Cloning, functional characterization and expression analysis of nuclear factor erythroid-2-related factor-2 of golden pompano (Trachinotus ovatus) and its response to air-exposure

Abstract

Nrf2 is an important component of Nrf2-ARE signaling pathway. However, information about Nrf2 in golden pompano (Trachinotus ovatus) is quiet limited. Thus, the full length of Nrf2 was cloned from T. ovatus in this study. The full-length cDNA sequence was 2376 bp in length and comprised of a 1848 bp ORF preceded by 123 bp 5′UTR, and followed by a 405 bp UTR. The putative amino acid sequence of the Nrf2 contained 615 residues, consisting of a conservative basic region leucin zipper. The N terminal portion of Nrf2 is rich in glutamic and aspartic acids and functioned as an acidic type of activation domain. The C terminus of the protein contained a region with heptad repeats of leucines. The phylogenetic tree showed that Seriola dumerili and T. ovatus were clustered as a branch, and combined with Mastacembelus armatus, Oreochromis niloticus and Takifugu rubripes. This branch of 5 species clustered with other branch of Oncorhynchus mykiss and Salmo salar. Nrf2 gene was predominantly expressed in liver and gut. The relative expression of Nrf2 in liver was significantly higher than that in brain, kidney, spleen and heart. After air-exposure, the expression level of HIF-1 alpha, keap1, Nrf2, HO-1, SOD and GSH-PX were significantly higher in air-exposure group than that in control group. This present study showed that Nrf2 plays a pivotal role in oxidative stress caused by air-exposure in T. ovatus, providing information about response to oxidative stress on the basis of the Nrf2-ARE pathway in T. ovatus.