A-kinase anchoring protein 8L interacts with mTORC1 and promotes cell growth

The mammalian target of rapamycin complex 1 (mTORC1) senses nutrients to mediate anabolic processes within the cell. Exactly how mTORC1 promotes cell growth remains unclear. Here, we identified a novel mTORC1-interacting protein called A-kinase anchoring protein 8L (AKAP8L). Using biochemical assays, we found that the N-terminal region of AKAP8L binds to mTORC1 in the cytoplasm. Importantly, loss of AKAP8L decreased mTORC1-mediated processes such as translation, cell growth and cell proliferation. AKAPs anchor protein kinase A (PKA) through PKA regulatory subunits, and we show that AKAP8L can anchor PKA through regulatory subunit Ia. Reintroducing full-length AKAP8L into cells restored mTORC1-regulated activities, whereas reintroduction of AKAP8L missing the N-terminal region that confers the interaction with mTORC1 did not. Our results suggest a multifaceted role for AKAPs in the cell. We conclude that mTORC1 appears to regulate protein translation, perhaps in part through AKAP8L.