Investigating ubiquitination-regulated cell cycle events underpinning malaria transmission

研究泛素化调节的细胞周期事件支撑疟疾传播

• 批准号: MR/Y013174/1
• 负责人: Nisha Philip
• 金额: $ 85.27万
• 依托单位: University of Edinburgh
• 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=MR%2FY013174%2F1
• 关键词: Investigating; ubiquitination; regulated; cell; cycle

Malaria is caused by the unicellular pathogen Plasmodium that threatens around 400 million people globally and results in over 0.5 million deaths annually, thereby continuing to be a major public health problem, and urgently requiring new therapeutics. Completion of the malaria parasite's complex lifecycle requires a mammalian host where it causes disease, as well as a mosquito vector responsible for spread of the disease. Consequently, effective elimination of malaria will require both curative and transmission blocking strategies. Similar to other eukaryotes, Plasmodium replicates it's genome to divide, proliferate and spread. However, several unusual characteristics of parasite genome replication can be exploited to combat the parasite, especially in stages crucial for parasite transmission. Parasite transmission to the mosquito is initiated by sexual male and female gametocytes. Upon experiencing the mosquito environment, the male gametocyte undergoes three rounds of genome replication (called mitosis) with an incredible speed of 10 minutes to form sperm-like gametes that fuse with the female cell. The fertilised zygote then undergoes further genome replication (called meiosis) to develop into a motile ookinete that is responsible for infecting mosquitoes. So how is mitosis in gametocytes and meiosis in zygotes regulated? We discovered that many proteins in gametocytes and zygotes are dynamically modified by the small protein, ubiquitin. Ubiquitin is reversibly attached to proteins to modulate their fate, including their stability, cellular localisation and level of activity, suggesting these reversible marks could play a key role during parasite genome replication. Importantly, an eraser of ubiquitin marks, Plasmodium USP7 (ubiquitin specific protease 7) is crucial for the parasite to complete both mitosis and meiosis. Since it is not experimentally possible to study meiosis in the human malaria parasite (P. falciparum), we will exploit the highly conserved rodent malaria model (P. berghei), to examine how USP7 regulates genome replication both during mitosis and meiosis. In this proposal we will uncover how USP7 prepares the parasite for initiation of DNA replication during transmission stages. Using state-of-the-art proteomics and microscopy techniques, we will identify partners and responders of USP7 and also determine how the enzyme activity and structure of parasite USP7 is divergent from its host's equivalent. Our findings will be influential in establishing platforms to screen for pharmacological USP7 inhibitors. Moreover, identifying how USP7 orchestrates both mitosis and meiosis will be useful in the development of improved therapeutic strategies that target and block multiple steps in parasite transmission.

疟疾是由单细胞病原体疟原虫引起的，该疟原虫在全球范围内威胁着约4亿人，每年导致超过50万人死亡，从而继续存在一个重大的公共卫生问题，并且紧急需要新的治疗剂。疟疾寄生虫复杂生命周期的完成需要引起疾病的哺乳动物宿主，以及负责疾病传播的蚊子载体。因此，有效消除疟疾将需要治愈和传输阻塞策略。与其他真核生物类似，疟原虫复制了其分裂，增殖和扩散的基因组。但是，可以利用寄生虫基因组复制的几种异常特征来对抗寄生虫，尤其是在寄生虫传播至关重要的阶段。寄生虫向蚊子传播是由性男性和女性配子细胞引发的。在经历了蚊子环境后，雄性配子细胞经历了三轮基因组复制（称为有丝分裂），其速度令人难以置信10分钟，以形成与雌性细胞融合的精子样配子。然后，受精的合子经历了进一步的基因组复制（称为减数分裂），形成了一种莫克尼特，该运动负责感染蚊子。那么，合子中的配子细胞和减数分裂的有丝分裂如何受到调节？我们发现，小型蛋白质泛素会动态地修饰配子细胞和合子中的许多蛋白质。泛素可逆地附着在蛋白质上，以调节其命运，包括它们的稳定性，细胞定位和活性水平，表明这些可逆标记在寄生虫基因组复制过程中可能起关键作用。重要的是，泛素标记的橡皮擦，疟原虫USP7（泛素特异性蛋白酶7）对于寄生虫完成有丝分裂和减数分裂至关重要。由于在实验上不可能研究人类疟原虫（恶性疟原虫）中的减数分裂，因此我们将利用高度保守的啮齿动物疟疾模型（P. berghei），以检查USP7如何调节有丝分裂和减数分裂过程中的基因组复制。在此提案中，我们将发现USP7如何准备在传输阶段开始DNA复制的寄生虫。使用最先进的蛋白质组学和显微镜技术，我们将确定USP7的合作伙伴和响应者，并确定寄生虫USP7的酶活性和结构与宿主的等效物的不同。我们的发现将在建立平台以筛选药理学USP7抑制剂方面具有影响力。此外，确定USP7如何编排有丝分裂和减数分裂将有助于发展改进的治疗策略，这些治疗策略针对寄生虫传播中的多个步骤。