Immunopotentiation on murine spleen lymphocytes induced by polysaccharide fraction of Panax ginseng via upregulating calcineurin activity.
Calcineurin (CN), a unique Ca2+/calmodulin (CaM)-dependent serine/threonine protein phosphatase, plays a pivotal role in the activation and proliferation of T lymphocytes. Based on the effective molecular screening model established in our laboratory, we found that a part of polysaccharides from the stem and leaves of Panax ginseng, termed PGP-SL, could activate CN activity. Subsequently, we investigated whether PGP-SL also has immunological competence on murine spleen lymphocytes. In the present study, we demonstrated that PGP-SL could significantly promote in vitro spleen lymphocyte proliferation in the absence of either concanavalin A or LPS in a concentration-dependent manner at concentrations ranging from 100 to 500 microg/ml (p<0.001). In addition, the proliferation of cyclosporin A (CsA)-treated spleen lymphocytes was also significantly promoted in the same pattern (p<0.001); the production of IL-2 was elevated and the effect appeared as early as 24 h after PGP-SL treatment. The results of RT-PCR also indicated that the IL-2 mRNA level was markedly enhanced, particularly at PGP-SL concentrations of 300 and 500 microg/ml, and Fura-2/AM fluorescence probe analysis showed that PGP-SL could dramatically increase the intracellular free calcium concentration of spleen lymphocytes, i.e. [Ca2+]i was significantly increased by approximately 181 and 107% at 300 and 500 microg/ml of PGP-SL, respectively. However, this effect could be totally inhibited by verapamil treatment. Taking our results together, we suggest that PGP-SL exhibits immunopotentiation effects on murine spleen lymphocytes by the Ca2+-CN-NFAT-IL-2 signaling pathway.
Zhang
Song-Dong
SD
Department of Biochemistry and Molecular Biology, Beijing Key Laboratory, Beijing Normal University, Beijing, China.
Yin
Yan-Xia
YX
Wei
Qun
Q
D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D019703:Calcineurin / Q000187:drug effects* / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D007376:Interleukin-2 / Q000096:biosynthesis; D008214:Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D051379:Mice; D050778:NFATC Transcription Factors / Q000187:drug effects / Q000378:metabolism; D005894:Panax / Q000737:chemistry*; D010940:Plant Proteins / Q000494:pharmacology*; D011134:Polysaccharides / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D015854:Up-Regulation
D000276:Adjuvants, Immunologic; D007376:Interleukin-2; D050778:NFATC Transcription Factors; C412712:PGP protein, plant; D010940:Plant Proteins; D011134:Polysaccharides; D012333:RNA, Messenger; D019703:Calcineurin