SQSTM1/p62 from Litopenaeus vannamei is involved in the immune response to Vibrio infection

Sequestosome 1 (SQSTM1 or p62) has multiple functional domains, and it can not only be involved in autophagy process, but also defend against oxidative stress by invoking the Keap1/Nrf2 signaling pathway. However, the role of p62 in the response of Pacific whiteleg shrimp Litopenaeus vannamei to bacterial infection is still unclear. This study successfully identified p62 from L. vannamei (Lv-p62). The length of the open reading frame (ORF) of Lv-p62 is 1908 bp, which encoded 635 amino acids, and had Phox and Bem1p domain (PB1), Zinc-binding and ubiquitin-associated (UBA) domains. The expression level of Lv-p62 in the hepatopancreas of healthy L. vannamei is the highest, and it could be significantly induced under the stimulation of Vibrio harveyi. Besides, knocking down Lv-p62 by using RNA interference technology could reduce the expression levels of Nrf2 (nuclear factor erythroid 2-related factor 2), LC3 (microtubule-associated protein 1 light chain 3) and autophagy-related gene (ATG3, ATG5 and ATG12). Compared with the stimulation with V. harveyi alone, stimulation with V. harveyi after knocking down Lv-p62 could reduce the expression of antioxidant-, autophagy- and apoptosis-related genes in L. vannamei. Moreover, knocking down Lv-p62 could reduce the apoptosis signal of hepatopancreas and the abnormal tissue structure caused by V. harveyi. These results indicated that Lv-p62 is involved in the immune response to Vibrio infection in L. vannamei, which further enriched the regulatory function of p62 and its role in the innate immunity of shrimp.