Protein Kinase A Intersects Src Signaling in Membrane Microdomains

Abrahamsen, Hilde; Vang, Torkel; Taskén, Kjetil

doi:10.1074/jbc.m211426200

Cited by 53 publications

(46 citation statements)

References 44 publications

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“…lines, as has been previously reported for cells infected with retroviral v-Src (Sefton et al, 1982) or transfected with FlagSrc (Abrahamsen et al, 2003).…”

Section: Resultsmentioning

confidence: 69%

PKA phosphorylation of Src mediates Rap1 activation in NGF and cAMP signaling in PC12 cells

Obara

Labudda

Dillon

et al. 2004

Journal of Cell Science

117

116

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Recent studies suggest that the tyrosine kinase Src plays an important role in the hormonal regulation of extracellular signal-regulated kinases (ERKs) via cyclic AMP (cAMP). Src has also been proposed to mediate signals downstream of nerve growth factor (NGF). Here, we report that the cAMP-dependent protein kinase A (PKA) induced the phosphorylation of Src at residue serine17 (S17) in multiple cell types including PC12, Hek293, AtT-20 and CHO cells. In PC12 cells, Src phosphorylation on S17 participates in the activation of the small G protein Rap1 by both cAMP and NGF. In these cells, Rap1 is required for cAMP/PKA signaling to ERKs and also for the sustained activation of ERKs by NGF. The activation of Rap1 by both cAMP and NGF was blocked by PP2, an inhibitor of Src family kinases, and by a Src mutant incapable of being phosphorylated by PKA (SrcS17A), consistent with the requirement of PKA phosphorylation of Src at S17 in these actions. PP2 and SrcS17A also inhibited the Rap1-dependent activation of ERKs by both agents. These results strongly indicate that PKA phosphorylation of Src at S17 is essential for cAMP and NGF signaling in PC12 cells and identify PKA as an important downstream target of NGF. PKA phosphorylation of Src may therefore be required for Rap1 activation in PC12 cells.

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“…lines, as has been previously reported for cells infected with retroviral v-Src (Sefton et al, 1982) or transfected with FlagSrc (Abrahamsen et al, 2003).…”

Section: Resultsmentioning

confidence: 69%

PKA phosphorylation of Src mediates Rap1 activation in NGF and cAMP signaling in PC12 cells

Obara

Labudda

Dillon

et al. 2004

Journal of Cell Science

117

116

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“…Thus, NF-AT ensures correct responses to complex biologic stimuli. The cAMP/PKA type I pathway thereby is known to induce Csk activation, 34 the major negative regulator of the Src-PTK Lck. 15 Additionally, PKA has been reported to directly phosphorylate NF-AT and thus inhibits nuclear entry of NF-AT via association with 14-3-3 proteins.…”

Section: Discussionmentioning

confidence: 99%

PKCθ and PKA are antagonistic partners in the NF-AT transactivation pathway of primary mouse CD3+ T lymphocytes

Hermann-Kleiter

Thuille

Pfeifhofer

et al. 2006

Blood

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We here investigate the crosstalk of PKC and PKA signaling during primary CD3 ؉ T-lymphocyte activation using pharmacologic inhibitors and activators in combination with our established panel of PKC isotype-deficient mouse T cells in vitro. PKC and PKA inversely affect the CD3/ CD28-induced IL-2 expression, whereas other PKC isotypes are dispensable in this signaling pathway. Gene ablation of PKC selectively results in a profound reduction of IL-2 production; however, complete abrogation of IL-2 production in these PKC ؊/؊ T cells was achieved only by simultaneous coactivation of the cAMP/PKA pathway in CD3 ؉ T cells. Conversely, the reduced IL-2 production in PKC inhibitor-treated T cells can be rescued by inhibition of the cAMP/PKA pathway in wild-type but not in PKC ؊ IntroductionFollowing T-cell receptor (TCR) stimulation, lymphocyte activation threshold is coordinated by a complex interplay of distinct signal transduction pathways. The "fine-tuning" of signaling cascades is considered as a crucial step during T-cell activation in order to result in adequate amplitude of an immune response. The molecular processes that regulate the precise level of the immune activation and their complex interpathway integration are, however, still poorly understood. Among several signaling pathways, protein kinase C (PKC) plays an important role in the cellular activation pathway downstream of the antigen receptor. PKC, in particular, is known to translocate to the immunologic synapse. 1 Once activated, PKC plays a critical role in TCR signaling. 2 This is confirmed by analysis of CD3 ϩ T cells of mice lacking PKC. Ex vivo, PKC-deficient T cells are mostly TCR unresponsive and deficient in the production of interleukin 2 (IL-2) due to an impaired transactivation of NF-B, AP-1, and NF-AT. [3][4][5] In strict contrast, the cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) pathway represents a negative regulatory mechanism that controls IL-2 expression in T cells. cAMP itself has been demonstrated to activate directly a class of cyclic nucleotide ion channels 6,7 as well as the Rap1 guanine exchange factors Epac1 and Epac2. 8 The principle cAMP receptor in lymphoid cells, however, is PKA. 9 cAMP is produced after TCR stimulation in T lymphocytes, suggesting the cAMP-mediated repression of T-cell activation may represent a physiologic negative feedback control mechanism. 10 Suppression of cAMP signaling is thus required for T-cell activation. 11 Among other mechanisms, cAMP inhibition is mediated by de novo transcriptional induction of phosphodiesterases (PDEs) upon T-cell activation. In T cells, PDE4 seems to play a particularly important role. 12,13 Increased PDE4 expression in T cells is associated with increased IL-2 production via its hydrolysis of cAMP. 12 Inversely, PDE4 blockade is shown to augment cAMP levels and thus known to abrogate cytokine secretion and proliferation in T cells through inhibition of NF-B and NF-AT and activation of CREB. 13 Several direct targets of cAMP/PKA signaling have be...

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“…G i , G s , and AC have been reported to segregate into lipid rafts (40,41). Therefore, we next examined whether these G proteins played a role in the raft-associated cAMP increase.…”

Section: Tcr-mediated Camp Production Is Increased Upon 3-isobutyl-1-mentioning

confidence: 99%

TCR- and CD28-Mediated Recruitment of Phosphodiesterase 4 to Lipid Rafts Potentiates TCR Signaling

Abrahamsen¹,

Baillie

Ngai

et al. 2004

The Journal of Immunology

Self Cite

122

138

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Ligation of the TCR along with the coreceptor CD28 is necessary to elicit T cell activation in vivo, whereas TCR triggering alone does not allow a full T cell response. Upon T cell activation of human peripheral blood T cells, we found that the majority of cAMP was generated in T cell lipid rafts followed by activation of protein kinase A. However, upon TCR and CD28 coligation, β-arrestin in complex with cAMP-specific phosphodiesterase 4 (PDE4) was recruited to lipid rafts which down-regulated cAMP levels. Whereas inhibition of protein kinase A increased TCR-induced immune responses, inhibition of PDE4 blunted T cell cytokine production. Conversely, overexpression of either PDE4 or β-arrestin augmented TCR/CD28-stimulated cytokine production. We show here for the first time that the T cell immune response is potentiated by TCR/CD28-mediated recruitment of PDE4 to lipid rafts, which counteracts the local, TCR-induced production of cAMP. The specific recruitment of PDE4 thus serves to abrogate the negative feedback by cAMP which is elicited in the absence of a coreceptor stimulus.

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Protein Kinase A Intersects Src Signaling in Membrane Microdomains

Cited by 53 publications

References 44 publications

PKA phosphorylation of Src mediates Rap1 activation in NGF and cAMP signaling in PC12 cells

PKA phosphorylation of Src mediates Rap1 activation in NGF and cAMP signaling in PC12 cells

PKCθ and PKA are antagonistic partners in the NF-AT transactivation pathway of primary mouse CD3+ T lymphocytes

TCR- and CD28-Mediated Recruitment of Phosphodiesterase 4 to Lipid Rafts Potentiates TCR Signaling

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