Regulation and activities of amyloidogenic proteins APP and TGFBI in physiological and pathological protein aggregation

淀粉样蛋白APP和TGFBI在生理和病理蛋白聚集中的调节和活性

• 批准号: BB/W00707X/1
• 负责人: Clive Wilson
• 金额: $ 72.27万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FW00707X%2F1
• 关键词: Regulation; activities; amyloidogenic; proteins; APP

Amyloidogenesis is the aggregation of normally soluble proteins into insoluble fibres. It is commonly observed in neurodegenerative disorders. For example, in Alzheimer's Disease, processed forms of a protein called APP self-aggregate to produce amyloid plaques in patients, and these plaques affect the survival of neurons. Similarly, defective forms of the TGFBI protein produce amyloid in the cornea and blindness. However, amyloid formation is not just pathological. For example, some hormones normally form inert amyloid structures called dense cores, which can be stored in cells prior to secretion.Combatting amyloid disease requires a better understanding of how amyloid formation is triggered and controlled. But studies in patients and in animals with Alzheimer's-like disease primarily focus on the end products of this process, plaques and memory loss. In fact, for proteins like APP and TGFBI, it has been unclear whether they are normally involved in protein aggregation or whether this is a uniquely pathological process. Large protein aggregates are typically only seen in disease, while normal protein aggregation generally involves the assembly of much smaller structures, making it difficult to follow this process using microscopy techniques suitable for living cells.We have been studying dense core formation in the fruit fly. Flies have equivalents of about 70% of human disease genes, including APP and TGFBI. It is often much easier to identify genes involved in biological processes and disease in flies and to watch these processes take place in living tissues. In fact, these animals are extensively used to study degenerative processes in Alzheimer's. We have identified a specific prostate-like cell in flies, the secondary cell, which makes dense cores that are over one thousand times larger than cores in other cells. This allowed us to follow the rapid formation of dense cores and how this is controlled for the first time in living tissues.Remarkably, we found that the fly equivalents of APP and TGFBI have complementary roles in making these dense cores. TGFBI is required for protein aggregation to take place, while APP ensures that micro-core structures coalesce together to make a single giant core. If a pathological form of APP is made in secondary cells, it changes the organisation of TGFBI in dense cores and stabilises them, so that they fail to disperse when secreted. Using the genetic approaches available in flies, we have already shown parallels between the control of dense core formation in secondary cells and plaque formation in humans, which both seem to involve small membranous droplets called exosomes.We will now study how APP and TGFBI work together to control dense core formation in secondary cells and how this process goes wrong when pathological versions of these amyloid proteins are made in these cells. We will also work out how altering the ways in which secreted proteins are guided through the secretory pathway changes these protein aggregation events in the cell, particularly focusing on whether pathological forms of APP or TGFBI behave differently to the normal proteins. Finally, we will test which of the large number of genes and cellular processes that have been suggested to play a role in Alzheimer's and neurodegeneration through studies in patients and animals are involved in normal and pathological APP and TGFBI aggregation in secondary cells. We will then work out precisely how they affect these processes.Our work will allow us to define how APP and TGFBI, two important amyloid proteins in disease, normally drive protein aggregation into insoluble dense cores. We will identify the genes that control this process and how pathological forms of APP and TGFBI interfere with this control. We will then be ideally positioned to collaborate with other researchers to determine which of these mechanisms is involved in amyloid disease in humans, and to develop approaches to block them.

淀粉样蛋白生成是正常可溶性蛋白质聚集成不溶性纤维。它通常在神经退行性疾病中观察到。例如，在阿尔茨海默病中，一种称为APP的蛋白质的加工形式在患者体内自我聚集以产生淀粉样斑块，这些斑块影响神经元的存活。同样，TGFBI蛋白质的缺陷形式在角膜中产生淀粉样蛋白并导致失明。然而，淀粉样蛋白的形成不仅仅是病理性的。例如，一些激素通常形成称为致密核心的惰性淀粉样蛋白结构，其可以在分泌前储存在细胞中。对抗淀粉样蛋白疾病需要更好地了解淀粉样蛋白形成是如何触发和控制的。但对阿尔茨海默病患者和动物的研究主要集中在这一过程的最终产物，斑块和记忆丧失。事实上，对于APP和TGFBI这样的蛋白质，目前还不清楚它们是否正常参与蛋白质聚集，或者这是否是一个独特的病理过程。大的蛋白质聚集体通常只在疾病中看到，而正常的蛋白质聚集体通常涉及更小结构的组装，因此很难使用适用于活细胞的显微镜技术来跟踪这一过程。我们一直在研究果蝇中致密核心的形成。苍蝇拥有相当于人类疾病基因的70%，包括APP和TGFBI。在果蝇中识别与生物过程和疾病有关的基因，并观察这些过程在活组织中的发生，往往要容易得多。事实上，这些动物被广泛用于研究阿尔茨海默氏症的退化过程。我们已经在果蝇中发现了一种特殊的前列腺样细胞，即次级细胞，它可以制造比其他细胞大一千倍的致密核心。这使我们能够跟踪致密核心的快速形成，以及如何在活组织中首次控制这一过程。值得注意的是，我们发现APP和TGFBI的苍蝇等价物在制造这些致密核心方面具有互补作用。TGFBI是蛋白质聚集所必需的，而APP则确保微核心结构聚结在一起形成一个巨大的核心。如果APP的病理形式在次级细胞中产生，它会改变TGFBI在致密核心中的组织并使其稳定，因此它们在分泌时无法分散。利用果蝇的遗传学方法，我们已经发现了次级细胞中致密核心形成的控制与人类斑块形成之间的相似之处，这两者似乎都涉及称为外泌体的小膜滴。我们现在将研究APP和TGFBI如何共同控制次级细胞中致密核心的形成，以及当这些细胞中产生这些淀粉样蛋白的病理版本时，这个过程是如何出错的。我们还将研究如何改变分泌蛋白通过分泌途径引导的方式，从而改变细胞中的这些蛋白质聚集事件，特别是关注APP或TGFBI的病理形式是否与正常蛋白质的行为不同。最后，我们将测试通过对患者和动物的研究表明在阿尔茨海默病和神经变性中发挥作用的大量基因和细胞过程中，哪些参与了正常和病理性APP和TGFBI在次级细胞中的聚集。我们的工作将使我们能够确定APP和TGFBI这两种疾病中重要的淀粉样蛋白在正常情况下如何驱动蛋白质聚集成不溶性致密核心。我们将确定控制这一过程的基因，以及APP和TGFBI的病理形式如何干扰这种控制。然后，我们将处于理想的位置，与其他研究人员合作，以确定这些机制中的哪一个与人类淀粉样蛋白疾病有关，并开发阻断它们的方法。

项目成果

A Rab6 to Rab11 transition is required for dense-core granule and exosome biogenesis in Drosophila secondary cells.

• DOI: 10.1371/journal.pgen.1010979
• 发表时间: 2023-10
• 期刊: PLoS genetics
• 影响因子: 4.5