Resistance to anti-IgM-induced apoptosis in a WEHI-231 subline is due to insufficient production of ceramide.
We describe the properties of a physiological cell death (PCD)-resistant subline of WEHI-231 generated from the PCD-susceptible WEHI-231.7 JM cell line maintained in our laboratory. The PCD-resistant WEHI-231.7 JMRE subline was uniquely resistant to anti-immunoglobulin (Ig)M-induced PCD but not to irradiation and etoposide. In these sublines, we compared the expression of genes implicated in regulating PCD. Northern analysis of c-myc, c-fos, egr-1, Fas, p53 and retinoblastoma revealed similar basal levels of expression in all sublines tested and comparable responses to anti-IgM treatment. Similarly, the expression of bcl-2, bcl-x, bax and IL-1 beta converting enzyme did not correlate with susceptibility to anti-IgM-induced PCD. Next, we systematically studied signal transduction events including: tyrosine phosphorylation, Ca++ flux, and ceramide production in the Jm and JMRE sublines. The tyrosine phosphorylation patterns and the Ca++ influx generated following sIgM engagement were very similar in the JM and JMRE sublines. In contrast, the generation of ceramide differed in the PCD-resistant and PCD-susceptible sublines. Ceramide is produced following cross-linking sIgM on WEHI-231.7 JM cells and causes PCD. Ceramide levels in anti-IgM-treated WEHI-231.7 JMRE cells are low and appear to be insufficient to induce PCD.
Gottschalk
A R
AR
University of Chicago, Department of Pathology, IL 60637, USA.
McShan
C L
CL
Kilkus
J
J
Dawson
G
G
Quintáns
J
J
D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D002518:Ceramides / Q000172:deficiency*; D005786:Gene Expression Regulation; D006801:Humans; D007075:Immunoglobulin M / Q000378:metabolism / Q000494:pharmacology*; D011519:Proto-Oncogenes / Q000235:genetics; D012313:RNA / Q000032:analysis
D002518:Ceramides; D007075:Immunoglobulin M; D012313:RNA