FIGURE 1.

Schematic overview of light-regulated translational control pathways in the SCN. Light at night activates mTORC1, which in turn regulates its translational effectors ribosomal protein S6 kinases (S6Ks, including S6K1, and S6K2) and eukaryotic translation initiation factor 4E-binding proteins (4E-BPs). 4E-BP phosphorylation leads to its dissociation from eIF4E and activation of cap-dependent translational initiation. Vip (vasoactive intestinal peptide) mRNA translation is regulated by 4E-BPs. In another pathway, photic ERK/MAPK activation leads to phosphorylation of eIF4E via MNK kinases and promotes mRNA translation of Per1 and Per2 in the SCN. Thus, the MAPK and mTOR pathways converge on eIF4E to regulate mRNA translation in the SCN.