Molecular cloning of human CREB-2: an ATF/CREB transcription factor that can negatively regulate transcription from the cAMP response element.

Abstract

The cAMP response element (CRE) is an octanucleotide motif (TGACGTCA) that mediates diverse transcriptional regulatory effects. In this report we describe the isolation and characterization of a full-length cDNA that encodes a CRE binding protein called CREB-2. Like other ATF/CREB transcription factors, the 351-amino acid CREB-2 protein contains a COOH-terminal leucine-zipper motif and an adjacent basic domain. CREB-2 mRNA is expressed ubiquitously in human tumor cell lines and mouse organs suggesting that it is involved in regulating transcription in a wide variety ofcell types. Overexpression ofCREB-2 resulted in a consistent and si t repression of CRE-dependent transcription in CV-1 cells. Deletional analyses localized the transcriptional repressor activity of CREB-2 to a 102-ami acid COOHterminal region (amino acids 249-351) that contains the leucine-zipper and basic domains of the molecule. These results demonstrate that CRE-dependent transcription can be both positively and negatively regulated by structurally related members of the ATF/CREB family.The transcription of many eukaryotic genes is regulated by the binding of sequence-specific transcription factors to modular cis-acting promoter and enhancer elements. The cAMP response element (CRE) is among the best studied of the cis-acting transcriptional enhancer motifs. This palindromic octanucleotide (TGACGTCA) has been identified (1-5) in the transcriptional regulatory regions of a large number of eukaryotic genes and has been shown to mediate diverse transcriptional effects including (i) conferring responsiveness to cAMP (1, 2); (ii) binding a cellular factor, ATF, and thereby conferring Ela responsiveness on several adenovirus genes (3); and (iii) modulating the basal activity of eukaryotic transcriptional enhancers including the human T-cell leukemia virus type I (4) and the c-fos protooncogene enhancers (5).Recent studies have resulted in the cloning of several CRE binding proteins that form the ATF/CREB family (6-11).These proteins share highly related COOH-terminal leucinezipper dimerization and basic DNA binding domains, but each contains a distinct NH2-terminal region. Although each of the ATF/CREB proteins appears to be capable of binding to the CRE as a homodimer, some of these proteins also bind to DNA as heterodimers (6,8,9). One of these proteins, CREB, has been shown to be a transcriptional activator that requires phosphorylation by protein kinase A (PKA) for its activity (12). A second protein, CRE-BP1 (also called HB16 and ATF-2) (6, 9, 10) binds to CRE sites as a heterodimer in conjunction with the JUN protein (9) and also interacts with the adenovirus Ela protein to activate transcription from CRE sites (13). Although a number of additional ATF/CREB proteins have been cloned (6), many ofthese clones represent partial-length cDNAs, and the transcriptional activities of most of these proteins remain unknown.In this report we describe the isolation and characterization of a cDNA clone that encodes an ubiquitously expressed CRE-bind...

ATF4 is directly recruited by TLR4 signaling and positively regulates TLR4-trigged cytokine production in human monocytes

“…35,36 ATF4 acts as a transcription activator and inhibitor. 35,[37][38][39][40] The results of our cytokine array assay revealed that ATF4 positively regulated the secretion of RANTES, sICAM-1, IL-6, IL-8 and IFN-c, all of which are proinflammatory cytokines. RANTES, a representative chemotactic factor, mediates T cell differentiation and cytokine release, and it is also a chemoattractant for blood monocytes, memory Thelper cells, mast leukocyte and eosinophils.…”

CRE DNA binding proteins bind to the AP-1 target sequence and suppress AP-1 transcriptional activity in mouse keratinocytes

“…Interference of the repressor function of CREMa by the DN CREB mutants could allow as yet unidenti®ed activator protein(s) to positively regulate AP-1 and CRE transcriptional activity in keratinocytes. Alternative targets of the A-CREB and KCREB mutants include CREB itself which exists in di erent phosphorylation states in keratinocytes and the transcriptional repressor, CREB-2 (Karpinski et al, 1992), that binds to the CRE without interacting with CRE activator proteins. Altering the ratios of activated and nonactivated forms of CREB through interactions with the DN constructs could result in di erences in the overall a b Figure 8 CREB family proteins repress AP-1 transcriptional activity.…”

Complexes containing activating transcription factor (ATF)/cAMP-responsive-element-binding protein (CREB) interact with the CCAAT/enhancer-binding protein (C/EBP)–ATF composite site to regulate Gadd153 expression during the stress response

“…The ATF4 (called CREB2 in this reference) expression plasmid (CMV-CREB2) was kindly provided by Dr. J. Leiden (Department of Medicine, University of Chicago, Chicago, IL, U.S.A.) [39]. The pCG-ATF3 expression vector was described previously [34].…”

“…The fulllength human clone was later isolated and named TAXREB67 [47] and CREB2 [39], while the mouse homologues are designated mATF4 [48], mTR67 [49] and C\EBP-related ATF (C\ATF) [50]. ATF4 has been demonstrated to activate transcription through interactions at ATF\CRE sites [39,46,48], and also through the interleukin-2 CD28 response element [51]. While there are reports showing that ATF4 can suppress promoter activity [52], others describe ' apparent ' transcriptional repression by ATF4 due to ' squelching ' under certain conditions [46].…”

“…In any case, our findings have provided direct evidence for the role of ATF4 in the transcriptional regulation of at least one gene, Gadd153, during at least one condition of stress. Given its ubiquitous expression [39], ATF4 is likely to serve a broader function in the stress response of mammalian cells.…”