title: NMDA receptors as a possible component of store-operated Ca²⁺ entry in human T-lymphocytes.
abstract: Elevation of intracellular Ca²⁺ in T-lymphocytes as a consequence of T cell antigen receptor activation triggers transcriptional programs resulting in effector cytokine secretion and immune response coordination. Increase of Ca²⁺ concentration in T-lymphocytes follows both the Ins(1,4,5)P(3)-dependent release from an intracellular store and subsequent influx from extracellular milieu. Flow cytometry and the fluorescent dye Fluo-4AM have been used to demonstrate that noncompetitive NMDA receptor antagonist (+)-MK801 inhibits Ca²⁺ influx in T cells induced by thapsigargin. Combination of thapsigargin and (+)-MK801 with following incubation does not affect Ca²⁺ mobilization from intracellular stores, while decreased Ca²⁺ entry was observed. Overall data indicate that the ion channel blocker (+)-MK801 is able to inhibit the Ca²⁺ influx and confirm our suggestion about involvement of NMDA receptor in the store-operated Ca²⁺ entry mechanisms in human T-lymphocytes. To identify the signal transduction pathways associated with NMDA receptors in mitogen-stimulated T-lymphocytes, the cells were incubated with (+)-MK801, then activity of key phosphorylated protein kinases of MAP-activated (pERK1/2, pSAPK/JNK, p-p38), Ca²⁺-dependent (pCaMKII), PI3/Akt-dependent (pGSK-3β), and PKC-activated (pPKCθ) pathways were detected. The data we obtained demonstrate that (+)-MK801 treatment leads to more prominent decrease in Ras-activated protein kinases pERK1/2 and Rac-activated proteins p-p38 and pSAPK/JNK, as compared to DAG-dependent pPKCθ and Ca²⁺-dependent pCaMKII. These results show that NMDA receptors are mainly involved in regulation of Ras/Rac-dependent signaling in T-lymphocytes.
authors: Institute of Biochemistry and Genetics, Ufa Research Center of the Russian Academy of Sciences, Ufa, Russia.
authors: L F
authors: LF
authors: Zainullina
authors: R S
authors: RS
authors: Yamidanov
authors: V A
authors: VA
authors: Vakhitov
authors: Yu V
authors: YV
authors: Vakhitova
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D016291:Dizocilpine Maleate / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D011494:Protein Kinases / Q000032:analysis / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D011948:Receptors, Antigen, T-Cell; D016194:Receptors, N-Methyl-D-Aspartate; D019284:Thapsigargin; D016291:Dizocilpine Maleate; D011494:Protein Kinases; D002118:Calcium