Involvement of Classical and Novel Protein Kinase C Isoforms in the Response of Human Vγ9Vδ2 T Cells to Phosphate Antigens

Abstract

Human γδ T cells expressing the Vγ9Vδ2 gene segments are activated polyclonally by phosphoantigens found on a wide variety of pathogenic organisms. After ligand exposure, Vγ9Vδ2 T cells proliferate and rapidly secrete large amounts of cytokines and chemokines that contribute to the innate immune response to these pathogens. Neither APCs nor costimulatory molecules are required. In this study we examined whether these phosphoantigens activate protein kinase Cθ (PKCθ). This novel PKC isoform is essential for Ag signaling through the αβ TCR in a costimulation-dependent fashion. The results showed that isopentenyl pyrophosphate (IPP), a soluble phospholigand released by mycobacteria, led to the rapid and persistent activation of PKCθ in γδ T cells, as determined by evidence of translocation and phosphorylation. In contrast, no ligand-dependent response was detected for PKCα/β or PKCδ. Using the inhibitors Gö6976 and rottlerin, a role for both conventional and novel PKC isoforms in IPP-induced proliferation, CD25 expression, and cytokine and chemokine production was demonstrated. Gel-shift assays indicated that the transcription factors NF-κB and AP-1 were downstream targets of PKC activation. IPP also induced the rapid and persistent phosphorylation of extracellular signal-regulated kinases 1 and 2, p38 mitogen-activated kinase, and stress-activated kinase/c-Jun N-terminal kinase, but only an inhibitor of conventional PKCs blocked these responses. We conclude that the γδ T cell response to phosphoantigens is regulated by both novel and conventional PKC isoforms, with PKCθ being more responsive to ligand stimulation and PKCα/β to growth-factor availability.

Transcriptional Profiling of γδ T Cells Identifies a Role for Vitamin D in the Immunoregulation of the Vγ9Vδ2 Response to Phosphate-Containing Ligands

“…Analysis of the results for genes associated with the early activation of T cells, such as Fynbinding protein, immediate early response 3 gene, and CD25 expression, showed that either IPP or Abs to CD3 activated V␦2 T cells (Table I). As expected, we also noted potent up-regulation of a number of proinflammatory cytokines and chemokines, many of which have been extensively documented as targets of phosphate-Ag activation in these cells (22,34) (Table I and data not shown). However, the cDNA screen also showed up-regulation of mRNA for the VDR in cells that had been activated with either IPP or CD3 (Table I).…”

“…Use of human tissues was approved by the Committee on Clinical Investigation of the Albert Einstein College of Medicine. Long-term cultures of V␦2 ϩ cells were established by stimulating once with IPP (30 M; Sigma-Aldrich) and were maintained with 50 U/ml IL-2 (National Cancer Institute) as described (34). V␦2 expression was determined by FACS (clone B6; BD Pharmingen).…”

PKCθ mediates pre-TCR signaling and contributes to Notch3-induced T-cell leukemia

“…To this end, PKCy is required for Notch3-dependent activation of the IKK complex. Therefore, we provide the first direct evidence, to our knowledge, that pre-TCR is able to regulate PKCy membrane translocation and activity, a property so far only described for a/b and g/d TCR Cipriani et al, 2002). Notably, such a pre-TCR activity is unveiled by Notch3 activation.…”

Impairment of TNF-α Production and Action by Imidazo[1,2- α] Quinoxalines, as Derivative Family Which Displays Potential Anti-Inflammatory Properties

“…(Table I). The 8A(or 8B)-activation of p38 MAPK could be associated with a cAMP-independent pathway, several signal transduction events enumerated in various cell types and stimuli (42)(43)(44)(45)(46), being possible. Strikingly, the 8A/8B activation did not potentiate the p38 MAPK phosphorylation promoted by anti-CD3 or TNF-o.. A full activation of the p38 MAPK by anti-CD3 in y8 T cells (or TNF-o.…”