PAR polarity proteins and Neurogenesis

PAR 极性蛋白和神经发生

• 批准号: BB/D010640/1
• 负责人: Jeremy Green
• 金额: $ 31.67万
• 依托单位: King's College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FD010640%2F1
• 关键词: PAR; polarity; proteins; Neurogenesis

Par polarity proteins in building the nervous system The brain develops from a thin sheet of cells in the embryo. During development to the adult, it becomes an extraordinarily complex structure with many layers and many different cell types. One of the ways of generating different cell types is by cells dividing asymmetrically, that is a cell becoming two daughter cells that are different from one another. Typically, one daughter cell is like its mother (i.e. a stem cell that can divide in the same way again) while the other is a more specialised cell such as a neuron. Such divisions are known to take place in the developing mammalian brain at many stages, and so how they are regulated is very important in understanding brain development in general. How do asymmetrical cell divisions happen in the developing brain? We have been studying a group of proteins that in flies and worms are needed for certain asymmetric cell divisions at several stages of development in non-neural tissues. To do this, we have used the Xenopus frog as an experimental system because, like humans, it is a vertebrate, but unlike humans or laboratory mice, its embryos are large and can be watched easily from spawning to tadpole stages, a period of four days. We decided to look at these proteins in the neural tissue. We found that when we deplete either of two of these proteins, known as Par-1 and Par-4, early neurons are no longer formed. When we introduce extra Par-1 protein in the wrong place, we can get extra neurons. This tells us that these Par proteins are important and so we want to discover how they work. We believe that both the loss and the gain of neurons we see happen because the earliest asymmetrical cell divisions in the thin sheet of cells that will make the brain are now not sufficiently asymmetrical. To test this idea, we will observe directly whether the daughter cells of the early divisions go on to become the same type of cell when Par-1 or Par-4 is altered. This involves either manually separating the cells early or tracking them in place and then using specific cell staining reagents to see what cell types they are. In a separate set of experiments, we will also find out whether the role of Par-1 and Par-4 is similar in other asymmetric divisions, specifically in the early skin and in the later cell divisions that give rise to neurons. We will also look at cells from mouse brains that are known to divide asymmetrically, but for which the role of Par-1 and Par-4 is completely unknown. Finally, in a third project, we will examine the biochemistry of what Par-1 and Par-4 are doing. They are both enzymes ('kinases') that add phosphate groups to other proteins. This is a common way that changes are transmitted from one part of a cell to another and there are hundreds of different kinases that each relays a different signal. We know some of the proteins that the Par kinases can regulate. Whether they do this during neuron development, we do not know / but can find out. We have special reagents ('phospho-specific-antibodies') that can be used to stain the specific candidate proteins only when they are phosphorylated. Sophisticated microscopes and image processing will show us exactly where and when the phosphorylation evens take place. Seeing where and when these phosphorylation events take place in the developing nervous system will enable us to draw a few more important linkages in the vast circuit diagram that drives development. Ultimately, all of the above studies will not only help us understand how brains are made, but it will also contribute to the knowledge that is needed to make cells that can repair the brains and spinal cords of patients.

在建立神经系统中的极性蛋白质大脑是从胚胎中的一层薄薄的细胞发育而来的。在发育到成年的过程中，它变成了一个非常复杂的结构，有许多层和许多不同的细胞类型。产生不同细胞类型的方法之一是细胞不对称分裂，即一个细胞变成两个彼此不同的子细胞。通常情况下，一个子细胞像它的母亲（即干细胞，可以以同样的方式再次分裂），而另一个是一个更专门的细胞，如神经元。已知这种分裂在哺乳动物大脑发育的许多阶段都发生，因此它们是如何被调节的，对于理解大脑的总体发育非常重要。发育中的大脑中如何发生不对称的细胞分裂？我们一直在研究一组蛋白质，这些蛋白质在苍蝇和蠕虫中是非神经组织发育的几个阶段中某些不对称细胞分裂所必需的。为了做到这一点，我们使用了非洲爪蟾作为实验系统，因为它和人类一样是一种脊椎动物，但与人类或实验室小鼠不同的是，它的胚胎很大，可以很容易地从产卵到蝌蚪阶段进行观察，为期四天。我们决定在神经组织中观察这些蛋白质。我们发现，当我们耗尽其中两种蛋白质（称为Par-1和Par-4）中的任何一种时，早期神经元就不再形成。当我们在错误的地方引入额外的Par-1蛋白时，我们可以得到额外的神经元。这告诉我们这些Par蛋白很重要，所以我们想知道它们是如何工作的。我们相信，我们所看到的神经元的损失和增加都是因为最早的不对称细胞分裂在薄的细胞片中，现在不足够不对称。为了验证这个想法，我们将直接观察当Par-1或Par-4发生改变时，早期分裂的子细胞是否继续成为同一类型的细胞。这涉及早期手动分离细胞或跟踪它们，然后使用特定的细胞染色试剂来查看它们是什么细胞类型。在另一组实验中，我们还将发现Par-1和Par-4在其他不对称分裂中的作用是否相似，特别是在早期皮肤和后期产生神经元的细胞分裂中。我们还将研究已知不对称分裂的小鼠大脑细胞，但Par-1和Par-4的作用完全未知。最后，在第三个项目中，我们将研究Par-1和Par-4所做的生物化学。它们都是将磷酸基团添加到其他蛋白质上的酶（激酶）。这是一种常见的方式，变化从细胞的一个部分传递到另一个部分，有数百种不同的激酶，每一种都传递不同的信号。我们知道Par激酶可以调节的一些蛋白质。我们不知道它们是否在神经元发育过程中这样做，但可以找到答案。我们有特殊的试剂（“磷酸化特异性抗体”），可用于染色特定的候选蛋白质，只有当它们被磷酸化。先进的显微镜和图像处理技术将告诉我们磷酸化发生的确切时间和地点。了解这些磷酸化事件在发育中的神经系统中何时何地发生，将使我们能够在驱动发育的庞大电路图中绘制出一些更重要的联系。最终，所有上述研究不仅将帮助我们了解大脑是如何形成的，而且还将有助于制造能够修复患者大脑和脊髓的细胞所需的知识。

项目成果

PAR-1 promotes primary neurogenesis and asymmetric cell divisions via control of spindle orientation.

PAR-1 通过控制纺锤体方向促进初级神经发生和不对称细胞分裂。

• DOI: 10.1242/dev.049833
• 发表时间: 2010
• 期刊: Development (Cambridge, England)
• 作者: Tabler JM

PAR1 specifies ciliated cells in vertebrate ectoderm downstream of aPKC.

• DOI: 10.1242/dev.009282
• 发表时间: 2007-12
• 期刊: Development (Cambridge, England)
• 作者: Ossipova O;Tabler J;Green JB;Sokol SY
• 通讯作者: Sokol SY

The distribution of Dishevelled in convergently extending mesoderm.

• DOI: 10.1016/j.ydbio.2013.07.012
• 发表时间: 2013-10-15
• 期刊: DEVELOPMENTAL BIOLOGY
• 影响因子: 2.7
• 作者: Panousopoulou, Eleni;Tyson, Richard A.;Bretschneider, Till;Green, Jeremy B. A.
• 通讯作者: Green, Jeremy B. A.