Developmentally regulated expression of the cold-inducible RNA-binding motif protein 3 in euthermic rat brain

mRNA-binding proteins are critical regulators of protein synthesis during neural development. We demonstrated previously that the cold-inducible mRNA-binding protein 3 (RBM3) is present within euthermic neurons and that it enhances translation. Other studies have attributed anti-apoptotic and proliferative functions to RBM3. Here we characterize the developmental expression of RBM3 in rat brain. RBM3 is expressed widely during early brain development, peaking in the first to second postnatal weeks. This is followed by a decline in most brain regions and a shift from a nuclear to a more somatodendritic distribution by ∼ P13. The highest levels of RBM3 in adult brain were observed in the cerebellum, olfactory bulb, proliferating cell fields and other regions reported to have high translation rates. RBM3 was expressed in glutamatergic and GABAergic cells, subtypes of which exhibited strong dendritic labeling for RBM3 mRNA and protein. Expression of RBM3 was also high in newly formed and migrating neurons marked by Ki67, nestin, and doublecortin, such as those in the subventricular zone and rostral migratory stream. These results indicate that expression of RBM3, a cold stress-responsive mRNA-binding protein, is dynamically regulated in the developing brain and suggest that it contributes to translation-dependent processes underlying proliferation, differentiation, and plasticity.