scholarly journals Endogenous CCAAT/Enhancer Binding Protein β and p300 Are Both Regulated by Growth Hormone to Mediate Transcriptional Activation

2005 ◽  
Vol 19 (8) ◽  
pp. 2175-2186 ◽  
Author(s):  
Tracy Xiao Cui ◽  
Graciela Piwien-Pilipuk ◽  
Jeffrey S. Huo ◽  
Julianne Kaplani ◽  
Roland Kwok ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Transcriptional Activation ◽  
Binding Protein ◽  
Enhancer Binding Protein ◽  
Ccaat Enhancer Binding Protein

A novel myeloid-restricted zebrafish CCAAT/enhancer-binding protein with a potent transcriptional activation domain

Blood ◽  
2001 ◽  
Vol 97 (9) ◽  
pp. 2611-2617 ◽  
Author(s):  
Susan E. Lyons ◽  
Bixiong C. Shue ◽  
Andrew C. Oates ◽  
Leonard I. Zon ◽  
P. Paul Liu
Keyword(s):  
Dna Binding ◽  
Transcriptional Activation ◽  
Binding Protein ◽  
Myeloid Cells ◽  
Mobility Shift ◽  
Nih3t3 Cells ◽  
Amino Terminal ◽  
Enhancer Binding Protein ◽  
Bzip Domain ◽  
Ccaat Enhancer Binding Protein

Abstract The CCAAT/enhancer-binding protein (C/EBP) family consists of transcription factors essential for hematopoiesis. The defining feature of the C/EBPs is a highly conserved carboxy-terminal bZIP domain that is necessary and sufficient for dimerization and DNA binding, whereas their amino-terminal domains are unique. This study reports a novelc/ebp gene (c/ebp1) from zebrafish that encodes a protein homologous to mammalian C/EBPs within the bZIP domain, but with an amino terminus lacking homology to any C/EBP or to any known sequence. In zebrafish embryos, c/ebp1 expression was initially observed in cells within the yolk sac circulation valley at approximately the 16-to 18-somite stage, and at 24 hours postfertilization (hpf), also in circulating cells. Mostc/ebp1+cells also expressed a known early macrophage marker, leukocyte-specific plastin (l-plastin). Expression of both markers was lost in cloche, a mutant affecting hematopoiesis at the level of the hemangioblast. Expression of both markers was retained in m683 andspadetail, mutants affecting erythropoiesis, but not myelopoiesis. Further, c/ebp1 expression was lost in a mutant with defective myelopoiesis, but intact erythropoiesis. These data suggest that c/ebp1 is expressed exclusively in myeloid cells. In electrophoretic mobility shift assays, c/ebp1 was able to bind a C/EBP consensus DNA site. Further, a chimeric protein containing the amino-terminal domain of c/ebp1 fused to the DNA-binding domain of GAL4 induced a GAL4 reporter 4000-fold in NIH3T3 cells. These results suggest that c/ebp1 is a novel member of the C/EBP family that may function as a potent transcriptional activator in myeloid cells.

Growth hormone induces CCAAT/enhancer binding protein α (C/EBPα) in cultured rat hepatocytes

2000 ◽  
Vol 32 (4) ◽  
pp. 618-626 ◽  
Author(s):  
Petra Strand ◽  
Linda Carlsson ◽  
Katarina Rask ◽  
Stanko Skrtic ◽  
Staffan Ekberg ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Binding Protein ◽  
Rat Hepatocytes ◽  
Enhancer Binding Protein ◽  
Ccaat Enhancer Binding Protein ◽  
Cultured Rat Hepatocytes

scholarly journals CCAAT-enhancer-binding protein α (C/EBPα) is required for the thyroid hormone but not the retinoic acid induction of phosphoenolpyruvate carboxykinase (PEPCK) gene transcription

1997 ◽  
Vol 322 (1) ◽  
pp. 343-349 ◽  
Author(s):  
Edwards A. PARK ◽  
Shulan SONG ◽  
Michelle OLIVE ◽  
William J. ROESLER
Keyword(s):  
Retinoic Acid ◽  
Thyroid Hormone ◽  
Dna Binding ◽  
Binding Site ◽  
Transcriptional Activation ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Binding Protein ◽  
Dominant Negative ◽  
Enhancer Binding Protein ◽  
Ccaat Enhancer Binding Protein

Transcription of the gene for phosphoenolpyruvate carboxykinase (PEPCK) is stimulated by cAMP, the thyroid hormone tri-iodothyronine (T3) and retinoic acid (RA). Regulation of PEPCK transcription by T3 involves two sites in the promoter including a thyroid-hormone-response element (TRE) and a CCAAT-enhancer-binding protein (C/EBP) binding site called P3(I). Mutation of either the TRE or P3(I) eliminates the T3 response. In this study, we examined the role of C/EBPs in the induction of PEPCK transcription by T3 and RA. PEPCK-CAT vectors were transfected into HepG2 cells. Co-transfection of a dominant negative C/EBP eliminated the T3 stimulation indicating that a member of the C/EBP family is required. To determine which C/EBP isoform was required, Gal4 fusion proteins were created that contained the Gal4 DNA-binding domain ligated to the transcriptional activation domain of C/EBPα, C/EBPβ or the cAMP-responsive-element-binding protein. A Gal4 DNA-binding site was introduced into the P3(I) site of the PEPCK-CAT vector. Only co-transfection of the Gal4-C/EBPα vector was able to restore T3 responsiveness to the PEPCK-CAT vector. The T3 and RA receptors are members of the nuclear receptor superfamily and bind to repeats of the AGGTCA motif. We found that the RA receptor can bind to sequences within the PEPCK-TRE and contribute to RA responsiveness of the PEPCK gene. However, the RA induction of PEPCK transcription was found to be independent of C/EBPs, further demonstrating the specificity of the involvement of C/EBPα in the T3 effect.

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