The mammalian target of rapamycin (mTOR) pathway, which is essential for cell proliferation, is repressed in certain cell types in hypoxia. However, hypoxia-inducible factor 2α (HIF2α) can act as a proliferation-promoting factor in some biological settings. This paradoxical situation led us to study whether HIF2α has a specific effect on mTORC1 regulation. Here we show that activation of the HIF2α pathway increases mTORC1 activity by upregulating expression of the amino acid carrier SLC7A5. At the molecular level we also show that HIF2α binds to the Slc7a5 proximal promoter. Our findings identify a link between the oxygen-sensing HIF2α pathway and mTORC1 regulation, revealing the molecular basis of the tumor-promoting properties of HIF2α in von Hippel-Lindau-deficient cells. We also describe relevant physiological scenarios, including those that occur in liver and lung tissue, wherein HIF2α or low-oxygen tension drive mTORC1 activity and SLC7A5 expression.

Graphical Abstract Highlights d HIF1a reduces intracellular aspartate levels d HIF1a impairs oxidative and reductive aspartate biosynthesis d The aspartate-generating GOT1 and GOT2 enzymes are repressed by HIF1a d Aspartate supplementation counteracts the antiproliferative influence of HIF1a In Brief Melé ndez-Rodríguez et al. show that HIF1a impairs oxidative and reductive aspartate biogenesis, which consequently drives HIF1a-dependent suppression of tumor cell proliferation. Mechanistically, HIF1a represses the aspartate-producing enzymes GOT1 and GOT2 in several biological settings, including human VHL-deficient renal cell carcinoma, in which HIF1a can act as a tumor suppressor.