The Role Of Occlusive Protein Claudin-2 In The Infection Of Cells With Silkworm Polyhedrosis Virus

Claudins,occlaudins,and junction adhesion molecule(JAM)and other proteins make up the tight junction structure of cells.They are widely present in epithelial cells and are the connection between cells.Among them,Claudin-2 protein is an important member of the Claudins protein family,and its structure includes four transmembrane domains,as well as two circular structures with different extracellular sizes.The ring structure between adjacent cells can combine with each other to form an open or closed channel between cells,and at the same time can form a complex with other tightly connected components to maintain the tight connection of cells and the function of forming a side channel.Studies have shown that the transfer of Claudin-2 and tumor cells is related to proliferation,inflammation,and virus infection.Existing studies have shown that some viral infections change the expression of Claudin-2,thereby destroying the tight junction structure of cells,which in turn affects the cell infection of the virus.The current research on Claudin-2 mainly focuses on the cell infection of mammalian viruses.The Bombyx mori cytoplasmic polyhedrosis virus(BmCPV)mainly infects the silkworm midgut epithelial cells specifically,causing the silkworm midgut type abscess.Studies have shown that the tight junction protein Zo-1(Zonula occludens-1)is involved in BmCPV cell infection.In order to further explore the role of the tight junction structure of cells in BmCPV-infected cells,this study took silkworm Claudin-2(Bombyx mori transmembrane protein 47,LOC101736066)as the object to explore its function in BmCPV-infected cells.It is hoped that on the basis of proving the function of silkworm Claudin-2 protein,it will further enrich the understanding of the mechanism of BmCPV invasion cells,and provide a new molecular therapeutic target for the prevention and treatment of silkworm midgut pus.Claudin-2's Open Reading Frame(ORF)is 615 bp and encodes 204 amino acid residues.There are four typical transmembrane domains of Claudins family proteins.The expression levels of Claudin-2 in different tissues of Bombyx mori are significantly different.The relative expression abundance in tracheal plexus is the highest,followed by ovary,followed by midgut,head,epidermis,silk gland,in fat body,martensi The relative expression abundance in the testis is the lowest;the expression level of Claudin-2 in the midgut tissue varies with the developmental stage.The results of cellular immunofluorescence showed that in the process of BmCPV infection,Claudin-2 interacted with BmCPV;Co-IP and yeast double hybrid results showed that Claudin-2 could interact with BmCPV VP7 protein,but Claudin-2 was not detected.Interaction with the viral protein VP3,it is speculated that Claudin-2 may participate in the process of cell infection through interaction with BmCPV VP7.Junction aladhesion molecule-1(JAM-1)is a receptor for mammalian reovirus infecting cells.During the infection process,viral protein ?1 binds to JAM-1 protein and is passed by Integrin ?1 Clathrin-mediated endocytosis pathway internalizes into cells;reovirus can interact with Claudin-2 and infect cells through redundant pathways.To further clarify the function of Claudin-2 in BmCPV-infected cells,a study was conducted Regulating the level of Claudin-2 and blocking the effect of antibodies on Claudin-2 on BmCPV-infected cells,the results showed that increasing the expression level of Claudin-2 in cells can increase the infectivity of cells to BmCPV,and conversely,knocking down the expression of Claudin-2 by RNAi,The infectivity of cells to BmCPV decreased accordingly;after blocking Claudin-2 with antibodies,the infectivity of cells to BmCPV showed a decrease.These results indicate that Claudin-2 has a promoting effect on BmCPV-infected cells,and there may also be redundant pathways for BmCPV-infected cells.