Transcriptome analysis of the liver of Eospalax fontanierii under hypoxia

Hypoxia can induce cell damage, inflammation, carcinogenesis, and inhibit liver regeneration in non-adapted species. Because of their excellent hypoxia adaptation features, subterranean rodents have been widely studied to clarify the mechanism of hypoxia adaptation. Eospalax fontanierii, which is a subterranean rodent found in China, can survive for more than 10 h under 4% O₂ without observable injury, while Sprague-Dawley rats can survive for less than 6 h under the same conditions. To explore the potential mechanism of hypoxia responses in E. fontanierii, we performed RNA-seq analysis of the liver in E. fontanierii exposed to different oxygen levels (6.5% 6h, 10.5% 44h, and 21%). Based on the bioinformatics analysis, 39,439 unigenes were assembled, and 56.78% unigenes were annotated using public databases (Nr, GO, Swiss-Prot, KEGG, and Pfam). In total, 725 differentially expressed genes (DEGs) were identified in the response to hypoxia; six with important functions were validated by qPCR. Those DEGs were mainly involved in processes related to lipid metabolism, steroid catabolism, glycolysis/gluconeogenesis, and the AMPK and PPAR signaling pathway. By analyzing the expression patterns of important genes related to energy associated metabolism under hypoxia, we found that fatty acid oxidation and gluconeogenesis were increased, while protein synthesis and fatty acid synthesis were decreased. Furthermore, the upregulated expression of specific genes with anti-apoptosis or anti-oxidation functions under hypoxia may contribute to the mechanism by which E. fontanierii tolerates hypoxia. Our results provide an understanding of the response to hypoxia in E. fontanierii, and have potential value for biomedical studies.