title: Cleavage of Dicer protein by I7 protease during vaccinia virus infection.
abstract: Dicer is the key component in the miRNA pathway. Degradation of Dicer protein is facilitated during vaccinia virus (VV) infection. A C-terminal cleaved product of Dicer protein was detected in the presence of MG132 during VV infection. Thus, it is possible that Dicer protein is cleaved by a viral protease followed by proteasome degradation of the cleaved product. There is a potential I7 protease cleavage site in the C-terminus of Dicer protein. Indeed, reduction of Dicer protein was detected when Dicer was co-expressed with I7 protease but not with an I7 protease mutant protein lack of the protease activity. Mutation of the potential I7 cleavage site in the C-terminus of Dicer protein resisted its degradation during VV infection. Furthermore, Dicer protein was reduced dramatically by recombinant VV vI7Li after the induction of I7 protease. If VV could facilitate the degradation of Dicer protein, the process of miRNA should be affected by VV infection. Indeed, accumulation of precursor miR122 was detected after VV infection or I7 protease expression. Reduction of miR122 would result in the suppression of HCV sub-genomic RNA replication, and, in turn, the amount of viral proteins. As expected, significant reduction of HCVNS5A protein was detected after VV infection and I7 protease expression. Therefore, our results suggest that VV could cleave Dicer protein through I7 protease to facilitate Dicer degradation, and in turn, suppress the processing of miRNAs. Effect of Dicer protein on VV replication was also studied. Exogenous expression of Dicer protein suppresses VV replication slightly while knockdown of Dicer protein does not affect VV replication significantly.
authors: Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan.
authors: Jhih-Si
authors: JS
authors: Chen
authors: Department of Biochemistry, Tzu Chi University, Hualien, Taiwan.
authors: Hui-Chun
authors: HC
authors: Li
authors: Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan.
authors: Shu-I
authors: SI
authors: Lin
authors: Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan.
authors: Chee-Hing
authors: CH
authors: Yang
authors: Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan.
authors: Wan-Yu
authors: WY
authors: Chien
authors: Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan.
authors: Ciao-Ling
authors: CL
authors: Syu
authors: Department of Laboratory Medicine and Medical Biotechnology, Tzu Chi University, Hualien, Taiwan; Department of Laboratory Medicine, Buddhist Tzu Chi General Hospital, Hualien, Taiwan.
authors: Shih-Yen
authors: SY
authors: Lo
mesh_terms: D015153:Blotting, Western; D048749:Cytokinesis / Q000235:genetics; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014615:Vaccinia / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D014616:Vaccinia virus / Q000235:genetics*; D014758:Viral Core Proteins / Q000235:genetics / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication / Q000235:genetics*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D053487:DEAD-box RNA Helicases; D035683:MicroRNAs; D012333:RNA, Messenger; D043244:Ribonuclease III; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins; C531907:MIRN122 microRNA, human; C080700:protein I7, vaccinia virus; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase; C408087:DICER1 protein, human