Apoptosis-stimulating protein of p53 (ASPP) participates in the regulation of apoptosis in Litopenaeus vannamei under ammonia-N and nitrite-N stress

Abstract

Apoptosis-stimulating protein of p53 (ASPP) is a key regulatory factor closely related to p53 in apoptosis pathway. To further investigate the molecular mechanisms of ASPP in Litopenaeus vannamei, the expression of LvASPP mRNA under ammonia-N and nitrite-N stress was explored, and the effects of knocking out LvASPP on mortality, histological damage, and the apoptosis pathway in L. vannamei under ammonia-N and nitrite-N stress were investigated. Healthy L. vannamei (7.78 ± 0.70 g) were used in this study. After shrimp were stressed with an ammonia-N concentration of 30.00 mg/L for 48 h, qRT-PCR was used to detect a significant increase in LvASPP mRNA expression in the hepatopancreas, gills, and muscle. Following 48 h of nitrite-N stress at a concentration of 60.00 mg/L, LvASPP mRNA expression was significantly increased in the hepatopancreas. The survival rate notably increased under 80 h of ammonia-N stress (25.00 mg/L) after LvASPP RNA interference (30 % more than the control group), and the number of shrimp deaths decreased after 48 h of nitrite-N stress. Moreover, under the stress of ammonia-N and nitrite-N respectively, LvASPP silencing reduced the expression of p53, and led to a decrease in the expression of apoptosis-related genes (Bax, Apaf-1, Caspase 9, MDM2). Caspase 3 activity, TUNEL-positive cells and the apoptotic index in the hepatopancreas markedly reduced under ammonia-N and nitrite-N stress. The potential pathway suggests that inhibiting LvASPP reduces the mRNA expression of p53, which leads to a decrease in Caspase 3 activity, inhibiting apoptosis in the hepatopancreatic cells of L. vannamei under ammonia-N and nitrite-N stress. These data indicate that the knockdown of LvASPP positively impacted the tolerance of L. vannamei to ammonia-N and nitrite-N stress by regulating the apoptosis pathway. This suggests that employing gene-targeted dsRNA could be an effective strategy for alleviating the environmental pressures faced by shrimp in aquaculture management.