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Molecular Characterization of Hemopexin in the Siberian Sturgeon (Acipenser baerii): Evolutionary Insights and Differential Expression Under Immune and Thermal Stresses

Year: 2025
Type: article
Abstract: Hemopexin (HPX) is a heme-binding glycoprotein involved in detoxification, oxidative stress regulation, and immune defense. In teleosts, gene duplication gave rise to Wap65-1 and Wap65-2, but the structure and function of ancestral HPX in basal actinopterygians remain poorly understood. Here, we characterized HPX from the Siberian sturgeon (Acipenser baerii), a slow-evolving chondrostean species that diverged prior to the teleost-specific duplication. Structural modeling and superimposed 3D alignment revealed high similarity between sturgeon HPX, human HPX, and Wap65-2, but not Wap65-1. Phylogenetic analysis placed sturgeon HPX in a distinct basal clade within the Actinopterygian lineage, positioned below the divergence of Wap65 paralogs. Tissue expression was liver-dominant but also evident in skin and kidney, and HPX transcripts increased during larval development. Under Aeromonas hydrophila challenge, HPX was strongly upregulated in immune-relevant tissues. Thermal challenge also induced modest, tissue-specific changes, particularly in peripheral tissues. These results indicate that ancestral HPX possessed multivalent stress responsiveness—primarily immune-related—with supplementary thermal sensitivity. The observed functional flexibility is consistent with the hypothesis that ancestral HPX functions were partitioned following Wap65 gene duplication in teleosts, with Wap65-1 evolving toward a specialized thermal response role.
DOI: 10.3390/ijms26167934
Language: English
Subfield: Immunology
Open Access status: gold
Estimated APC paid: $3,499
OpenAlex ID: W4413272032
FWCI: 1.472
Cites: 49
Cited by: 5
Related to: 10