EncystR: A novel entry point for uncovering the regulation of encystation in Giardia

项目摘要 包囊的形成在各种原生生物中普遍存在，但大多数原生动物对包囊的调控知之甚少。 物种。当寄生虫从增殖性滋养体转变为贾第虫时，会发生主要的形态变化。 到感染性的包囊。重要的是，这些变化导致寄生虫从宿主肠道释放，因此 这一过程可以有针对性地清除感染。尽管它很重要，但人们对它的了解很少 触发和维持贾第虫囊化的信号事件。在一项令人兴奋的突破中，我们发现 EncystR是囊化的负调控因子，它代表了发育过程中的一个新的控制点。 程序。EncystR可能是为任何寄生虫确定的第一个囊化受体；它是如何与 对包囊作用的下游监管尚未解决。已有研究表明，相关蛋白质可以作为 传感器、蛋白质运输受体和溶质转运体。EncystR定位于细胞质膜 营养滋养体，在囊化刺激下，EncystR被内化。通过跟踪EncystR贩运 我们鉴定出一种新的酸性隔室。这个阶段诱导的隔室由ESCRT组件标记 通常参与多泡小体(MVB)的形成。贾第虫被认为缺乏MVB和常规 溶酶体，所以这一发现是一个惊喜，代表着另一个令人兴奋的治疗机会。EncystR 是迄今为止发现的最上游的加密调控因子；因此，发现它的生物学将导致 对包埋的规则有了更深的理解。EncystR是否是一种GPCR样受体 在配体结合时改变构象以招募效应蛋白，在溶质运输中起作用，在 将蛋白质运送到新的隔室，或某种组合仍不清楚。在这里，我们重点关注 揭示EncystR调控分化的机制基础及其目的 运输到新奇的酸性隔间。作为迄今为止发现的最上游的加密监管机构， EncystR是探索这一关键的、与疾病相关的过程的新切入点。建议的研究将会：(1) 揭示EncystR相互作用组：(2)确定EncystR是否转运小分子代谢物； (3)确定EncystR与新的酸性隔间的空间关系；(4)揭示命运 到达酸性隔室后的EncystR。这项研究的结果将有助于确定目标 EncystR的未来机制研究和所需的完整调控级联的描绘 沉淀法。

Project Summary Cyst formation is ubiquitous across the diversity of protists, yet its regulation is poorly understood in most species. Major morphological changes occur as the parasite Giardia transitions from proliferative trophozoites to infectious cysts. Importantly, these changes cause the parasites to release from the host intestine, thus this process could be targeted to clear infections. Despite its importance, very little is understood about the signaling events that trigger and sustain Giardia encystation. In an exciting breakthrough, we identified EncystR, a negative regulator of encystation, which represents a novel control point in this developmental program. EncystR is potentially the first encystation receptor identified for any parasite; how it connects with downstream regulation of encystation is unresolved. It has been shown that related proteins can function as sensors, protein trafficking receptors and solute transporters. EncystR localizes to the plasma membrane in vegetative trophozoites, and, upon encystation stimuli, EncystR is internalized. By following EncystR trafficking we identified a novel acidic compartment. This stage induced compartment is marked by ESCRT components typically involved in multivesicular body (MVB) formation. Giardia is thought to lack MVBs and conventional lysosomes, so this discovery was a surprise and represents another exciting therapeutic opportunity. EncystR is the furthest upstream regulator of encystation identified to date; therefore, uncovering its biology will lead to a deeper understanding of the regulation of encystation. Whether EncystR is a GPCR-like receptor that changes conformation upon ligand binding to recruit effector proteins, has a role in solute transport, a role in trafficking proteins to the novel compartment, or some combination remains unknown. Here, we focus on uncovering the mechanistic basis of EncystR’s role in regulating differentiation as well as the purpose of its trafficking to the novel acidic compartment. As the most upstream regulator of encystation identified to date, EncystR is a new entry point for probing this critical, disease-relevant process. The proposed studies will: (1) reveal the EncystR interactome; (2) determine whether or not EncystR transports small molecule metabolites; (3) define the spatial relationship between EncystR and the novel acidic compartment; and (4) uncover the fate of EncystR after reaching the acidic compartment. The outcomes of this study will facilitate the targeting of future mechanistic studies of EncystR and the delineation of the full regulatory cascade needed for encystation.