MiR-155 regulates apoptosis induced by FC-EPS incubation via targeting the talin-1 gene in EPC

Incubation of Flavobacterium columnare exopolysaccharide (FC-EPS) significantly increases the expression of miR-155 in epithelioma papulosum cyprinid (EPC) cell line, leading to cell apoptosis. In order to study the mechanism of miR-155 in FC-EPS induced apoptosis, RNAi technology was used in this research. It was found that both overexpression of miR-155 and talin-1 knockout could inhibit apoptosis induced by FC-EPS incubation. Then, talin-1 was identified as the target protein of miR-155 by EMSA assay. During the process of apoptosis induced by FC-EPS incubation, the Talin-1 protein was significantly increased, and the activation of apoptosis executioner caspase-3 protein was detected. At the same time, two talin-1 isomers (about 200 ku and 250 ku, respectively) were obtained. Subsequently, the talin-1 gene inserted in plasmid pcDNA3.1 was constructed and transfected into EPC cells, the overexpressed Talin-1 protein delayed and prolonged the process of apoptosis, and two Talin-1 isomers mentioned above were detected. However, apoptosis did not occur when EPC cells were transfected with FC-EPS; on this occasion, the Talin-1 protein in EPC went down at first, then returned to normal level. Hence, in the context of apoptosis induced by FC-EPS incubation, EPC cells reduces apoptosis by regulating the level of mRNA and protein transcription of talin-1 through up-regulation of miR-155 and producing Talin-1 isomers. This paper provides a new idea for effective prevention and treatment of F. columnare diseases.