• Molecules and Cells
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• v.23 no.1
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• pp.23-29
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• 2007

Cyclic AMP-responsive element binding protein (CREB) is known to be associated with angiogenesis. In the present study we investigated the possible role of CREB in the expression of vascular endothelial growth factor (VEGF) by mouse macrophages. Over-expression of CREB increased VEGF secretion by cells of the RAW264.7 mouse macrophage cell line. It also increased the promoter activity of a mouse reporter driven by the VEGF promoter, while a dominant negative CREB (DN-CREB) abrogated the activity, suggesting that CREB mediates VEGF transcription. Forskolin, an adenylyl cyclase activator, stimulated VEGF transcription, and the PKA inhibitor H89 abolished this effect. IFN-${\gamma}$, a potent cytokine, stimulated VEGF expression only in part through the PKA-CREB pathway. These results indicate that PKA phosphorylates CREB and so induces VEGF gene expression. An analysis of mutant promoters revealed that one of the putative CREB responsive elements (CREs), at -399 ~ -388 in the promoter, is critical for CREB-mediated VEGF promoter activity, and the significance of this CRE was confirmed by chromatin immunoprecipitation assays.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.6
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• pp.671-676
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• 1998

In the present study, we first examined whether the changes in the DNA binding activities of the transcription factors, cAMP response element binding protein (CREB) and activator protein-1 (AP-1) mediate the long-term effects of morphine in differentiated SH-SY5Y human neuroblastoma cells. The increases in CREB and AP-1 DNA binding activities were time-dependent up to 6 days of morphine treatment (1, 4, and 6 days). However, the significant reduction in the DNA binding activities of CREB and AP-1 was observed after 10 days of chronic morphine $(10\;{\mu}M)$ administration. Secondly, we examined whether the changes of CREB and AP-1 DNA binding activities could be modulated by dopamine and haloperidol. Dopamine cotreatment moderately increased the levels of the CREB and AP-1 DNA binding activities induced by 10 days of chronic morphine treatment, and haloperidol cotreatment also resulted in a moderate increase of the CREB and AP-1 DNA binding activities. However, dopamine or haloperidol only treatment showed a significant increase or decrease of the CREB and AP-1 DNA binding activities, respectively. In the case of acute morphine treatment, the CREB and AP-1 DNA binding activities were shown to decrease in a time-dependent manner (30, 60, 90, and 120 min). Taken these together, in differentiated SH-SY5Y cells, morphine tolerance seems to involve simultaneous changes of the CREB and AP-1 DNA binding activities. Our data also suggest the possible involvement of haloperidol in prevention or reversal of morphine tolerance at the transcriptional level.

• BMB Reports
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• v.47 no.4
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• pp.197-202
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• 2014

SOX3 is one of the earliest neural markers in vertebrates, playing the role in specifying neuronal fate. In this study we have established first functional link between CREB and human SOX3 gene which both have important roles in the nervous system throughout development and in the adulthood. Here we demonstrate both in vitro and in vivo that CREB binds to CRE half-site located -195 to -191 within the human SOX3 promoter. Overexpression studies with CREB or its dominant-negative inhibitor A-CREB indicate that this transcription factor acts as a positive regulator of basal SOX3 gene expression in NT2/D1 cells. This is further confirmed by mutational analysis where mutation of CREB binding site results in reduction of SOX3 promoter activity. Our results point at CREB as a positive regulator of SOX3 gene transcription in NT2/D1 cells, while its contribution to RA induction of SOX3 promoter is not prominent.

• Molecules and Cells
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• v.46 no.7
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• pp.399-413
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• 2023

cAMP responsive element-binding protein (CREB) is one of the most intensively studied phosphorylation-dependent transcription factors that provide evolutionarily conserved mechanisms of differential gene expression in vertebrates and invertebrates. Many cellular protein kinases that function downstream of distinct cell surface receptors are responsible for the activation of CREB. Upon functional dimerization of the activated CREB to cis-acting cAMP responsive elements within the promoters of target genes, it facilitates signal-dependent gene expression. From the discovery of CREB, which is ubiquitously expressed, it has been proven to be involved in a variety of cellular processes that include cell proliferation, adaptation, survival, differentiation, and physiology, through the control of target gene expression. In this review, we highlight the essential roles of CREB proteins in the nervous system, the immune system, cancer development, hepatic physiology, and cardiovascular function and further discuss a wide range of CREB-associated diseases and molecular mechanisms underlying the pathogenesis of these diseases.

• Journal of Pharmacopuncture
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• v.21 no.1
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• pp.35-40
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• 2018

Objective: The role of BDNF (brain-derived neurotrophic factor), CREB (cAMP response element binding) and VGF neuropeptide has been proved in antidepressant activity of long term saffron administration in the rat hippocampus. In this study we evaluated the role of these proteins in antidepressant activity of saffron in long term administration in the rat cerebellum. Methods: Saffron aqueous extract (40 and 80 mg/kg/day) and imipramine (10 mg/kg/day) were administered intraperitoneally for 21 days to rats. At the end of experiment, animals were sacrificed and cerebellums were separated. The protein levels of BDNF, VGF, CREB and P- CREB in the rat cerebellum were evaluated using western blot analysis. Results: Saffron aqueous extract (80mg/kg/day) caused significant increase in protein level of P-CREB in long term treatment in the rat cerebellum. The increases in the protein levels of VGF, CREB and BDNF were not significant. Conclusion: In summary, our results showed that antidepressant effect of saffron in rat cerebellum might be due to the enhanced phosphorylation of CREB.

• BMB Reports
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• v.40 no.4
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• pp.525-531
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• 2007

As a $\beta_2$-adrenergic agonist, clenbuterol decreases body fat, but the molecular mechanism underlying this process is unclear. In the present study, we treated 293T and L-02 cells with clenbuterol and found that clenbuterol downregulates SREBP-1c expression and upregulates CREB1 expression. Considering SREBP-1c has the function of regulating the transcription of several lipogenic enzymes, we considered that the downregulation of SREBP-1c is responsible for body fat reduction by clenbuterol. Many previous studies have found that clenbuterol markedly increases intracellular cAMP levels, therefore, we also investigated whether CREB1 is involved in this process. The data from our experiments indicate that CREB1 overexpression inhibits SREBP-1c transcription, and that this action is antagonized by CREB2, a competitive inhibitor of CREB1. Furthermore, since PPARs are able to repress SREBP-1c transcription, we investigated whether clenbuterol and CREB1 function via a pathway involving PPAR activation. However, our results showed that clenbuterol or CREB1 overexpression suppressed PPARs transcription in 293T and L-02 cells, which suggested that they impair SREBP-1c expression in other ways.

• Archives of Pharmacal Research
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• v.25 no.3
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• pp.370-374
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• 2002

Administration of dopamine agonist, apomorphine (2 mg/kg, s.c.), produces cage climbing behavior in mice that exhibit typical dopaminergic stimulation. The present study investigated the pCREB expression level in several brain regions following apomorphine treatment in order to determine whether the increased the dopaminergic activation produced by apomorphine accompanies the changes in pCREB immunoreactivity. A mouse brain was removed at 0min, 10 min, 30 min, 1 h, 2 h, 7 h, and 24 h after apomorphine treatment. The brain tissue was fixed by an intracardiac perfusion with ice-cold 4％ paraformaldehyde in PBS. Immunohistochemical study was conducted using the ABC-DAB method. The data showed that the immunoreactivity of pCREB increased in the striatum, nucleus-accumbens, piriform cortex and the dentate gyrus of the hippocampus of a mouse brain 30 min after the apomorphine treatment. Increased immunoreactivity began to diminish 2 h after the apomorphine treatment in all the brain regions measured. The time course for the pCREB immunoreactivity was similar to the behavioral response induced by the apomorphine treatment. These results suggest that activation of the dopamine receptor is accompanied by an increase in pCREB expression in the mouse brain.

• Tuberculosis and Respiratory Diseases
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• v.59 no.6
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• pp.631-637
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• 2005

Background : Transcriptional factors of the CREB(cAMP Response Element Binding Protein) are involved in the regulation of gene expression in response to a variety of signaling pathways. Proteins produced by the CREB genes play key roles in many physiological processes, including memory and long-term potentiation. The retinoic acid receptor (RAR) axis mediates epithelial cell differentiation and proliferation in many tissues including the lung. Material and method : The RAR and CREB expression levels were examined in 60 adenocarcinomas and 60 squamous cell carcinomas of the lung using immunohistochemical staining. Results : 1) RAR protein expression was found in 58.3%(35/60) of adenocarcinomas and 36.7%(22/60) of squamous cell carcinomas(P<0.05). 2) RAR protein expression was found in 80%(16/20) of well differentiated adenocarcinomas, 60%(12/20) of moderately differentiated adenocarcinomas, and 35%(7/20) of poorly differentiated adenocarcinomas (P<0.01). 3) RAR protein expression was found in 45%(9/20) of well differentiated squamous cell carcinomas, 35%(7/20) of moderately differentiated squamous cell carcinomas, and 30%(6/20) of poorly differentiated squamous cell carcinomas (P>0.05). 4) CREB expression was found in 61.7%(37/60) of adenocarcinomas and 40%(24/60) of squamous cell carcinomas( P<0.05). 5) CREB expression was found in 85%(17/20) of well differentiated adenocarcinomas, 60%(12/20) of moderately differentiated adenocarcinomas, and 40%(8/20) of poorly differentiated adenocarcinomas (P<0.01). 6) CREB expression was found in 45%(9/20) of well differentiated squamous cell carcinomas, 35%(7/20) of moderately differentiated squamous cell carcinomas, and 35%(8/20) of poorly differentiated squamous cell carcinomas(P>0.05). 7) RAR and CREB expression was found in 68.5% of lung cancers, and there was a significant correlation between them(P<0.05). Conclusion : RAR and CREB expression can be used to indirectly determine the malignant potentiality of a cell.

• Journal of Gastric Cancer
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• v.8 no.4
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• pp.182-188
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• 2008

Purpose: Transcriptional factors of CREB (cAMP response element binding protein) are involved in regulating the gene expression in response to a variety of signaling pathways. The proteins produced by the CREB genes play key roles in many physiological processes, including memory and long-term potentiation. The retinoic acid receptor (RAR) axis mediates epithelial cell differentiation and proliferation in many tissues. This study examined the expressions of RAR and CREB and their relationship with the clinicopathologic factors and their significance. Materials and Methods: The levels of the RAR and CREB expressions were measured in 150 gastric adenocarcinomas by performing immunohistochemical staining. Results: 1. An RAR protein expression was found in 63.3% of the adenocarcinomas (95/150) and a CREB expression was found in 60.7% (91/150) of the adenocarcinomas. 2. An RAR protein expression was found in 72.2% (78/108) of the intestinal type adenocarcinomas and in 40.5% (17/42) of the diffuse type adenocarcinomas (P<0.05). Based on the depth of invasion, an RAR protein expression was found in 58.3% (14/24) of the T1 adenocarcinomas, in 61.9% (13/21) of the T2 adenocarcinomas, in 63.5% (61/96) of the T3 adenocarcinomas, in 77.8% (7/9) of the T4 adenocarcinomas and in 74.7% (62/83) of the adenocarcinomas with lymph node metastasis and in 49.2% (33/67) of the adenocarcinomas without lymph node metastasis (P<0.01). 3. A CREB expression was found in 69.4% (75/108) of the intestinal type and in 38.1% (16/42) of the diffuse type (P>0.05). Based on the depth of invasion, a CREB expression was found in 50% (12/24) of the T1 adenocarcinomas, in 52.4% (11/21) of the T2 adenocarcinomas, in 64.6% (62/96) of the T3 adenocarcinomas, in 66.6% (6/9) of the T4 adenocarcinomas, in 71.1% (59/83) of the adenocarcinomas with lymph node metastasis and in 47.8% (32/67) of the adenocarcinomas without lymph node metastasis (P<0.01). 4. The RAR protein and CREB expressions coincided in 71.4% of the gastric adenocarcinomas and a significant correlation between them was found (P<0.05). Conclusion: We found a significant relationship between the expression of RAR and CREB and the histology and lymph node metastasis of gastric cancer. Further studies are needed to confirm their biologic meaning in gastric carcinogenesis.

• Animal cells and systems
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• v.13 no.3
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• pp.289-295
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• 2009

Cyclic AMP-mediated signaling pathways regulate a number of cellular functions. In this study, we examined the regulatory role of cAMP signaling pathways in chondrogenesis of chick limb bud mesenchymal cells in vitro. Forskolin, which increases cellular cAMP levels by the activation of adenylate cyclase, enhanced chondrogenic differentiation. Inhibition of PKA with specific inhibitors (H89 or KT5720) blocked pre-cartilage condensation stage, indicating that chondrogenesis is regulated by the increase in cellular cAMP level and subsequent activation of PKA. Downstream signaling pathway of PKA leading to gene expression was investigated by examination of several nuclear transcription factors. Forskolin treatment increased transcription level for a cartilage-specific marker gene Sox9. However, inhibition of PKA with H89 led to restore expression of Sox9, indicating PKA activity was required to regulate the expression of Sox9 in chondrogenesis. In addition, CREB was highly phosphorylated at early stage of mesenchyme culture, and followed by progressive dephosphorylation. CBP and ATF, another CRE related proteins were transiently expressed at the early stage of chondrogenesis with a pattern similar to CREB phosphorylation. Electrophoretic mobility shift assays confirmed that the binding activity of CREB to the CRE is closely correlated to the phosphorylation pattern of CREB. Therefore, cAMP-mediated signal transduction to nuclear events for the induction of genes appeared to be required at the early stage of chick limb bud chondrogenesis.