Molecular characterization and expression analysis of hypoxia-inducible factor-1α, factor-2α, and factor-3α and physiological response to hypoxia exposure in Amur minnow (Phoxinus lagowskii)

• Published in: Aquaculture international 2022-04, Vol.30 (2), p.607-632
• Main Authors: Yang, Yuting, Dong, Zhongdian, Chen, Xi, Wang, Zhen, Zhang, Dawei, Liang, Liqun, Mu, Weijie
• Format: Article
• Language: English
• Subjects: Amino acids; Antioxidants; Biomedical and Life Sciences; Fluorescence; Freshwater & Marine Ecology; Freshwater fishes; Genes; Heart; Hybridization; Hypoxia; Life Sciences; Liver; Oxidative stress; Oxygenation; Phoxinus lagowskii; Recovery; Serine; Spleen; Zoology
• ISSN: 0967-6120; 1573-143X
• DOI: 10.1007/s10499-021-00826-y

To further enhance our understanding of hypoxia tolerance in the fish Phoxinus lagowskii , hypoxia-inducible-factor (HIF) genes were cloned to analyze their biological function during hypoxia exposure. The complete cDNAs of HIF-1α, HIF-2α, and HIF-3α were 2912, 3444, and 2228 bp in length, encoding 773, 829, and 641 amino acid residues, respectively. The HIF-1α and HIF-2α proteins contain HLH, PAS-A, PAS-B, PAC, N-TAD, and C-TAD domains, while HIF-3α has no C-TAD domain. A high number of serine residues in the oxygen-dependent degradation (ODD) domain are connected with hypoxia tolerance in fish. More than 40 serine residues were found in the ODD domain of HIF-α genes in P. lagowskii , suggesting that P. lagowskii has a high potential for hypoxia tolerance. The HIF-α genes were highly expressed in the heart, spleen, and liver of P. lagowskii , suggesting an important role for these genes in modulating the circulatory and metabolic responses to hypoxia. Relative long-term hypoxia exposure and recovery resulted in significantly increased transcript abundance for three genes in liver, gill, and spleen, but short-term exposure and recovery did not, which is indicative of a unique characteristic of hypoxia-tolerant fish. In addition, this study found for the first time that P. lagowskii upregulates HIF-3α within 24 h of liver hypoxia, confirming that HIF-3α plays an important role in liver homeostasis. Therefore, we performed fluorescence in situ hybridization on HIF-3α after inducing liver hypoxia. We also constructed an overexpression vector pcDNA3.1-HIF-3α and transfected it into CIK cells. The results showed that overexpression of HIF-3α significantly increased the expression of hypoxia-related genes such as P53, Glut1, VEGF, and VHL. Moreover, our results showed that enzymes of the defense and antioxidant mechanisms showed a noticeable increase in relatively long-term hypoxia to counteract the oxidative stress generated after re-oxygenation.