An Essential Role of cAMP Response Element Binding Protein in Ginsenoside Rg1-Mediated Inhibition of Na+/Glucose Cotransporter 1 Gene Expression

2015 ◽  
Vol 88 (6) ◽  
pp. 1072-1083 ◽  
Author(s):  
Chun-Wen Wang ◽  
Shih-Chieh Su ◽  
Shu-Fen Huang ◽  
Yu-Chuan Huang ◽  
Fang-Na Chan ◽  
...  
2003 ◽  
Vol 369 (3) ◽  
pp. 477-484 ◽  
Author(s):  
Antonio De LUCA ◽  
Anna SEVERINO ◽  
Paola De PAOLIS ◽  
Giuliano COTTONE ◽  
Luca De LUCA ◽  
...  

Thyroid hormone receptors (TRs) and members of the myocyte enhancer factor 2 (MEF2) family are involved in the regulation of muscle-specific gene expression during myogenesis. Physical interaction between these two factors is required to synergistically activate gene transcription. p300/cAMP-response-element-binding-protein ('CREB')-binding protein (CBP) interacting with transcription factors is able to increase their activity on target gene promoters. We investigated the role of p300 in regulating the TR—MEF2A complex. To this end, we mapped the regions of these proteins involved in physical interactions and we evaluated the expression of a chloramphenicol acetyltransferase (CAT) reporter gene in U2OS cells under control of the α-myosin heavy chain promoter containing the thyroid hormone response element (TRE). Our results suggested a role of p300/CBP in mediating the transactivation effects of the TR—retenoid X receptor (RxR)—MEF2A complex. Our findings showed that the same C-terminal portion of p300 binds the N-terminal domains of both TR and MEF2A, and our in vivo studies demonstrated that TR, MEF2A and p300 form a ternary complex. Moreover, by the use of CAT assays, we demonstrated that adenovirus E1A inhibits activation of transcription by TR—RxR—MEF2A—p300 but not by TR—RxR—MEF2A. Our data suggested that p300 can bind and modulate the activity of TR—RxR—MEF2A at TRE. In addition, it is speculated that p300 might modulate the activity of the TR—RxR—MEF2A complex by recruiting a hypothetical endogenous inhibitor which may act like adenovirus E1A.


2005 ◽  
Vol 16 (7) ◽  
pp. 3365-3376 ◽  
Author(s):  
Ju-Ming Wang ◽  
Joseph T. Tseng ◽  
Wen-Chang Chang

The CCAAT/enhancer binding protein δ (C/EBPδ, CRP3, CELF, NF-IL6β) regulates gene expression and plays functional roles in many tissues, such as in acute phase response to inflammatory stimuli, adipocyte differentiation, and mammary epithelial cell growth control. In this study, we examined the expression of human C/EBPδ (NF-IL6β) gene by epidermal growth factor (EGF) stimulation in human epidermoid carcinoma A431 cells. NF-IL6β was an immediate-early gene activated by the EGF-induced signaling pathways in cells. By using 5′-serial deletion reporter analysis, we showed that the region comprising the –347 to +9 base pairs was required for EGF response of the NF-IL6β promoter. This region contains putative consensus binding sequences of Sp1 and cAMP response element-binding protein (CREB). The NF-IL6β promoter activity induced by EGF was abolished by mutating the sequence of cAMP response element or Sp1 sites in the –347/+9 base pairs region. Both in vitro and in vivo DNA binding assay revealed that the CREB binding activity was low in EGF-starved cells, whereas it was induced within 30 min after EGF treatment of A431 cells. However, no change in Sp1 binding activity was found by EGF treatment. Moreover, the phosphatidylinositol 3 (PI3)-kinase inhibitor (wortmannin) and p38MAPK inhibitor (SB203580) inhibited the EGF-induced CREB phosphorylation and the expression of NF-IL6β gene in cells. We also demonstrated that CREB was involved in regulating the NF-IL6β gene transcriptional activity mediated by p38MAPK. Our results suggested that PI3-kinase/p38MAPK/CREB pathway contributed to the EGF activation of NF-IL6β gene expression.


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