Insights Into miRNA-mRNA Regulatory Mechanisms of Cold Adaptation in Gymnocypris eckloni: Ubiquitin-Mediated Proteolysis Is Pivotal for Adaptive Energy Metabolism

Abstract

This study aimed to understand cold stress adaptations mechanism in fish. Thus, the transcriptional response to cold conditions in <i>Gymnocypris eckloni</i> was evaluated using RNA-seq and microRNA (miRNA)-seq analyses. Low-temperature (LT) group <i>G. eckloni</i> was cultivated outdoors in waters cooled to 2-4°C for 3 weeks, while individuals in the control temperature (CT) group were exposed to 14-16°C. Significantly different responses were observed in both mRNA and miRNA expression profiles, with more mRNAs (1,833 and 1,869 mRNAs were up- and downregulated, respectively) and fewer miRNAs (15 and 6 were up- and downregulated, respectively) observed in the LT group individuals relative to the CT group individuals. A miRNA-mRNA network involved in the regulation of <i>G. eckloni</i> responses to cold stress was constructed; this network included ubiquitin-mediated proteolysis, protein processing, and oxidative phosphorylation. These results provided new insights into mechanisms of cold tolerance by fish, including decreased metabolic activity in addition to proteolysis.