Differential roles of PKC-theta in the regulation of intracellular calcium concentration in primary T cells. Export

@article{citeulike:599319, abstract = {Activation of T lymphocytes requires protein kinase C theta (PKC-theta) and an appropriately elevated free intracellular Ca2+ concentration ([Ca2+]i). Here, we show that phorbol 12 myristate 13-acetate (PMA) inhibited Ca2+ influx in wild-type but not PKC-theta-/- T cells, suggesting that PKC-theta plays a role in PMA-mediated inhibition of Ca2+ influx. In contrast, T cell receptor (TCR) crosslinking in the same PKC-theta-/- T cells did result in significantly decreased [Ca2+]i compared to wild-type T cells, suggesting a positive role for PKC-theta in TCR-mediated Ca2+ mobilization. In PKC-theta-/- mice, peripheral mature T cells, but not developing thymocytes, displayed significantly decreased TCR-induced Ca2+ influx and nuclear factor of activated T cells (NFAT) translocation upon sub-optimal TCR crosslinking. The decreased intracellular free Ca2+ was due to changes in Ca2+ influx but not efflux, as observed in extracellular and intracellular Ca2+ mobilization studies. However, these differences in Ca2+ influx and nuclear factor of activated T cells (NFAT) translocation disappeared with increasing intensity of TCR crosslinking. The enhancing effect of PKC-theta on Ca2+ influx is not only dependent on the strength of TCR crosslinking but also on the developmental stage of T cells. The underlying mechanism involved phospholipase Cgamma1 activation and inositol triphosphate production. Furthermore, knockdown of endogenous PKC-theta expression in Jurkat cells resulted in significant inhibition of TCR-induced activation of NFAT, as evidenced from NFAT reporter studies. Forced expression of a constitutively active form of calcineurin in PKC-theta-/- Jurkat cells could readily overcome the above inhibition. Thus, PKC-theta can both positively and negatively regulate the Ca2+ influx that is critical for NFAT activity.}, address = {Department of Microbiology and Immunology, College of Medicine, University of Illinois, Chicago, IL 60612, USA.}, author = {Manicassamy, S. and Sadim, M. and Ye, R. D. and Sun, Z.}, citeulike-article-id = {599319}, citeulike-linkout-0 = {http://dx.doi.org/10.1016/j.jmb.2005.10.043}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/16309697}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=16309697}, day = {20}, doi = {10.1016/j.jmb.2005.10.043}, issn = {0022-2836}, journal = {J Mol Biol}, keywords = {calcium, pkc, t-cells}, month = {January}, number = {3}, pages = {347--359}, posted-at = {2006-04-25 08:55:33}, priority = {2}, title = {Differential roles of PKC-theta in the regulation of intracellular calcium concentration in primary T cells.}, url = {http://dx.doi.org/10.1016/j.jmb.2005.10.043}, volume = {355}, year = {2006} }

TY - JOUR ID - citeulike:599319 L3 - citeulike-article-id:599319 N2 - Activation of T lymphocytes requires protein kinase C theta (PKC-theta) and an appropriately elevated free intracellular Ca2+ concentration ([Ca2+]i). Here, we show that phorbol 12 myristate 13-acetate (PMA) inhibited Ca2+ influx in wild-type but not PKC-theta-/- T cells, suggesting that PKC-theta plays a role in PMA-mediated inhibition of Ca2+ influx. In contrast, T cell receptor (TCR) crosslinking in the same PKC-theta-/- T cells did result in significantly decreased [Ca2+]i compared to wild-type T cells, suggesting a positive role for PKC-theta in TCR-mediated Ca2+ mobilization. In PKC-theta-/- mice, peripheral mature T cells, but not developing thymocytes, displayed significantly decreased TCR-induced Ca2+ influx and nuclear factor of activated T cells (NFAT) translocation upon sub-optimal TCR crosslinking. The decreased intracellular free Ca2+ was due to changes in Ca2+ influx but not efflux, as observed in extracellular and intracellular Ca2+ mobilization studies. However, these differences in Ca2+ influx and nuclear factor of activated T cells (NFAT) translocation disappeared with increasing intensity of TCR crosslinking. The enhancing effect of PKC-theta on Ca2+ influx is not only dependent on the strength of TCR crosslinking but also on the developmental stage of T cells. The underlying mechanism involved phospholipase Cgamma1 activation and inositol triphosphate production. Furthermore, knockdown of endogenous PKC-theta expression in Jurkat cells resulted in significant inhibition of TCR-induced activation of NFAT, as evidenced from NFAT reporter studies. Forced expression of a constitutively active form of calcineurin in PKC-theta-/- Jurkat cells could readily overcome the above inhibition. Thus, PKC-theta can both positively and negatively regulate the Ca2+ influx that is critical for NFAT activity. IS - 3 JF - J Mol Biol SN - 0022-2836 AD - Department of Microbiology and Immunology, College of Medicine, University of Illinois, Chicago, IL 60612, USA. EP - 359 TI - Differential roles of PKC-theta in the regulation of intracellular calcium concentration in primary T cells. VL - 355 SP - 347 KW - calcium KW - pkc KW - t-cells AU - Manicassamy, S AU - Sadim, M AU - Ye, RD AU - Sun, Z PY - 2006/01/20/ UR - http://dx.doi.org/10.1016/j.jmb.2005.10.043 ER -