Proteomic Analysis of the Differential Protein Expression Reveals Nuclear GAPDH in Activated T Lymphocytes

Abstract

Despite the important role of T cell activation in the adaptive immunity, very little is known about the functions of proteins that are differentially expressed in the activated T cells. In this study, we have employed proteomic approach to study the differentially expressed proteins in activated T cells. A total of 25 proteins was characterized that displayed a decreased expression, while a total of 20 proteins was characterized that displayed an increased expression in the activated T cells. Among them, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was identified unexpectedly as one of the up-regulated proteins. Western blot analysis of proteins separated by 2-dimensional gel electrophoresis had identified several modified GAPDHs which were detectable only in the activated T cells, but not in resting T cells. These modified GAPDHs had higher molecular mass and more basic PI, and were present in the nucleus of activated T cells. Promoter occupancy studies by chromatin immunoprecipitation assay revealed that nuclear GAPDH could be detected in the promoter of genes that were up-regulated during T cell activation, but not in the promoter of genes that were not unaffected or down-regulated. Our results suggest that nuclear GAPDH may function as transcriptional regulator in activated T cells.

Extracellular ATP Exerts Opposite Effects on Activated and Regulatory CD4+ T Cells via Purinergic P2 Receptor Activation

“…GAPDH was used as internal control also in activated CD4 + T cells because its mRNA level remains unchanged compared with unstimulated CD4 + T cells (32 …”

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“…GAPDH is an abundant enzyme of $37 kDa that catalyzes the sixth step of glycolysis in the cytosol and translocates to the nucleus when it is activated in T-lymphocytes (22 (Fig 3a). These cells suspended in PBS were placed on clean glass slides; cell size measurements were performed over a period of one to 2 h and no cell size increase was observed.…”

Increased expression and phosphorylation of the two S100A9 isoforms in mononuclear cells from patients with systemic lupus erythematosus: A proteomic signature for circulating low-density granulocytes

“…Likewise, RSP-1 did not show any positive correlation with any of the proteins tested, while LDH-A protein levels correlated positively with Profilin-1 (spot 18), AldoA, and GAPDH (spot 11). Although some of these proteins are considered housekeeping, it is interesting to note that GAPDH, and AldoA are differentially expressed in PHA-activated T cells as compared with resting T cells [39].…”