Cloning and expression analysis of hif-1 alpha and downstream genes during hypoxic stress in cobia (Rachycentron canadum)

Hypoxia is a lack of required oxygen to meet the metabolic demands of living organisms. Cellular hypoxia occurs when the molecular oxygen, essential to maintain sufficient adenosine triphosphate (ATP) levels for normal physiological function, surpasses the vascular supply. Tissue hypoxia can arise during a range of diseases. As molecular oxygen is a crucial metabolic energy source for all living organisms, animals manage the intracellular oxygen levels to sustain homeostasis, with the upregulation of genes that improve tissue perfusion and anaerobic ATP creation via glycolysis. This is facilitated by the hypoxia-inducible factors (HIFs). Hypoxia-inducible factor 1 alpha (hif-1a) is the core regulator of the hypoxia response and plays a crucial role in the cellular/molecular response to hypoxic stress by regulating the transcription of target genes. In the present study, hif-1a cDNA was identified and cloned from cobia (Rachycentron canadum), using rapid amplification of cDNA ends (RACE). The hif-1a and downstream mRNA expression levels in various tissues were then determined. The full length of hif-1a cDNA is 3642 bp, with a 2292 bp open reading frame (ORF), a 5 ' non-coding region (5 '-UTR) of 293 bp, 3 ' non-coding region (3 '-UTR) of 1057 bp, and encoding 764 amino acids. The encoded protein contains the basic helix-loop-helix domain (amino acid 22-77), PER-Arnt-SIM domain (amino acid 88-154 and 230-296), and the PAS-associated C-terminal domain (amino acid 302-345). hif-1a mRNA expression was detected in nine tissues, with the highest expression observed in the liver, and the lowest expression in the intestine and spleen. hif-1a, erythropoietin (epo), and vascular endothelial growth factor (vegf) gene expressions were analyzed in the gill, intestine, liver, and muscle under hypoxic stress. In the gills, hif-1a expression was significantly increased at all hypoxia time points as well as in the liver. Erythropoietin (epo) and vascular endothelial growth factor (vegf) showed similar trends, with a significant decrease followed by a significant increase. In the muscle, the expression of all three genes was higher than the control group after hypoxic stress. These results indicate that the expression patterns of hif-1a and related genes after hypoxic stress are tissue-specific and play an essential role in cobia's response to hypoxia.

Automated summary

Hypoxia refers to the lack of oxygen required by living organisms to meet their metabolic needs. The expression patterns of hif-1a and related genes in response to hypoxic stress are tissue-specific and play an important role in cobia's response to hypoxia. The key regulator of the hypoxia response, hif-1a, was identified and cloned from cobia, and its expression levels in various tissues were determined.