エゾリス（旭川医科大学RI実験施設 長原稔和氏提供）
日本動物学会北海道支部 第608回支部講演会
日時：2025年10月8日（水） 17時～18時
場所：北海道大学 理学部5号館8階 813号室
演者：Dr. Hongdi WANG （the Evolutionary Neurobiology Unit, Okinawa Institute of Science and Technology OIST）
演題：Evolutionary implementation of hypoxic adaptation in ancestral metazoan metabolism by the HIF pathway
要旨：The rise of atmospheric oxygen throughout Earth’s history profoundly shaped the evolution and diversification of animal life. To survive hypoxic stress in fluctuating oxygen environments, animals evolved oxygen-sensing mechanisms, among which the hypoxia-inducible factor (HIF) pathway plays a central role. While extensively studied in bilaterians, the evolutionary origin and genome-wide conservation of the HIF pathway remain unclear in early diverging metazoans. Here, using the cnidarian Nematostella vectensis, we combined hypoxia treatment, Nv_HIFa knockdown, and transcriptomic profiling to investigate the function and regulatory targets of the HIF pathway. We found that Nematostella possesses a complete and functional HIF signaling system. Comparative genomic and transcriptomic analyses with bilaterian species revealed that key components and targets of the HIF pathway are conserved between cnidarians and bilaterians. Interestingly, we found that HIF regulates the expression of oxygen-sensing hydroxylases and JmjC-domain-containing histone demethylases in Nematostella, which accumulate during hypoxia and become rapidly active upon reoxygenation. Our findings suggest that a functionally integrated HIF feedback loop and epigenetic response system had already evolved in the last common ancestor of cnidarians and bilaterians. Moreover, based on the evolutionary pattern of HIF and its targets, we propose that the HIF pathway originated in response to foreseeable short-term hypoxia–reoxygenation cycles in shallow marine environments, rather than as a direct adaptation to long-term atmospheric oxygen trends. This study provides molecular evidence that oxygen fluctuation was a key selective force driving the emergence of hypoxia-response systems during early animal evolution.
世話人：
和多 和宏（北海道大学 理学研究院）
wada[a]sci.hokudai.ac.jp
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