Molecular characterization and gene expression analysis of hypoxia-inducible factor and its inhibitory factors in kuruma shrimp Marsupenaeus japonicus

In shrimp aquaculture, overcrowded farming causes fluctuations in dissolved oxygen concentrations. Low-oxygen conditions (hypoxia) affect shrimp growth. Hypoxia-inducible factor (HIF) is a transcriptional factor in the basic helix-loop-helix/PAS family and is activated in response to hypoxic stress. However, little is known about HIF and other inhibitors of the HIF pathway in crustaceans. In this study, we cloned MjHIF-1α, an inhibitory factor, MjFIH-1 (factor inhibiting HIF-1α), and MjVHL (Von Hippel-Lindau tumor suppressor) from kuruma shrimp (Marsupenaeus japonicus). MjVHL is the first crustacean VHL ortholog to be cloned. MjHIF-1α, MjFIH-1, and MjVHL exhibit significant sequence similarity and share key functional domains with previously described vertebrate and invertebrate genes. As a result of gene expression analysis in various tissues, MjHIF-1α and MjVHL were more highly expressed in the intestine than in any other organ tissues. In hypoxia experiments, HIF-induced expression levels of MjHIF-1α in the hypoxic group increased significantly for 24 h after initiating hypoxia stimulation and expression of MjVHL decreased significantly for 6 h after hypoxia stimulation (P < 0.05).