人诺如病毒调控肠上皮细胞水通道蛋白表达的分子机制

Human norovirus (HuNoV) has become the major pathogen of acute nonbacterial gastroenteritis. All age groups are susceptible to HuNoV infection. It is difficult to control HuNoV transmission once the virus outbreak takes place. Due to the genetic diversity of HuNoV and the lack of an in vitro culture system and an animal model, the molecular mechanism underlying HuNoV infection induced diarrhea is still unknown. Previous studies reveal that diarrhea is the leading cause of death in children under the age of 5, and the abnormal expression of AQP on intestines is the direct cause of diarrhea. Our preliminary experimental results showed that infection with HuNoV-positive stool sample or transfection with HuNoV complete cDNA clone induced the expression of AQP1. Moreover, the expression of AQP1 was also increased following transfection with HuNoV VP1 or VP2. However, it remains unclear whether HuNoV can induce the expression of other AQPs and if so how HuNoV regulates their expression. In this proposed study, we intend to investigate AQP expression regulated by HuNoV at infection level using the infectious clone of a Chinese HuNoV GII.4 clinical isolate. We will further define the molecular mechanism of AQP expression regulated by HuNoV. The research outcomes would be important not only for revealing the potential mechanism underlying how HuNoV causes infectious diarrhea, but also for the development of drug candidates against diarrhea induced by HuNoV.

人诺如病毒（HuNoV）是急性非细菌性流行肠胃炎的主要病原，易感于各年龄段的人群，一旦爆发很难控制。由于HuNoV的遗传多样性以及缺乏自然的体外培养系统和动物模型，目前对HuNoV感染性腹泻的机理缺乏了解。早期研究显示腹泻是全球5岁以下儿童感染致死的第二大病因，而肠组织部位分布的水通道蛋白（aquaporin，AQP）表达异常是导致腹泻最直接的原因。我们前期预研表明：HuNoV GII.4阳性粪便样品感染或全长cDNA转染可显著上调AQP1的表达且其VP1和VP2蛋白也可显著上调AQP1的表达，但对HuNoV是否调控AQP其它家族成员及调控的机制不清楚。本项目拟利用我们构建的中国株HuNoV GII.4感染性克隆在感染水平探究HuNoV对肠上皮细胞AQP表达的影响及其作用机制。预期研究结果不仅有助于揭示HuNoV感染性腹泻的潜在机理，并且可为抗HuNoV感染性腹泻药物的研发提供理论依据。

人诺如病毒（HuNoV）是急性非细菌性胃肠炎的主要病原。由于缺乏体外培养系统和合适的动物模型，HuNoV引发腹泻的机制尚不清楚。本研究表明，HuNoV可有在mRNA和蛋白水平诱导肠上皮细胞Caco2、人肠组织及原代肠上皮细胞群AQP1的表达，然而同为肠道病毒的EV71却不能诱导AQP1的表达。进一步研究发现HuNoV的大衣壳蛋白VP1在促进AQP1表达中发挥重要作用。HuNoV通过NF-κB信号通路诱导AQP1的表达。机制上的深入研究发现HuNoV通过磷酸化和降解IκBα促进p65的表达和磷酸化。通过建立人肠上皮屏障模型，证明HuNoV和VP1可以通过AQP1通道增加肠上皮屏障的通透性。总而言之，本研究发现HuNoV通过磷酸化和降解IκBα激活NF-κB信号通路从而诱导AQP1的表达。这项研究的发现不仅揭示了HuNoV引发腹泻的潜在机制，而且对开发针对HuNoV的抗病毒药物也有一定的指导意义。