T cell receptor induced intracellular redistribution of type I protein kinase A.
The productive activation of CD4(+) T lymphocytes, leading to proliferation and cytokine secretion, requires precise temporal regulation of intracellular cyclic AMP concentrations. The major effector molecule activated by cyclic AMP in mammalian cells is the cyclic AMP-dependent protein kinase A (PKA). The type I PKA isozyme mediates the inhibitory effects of cyclic AMP on T-cell activation. Using laser scanning confocal microscopy, we demonstrated that the regulation of PKA type I activity involves spatial redistribution of PKA type I molecules following T-cell receptor (TCR) stimulation. In resting T cells, PKA type I was located in membrane proximal regions and distributed equally across the cell. Shortly after antigen engagement, T cells and antigen-presenting cells formed an area of intense contact, known as the immunological synapse. TCR concentrated at the synapse, whereas PKA type I molecules redistributed to the opposite cell pole within 10 min after T-cell stimulation. Type I PKA redistribution was solely dependent on TCR signalling, because we observed the same temporal and spatial distribution after antibody-mediated cross-linking of the TCR-associated CD3 complex. Segregation of TCR and PKA type I molecules was maintained for at least 20 min. Thirty minutes after stimulation, PKA type I partially colocalized with the TCR. After 60 min, PKA type I distribution again approached the resting state. Considering that initial TCR signals lead to increases in intracellular cyclic AMP, PKA type I molecules may be targeted towards localized cyclic AMP accumulations or transported away from these areas, depending on the requirements of the cellular response.
Zhou
Wenhong
W
Department of Microbiology and Immunology, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.
Vergara
Leoncio
L
König
Rolf
R
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*
D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D017868:Cyclic AMP-Dependent Protein Kinases