scholarly journals Identification of a novel determinant for basic domain-leucine zipper DNA binding activity in the acute-phase inducible nuclear factor-interleukin-6 transcription factor.

1994 ◽  
Vol 269 (14) ◽  
pp. 10341-10351
Author(s):  
A.R. Brasier ◽  
A. Kumar
2002 ◽  
Vol 103 (4) ◽  
pp. 381-390 ◽  
Author(s):  
Dan D. HERSHKO ◽  
Bruce W. ROBB ◽  
Eric S. HUNGNESS ◽  
Guangju LUO ◽  
Xialing GUO ◽  
...  

Previous studies have suggested that the production of interleukin-6 (IL-6) is increased in the intestinal mucosa during inflammation, and that nuclear factor-κB (NF-κB) is an important regulator of the IL-6 gene in the enterocyte. We tested the hypothesis that sodium arsenite inhibits IL-6 production in stimulated enterocytes and that this effect of arsenite is caused by down-regulation of NF-κB activity. Cultured Caco-2 cells were treated with sodium arsenite and were then stimulated with IL-1β. IL-6 production and gene expression were determined by ELISA and reverse transcriptase–PCR respectively. NF-κB DNA binding activity was determined by electrophoretic mobility shift assay. IL-1β increased NF-κB DNA binding activity, IL-6 mRNA levels and IL-6 production. These effects of IL-1β were inhibited by treatment of the cells with sodium arsenite in a dose- and time-dependent fashion. When cells were transfected with a plasmid expressing the p65 subunit of NF-κB, the inhibitory effect of sodium arsenite on NF-κB activity and IL-6 production was blunted. These results suggest that sodium arsenite inhibits IL-6 production in enterocytes subjected to an inflammatory stimulus, and that this effect, at least in part, reflects down-regulated NF-κB activity.


2001 ◽  
Vol 29 (6) ◽  
pp. 688-691 ◽  
Author(s):  
K. J. Campbell ◽  
N. R. Chapman ◽  
N. D. Perkins

The cellular response to DNA-damaging agents is partly mediated by DNA-binding transcription factors such as p53 and nuclear factor κB (NF-κB). Typically NF-κB activation is associated with resistance to apoptosis. Following stimulation with UV light however, NF-κB activation has been shown to be required for programmed cell death. To study this effect further and to determine the relationship between NF-κB and p53 function, we have examined the effect of UV light on U2OS cells. UV stimulation resulted in the activation of NF-κB DNA-binding and the induction of p53. Surprisingly, and in contrast with tumour necrosis factor α stimulation, this UV-induced NF-κB was transcriptionally inert. These observations suggest a model in which the NF-κB switch from an anti-apoptotic to a pro-apoptotic role within the cell results from modulation of its ability to stimulate gene expression, possibly as a result of the ability of p53 to sequester transcriptional co-activator proteins such as p300/CREB (cAMP-response-element-binding protein)-binding protein.


1986 ◽  
Vol 6 (12) ◽  
pp. 4723-4733
Author(s):  
L A Chodosh ◽  
R W Carthew ◽  
P A Sharp

A simple approach has been developed for the unambiguous identification and purification of sequence-specific DNA-binding proteins solely on the basis of their ability to bind selectively to their target sequences. Four independent methods were used to identify the promoter-specific RNA polymerase II transcription factor MLTF as a 46-kilodalton (kDa) polypeptide. First, a 46-kDa protein was specifically cross-linked by UV irradiation to a body-labeled DNA fragment containing the MLTF binding site. Second, MLTF sedimented through glycerol gradients at a rate corresponding to a protein of native molecular weight 45,000 to 50,000. Third, a 46-kDa protein was specifically retained on a biotin-streptavidin matrix only when the DNA fragment coupled to the matrix contained the MLTF binding site. Finally, proteins from the most highly purified fraction which were eluted and renatured from the 44- to 48-kDa region of a sodium dodecyl sulfate-polyacrylamide gel exhibited both binding and transcription-stimulatory activities. The DNA-binding activity was purified 100,000-fold by chromatography through three conventional columns plus a DNA affinity column. Purified MLTF was characterized with respect to the kinetic and thermodynamic properties of DNA binding. These parameters indicate a high degree of occupancy of MLTF binding sites in vivo.


1993 ◽  
Vol 13 (12) ◽  
pp. 7802-7812
Author(s):  
M Ivey-Hoyle ◽  
R Conroy ◽  
H E Huber ◽  
P J Goodhart ◽  
A Oliff ◽  
...  

E2F is a mammalian transcription factor that appears to play an important role in cell cycle regulation. While at least two proteins (E2F-1 and DP-1) with E2F-like activity have been cloned, studies from several laboratories suggest that additional homologs may exist. A novel protein with E2F-like properties, designated E2F-2, was cloned by screening a HeLa cDNA library with a DNA probe derived from the DNA binding domain of E2F-1 (K. Helin, J. A. Lees, M. Vidal, N. Dyson, E. Harlow, and A. Fattaey, Cell 70:337-350, 1992). E2F-2 exhibits overall 46% amino acid identity to E2F-1. Both the sequence and the function of the DNA and retinoblastoma gene product binding domains of E2F-1 are conserved in E2F-2. The DNA binding activity of E2F-2 is dramatically enhanced by complementation with particular sodium dodecyl sulfate-polyacrylamide gel electrophoresis-purified components of HeLa cell E2F, and anti-E2F-2 antibodies cross-react with components of purified HeLa cell E2F. These observations are consistent with a model in which E2F binds DNA as a heterodimer of two distinct proteins, and E2F-2 is functionally and immunologically related to one of these proteins.


1993 ◽  
Vol 13 (12) ◽  
pp. 7429-7438
Author(s):  
R Wisdon ◽  
I M Verma

The Fos family of proteins now includes seven members: the retroviral proteins FBR-v-Fos and FBJ-v-Fos and the cellular proteins c-Fos, FosB, FosB2, Fra1, and Fra2. Four proteins (FBR-v-Fos, FBJ-v-Fos, c-Fos, and FosB) transform established rodent fibroblast cell lines, while three (FosB2, Fra1, and Fra2) do not. As all family members display sequence-specific DNA-binding activity as part of a heterodimeric complex with Jun proteins, other features must account for the differences in transforming potential. We demonstrate here that all transforming members have a C-terminal transactivation domain that is lacking in nontransforming members. The nontransforming proteins Fra1 and Fra2 can be converted to transforming proteins by fusion of a transactivation domain from either FosB or VP16. We also demonstrate that differences in the basic region-leucine zipper domain affecting either the affinity or sequence specificity of DNA binding are not determinants of the difference in transforming potential among members of the Fos family. The results further define the functional requirements for transformation by Fos proteins and suggest that the subunit composition of AP1 complexes is an important determinant of mitogenic signalling capability.


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