Aspartate inhibits mTORC1 activity and impairs reactivation of HIV-1 provirus

The mTORC1 complex regulates cell growth in response to various nutrients, including amino acids. We demonstrate that, unlike all other amino acids, aspartate inhibits mTORC1 kinase activity. An shRNA screen revealed that multiple genes related to aspartate metabolism modulate HIV-1 provirus expression. From this observation, we discovered that the cell-permeable aspartate analogs acid dimethyl ester (ADE) and aspartic acid di-tert-butyl ester (ADTB) suppress reactivation of latent HIV-1 expression in T cells and inhibit mTORC1 signaling. mTORC1 was also inhibited by the addition of excess aspartate to Jurkat or HEK293 cells overexpressing the aspartate transporter EAAT1. Aspartate was found to directly inhibit mTORC1 kinase activity in vitro . These observations demonstrate that mTORC1 signaling is inhibited by excess aspartic acid, and we propose that intracellular aspartate levels act as a sensor to regulate anabolic metabolism. Furthermore, these results indicate that therapeutic manipulation of intracellular aspartate concentrations may provide a novel means of modulating HIV-1 provirus expression.

IMPORTANCE

Elevated intracellular concentrations of aspartic acid and cell-permeable aspartate analogs were found to suppress HIV-1 expression in T-cell lines and CD4+ cells from people living with HIV. Accordingly, we show this effect is mediated by inhibition of mTORC1 signaling, and that aspartate inhibits mTORC1 kinase activity in vitro . We propose that intracellular aspartate levels act as a sensor to regulate anabolic metabolism.