Molecular characterization of three caspases from Bostrychus sinensis and their transcriptional responses to bacteria and viruses

Abstract

The caspase family proteins are aspartate‐specific cysteine proteases that transmit extracellular signals to cells, ultimately cause apoptosis and therefore play a key role in cellular immunity. In this study, we cloned and characterized three caspases from Chinese black sleeper (Bostrychus sinensis), Bscasp‐1, Bscasp‐8 and Bscasp‐9. Real‐time PCR analysis showed that Bscasp‐1, Bscasp‐8 and Bscasp‐9 were universally expressed in all tested tissues of B. sinensis. Expression analyses showed that after poly(I:C) stimulation and bacterial (Vibrio parahaemolyticus) infection, the three caspases were significantly upregulated. After poly(I:C) stimulation, the change of Bscasp‐1 expression in the head kidney was the most obvious; peak expression was about 80.78‐fold more than that of the control. In addition, the expression of Bscasp‐8 and Bscasp‐9 in the peripheral blood and liver was 167.99‐ and 17.98‐fold higher than that in the control group, respectively. After V. parahaemolyticus infection, the expression peaks of Bscasp‐1 and Bscasp‐8 in the peripheral blood and spleen were 85.82‐fold and 280.83‐fold that of the control. However, the expression of Bscasp‐9 in the peripheral blood was upregulated only 8.33‐fold higher than that in the control group. These results indicate that Bscasp‐1, Bscasp‐8 and Bscasp‐9 are likely involved in response to viral and bacterial infection.