Cyclic AMP/PKA-Mediated Regulation of Mitochondria and Branched-Chain Amino Acid Metabolism in S49 Lymphoma Cells

The role of mitochondria in responses mediated by the second messenger cAMP acting via protein kinase A (PKA) is poorly understood. To assess such a role, we used quantitative proteomic analysis of mitochondria-enriched fractions and performed functional and morphological studies of wild-type (WT) and kin- (PKA-null) murine S49 T lymphoma cells. We found increased abundance of 110 proteins, including 8 involved in branched-chain amino acid (BCAA) metabolism, in WT, but not kin-, S49 cells incubated for 16 hr with the cell-permeable cAMP analog 8-CPT-cAMP (CPT). CPT also increased mRNA expression of genes involved in BCAA metabolism in WT, but not kin-, S49 cells. In addition, CPT enhanced survival of WT cells (but not kin- cells or WT cells in the presence of the PKA inhibitor H89) grown in media lacking glutamine. Studies using a Seahorse XF analyzer revealed that CPT enhanced the maximal rate of respiration and the capacity of WT cells to oxidize BCAA, while diminishing glycolytic flux (indicated by ext...