RBM3 deficiency impairs body temperature control in response to cold stimulation

Mammals are thermostatic animals capable of regulating their body temperature within a precise range, irrespective of ambient temperature conditions. However, the precise mechanisms by which a body temperature is controlled dependent on ambient temperature are still unclear. Here, we report that RNA binding motif protein 3 (RBM3), one of the cold-responsive proteins, regulates body temperature via expressing thermogenic genes during the late-postnatal period. The body temperature in Rbm3 knockout (KO) juvenile mice was unstable and increased vulnerability to cold exposure. In addition, Rbm3 KO mice exhibited increased lipid droplets in brown adipose tissue (BAT) and abnormal histology. The single-cell RNA-seq (scRNA-seq) analysis revealed that RBM3 is highly expressed in proliferating and differentiating cells in BAT. Moreover, RBM3 was necessary for upregulating thermogenic genes after cold shock. Notably, RBM3 interacted with UCP1 mRNA in vivo, thereby stabilizing its mRNA levels. Lastly, RBM3 regulated neuronal activity in the dorsomedial hypothalamic nucleus (DMH) under a cold environment. These data suggest that RBM3 regulates thermogenesis in juvenile mice through both upregulating thermogenic genes in BAT and activating DMH neurons after cold exposure.