Altered signal transduction secondary to surface IgM cross-linking on B-chronic lymphocytic leukemia cells. Differential activation of the phosphatidylinositol-specific phospholipase C
| Autor: | Claire Hivroz, Gény B, Jc, Brouet, Grillot-Courvalin C |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
B-Lymphocytes
HLA-D Antigens Inositol Phosphates Receptor Aggregation Immunology Receptors Antigen B-Cell In Vitro Techniques Thionucleotides Lymphocyte Activation Phosphatidylinositols Burkitt Lymphoma Enzyme Activation GTP-Binding Proteins Guanosine 5'-O-(3-Thiotriphosphate) Type C Phospholipases Phorbol Esters Tumor Cells Cultured Humans Immunology and Allergy Guanosine Triphosphate Signal Transduction |
| Zdroj: | Europe PubMed Central |
| ISSN: | 1550-6606 0022-1767 |
| DOI: | 10.4049/jimmunol.144.6.2351 |
| Popis: | To further study the mechanisms by which surface Ig triggering activates the inositol phospholipid signaling pathway, we have used B cells from chronic lymphocytic leukemia patients which, as previously described, display two patterns of response upon sIg cross-linking: in one group this cross-linking induces an inositol phosphate release, an intracellular free Ca2+ concentration elevation and a subsequent cell proliferation; in a second group none of these events occur although there is an increased class II Ag expression following anti-mu stimulation as in the first group. We have been able to demonstrate that the phosphatidyl inositol specific phospholipase C (PI-PLC) can be activated in permeabilized B cells from the first group by direct stimulation, with GPT gamma S, of a guanine nucleotide binding (G) protein. In addition, since anti-mu + GTP gamma S stimulate an increased inositol phosphate production in these cells, this suggests that surface Ig cross-linking activates PI-PLC via a G protein. However, in cells from the second group no inositol phosphate is released after GTP gamma S stimulation although PI-PLC can be directly activated by high Ca2+ concentrations. This reflects in these cells, an interruption of the signaling cascade sIg/G protein/PI-PLC at the level of the G protein or at the G protein/PI-PLC coupling. In cells from both groups PMA treatment, which is known to alter phosphatidyl inositol metabolism in B cells, completely inhibits PI-PLC activation even by high Ca2+ concentrations. These studies show that the phosphatidyl inositol-dependent signaling cascade after surface Ig triggering can be altered at different levels in B cells. |
| Databáze: | OpenAIRE |
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