How do Fbxo7 and PI31 control sperm morphogenesis and male fertility?

Fbxo7 和 PI31 如何控制精子形态发生和男性生育能力？

• 批准号: BB/X014177/1
• 负责人: Heike Laman
• 金额: $ 69.68万
• 依托单位: University of Cambridge
• 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%2FX014177%2F1
• 关键词: How; do; Fbxo7; PI31; control

Sperm cells are the smallest cells in the body, having shed virtually all of their cellular contents in order to swim faster. The production of mature sperm thus involves perhaps the most radical changes in cellular shape in all of mammalian biology. As sperm cells develop, they are dragged into deep indentations ("crypts") within nurse cells (Sertoli cells) that support and sculpt them. Therein, developing sperm cells make ready their cytoplasm for elimination, and package it up for disposal by the Sertoli cells. As the sperm realise their final shape, they are pushed back out of the crypts, and finally released as free-living, mature sperm cells. As yet, little is understood about the processes that coordinate this transformation and control how each cell is moulded into its final shape. We recently discovered that a protein called Fbxo7 is critical for sperm remodelling at a precise time in the process of assuming this streamlined shape. In male mice that lack Fbxo7, sperm cells develop normally up to the point where they enter the crypts - however the cells never leave the crypts and instead all die at once. This shows that Fbxo7 is necessary for the cellular remodelling steps to make a sperm. We know that Fbxo7 plays a role in maintaining the function of mitochondria - which supply cells with energy - and in disposing of defective mitochondria. Fbxo7 performs many of its functions by adding a small tag, called ubiquitin, onto other "target" proteins. This ubiquitin tag usually causes the target proteins to be disposed of by a large degrading enzyme called the proteasome, but in some cases, it can alter the target protein's function or move it around the cell. Fbxo7 also interacts with a partner protein called PI31 that attaches proteasomes to motor proteins to move them around within a cell. Our findings suggest that the addition of ubiquitin to target proteins by Fbxo7, with or without the help of its partner PI31, is likely to be akey factor in regulating mitochondria and/or proteasome trafficking inside the cell during the final phase of sperm remodelling.Our key goals are:1. To find out what is going wrong in the testes of males lacking Fbxo7 and PI31 - are the mitochondria fragmented or deformed, are they being carried to the right location within the cell, and are they working normally? Alternatively, is there a problem with proteasome localisation? We will investigate this using fluorescence microscopy and electron microscopy in conjunction with staining for markers of each of these processes.2. To identify what Fbxo7 is doing biochemically in normal testes - what is it attaching ubiquitin to, and what effect does this have? Does it require help from PI31? What proteins associate with proteasomes when sperms are being sculpted and how is this controlled by Fbxo7 and PI31. We will investigate this by comparing the ubiquitin-tagged proteins and the proteasome-associated proteins in cells from mice lacking Fbxo7 and PI31.Understanding how these events take place is important from both a pure science and a medical perspective - for example, understanding Fbxo7 function may help us understand and eventually treat sterility in some infertile patients who make no sperm. Conversely, selectively interfering with Fbxo7 function in the testes could become the basis for novel methods of male contraception. Fbxo7 is also important in other tissues: many different cell types such as red blood cells and nerve cells also undergo remodelling to transform their shapes, and Fbxo7 deficiency is also associated with anaemia and neurological conditions such as Parkinson's disease. Understanding how Fbxo7 and PI31 control cell shape in the testis may shed light on their role(s) in these other diseases as well.

精子细胞是身体中最小的细胞，为了游得更快，几乎已经脱落了所有的细胞内容物。因此，成熟精子的产生可能涉及哺乳动物生物学中细胞形状的最根本变化。随着精子细胞的发育，它们被拖进支持和塑造它们的滋养细胞（支持细胞）内的深凹（“隐窝”）。在那里，发育中的精子细胞准备好它们的细胞质，并将其包装起来，供支持细胞处理。当精子实现它们的最终形状时，它们被推出隐窝，最终作为自由生活的成熟精子细胞释放出来。到目前为止，人们对协调这种转变并控制每个细胞如何塑造成最终形状的过程知之甚少。我们最近发现，一种名为Fbxo 7的蛋白质对于精子在呈现这种流线型形状的过程中的精确时间重塑至关重要。在缺乏Fbxo 7的雄性小鼠中，精子细胞正常发育，直到它们进入隐窝-然而细胞永远不会离开隐窝，而是立即全部死亡。这表明Fbxo 7是细胞重塑步骤所必需的。我们知道，Fbxo 7在维持线粒体功能（为细胞提供能量）和处理有缺陷的线粒体方面发挥作用。fbxo 7通过在其他“目标”蛋白质上添加一个称为泛素的小标签来执行其许多功能。这种泛素标签通常会导致靶蛋白被称为蛋白酶体的大型降解酶处理，但在某些情况下，它可以改变靶蛋白的功能或使其在细胞内移动。Fbxo 7还与一种名为PI 31的伴侣蛋白相互作用，PI 31将蛋白酶体附着在马达蛋白上，使其在细胞内移动。我们的研究结果表明，Fbxo 7在其伴侣PI 31的帮助下或不帮助下将泛素添加到靶蛋白，可能是在精子重塑的最后阶段调节细胞内线粒体和/或蛋白酶体运输的关键因素。为了找出缺乏Fbxo 7和PI 31的男性睾丸中的问题-线粒体是否断裂或变形，它们是否被携带到细胞内的正确位置，以及它们是否正常工作？或者，蛋白酶体定位有问题吗？我们将使用荧光显微镜和电子显微镜结合这些过程的标记物染色来研究这一点。为了确定Fbxo 7在正常睾丸中的生物化学作用-它将泛素连接到什么上，这有什么影响？是否需要PI 31的帮助？当精子被塑造时，哪些蛋白质与蛋白酶体相关，以及Fbxo 7和PI 31是如何控制的。我们将通过比较缺乏Fbxo 7和PI 31的小鼠细胞中的泛在蛋白标记蛋白和蛋白酶体相关蛋白来研究这一点。从纯科学和医学角度来看，了解这些事件如何发生都很重要-例如，了解Fbxo 7功能可能会帮助我们了解并最终治疗一些不产生精子的不孕症患者的不育症。相反，选择性干扰睾丸中的Fbxo 7功能可能成为男性避孕新方法的基础。Fbxo 7在其他组织中也很重要：许多不同的细胞类型，如红细胞和神经细胞也会经历重塑以改变其形状，Fbxo 7缺乏也与贫血和神经系统疾病如帕金森病有关。了解Fbxo 7和PI 31如何控制睾丸中的细胞形状也可能揭示它们在这些其他疾病中的作用。