Cholesterol depletion disrupts lipid rafts and modulates the activity of multiple signaling pathways in T lymphocytes.
Eur J Immunol
Lipid rafts are specialized plasma membrane microdomains, in which glycosphingolipids and cholesterol are major structural components. In T lymphocytes, several signaling proteins are associated with lipid rafts including the protein tyrosine kinase LCK and the adapter protein LAT. To investigate their importance in T cell signaling, lipid rafts were disrupted by depleting cholesterol with methyl-beta-cyclodextrin (MbetaCD). This transiently induced tyrosine phosphorylation of multiple proteins, including the ZAP-70 tyrosine kinase, its associated T cell antigen receptor zeta chain, LAT and phospholipase Cgamma1. Tyrosine phosphorylation was dependent on expression of LCK in lipid rafts. Depletion of cholesterol also resulted in activation of the Ras-ERK pathway. This was largely dependent on phorbol ester-sensitive protein kinase C (PKC) and the PKC-theta isoform translocated to the plasma membrane following MbetaCD treatment. MbetaCD did not stimulate intracellular Ca2+ fluxes; however, consistent with its ability to stimulate Ras, MbetaCD synergized with a Ca2+ ionophore to induce formation of the transcription factor NF-AT. These data indicate a crucial role for cholesterol in the regulation of signaling pathways in T cells, which is likely to reflect its importance in the formation of plasma membrane lipid rafts.
|Title:||Cholesterol depletion disrupts lipid rafts and modulates the activity of multiple signaling pathways in T lymphocytes.|
|Keywords:||Antibodies, Monoclonal, Antigens, CD3, Calcium Signaling, Cell Membrane, Cholesterol, Cyclodextrins, Enzyme Activation, Humans, Ionophores, Isoenzymes, Jurkat Cells, Lymphocyte Specific Protein Tyrosine Kinase p56(lck), Membrane Lipids, Membrane Proteins, Mitogen-Activated Protein Kinases, Phosphorylation, Protein Kinase C, Signal Transduction, T-Lymphocytes, Tyrosine, beta-Cyclodextrins|
|UCL classification:||UCL > School of Life and Medical Sciences
UCL > School of Life and Medical Sciences > Faculty of Medical Sciences
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