Direct evidence of involvement of glycosylphosphatidylinositol-anchored proteins in the heavy metal-mediated signal delivery into T lymphocytes.
The biological significance of the action of glycosylphosphatidylinositol (GPI)-anchored proteins in cell physiology and pathology when stimulated with their natural agonists is not known. Here we provide evidence that GPI-anchored proteins play a crucial role in the recently defined heavy metal (HgCl2)-triggered signal delivery to T lymphocytes. Thiol-reactive HgCl2, a multi-potent crosslinker of cell membrane proteins, induced heavy aggregation of Thy-1, a representative GPI-anchored protein, on murine thymocytes, and delivered a signal to induce heavy tyrosine phosphorylation of cellular proteins. This rather unusual signal delivery by HgCl2 is diminished by the pre-treatment of cells with phosphatidylinositol-specific phospholipase C, which partially cleaved GPI-anchored proteins from the cell surface. Direct evidence for the involvement of GPI or GPI-anchored proteins in the HgCl2-mediated signaling is provided by the loss of signaling in a mutant thymoma cell line defective in the phosphatidylinositol glycan-class A gene (PIG-A), and its restoration in a transfectant with PIG-A.
Pu
M
M
Department of Immunology, Nagoya University School of Medicine, Japan.
Ma
L
L
Ohkusu
K
K
Isobe
K
K
Taguchi
R
R
Ikezawa
H
H
Hamaguchi
M
M
Nakashima
I
I
D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D005434:Flow Cytometry; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008627:Mercuric Chloride / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D013945:Thymoma; D013953:Thymus Neoplasms; D014407:Tumor Cells, Cultured
D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D008627:Mercuric Chloride; D010727:Phosphoric Diester Hydrolases; D054801:Phosphoinositide Phospholipase C; D043265:Phosphatidylinositol Diacylglycerol-Lyase