NF-kappaB activity is constitutively elevated in c-Abl null fibroblasts.
The c-abl proto-oncogene encodes a nonreceptor tyrosine kinase involved in many cellular processes, including signaling from growth factor and antigen receptors, remodeling the cytoskeleton, and responding to DNA damage and oxidative stress. Many downstream pathways are affected by c-Abl. Elevated c-Abl kinase activity can inhibit NF-kappaB activity by stabilizing the inhibitory protein IkappaB alpha, raising the possibility that c-Abl-deficient cells might have increased NF-kappaB activity. We examined the levels of NF-kappaB activity in primary mouse embryonic fibroblasts (MEFs) derived from wild-type and c-Abl knockout mice and found that the knockout MEFs indeed exhibited elevated NF-kappaB activity in response to stimulation as well as constitutively elevated NF-kappaB activity. Thus, endogenous c-Abl is a negative regulator of basal and inducible NF-kappaB activity. Examination of various points of NF-kappaB regulation revealed that unstimulated c-Abl knockout MEFs do not exhibit an increase in IkappaB alpha degradation, p65/RelA nuclear translocation, or DNA binding of NF-kappaB subunits. They do, however, show reduced levels of the histone deacetylase HDAC1, a negative regulator of basal NF-kappaB activity. Unstimulated c-Abl knockout MEFs are less responsive to induction of NF-kappaB activity by trichostatin A, an HDAC inhibitor, suggesting that c-Abl might play a role in the HDAC-mediated repression of basal NF-kappaB activity.
Liberatore
Rachel A
RA
Department of Biochemistry and Molecular Biophysics, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Goff
Stephen P
SP
Nunes
Irene
I
D021581:Active Transport, Cell Nucleus; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016313:Genes, abl; D056572:Histone Deacetylase Inhibitors; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006877:Hydroxamic Acids / Q000494:pharmacology; D020672:I-kappa B Proteins / Q000378:metabolism; D053583:Interleukin-1beta / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D016315:Proto-Oncogene Proteins c-abl / Q000172:deficiency* / Q000235:genetics; D015398:Signal Transduction; D051996:Transcription Factor RelA / Q000378:metabolism; D015533:Transcriptional Activation; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D020672:I-kappa B Proteins; D053583:Interleukin-1beta; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; C012589:trichostatin A; D004247:DNA; D006861:Hydrogen Peroxide; D016315:Proto-Oncogene Proteins c-abl