Low-oxygen sensors in fish: their activity, role, and links to the body’s daily clock

Hypoxia-inducible transcription factors may control the expression of hundreds of genes under low oxygen conditions.

• Three Hif-α isoforms, Hif-1α, Hif-2α, and Hif-3α, are expressed in vertebrates and may form functional pairs with Hif-1β.
• The existence of paralogues in fish suggests potential for specialized functions among the isoforms.
• Hif proteins are crucial not only for the hypoxic response but also for proper development and organ differentiation in fish embryos.
• Specific functions of Hif proteins have been identified in gill and gonadal tissues.
• The hypoxia signaling pathway is linked with the circadian clock, affecting metabolic and redox signaling.
• Recent findings in zebrafish reveal how hypoxia can dampen the transcriptional clock through metabolic changes.

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