Altered lipid raft–associated signaling and ganglioside expression in T lymphocytes from patients with systemic lupus erythematosus
Elizabeth C. Jury, … , Rizgar A. Mageed, David A. Isenberg
Elizabeth C. Jury, … , Rizgar A. Mageed, David A. Isenberg
Published April 15, 2004
Citation Information: J Clin Invest. 2004;113(8):1176-1187. https://doi.org/10.1172/JCI20345.
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Article Autoimmunity

Altered lipid raft–associated signaling and ganglioside expression in T lymphocytes from patients with systemic lupus erythematosus

Abstract

Systemic lupus erythematosus (SLE) is characterized by abnormalities in T lymphocyte receptor–mediated signal transduction pathways. Our previous studies have established that lymphocyte-specific protein tyrosine kinase (LCK) is reduced in T lymphocytes from patients with SLE and that this reduction is associated with disease activity and parallels an increase in LCK ubiquitination independent of T cell activation. This study investigated the expression of molecules that regulate LCK homeostasis, such as CD45, C-terminal Src kinase (CSK), and c-Cbl, in lipid raft domains from SLE T cells and investigated the localization of these proteins during T cell receptor (TCR) triggering. Our results indicate that the expression of raft-associated ganglioside, GM1, is increased in T cells from SLE patients and LCK may be differentially regulated due to an alteration in the association of CD45 with lipid raft domains. CD45 tyrosine phosphatase, which regulates LCK activity, was differentially expressed and its localization into lipid rafts was increased in T cells from patients with SLE. Furthermore, T cells allowed to “rest” in vitro showed a reversal of the changes in LCK, CD45, and GM1 expression. The results also revealed that alterations in the level of GM1 expression and lipid raft occupancy cannot be induced by serum factors from patients with SLE but indicated that cell-cell contact, activating aberrant proximal signaling pathways, may be important in influencing abnormalities in T cell signaling and, therefore, function in patients with SLE.

Authors

Elizabeth C. Jury, Panagiotis S. Kabouridis, Fabian Flores-Borja, Rizgar A. Mageed, David A. Isenberg

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Figure 1

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Increased GM1 expression and reduced colocalization of LCK with lipid ra...
Increased GM1 expression and reduced colocalization of LCK with lipid raft (LR) domains in T cells from patients with SLE. Purified T cells from 12 patients with SLE, 8 healthy controls, and 6 patients with RA were fixed, made permeable, and stained for LCK-FITC by indirect immunofluorescence; lipid rafts were visualized using PE-conjugated CTB. Cells were viewed by confocal microscopy, and images were analyzed for individual LCK or CTB staining patterns and for areas of colocalization (yellow color); quantitative results are based on the “reading” of an average of 50 cells for each sample. (A) Representative experiment showing CTB binding in SLE T cells compared with control T cells (Normal) (upper panels). Semiquantitation of CTB binding is shown using MFI (± SEM); five images were analyzed from five patients with SLE and four healthy controls (lower panel). (B) LCK/CTB overlay images comparing SLE and normal T cells (Normal) (upper panels). Quantitative results showing the percent of CD3+ cells displaying areas of LCK/LR colocalization in SLE patients and healthy controls; each symbol represents one patient with an average of 50 cells analyzed (lower panel). Scale bars, 5 μm.