Proteome analysis reveals caspase activation in hyporesponsive CD4 T lymphocytes induced in vivo by the oral administration of antigen.
The oral administration of antigen can lead to systemic antigen-specific hyporesponsiveness, also known as oral tolerance. This phenomenon is a representative form of immune tolerance to exogenous antigen under physiological conditions. We have previously reported that long term feeding of dietary antigen to ovalbumin-specific T cell receptor (TCR) transgenic mice induced oral tolerance of peripheral T cells with impairment in their TCR-induced calcium-signaling pathway. In this study, we utilized two-dimensional electrophoresis to compare intracellular protein expression patterns of orally tolerant and unsensitized CD4 T cells. We detected 26 increased and 16 decreased protein spots and identified 35 of these by mass spectrometry. The results indicated that the expression of caspases was up-regulated and that the protein levels of intact proteins susceptible to caspase cleavage, such as Grb2-related adaptor downstream of Shc (GADS), were decreased in orally tolerant CD4 T cells. Western blotting experiments confirmed that expression of the active form of caspase-3 and the antiapoptotic factor, X-linked inhibitor of apoptosis, were both up-regulated in orally tolerant CD4 T cells, which were found to be nonapoptotic. We further demonstrated that orally tolerant CD4 T cells could not form normal TCR signaling complexes associated with GADS and showed down-regulated phospholipase C-gamma1 activation, which is likely to contribute to the impairment of TCR-induced calcium signaling. Our findings indicate that orally tolerant CD4 T cells up-regulate caspase activation and show decreased levels of caspase-targeted proteins, including TCR signaling-associated molecules, while up-regulating antiapoptotic factors, all of which appear to contribute to their unique tolerant characteristics.
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Tomohiro
T
Kaji
Satoshi
S
Hachimura
Wataru
W
Ise
Shuichi
S
Kaminogawa
D048868:Adaptor Proteins, Signal Transducing; D000284:Administration, Oral; D000818:Animals; D000941:Antigens / Q000494:pharmacology*; D017209:Apoptosis; D015153:Blotting, Western; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D002455:Cell Division; D002469:Cell Separation; D053938:DNA Fragmentation; D015536:Down-Regulation; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D011233:Precipitin Tests; D011506:Proteins / Q000378:metabolism; D020543:Proteome; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D015398:Signal Transduction; D016622:Silver Staining; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013154:Spleen / Q000166:cytology; D013997:Time Factors; D015854:Up-Regulation; D051636:X-Linked Inhibitor of Apoptosis Protein
D048868:Adaptor Proteins, Signal Transducing; D000941:Antigens; D002352:Carrier Proteins; C498726:Mona protein, mouse; D011506:Proteins; D020543:Proteome; D011948:Receptors, Antigen, T-Cell; D051636:X-Linked Inhibitor of Apoptosis Protein; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D002118:Calcium