RNF125 mediated influenza M2 protein degradation

• Main Authors: Jyun-Yu Chen, 陳浚宇
• Other Authors: Chi-Ju Chen
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/2deqzw

碩士 === 國立陽明大學 === 微生物及免疫學研究所 === 107 === Influenza A virus belongs to Orthomyxoviridae, and is a common pathogen to human. Influenza viruses cause yearly outbreak around the world, resulting in about three to five millions cases of sever illness. Because the virus mutates frequently, we have to predict vaccine strains every year, moreover preexisting immunity cannot provide protection fully. Mutations also render influenza viruses resistance to current antivirals. A better understanding of host-virus interaction may helps us identify potential target for new antiviral drugs. Activation of RIG-I-like Receptors ( RLR ) signaling pathway induces type I interferon production to defend against influenza infection. This signal is transmitted through the aggregation of the adaptor protein MAVS on mitochondria. Previously, we found that activation of RIG-I promoted protein degradation of influenza viral proteins. M2 and PB1-F2 were the most affected, so we try to understand the possible mechanism mediating their degradation. We have found that RNF125, an unbiquitin E3 ligase known to regulate RIG-I signaling negatively, played a role in RIG-I-induced PB1-F2 protein degradation. Here, we extended the study to M2. On the other hand, using different pharmacological inhibitors has previous helped us identified the autophagy may be part of RIG-I- induced viral protein degradation. In this study, we examined the role of autophagy in RNF125-mediated M2 degradation. First, we found the overexpression of RNF125 facilitated the protein degradation of M2. Consistently, knockdown of RNF125 reduced RIG-I-induced M2 degradation. Next, by using pharmacological inhibitors, we found the M2 expression could be partially rescued by autophagy inhibitor including 3-MA and Bafilomycin-A1, suggesting M2 might be degraded through autophagy upon RIG-I activation. Surprisingly, we didn’t observe the proteasome inhibitors, such as MG132 and lactacystin, can reduce degradation. Finally, we investigated that whether RNF125 affects influenza virus ( PR8 ) during infection. We found that in presence of overexpressed RNF125, M2 expression was reduced moderately. This may lead to the reduction of viral tirter we observed. We concluded that RNF125 may play a role in RIG-I-mediatied antivral activity through enhancing viral protein degradation.