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...

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Changes in physiology and attentional performance associated with smoking abstinence were characterized in 67 female smokers during low-stress and high-stress conditions. Abstinence was associated with decreases in cognitive performance, heart rate, and electroencephalographic (EEG) activation but with no change in serum estradiol or progesterone. Effects of quitting showed no tendency to resolve across the 31 days of abstinence. EEG deactivation and heart rate slowing were greater during a math task (high stress) than during relaxation (low stress). Individuals high in trait depression or nicotine dependence or with at least one dopamine D(2) receptor A1 allele experienced greater EEG deactivation following abstinence, especially in the right hemisphere during the stressful task. Thus, findings support the situation x trait adaptive response model of abstinence effects and emphasize the value of multiple dependent measures when characterizing abstinence responses.

The SAND domain is a conserved sequence motif found in a number of nuclear proteins, including the Sp100 family and NUDR. These are thought to play important roles in chromatin-dependent transcriptional regulation and are linked to many diseases. We have determined the three-dimensional (3D) structure of the SAND domain from Sp100b. The structure represents a novel alpha/beta fold, in which a conserved KDWK sequence motif is found within an alpha-helical, positively charged surface patch. For NUDR, the SAND domain is shown to be sufficient to mediate DNA binding. Using mutational analyses and chemical shift perturbation experiments, the DNA binding surface is mapped to the alpha-helical region encompassing the KDWK motif. The DNA binding activity of wild type and mutant proteins in vitro correlates with transcriptional regulation activity of full length NUDR in vivo. The evolutionarily conserved SAND domain defines a new DNA binding fold that is involved in chromatin-associated transcriptional regulation.