与剪接的蛋白质结合并交谈。这项研究的一部分将准确地确定DNA损伤如何改变斑点处PPIns的数量，以及哪些剪接蛋白对PPIns的增加做出反应。这就遗漏了PPins如何到达并停留在斑点中的奥秘。以一种完美的协调方式，我们发现参与剪接的蛋白质之一，称为SRSF 2，能够与PPIns结合，并且对于将PPIns带到斑点并将其保持在那里至关重要。SRSF 2是如何做到这一点的将构成本研究的主要部分。剪接工作的好坏对生命本身和人类生命剪接能力的变化至关重要。此外，SRSF 2经常在血液癌症中发生突变。PPIns是由一种叫做酶的蛋白质家族制造和去除的，我们希望制造出类似药物的分子来抑制它们。这些可以用来专门控制细胞核中PPIns的水平;然后可以用来治疗癌症等多种疾病，也许还有助于衰老。