CREB (cAMP response element binding protein) and C/EBPalpha (CCAAT/enhancer binding protein) are required for the superstimulation of phosphoenolpyruvate carboxykinase gene transcription by adenoviral E1a and cAMP. Biochem J 2000 Dec 01;352 Pt 2(Pt 2):335-42
Date
11/22/2000Pubmed ID
11085926Pubmed Central ID
PMC1221464DOI
10.1042/0264-6021:3520335Scopus ID
2-s2.0-0034535607 (requires institutional sign-in at Scopus site) 10 CitationsAbstract
In the present study, we observed superstimulated levels of cAMP-stimulated transcription from the phosphoenolpyruvate carboxykinase (PEPCK) gene promoter in cells infected with wild-type adenovirus expressing 12 S and 13 S E1a proteins, or in cells expressing 13 S E1a alone. cAMP-stimulated transcription was inhibited in cells expressing only 12 S E1a, but slightly elevated in cells expressing E1a proteins with mutations in conserved regions 1 or 2, leading us to conclude that the superstimulation was mediated by conserved region 3 of 13 S E1a. E1a failed to enhance cAMP-stimulated transcription from promoters containing mutations that abolish binding by cAMP response element binding protein (CREB) or CCAAT/enhancer binding proteins (C/EBPs). This result was supported by experiments in which expression of dominant-negative CREB and/or C/EBP proteins repressed E1a- and cAMP-stimulated transcription from the PEPCK gene promoter. In reconstitution experiments using a Gal4-responsive promoter, E1a enhanced cAMP-stimulated transcription when chimaeric Gal4-CREB and Gal4-C/EBPalpha were co-expressed. Phosphorylation of CREB on serine-133 was stimulated in cells treated with dibutyryl cAMP, whereas phosphorylation of C/EBPalpha was increased by E1a expression. Our data support a model in which cAMP agonists increase CREB activity and stimulate PEPCK gene transcription, a process that is enhanced by E1a through the phosphorylation of C/EBPalpha.
Author List
Routes JM, Colton LA, Ryan S, Klemm DJAuthor
John M. Routes MD Chief, Professor in the Pediatrics department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Adenovirus E1A ProteinsCCAAT-Enhancer-Binding Protein-alpha
Cell Line
Cyclic AMP
Cyclic AMP Response Element-Binding Protein
Gene Expression Regulation, Enzymologic
Humans
Phosphorylation
Promoter Regions, Genetic
Transcription, Genetic
