title: Identification and functional characterization of voltage-dependent calcium channels in T lymphocytes.
abstract: In T lymphocytes, sustained calcium (Ca2+) influx through Ca2+ channels localized in the plasma membrane is critical for T cell activation and proliferation. Previous studies indicated that voltage-dependent Ca2+ channels (VDCCs) play a role in Ca2+ mobilization during T lymphocyte activation. However, the role of VDCCs in otherwise nonexcitable cells is still poorly understood. We used RT-PCR to identify a transcript encoding the pore-forming alpha1F-subunit of an L-type Ca2+ channel in T lymphocytes. Its identity was confirmed by DNA sequencing. To further investigate the contribution of Ca2+ influx through VDCCs, we assessed the effects of the 1,4-dihydropyridine L-type Ca2+ channel agonist, (+/-) Bay K 8644, and antagonist, nifedipine, on the human Jurkat T cell leukemia line, human peripheral blood T lymphocytes and mouse splenocytes. We found that treatment of T lymphocytes with (+/-) Bay K 8644 increased intracellular Ca2+ and induced the activation of phosphoextracellular-regulated kinase 1/2 (Erk1/2), whereas nifedipine blocked Ca2+ influx, the activity of Erk1/2 and nuclear factor of activated T cells (NFAT), interleukin-2 (IL-2) production, and IL-2 receptor expression. Nifedipine also significantly suppressed splenocyte proliferation in an in vitro mixed lymphocyte reaction and the proliferation of male antigen (H-Y)-specific T cell receptor-transgenic CD8+ T cells in transplanted male mice in vivo. Taken together these novel findings indicate that an L-type Ca2+ channel plays a significant role in the Ca2+ influx pathways mediating T lymphocyte activation and proliferation in vitro and in vivo.
authors.affiliation: Biomedical Research Centre, the Biotechnology Laboratory, Department of Microbiology and Immunology, University of British Columbia, 2222 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Maya F
authors.initials: MF
authors.lastname: Kotturi
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Carlow
authors.forename: Junella C
authors.initials: JC
authors.lastname: Lee
authors.forename: Hermann J
authors.initials: HJ
authors.lastname: Ziltener
authors.forename: Wilfred A
authors.initials: WA
authors.lastname: Jefferies
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000235:genetics / Q000502:physiology*; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D019169:Jurkat Cells; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry / Q000302:isolation & purification; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000737:chemistry* / Q000502:physiology*
chemical_list: D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D012333:RNA, Messenger; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium