Does PTPN22 regulate the switch between glycolysis and oxidative phosphorylation? (360G-Wellcome-202413_Z_16_Z)

Previous research has shown that the metabolic profiles in the blood of rheumatoid arthritis patients differ significantly from controls and relate closely to the level inflammation. Changes observed are likely to result from the high number of active immune cells present in the arthritic joint. The switch between different metabolic states of the cells is governed by a number of signalling pathways that ultimately involve AKT/PI3 kinase regulation of mTOR. It was shown that overexpression of PTPN22, which encodes the lymphoid-specific phosphatase Lyp, led to changes in phosphorylation of AKT and PI3 kinase. It may be the case that PTPN 22 differentially regulates this pathway and thus alters the switch between metabolic states, with the result that chronic inflammation is perpetuated. I will test the hypothesis that PTPN22 regulates the switch between glycolysis and oxidative phosphorylation. I will test this by using shRNA to knock down of Lyp expression in Jurkat cells and by using a Lyp inhibitor. Lyp phosphatase activity will be assessed using an activity assay. Whole cell phosphotyrosine immunoblots before and after activation will reveal if substantial changes in phosphorylation occur and possibly identify specific hyperphosphorylated targets of Lyp in the cells.