MicroRNA transcriptomics in liver of the freeze-tolerant gray tree frog (Dryophytes versicolor) indicates suppression of energy-expensive pathways.

ABSTRACT

The rapid and reversible nature of microRNA (miRNA) transcriptional regulation is ideal for implementing global changes to cellular processes and metabolism, a necessary asset for the freeze-tolerant gray tree frog (Dryophytes versicolor). D. versicolor can freeze up to 42% of its total body water during the winter and then thaw completely upon more favorable conditions of spring. Herein, we examined the freeze-specific miRNA responses in the gray tree frog using RBiomirGS, a bioinformatic tool designed for the analysis of miRNA-seq transcriptomics in non-genome sequenced organisms. We identified 11 miRNAs differentially regulated during freezing (miR-140-3p, miR-181a-5p, miR-206-3p, miR-451a, miR-19a-3p, miR-101-3p, miR-30e-5p, miR-142-3p and -5p, miR-21-5p, and miR-34a-5p). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis suggests these miRNAs play roles in downregulating signaling pathways, apoptosis, and nuclear processes while enhancing ribosomal biogenesis. Overall, these findings point towards miRNA inducing a state of energy conservation by downregulating energy-expensive pathways, while ribosomal biogenesis may lead to prioritization of critical processes for freeze-tolerance survival.