LSP1 regulates anti-IgM induced apoptosis in WEHI-231 cells and normal immature B-cells
Expression of LSP1, a 330 amino acid intracellular phosphoprotein, is restricted to lymphocytes, macrophages and neutrophils. In B-lymphoma cell lines LSP1 co-caps with membrane IgM after stimulation with anti-IgM. We used the LSP1 + B-lymphoma cell line WEHI-231/89 and normal lipopolysaccharide tre...
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Veröffentlicht in: | Molecular immunology 1999-04, Vol.36 (6), p.349-359 |
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Zusammenfassung: | Expression of LSP1, a 330 amino acid intracellular phosphoprotein, is restricted to lymphocytes, macrophages and neutrophils. In B-lymphoma cell lines LSP1 co-caps with membrane IgM after stimulation with anti-IgM. We used the LSP1
+ B-lymphoma cell line WEHI-231/89 and normal lipopolysaccharide treated immature B-cells from
Lsp1
−/− and wild type mice to determine a role for LSP1 in signaling through membrane IgM. WEHI-231/89 cells were transfected with a truncated LSP1 protein containing the COOH-terminal residues 179–330. The three transfectants expressing the LSP1 truncate were significantly more susceptible to anti-IgM induced apoptosis than the parental cells or G418
r control cell lines, while anti-IgM induced growth arrest was not affected. Expression of the LSP1 truncate increased the extent of anti-IgM induced loss of mitochondrial membrane potential, ΔΨ
m indicating that LSP1 acts at a early stage in BCR mediated apoptosis. Expression of the LSP1 truncate in WEHI-231/89 cells increased susceptibility to ionomycin induced apoptosis but had no effect on apoptosis induced by nocodazole, sorbitol, C2-ceramide or H
2O
2. A role for LSP1 in anti-IgM induced apoptosis was confirmed using normal immature B-cells from 129/SvJ-
Lsp1
−/− mice which were less susceptible to anti-IgM induced apoptosis than those isolated from wild-type 129/SvJ mice. These results suggest that LSP1 regulates a Ca
2+-dependent step in the induction phase of anti-IgM mediated apoptosis. |
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ISSN: | 0161-5890 1872-9142 |
DOI: | 10.1016/S0161-5890(99)00055-3 |