Rosmarinic acid inhibits Ca2+-dependent pathways of T-cell antigen receptor-mediated signaling by inhibiting the PLC-gamma 1 and Itk activity.
Rosmarinic acid (RosA) is a hydroxylated compound frequently found in herbal plants and is mostly responsible for anti-inflammatory and antioxidative activity. Previously, we observed that RosA inhibited T-cell antigen receptor (TCR)- induced interleukin 2 (IL-2) expression and subsequent T-cell proliferation in vitro. In this study, we investigated in detail inhibitory mechanism of RosA on TCR signaling, which ultimately activates IL-2 promoter by activating transcription factors, such as nuclear factor of activated T cells (NF-AT) and activating protein-1 (AP-1). Interestingly, RosA inhibited NF-AT activation but not AP-1, suggesting that RosA inhibits Ca(2+)-dependent signaling pathways only. Signaling events upstream of NF-AT activation, such as the generation of inositol 1,4,5-triphosphate and Ca(2+) mobilization, and tyrosine phosphorylation of phospholipase C-gamma 1 (PLC-gamma 1) were strongly inhibited by RosA. Tyrosine phosphorylation of PLC-gamma 1 is largely dependent on 3 kinds of protein tyrosine kinases (PTKs), ie, Lck, ZAP-70, and Itk. We found that RosA efficiently inhibited TCR-induced tyrosine phosphorylation and subsequent activation of Itk but did not inhibit Lck or ZAP-70. ZAP-70-dependent signaling pathways such as the tyrosine phosphorylation of LAT and SLP-76 and serine/threonine phosphorylation of mitogen-activated protein kinases (MAPKs) were intact in the presence of RosA, confirming that RosA suppresses TCR signaling in a ZAP-70-independent manner. Therefore, we conclude that RosA inhibits TCR signaling leading to Ca(2+) mobilization and NF-AT activation by blocking membrane-proximal events, specifically, the tyrosine phosphorylation of inducible T cells kinase (Itk) and PLC-gamma 1.
Kang
Mi-Ae
MA
Signal Transduction Laboratory, Mogam Biotechnology Research Institute, Gyunggido, Korea.
Yun
Su-Young
SY
Won
Jonghwa
J
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D020013:Calcium Signaling / Q000187:drug effects*; D002352:Carrier Proteins / Q000378:metabolism; D002934:Cinnamates / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D053630:Depsides; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D051380:GRB2 Adaptor Protein; D006801:Humans; D019169:Jurkat Cells / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000502:physiology; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016853:Muromonab-CD3 / Q000494:pharmacology; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D051966:Phospholipase C gamma; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology; D011506:Proteins / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000187:drug effects* / Q000276:immunology; D014157:Transcription Factors / Q000378:metabolism; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors*; D051746:ZAP-70 Protein-Tyrosine Kinase; D000097123:Rosmarinic Acid
D048868:Adaptor Proteins, Signal Transducing; D000894:Anti-Inflammatory Agents, Non-Steroidal; D002352:Carrier Proteins; D002934:Cinnamates; D004268:DNA-Binding Proteins; D053630:Depsides; D004791:Enzyme Inhibitors; D051380:GRB2 Adaptor Protein; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D016853:Muromonab-CD3; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D051966:Phospholipase C gamma; D010750:Phosphoproteins; D011505:Protein-Tyrosine Kinases; D011506:Proteins; D011948:Receptors, Antigen, T-Cell; D014157:Transcription Factors; D010738:Type C Phospholipases; D051746:ZAP-70 Protein-Tyrosine Kinase; D000097123:Rosmarinic Acid; C495948:GRB2 protein, human; C495949:Grb2 protein, mouse; C110810:LAT protein, human; C491734:Lat protein, mouse; C092947:SLP-76 signal Transducing adaptor proteins; C497261:ZAP70 protein, human; C497262:Zap70 protein, mouse; C080813:emt protein-tyrosine kinase