Changes in the Turnover of the Cellular Proteome during Metabolic Reprogramming: A Role for mtROS in Proteostasis

The
role played by protein turnover in metabolic reprogramming
is unknown. Herein, using a SILAC approach, we have studied the changes
in the half-life of 266 proteins of energy metabolism and of translation
during the metabolic switch induced by the prolyl hydroxylases inhibitor
dimethyloxalylglycine (DMOG). DMOG induces HIF-1α expression
and triggers the activation of glycolysis and the concurrent inhibition
of mitochondrial respiration in colon cancer cells. Changes in the
activity of energy provision pathways correlated with increased turnover
rates of glycolytic enzymes and the stabilization of mitochondrial
proteins. Moreover, reprogramming also stabilized the proteins of
translation. The partial DMOG-mediated arrest of the synthesis of
mitochondrial and translation proteins results from the inhibition
of the mTORC1/p70SK/S6 signaling pathway. In contrast, DMOG stimulated
the synthesis of glycolytic enzymes, emphasizing the opposite and
differential regulation of the two pathways of energy provision. Addition
of MitoQ, a mitochondrial reactive oxygen species (mtROS) scavenger,
stabilized the turnover of cellular proteins similarly as when protein
degradation is inhibited with leupeptin, a serine-protease inhibitor.
Overall, the results show that the higher the activity of a pathway
the lower is the half-life of the proteins involved and suggest a
role for mtROS in cellular proteostasis. Data are available via ProteomeXchange
with identifier PXD013482.