Cyclic adenosine 3',5'-monophosphate (cAMP) enhances cAMP-responsive element binding (CREB) protein phosphorylation and phospho-CREB interaction with the mouse steroidogenic acute regulatory protein gene promoter.

Abstract	Steroidogenic acute regulatory protein (StAR) transcription is regulated through cAMP-protein kinase A-dependent mechanisms that involve multiple transcription factors including the cAMP-responsive element binding protein (CREB) family members. Classically, binding of phosphorylated CREB to cis-acting cAMP-responsive elements (5'-TGACGTCA-3') within target gene promoters leads to recruitment of the coactivator CREB binding protein (CBP). Herein we examined the extent of CREB family member phosphorylation on protein-DNA interactions and CBP recruitment with the StAR promoter. Immunoblot analysis revealed that CREB, cAMP-responsive element modulator (CREM), and activating transcription factor (ATF)-1 are expressed in MA-10 mouse Leydig tumor cells, yet only CREB and ATF-1 are phosphorylated. (Bu)2cAMP treatment of MA-10 cells increased CREB phosphorylation approximately 2.3-fold within 30 min but did not change total nuclear CREB expression levels. Using DNA-affinity chromatography, we now show that CREB and ATF-1, but not CREM, interact with the StAR promoter, and this interaction is dependent on the activator protein-1 (AP-1) cis-acting element within the cAMP-responsive region. In addition, (Bu)2cAMP-treatment increased phosphorylated CREB (P-CREB) association with the StAR promoter but did not influence total CREB interaction. In vivo chromatin immunoprecipitation assays demonstrated CREB binding to the StAR proximal promoter is independent of (Bu)2cAMP-treatment, confirming our in vitro analysis. However, (Bu)2cAMP-treatment increased P-CREB and CBP interaction with the StAR promoter, demonstrating for the first time the physical role of P-CREB:DNA interactions in CBP recruitment to the StAR proximal promoter.
Authors	Brian F Clem, Elizabeth A Hudson, Barbara J Clark
Journal	Endocrinology (Endocrinology) Vol. 146 Issue 3 Pg. 1348-56 (Mar 2005) ISSN: 0013-7227 [Print] United States
PMID	15550512 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
Chemical References	Activating Transcription Factor 1 Atf1 protein, mouse Cyclic AMP Response Element-Binding Protein DNA-Binding Proteins Histones Nuclear Proteins Phosphoproteins Trans-Activators Transcription Factors steroidogenic acute regulatory protein DNA Cyclic AMP CREB-Binding Protein Crebbp protein, mouse
Topics	Acetylation Activating Transcription Factor 1 Animals CREB-Binding Protein Cell Nucleus (metabolism) Chromatin Immunoprecipitation Chromatography Cyclic AMP (metabolism) Cyclic AMP Response Element-Binding Protein (metabolism) DNA (chemistry) DNA-Binding Proteins (metabolism) Electrophoresis, Polyacrylamide Gel Histones (metabolism) Immunoblotting Leydig Cells Male Mice Nuclear Proteins (metabolism) Phosphoproteins (genetics) Phosphorylation Promoter Regions, Genetic Signal Transduction Time Factors Trans-Activators (metabolism) Transcription Factors (metabolism)

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