Hy. Lee et al., ROLE OF REL-RELATED FACTORS IN CONTROL OF C-MYC GENE-TRANSCRIPTION INRECEPTOR-MEDIATED APOPTOSIS OF THE MURINE B-CELL WEHI-231 LINE, The Journal of experimental medicine, 181(3), 1995, pp. 1169-1177
Treatment of immature murine B lymphocytes with an antiserum against t
heir 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 treatmen
t of WEHI 231 cells causes an early, transient increase in the levels
of c-myc messenger RNA and gene transcription, followed by a rapid dec
line below control values. Given the evidence for a role of the c-myc
gene in promoting apoptosis, we have characterized the nature and kine
tics of changes in the binding of Rel-related factors, which modulate
c-myc promoter activity. In exponentially growing WEHI 231 cells, mult
iple 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. Cotr
ansfection of an inhibitor of NF-kappa B (I kappa B)-alpha expression
vector reduced c-myc-promoter/upstream/exon1-CAT reporter construct ac
tivity, indicating the role of Rel factor binding in c-myc basal expre
ssion in these cells. Treatment with anti-sIg resulted in a rapid tran
sient increase in the rate of c-myc gene transcription and in the bind
ing of Rel factors. At later times, formation of p50 homodimer complex
es occurred. In cotransfection analysis, p65 and c-Rel expression pote
ntly and modestly transactivated the c-myc promoter, respectively, whe
reas, overexpression of the p50 subunit caused a significant drop in i
ts activity. The role of activation of Rel-family binding was demonstr
ated directly upon addition of the antioxidant pyrrolidinedithiocarbam
ate, which inhibited the anti-sIg-mediated activation of the endogenou
s c-myc gene. Similarly, induction after anti-sIg treatment of a trans
fected c-myc promoter was abrogated upon cotransfection of an I kappa
B-alpha expression vector. These results implicate the Rel-family in I
g receptor-mediated signals controlling the activation of c-myr gene t
ranscription in WEHI 231 cells, and suggest a role for this family in
apoptosis of this line, which is mediated through a c-myc signaling pa
thway.