[Note: The main job of the body’s T cells is to fight infection. These Danish researchers found that when T cells encounter a pathogen, they expose a vitamin D receptor that searches for vitamin D, and they will not activate without it.]
Phospholipase C (PLC) isozymes are key signaling proteins downstream of many extracellular stimuli. Here we show that naive human T cells had very low expression of PLC-?1 and that this correlated with low T cell antigen receptor (TCR) responsiveness in naive T cells.
However, TCR triggering led to an upregulation of ~75-fold in PLC-?1 expression, which correlated with greater TCR responsiveness.
Induction of PLC-?1 was dependent on vitamin D and expression of the vitamin D receptor (VDR).
Naive T cells did not express VDR, but VDR expression was induced by TCR signaling via the alternative mitogen-activated protein kinase p38 pathway.
Thus, initial TCR signaling via p38 leads to successive induction of VDR and PLC-?1, which are required for subsequent classical TCR signaling and T cell activation.
Source: Nature Immunology, Mar 7, 2010. doi:10.1038/ni.1851 by von Essen MR, Kongsbak M, Schjerling P, Olgaard K, Odum N, Geisle C. Department of International Health, Immunology and Microbiology; Center for Healthy Aging, Faculty of Health Sciences; Department of Biology, Faculty of Science; Institute of Sports Medicine and Department of Nephrology, Bispebjerg Hospital, Rigshospitalet and Faculty of Health Sciences, University of Copenhagen, Denmark. [E-mail: firstname.lastname@example.org]