Intracellular magnesium movements and lymphocyte activation.
Activation of lymphocytes through ligation of the antigen receptor complex initiates activation of phospholipase C-gamma (PLC). Activated PLC hydrolyses phosphatidylinositol-4,5-bisphosphate into diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (InsP3). InsP3 mediates the release of Ca2+ from intracellular stores into the cytoplasm, while InsP4 and InsP3 mobilize extracellular Ca2+. Both processes contribute to the temporary increase in [Ca2+]i that is observed after lymphocyte activation. Because of the availability of Mg(2+)-sensitive and specific fluorochromes like Mag-indo-1 it is now possible to monitor potential changes in [Mg2+]i. In lymphocytes that have responded to receptor activation with high [Ca2+]i, an increase in [Mg2+]i can be found. The [Mg2+]i is in the range that enables it to modulate the activity of a number of cellular enzymes, including key enzymes in the PLC transmembrane signalling pathway. It can be speculated that a differential Mg2+ mobilization response will have consequences for the ultimate cellular response to receptor activation.
Rijkers
G T
GT
Department of Immunology, University Hospital for Children and Youth Het Wilhelmina Kinderziekenhuis Utrecht, The Netherlands.
Henriquez
N
N
Griffioen
A W
AW
D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000502:physiology; D006801:Humans; D008213:Lymphocyte Activation; D008274:Magnesium / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism
D010716:Phosphatidylinositols; D011505:Protein-Tyrosine Kinases; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D008274:Magnesium; D002118:Calcium