Regulation of CD45-induced signaling by galectin-1 in Burkitt lymphoma B cells.
It has been well established that Galectin-1 (GAL1), a beta-galactoside-binding protein, regulates the viability of lymphoid cells. However, the signaling pathway governed by the binding of GAL1 to the cell membrane is not understood. As a first step towards the elucidation of GAL1-initiated signaling events leading to a reduced viability of Burkitt lymphoma B cells, we tried to characterize the initial events induced by the binding of GAL1 to its receptor. This characterization was performed in BL36 cells, a Burkitt lymphoma cell line sensitive to GAL1. The results were as follows: (1) when solubilized cell membrane lysates were affinity bound to immobilized GAL1 and eluted by competition, the tyrosine phosphatase glyco-protein CD45 was found in the eluate, highlighting the role of CD45 as a receptor of GAL1; (2) the phosphatase activity of cell membranes diminished after incubation with GAL1; (3) immunoprecipitation experiments demonstrated that the phosphotyrosine kinase Lyn was dysregulated in cells that have been cultured in medium containing 700 nM GAL1, and (4) that the ratio between two isoforms of Lyn was modified during the treatment with GAL1. The regulation of Lyn therefore seems to be a key event in the action of GAL1.
Fouillit
M
M
Université Paris 13, Biochimie Cellulaire des Hémopathies Lymphoïdes, 93017 Bobigny, France.
Joubert-Caron
R
R
Poirier
F
F
Bourin
P
P
Monostori
E
E
Levi-Strauss
M
M
Raphael
M
M
Bladier
D
D
Caron
M
M
D001402:B-Lymphocytes / Q000378:metabolism*; D002051:Burkitt Lymphoma / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005434:Flow Cytometry; D037483:Galectin 1; D006388:Hemagglutinins / Q000378:metabolism*; D006801:Humans; D017493:Leukocyte Common Antigens / Q000502:physiology*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D011994:Recombinant Proteins; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D019061:src-Family Kinases / Q000378:metabolism
D037483:Galectin 1; D006388:Hemagglutinins; D011994:Recombinant Proteins; D019061:src-Family Kinases; D010749:Phosphoprotein Phosphatases; D017493:Leukocyte Common Antigens