Role of Rel-related factors in control of c-myc gene transcription in receptor-mediated apoptosis of the murine B cell WEHI 231 line.
Treatment of immature murine B lymphocytes with an antiserum against their surface immunoglobulin (sIg)M results in cell death via apoptosis. The WEHI 231 B cell line (IgM, kappa) has been used extensively as a model for this anti-Ig receptor-mediated apoptosis. Anti-sIg treatment of WEHI 231 cells causes an early, transient increase in the levels of c-myc messenger RNA and gene transcription, followed by a rapid decline below control values. Given the evidence for a role of the c-myc gene in promoting apoptosis, we have characterized the nature and kinetics of changes in the binding of Rel-related factors, which modulate c-myc promoter activity. In exponentially growing WEHI 231 cells, multiple Rel-related binding activities were detectable. The major binding species was identified as p50/c-Rel heterodimers; only minor amounts of nuclear factor kappa B (NF-kappa B) (p50/p65) were detectable. Cotransfection of an inhibitor of NF-kappa B (I kappa B)-alpha expression vector reduced c-myc-promoter/upstream/exon1-CAT reporter construct activity, indicating the role of Rel factor binding in c-myc basal expression in these cells. Treatment with anti-sIg resulted in a rapid transient increase in the rate of c-myc gene transcription and in the binding of Rel factors. At later times, formation of p50 homodimer complexes occurred. In cotransfection analysis, p65 and c-Rel expression potently and modestly transactivated the c-myc promoter, respectively, whereas, overexpression of the p50 subunit caused a significant drop in its activity. The role of activation of Rel-family binding was demonstrated directly upon addition of the antioxidant pyrrolidinedithiocarbamate, which inhibited the anti-sIg-mediated activation of the endogenous c-myc gene. Similarly, induction after anti-sIg treatment of a transfected c-myc promoter was abrogated upon cotransfection of an I kappa B-alpha expression vector. These results implicate the Rel-family in Ig receptor-mediated signals controlling the activation of c-myc gene transcription in WEHI 231 cells, and suggest a role for this family in apoptosis of this line, which is mediated through a c-myc signaling pathway.
Lee
H
H
Department of Biochemistry, Boston University Medical School, Massachusetts 02118.
Arsura
M
M
Wu
M
M
Duyao
M
M
Buckler
A J
AJ
Sonenshein
G E
GE
D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D016259:Genes, myc; D016393:Lymphoma, B-Cell / Q000235:genetics / Q000473:pathology; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000502:physiology*; D020569:Proto-Oncogene Proteins c-rel; D011947:Receptors, Antigen, B-Cell / Q000502:physiology*; D011971:Receptors, Immunologic / Q000502:physiology*; D014158:Transcription, Genetic
D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel; D011947:Receptors, Antigen, B-Cell; D011971:Receptors, Immunologic