Regulation of the transcription factor NF-κB involves proteasome-mediated processing of the NF-κB1 p105 precursor protein, which generates the p50 subunit of NF-κB. The processing of p105 occurs constitutively in vivo but can be markedly enhanced by various cellular activation agents, although the underlying regulatory mechanism is not yet clear. In the present study, we demonstrate that signal-mediated induction of p105 processing in human T cells is associated with de novo synthesis of this precursor protein. Transient transfection studies performed in COS7 cells revealed that the newly synthesized p105 protein appears to be more rapidly processed compared to its accumulated form that is already associated with the processed product p50. Interestingly, the processing rate of p105 is markedly inhibited in cells co-transfected with p50 or other NF-κB subunits, including RelA and c-Rel, that physically interact with p105. These findings suggest that the processing of p105 is subject to negative regulation by the various NF-κB subunits. We further demonstrate that p105 undergoes degradation in lipopolysaccharide-stimulated human monocytic cells. However, the inducible degradation of p105 is not coupled with the generation of p50. Together, these studies demonstrate that the processing and inducible degradation of p105 are differentially regulated.
|Original language||English (US)|
|Number of pages||8|
|State||Published - Jul 5 1996|
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cancer Research