scholarly journals Cross-coupling of signal transduction pathways: the dioxin receptor mediates induction of cytochrome P-450IA1 expression via a protein kinase C-dependent mechanism.

1993 ◽  
Vol 13 (1) ◽  
pp. 677-689 ◽  
Author(s):  
A Berghard ◽  
K Gradin ◽  
I Pongratz ◽  
M Whitelaw ◽  
L Poellinger
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Dna Binding ◽  
Binding Activity ◽  
Dna Binding Activity ◽  
Kinase C ◽  
The Individual ◽  
Dioxin Receptor

Signal transduction by dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin) is mediated by the intracellular dioxin receptor which, in its dioxin-activated state, regulates transcription of target genes encoding drug-metabolizing enzymes, such as cytochrome P-450IA1 and glutathione S-transferase Ya. Exposure of the dioxin receptor to dioxin leads to an apparent translocation of the receptor to the nucleus in vivo and to a rapid conversion of the receptor from a latent, non-DNA-binding form to a species that binds to dioxin-responsive positive control elements in vitro. This DNA-binding form of receptor appears to be a heterodimeric complex with the helix-loop-helix factor Arnt. In this study, we show that activation of the cytochrome P-450IA1 gene and minimal dioxin-responsive reporter constructs by the dioxin receptor was inhibited following prolonged treatment of human keratinocytes with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate. Inhibition of the receptor-mediated activation response was also achieved by treatment of the cells with a number of protein kinase inhibitors, one of which, calphostin C, shows selectivity for protein kinase C. Taken together, these data suggest that protein kinase C-dependent phosphorylation may play an essential role in the dioxin signaling pathway. This hypothesis is supported by the observation that pretreatment of the cells with 12-O-tetradecanoylphorbol-13-acetate inhibited the DNA-binding activity of the dioxin receptor in vivo. In vivo, the dioxin receptor was found to be a phosphoprotein. In vitro, dephosphorylation of the ligand-activated, heteromeric dioxin receptor form or dephosphorylation of the individual ligand-binding and Arnt receptor subunits inhibited the xenobiotic response element-binding activity. Moreover, dephosphorylation experiments with the individual receptor subunits prior to assembly of the xenobiotic response element-binding receptor form indicated that phosphorylation seemed to be important for the DNA-binding activity per se of the receptor, whereas Arnt appeared to require phosphorylation to interact with the receptor. Finally, a protein kinase C inhibitor-sensitive cytosolic catalytic activity that could restore the DNA-binding activity of the dephosphorylated dioxin receptor form was identified.

Cross-coupling of signal transduction pathways: the dioxin receptor mediates induction of cytochrome P-450IA1 expression via a protein kinase C-dependent mechanism

1993 ◽  
Vol 13 (1) ◽  
pp. 677-689
Author(s):  
A Berghard ◽  
K Gradin ◽  
I Pongratz ◽  
M Whitelaw ◽  
L Poellinger
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Dna Binding ◽  
Binding Activity ◽  
Dna Binding Activity ◽  
Kinase C ◽  
The Individual ◽  
Dioxin Receptor

Signal transduction by dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin) is mediated by the intracellular dioxin receptor which, in its dioxin-activated state, regulates transcription of target genes encoding drug-metabolizing enzymes, such as cytochrome P-450IA1 and glutathione S-transferase Ya. Exposure of the dioxin receptor to dioxin leads to an apparent translocation of the receptor to the nucleus in vivo and to a rapid conversion of the receptor from a latent, non-DNA-binding form to a species that binds to dioxin-responsive positive control elements in vitro. This DNA-binding form of receptor appears to be a heterodimeric complex with the helix-loop-helix factor Arnt. In this study, we show that activation of the cytochrome P-450IA1 gene and minimal dioxin-responsive reporter constructs by the dioxin receptor was inhibited following prolonged treatment of human keratinocytes with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate. Inhibition of the receptor-mediated activation response was also achieved by treatment of the cells with a number of protein kinase inhibitors, one of which, calphostin C, shows selectivity for protein kinase C. Taken together, these data suggest that protein kinase C-dependent phosphorylation may play an essential role in the dioxin signaling pathway. This hypothesis is supported by the observation that pretreatment of the cells with 12-O-tetradecanoylphorbol-13-acetate inhibited the DNA-binding activity of the dioxin receptor in vivo. In vivo, the dioxin receptor was found to be a phosphoprotein. In vitro, dephosphorylation of the ligand-activated, heteromeric dioxin receptor form or dephosphorylation of the individual ligand-binding and Arnt receptor subunits inhibited the xenobiotic response element-binding activity. Moreover, dephosphorylation experiments with the individual receptor subunits prior to assembly of the xenobiotic response element-binding receptor form indicated that phosphorylation seemed to be important for the DNA-binding activity per se of the receptor, whereas Arnt appeared to require phosphorylation to interact with the receptor. Finally, a protein kinase C inhibitor-sensitive cytosolic catalytic activity that could restore the DNA-binding activity of the dephosphorylated dioxin receptor form was identified.

scholarly journals Jun is phosphorylated by several protein kinases at the same sites that are modified in serum-stimulated fibroblasts.

1992 ◽  
Vol 12 (10) ◽  
pp. 4694-4705 ◽  
Author(s):  
S J Baker ◽  
T K Kerppola ◽  
D Luk ◽  
M T Vandenberg ◽  
D R Marshak ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Dna Binding ◽  
Glycogen Synthase ◽  
In Vitro Transcription ◽  
Binding Activity ◽  
Dna Binding Activity ◽  
Serum Stimulation ◽  
Dependent Protein

c-jun is a member of the family of immediate-early genes whose expression is induced by factors such as serum stimulation, phorbol ester, and differentiation signals. Here we show that increased Jun synthesis after serum stimulation is accompanied by a concomitant increase in phosphorylation. Several serine-threonine kinases were evaluated for their ability to phosphorylate Jun in vitro. p34cdc2, protein kinase C, casein kinase II, and pp44mapk phosphorylated Jun efficiently, whereas cyclic AMP-dependent protein kinase and glycogen synthase kinase III did not. The sites phosphorylated by p34cdc2 were similar to those phosphorylated in vivo after serum induction. The major sites of phosphorylation were mapped to serines 63, 73, and 246. Phosphorylation of full-length Jun with several kinases did not affect the DNA-binding activity of Jun homodimers or Fos-Jun heterodimers. Comparison of the DNA binding and in vitro transcription properties of wild-type and mutated proteins containing either alanine or aspartic acid residues in place of Ser-63, -73, and -246 revealed only minor differences among homodimeric complexes and no differences among Fos-Jun heterodimers. Thus, phosphorylation of Jun did not produce a significant change in dimerization, DNA-binding, or in vitro transcription activity. The regulatory role of phosphorylation in the modulation of Jun function is likely to be considerably more complex than previously suggested.

Activation of protein kinase C decreases phosphorylation of c-Jun at sites that negatively regulate its DNA-binding activity

Cell ◽  
1991 ◽  
Vol 64 (3) ◽  
pp. 573-584 ◽  
Author(s):  
William J. Boyle ◽  
Tod Smeal ◽  
Libert H.K. Defize ◽  
Peter Angel ◽  
James R. Woodgett ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Dna Binding ◽  
Binding Activity ◽  
Dna Binding Activity ◽  
Kinase C

scholarly journals Aggregation of the FcRI in Mast Cells Induces the Synthesis of Fos-interacting Protein and Increases Its DNA Binding Activity: The Dependence on Protein Kinase C-

1996 ◽  
Vol 271 (3) ◽  
pp. 1514-1519 ◽  
Author(s):  
Iris Lewin ◽  
Jasmine Jacob-Hirsch ◽  
Zhao Cheng Zang ◽  
Valentina Kupershtein ◽  
Zoltan Szallasi ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Mast Cells ◽  
Protein Kinase ◽  
Dna Binding ◽  
Binding Activity ◽  
Interacting Protein ◽  
Dna Binding Activity ◽  
Kinase C

Jun is phosphorylated by several protein kinases at the same sites that are modified in serum-stimulated fibroblasts

1992 ◽  
Vol 12 (10) ◽  
pp. 4694-4705
Author(s):  
S J Baker ◽  
T K Kerppola ◽  
D Luk ◽  
M T Vandenberg ◽  
D R Marshak ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Dna Binding ◽  
Glycogen Synthase ◽  
In Vitro Transcription ◽  
Binding Activity ◽  
Dna Binding Activity ◽  
Serum Stimulation ◽  
Dependent Protein

c-jun is a member of the family of immediate-early genes whose expression is induced by factors such as serum stimulation, phorbol ester, and differentiation signals. Here we show that increased Jun synthesis after serum stimulation is accompanied by a concomitant increase in phosphorylation. Several serine-threonine kinases were evaluated for their ability to phosphorylate Jun in vitro. p34cdc2, protein kinase C, casein kinase II, and pp44mapk phosphorylated Jun efficiently, whereas cyclic AMP-dependent protein kinase and glycogen synthase kinase III did not. The sites phosphorylated by p34cdc2 were similar to those phosphorylated in vivo after serum induction. The major sites of phosphorylation were mapped to serines 63, 73, and 246. Phosphorylation of full-length Jun with several kinases did not affect the DNA-binding activity of Jun homodimers or Fos-Jun heterodimers. Comparison of the DNA binding and in vitro transcription properties of wild-type and mutated proteins containing either alanine or aspartic acid residues in place of Ser-63, -73, and -246 revealed only minor differences among homodimeric complexes and no differences among Fos-Jun heterodimers. Thus, phosphorylation of Jun did not produce a significant change in dimerization, DNA-binding, or in vitro transcription activity. The regulatory role of phosphorylation in the modulation of Jun function is likely to be considerably more complex than previously suggested.

scholarly journals Induction of the DNA-binding activity of c-jun/c-fos heterodimers by the hepatitis B virus transactivator pX.

1994 ◽  
Vol 14 (2) ◽  
pp. 989-998 ◽  
Author(s):  
G Natoli ◽  
M L Avantaggiati ◽  
P Chirillo ◽  
A Costanzo ◽  
M Artini ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Hepatitis B Virus ◽  
Protein Kinase ◽  
Dna Binding ◽  
Hepatitis B ◽  
Cell Lines ◽  
Binding Activity ◽  
Dna Binding Activity ◽  
Kinase C ◽  
B Virus

The hepatitis B virus (HBV) X protein (pX) is capable of activating transcription regulated by viral and cellular promoters containing binding sites for different transcription factors, including AP1. In this study we have analyzed the mechanisms of AP1 induction by pX. The hepatitis B virus transactivator was able to activate TRE (12-O-tetradecanoylphorbol-13-acetate response element)-directed transcription in different cell lines, including HepG2, HeLa, CV1, and PLC/PRF/5 cells. pX-induced AP1 activation in HepG2 cells was associated with an increase in the DNA-binding activity of c-Jun/c-Fos heterodimers, which was not dependent either on an increase in the overall amount of c-Fos and c-Jun proteins in the cells or on formation of dimers between pX and the two proteins, thus suggesting the involvement of posttranslational modifications of the transcription factor. The observation that the overexpression of c-Jun and c-Fos in the cells results in a strong augmentation of the effect of pX on TRE-directed transcription is additional evidence indicating the involvement of posttranscriptional modifications of c-Jun/c-Fos heterodimers. The increased AP1 binding observed in the presence of pX was unaffected by the protein kinase C inhibitors calphostin C and sphingosine and by the protein kinase A inhibitor HA1004, while it was almost completely blocked by staurosporine, a potent and nonspecific protein kinase inhibitor, suggesting that protein kinase C- and A-independent phosphorylation events might play a role in the phenomenon. The ability of pX also to increase TRE-directed transcription in cell lines in which AP1-binding activity is not increased (i.e., HeLa, CV1, and PLC/PRF/5 cells) suggests that pX can activate canonical TRE sites by different mechanisms as well.

Differential use of SCL/TAL-1 DNA-binding domain in developmental hematopoiesis

Blood ◽  
2008 ◽  
Vol 112 (4) ◽  
pp. 1056-1067 ◽  
Author(s):  
Mira T. Kassouf ◽  
Hedia Chagraoui ◽  
Paresh Vyas ◽  
Catherine Porcher
Keyword(s):  
Dna Binding ◽  
Molecular Mechanisms ◽  
Binding Activity ◽  
Hematopoietic Stem ◽  
Helix Loop Helix ◽  
Experimental Systems ◽  
Dna Binding Activity ◽  
Independent Functions

Abstract Dissecting the molecular mechanisms used by developmental regulators is essential to understand tissue specification/differentiation. SCL/TAL-1 is a basic helix-loop-helix transcription factor absolutely critical for hematopoietic stem/progenitor cell specification and lineage maturation. Using in vitro and forced expression experimental systems, we previously suggested that SCL might have DNA-binding–independent functions. Here, to assess the requirements for SCL DNA-binding activity in vivo, we examined hematopoietic development in mice carrying a germline DNA-binding mutation. Remarkably, in contrast to complete absence of hematopoiesis and early lethality in scl-null embryos, specification of hematopoietic cells occurred in homozygous mutant embryos, indicating that direct DNA binding is dispensable for this process. Lethality was forestalled to later in development, although some mice survived to adulthood. Anemia was documented throughout development and in adulthood. Cellular and molecular studies showed requirements for SCL direct DNA binding in red cell maturation and indicated that scl expression is positively autoregulated in terminally differentiating erythroid cells. Thus, different mechanisms of SCL's action predominate depending on the developmental/cellular context: indirect DNA binding activities and/or sequestration of other nuclear regulators are sufficient in specification processes, whereas direct DNA binding functions with transcriptional autoregulation are critically required in terminal maturation processes.

Sign in / Sign up

Export Citation Format

Share Document