Integrated transcriptomic analysis of mRNA and miRNA in Brown adipose tissue of the greater horseshoe bats during hibernation.

Hibernation enables animals survive harsh environments by conserving energy through reduced metabolism and body temperature. Brown adipose tissue (BAT) plays a critical role in non-shivering thermogenesis, crucial for warming up during arousal phase. The greater horseshoe bats (Rhinolophus nippon) are typical hibernators and non-shivering thermogenesis in BAT tissue may persist throughout the arousal process in bats. This study examines gene expression and regulatory changes in BAT of these bats across active, hibernation, and arousal phases using transcriptome and miRNA sequencing. A total of 2721 differentially expressed mRNAs and 268 differentially expressed miRNAs were identified. The results reveal that the BAT transcriptome undergoes state-dependent remodeling throughout the hibernation process. The most pronounced divergence occurs between the active phase and torpor, involving cell cycle arrest, immunosuppression, thermogenic signal desensitization, and upregulation of lipid metabolism and autophagy pathways, reflecting the coordinated adaptation of energy conservation and thermogenic reserve. In contrast, transcriptional alterations between torpor and arousal are extremely limited, indicating that torpid BAT is already pre-primed for thermogenesis and requires only modest transcriptional adjustments to activate heat production. Notably, although body temperature recovers to active-phase levels during arousal, the molecular signature of BAT remains highly similar to that of the torpid state. Furthermore, the core thermogenic gene UCP1 showed no significant expression differences across the three groups. In conclusion, this study systematically delineates the miRNA-mRNA regulatory landscape of bat BAT across the hibernation process, and deepens our understanding of the thermoregulatory mechanisms underlying mammalian hibernation.