Calcium Dynamics of Ex Vivo Long-Term Cultured CD8(+) T Cells Are Regulated by Changes in Redox Metabolism

• Type of Material: Article
• Authors: Catherine A. Rivet, Georgia Institute of Technology; Ariel S. Kniss-James, Georgia Institute of Technology; Margaret A. Gran, Georgia Institute of Technology; Anish Potnis, Georgia Institute of Technology; Abby Hill, Georgia Institute of Technology; Hang Lu, Georgia Institute of Technology; Melissa Kemp, Emory University
• Language: English
• Date: 2016-08-15
• Publisher: Public Library of Science
• Publication Version: Final Published Version
• Copyright Statement: © 2016 Rivet et al.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pone.0159248
• Title of Journal or Parent Work: PLoS ONE
• ISSN: 1932-6203
• Volume: 11
• Issue: 8
• Start Page: e0159248
• End Page: e0159248
• Grant/Funding Information: Support for this work was provided by the National Institutes of Health awards R01AI088023A and DP2OD006483.; Financial support to AK provided through NSF Graduate Research Fellowship Grant DGE-1148903, P.E.O. Scholar Award, and NIH Training Grant 32GM105490.
• Keywords: KINETIC-MODEL; Oxidation; ENDOPLASMIC-RETICULUM; MEMBRANE CA2+-ATPASE; Calcium signaling; LYMPHOCYTE-ACTIVATION; Mitochondria; GENE-EXPRESSION; INOSITOL 1,4,5-TRISPHOSPHATE RECEPTOR; OPERATED CA2+ ENTRY; T cell receptors; Multidisciplinary Sciences; Science & Technology; Cytotoxic T cells; SIGNAL-TRANSDUCTION; AGE-RELATED ALTERATIONS; Oxidation-reduction reactions; CARDIAC MYOCYTES; T cells; Redox signaling
• Research Categories: Engineering, Biomedical; Biology, Bioinformatics

Abstract

T cells reach a state of replicative senescence characterized by a decreased ability to proliferate and respond to foreign antigens. Calcium release associated with TCR engagement is widely used as a surrogate measure of T cell response. Using an ex vivo culture model that partially replicates features of organismal aging, we observe that while the amplitude of Ca2+ signaling does not change with time in culture, older T cells exhibit faster Ca2+ rise and a faster decay. Gene expression analysis of Ca2+ channels and pumps expressed in T cells by RT-qPCR identified overexpression of the plasma membrane CRAC channel subunit ORAI1 and PMCA in older T cells. To test whether overexpression of the plasma membrane Ca2+ channel is sufficient to explain the kinetic information, we adapted a previously published computational model by Maurya and Subramaniam to include additional details on the store-operated calcium entry (SOCE) process to recapitulate Ca2+ dynamics after T cell receptor stimulation. Simulations demonstrated that upregulation of ORAI1 and PMCA channels is not sufficient to explain the observed alterations in Ca2+ signaling. Instead, modeling analysis identified kinetic parameters associated with the IP3R and STIM1 channels as potential causes for alterations in Ca2+ dynamics associated with the long term ex vivo culturing protocol. Due to these proteins having known cysteine residues susceptible to oxidation, we subsequently investigated and observed transcriptional remodeling of metabolic enzymes, a shift to more oxidized redox couples, and post-translational thiol oxidation of STIM1. The model-directed findings from this study highlight changes in the cellular redox environment that may ultimately lead to altered T cell calcium dynamics during immunosenescence or organismal aging.