Examination of the role of hypoxia-inducible factor-1α (HIF-1α) in preventing hemocyte apoptosis in whiteleg shrimp (Litopenaeus vannamei)

Air exposure can induce excessive hypoxia and apoptosis in aquatic organisms. Moreover, it can even lead to severe mortality. In this study, RNA interference was employed to investigate the role of hypoxia-inducible factor-1 alpha (HIF-1 alpha) in alleviating hemocyte apoptosis in whiteleg shrimps (Litopenaeus vannamei) suffering air exposure at 15 degrees C for 6 h during simulated waterless transportation. Reactive oxygen species (ROS) production, hemocyte subpopulation percentage, and expression levels of heat shock protein 70 (HSP70), caspase-3, and cytochrome c were also determined. HIF-1 alpha knockdown showed a significant aggravation of hemocyte apoptosis with the increase of ROS production, hyalinocyte percentage, semi granulocyte percentage, and the expression levels of caspase-3 and cytochrome c under air exposure (p < 0.05). However, HSP70 expression and granulocyte (GC) percentage were significantly reduced by HIF-1 alpha knockdown (p < 0.05). Results suggested that HIF-1 alpha could protect the hemocytes from apoptosis by upregulating the expression of HSP70 that contributed to air exposure adaption and blocking the apoptosis pathway through decreasing intracellular ROS, inhibiting GC degranulation, and preventing cytochrome c and caspase-3 expression. This work can help reveal the survival mechanism of the HIF-1 alpha/HSP70 signaling pathway in whiteleg shrimp to endure air exposure.