Hypoxia-inducible factor (HIF) is a crucial regulator of cellular and systemic responses to low oxygen levels. Here we firstly cloned three HIF-α isoforms from the basal branches of Osteichthyes and used computational tools to characterise the molecular change underlying the functional divergence of HIF-α isoforms in different lineages. Only the HIF-1α and HIF-2α in African lungfish and amphibians were found under positive selection. HIF-1α and -2α were less functionally divergent in basal ray-finned fish than in teleosts, and showed conserved but different transcriptional activity towards specific target genes.
Keywords: C-ODD, C-terminal oxygen dependent degradation domain; C-TAD, C-terminal trans-activation domain; Functional divergence; HIF-α; N-ODD, N-terminal oxygen dependent degradation domain; N-TAD, N-terminal trans-activation domain; Osteichthyes; Positive selection.