Molecular Basis of Intestinal Cryptosporidiosis

 描述（由申请方提供）：隐孢子虫是一种普遍存在的病原体，感染人类胃肠道上皮。这种寄生虫在医学上具有重要意义，因为免疫功能低下的人，包括艾滋病，癌症和移植患者的感染通常会导致危及生命的疾病。隐孢子虫也是发展中国家幼儿腹泻的常见原因。目前没有完全有效的治疗方法可用于 感染目前对寄生虫生物学和寄生虫-宿主相互作用的分子机制的理解是有限的。在我们的初步研究中，我们对隐孢子虫非编码RNA（ncRNA）进入感染宿主细胞核的递送进行了新的观察。我们的研究结果还表明，隐孢子虫感染抑制了一组基因的转录，这些基因编码对肠上皮细胞分化和代谢至关重要的效应蛋白。 重要的是，该基因组的反式抑制与抑制性表观遗传标记（例如，H3 K9 me 3）与它们的基因位点的关系，其中涉及寄生虫ncRNA的核存在。因此，我们将测试的假设，隐孢子虫感染诱导表观遗传组蛋白甲基化的宿主细胞通过核交付特定的寄生虫ncRNA，导致转录抑制基因的病理影响在主机。利用遗传学方法和尖端技术，我们将确定寄生虫ncRNA在感染宿主细胞中的核递送机制（目的1），阐明感染如何诱导抑制性H3 K9甲基化的富集，导致感染上皮细胞中基因的反式阻遏（目的2），并确定寄生虫ncRNA核递送在感染宿主细胞中的作用。 通过评估隐孢子虫病对宿主细胞中组蛋白甲基化的染色质富集的影响，研究隐孢子虫病的发病机制（目的3）。本研究的结果将揭示有价值的信息abou寄生虫-宿主相互作用，并使未来的研究，旨在阻断特定的转录事件作为一种新的治疗感染。

 DESCRIPTION (provided by applicant): Cryptosporidium is a ubiquitous pathogen that infects the gastrointestinal epithelium in humans. This parasite is of great medical importance as infections in immunocompromised humans, including AIDS, cancer, and transplant patients, often lead to life-threatening illness. Cryptosporidium is also a common cause of diarrhea in young children in developing countries. There is currently no fully effective therapy available for the infection. Current understanding of the parasite biology and the molecular mechanisms of parasite-host interactions is limited. In our preliminary study, we made a novel observation on the delivery of Cryptosporidium non-coding RNAs (ncRNAs) into the nuclei of infected host cells. Our results also show that cryptosporidial infection suppresses transcription of a panel of genes that code effector proteins key to intestinal epithelial cell differentiation and metabolism. Importantly, transsuppression of this gene panel is associated with enrichment of suppressive epigenetic markers (e.g., H3K9me3) to their gene loci with the involvement of nuclear presence of parasite ncRNAs. Therefore, we will test the hypothesis that cryptosporidial infection induces epigenetic histone methylations in host cells through nuclear delivery of specific parasite ncRNAs, resulting in transcriptional suppression of genes with pathological effects in the host. Using genetic approaches and cutting-edge technologies, we will determine the mechanisms of nuclear delivery of parasite ncRNAs in infected host cells (Aim 1), elucidate how infection induces enrichment of suppressive H3K9 methylation, resulting in transrepression of genes in infected epithelial cells (Aim 2), and determine the role of parasite ncRNA nuclear delivery in the pathogenesis of cryptosporidiosis by assessing its impact on chromatin enrichment of histone methylations in host cells (Aim 3). The results of this study will reveal valuable information abou parasite-host interactions and make possible future investigations aimed at blocking specific transcriptional events as a novel treatment for the infection.