Down-regulation apoptosis signal-regulating kinase 1 gene reduced the Litopenaeus vannamei hemocyte apoptosis in WSSV infection

• Identification of apoptosis signal-regulating kinase 1 in Litopenaeus vannamei (designated as LvASK-1).
• Knocked-down LvASK-1 caused a lower shrimp hemocyte apoptotic ratio of L. vannamei upon WSSV infection.
• Knocked-down LvASK-1 result in a lower cumulative mortality of L. vannamei upon WSSV infection.

Apoptosis signal-regulating kinase 1 (ASK1), a mitogen-activated protein kinase kinase kinase, is crucial in various cellular responses. In the present study, we identified and characterized an ASK1 homolog from Litopenaeus vannamei (LvASK1). The full-length cDNA of LvASK1 was 5400 bp long, with an open reading frame encoding a putative 1420 amino acid protein. LvASK1 was highly expressed in muscle, hemocyte, eyestalk and heart. Real-time RT-PCR analysis showed that the expression of the LvASK1 was upregulated during the white spot syndrome virus (WSSV) challenge. The knocked-down expression of LvASK1 by RNA interference significantly reduced the apoptotic ratio of the hemocytes collected from WSSV-infected L. vannamei. Furthermore, the down-regulation of LvASK1 also decreased the cumulative mortality of WSSV-infected L. vannamei. These results suggested that down-regulation of LvASK1 decreased the apoptotic rate of hemocytes in WSSV-infected shrimp, and that it could contribute to the reduction of cumulative mortality in WSSV-infected L. vannamei.