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...

The recent definition of a consensus DNA binding sequence for the Ets family of transcription factors has aflowed the identification of potential Ets binding sites in the promoters and enhancers of many inducible T-cell genes. In the studies described in this report, we have identified two potential Ets binding sites, EBS1 and EBS2, which are conserved in both the human and murine interleukin-2 enhancers. Within the human enhancer, these two sites are located within the previously defined DNase I footprints, NFAT-1 and NFIL-2B, respectively. Electrophoretic mobility shift and methylation interference analyses demonstrated that EBS1 and EBS2 are essential for the formation of the NFAT-1 and NFIL-2B nuclear protein complexes. Furthermore, in vitro mutagenesis experiments demonstrated that inducible interleukin-2 enhancer function requires the presence of either EBSI or EBS2. Two well-characterized Ets family members, Ets-1 and Ets-2, are reciprocally expressed during T-cell activation. Surprisingly, however, neither of these proteins bound in vitro to EBS1 or EBS2. We therefore screened a T-cell cDNA library under low-stringency conditions with a probe from the DNA binding domain of Ets-1 and isolated a novel Ets family member, Elf-1. Elf-1 contains a DNA binding domain that is nearly identical to that of E74, the ecdysone-inducible Drosophia transcription factor required for metamorphosis (hence the name Elf-1, for E74-like factor 1). Elf-1 bound specifically to both EBS1 and EBS2 in electrophoretic mobility shift assays. It also bound to the purine-rich CD3R element from the human immunodeficiency virus type 2 long terminal repeat, which is required for inducible virus expression in response to signalling through the T-cell receptor. Taken together, these results demonstrate that multiple Ets family members with apparently distinct DNA binding specificities regulate differential gene expression in resting and activated T cells.

We assessed feeding-related developmental anomalies in the LgDel mouse model of chromosome 22q11 deletion syndrome (22q11DS), a common developmental disorder that frequently includes perinatal dysphagia – debilitating feeding, swallowing and nutrition difficulties from birth onward – within its phenotypic spectrum. LgDel pups gain significantly less weight during the first postnatal weeks, and have several signs of respiratory infections due to food aspiration. Most 22q11 genes are expressed in anlagen of craniofacial and brainstem regions critical for feeding and swallowing, and diminished expression in LgDel embryos apparently compromises development of these regions. Palate and jaw anomalies indicate divergent oro-facial morphogenesis. Altered expression and patterning of hindbrain transcriptional regulators, especially those related to retinoic acid (RA) signaling, prefigures these disruptions. Subsequently, gene expression, axon growth and sensory ganglion formation in the trigeminal (V), glossopharyngeal (IX) or vagus (X) cranial nerves (CNs) that innervate targets essential for feeding, swallowing and digestion are disrupted. Posterior CN IX and X ganglia anomalies primarily reflect diminished dosage of the 22q11DS candidate gene Tbx1. Genetic modification of RA signaling in LgDel embryos rescues the anterior CN V phenotype and returns expression levels or pattern of RA-sensitive genes to those in wild-type embryos. Thus, diminished 22q11 gene dosage, including but not limited to Tbx1, disrupts oro-facial and CN development by modifying RA-modulated anterior-posterior hindbrain differentiation. These disruptions likely contribute to dysphagia in infants and young children with 22q11DS.

Highlights d Cortical connections decrease in a DiGeorge/22q11 deletion syndrome mouse model d Under-connectivity reflects reduced dendrite, axon, and synapse growth d Txrnd2, a 22q11 gene, regulates mitochondrial metabolism and neuron growth d Cortical connections and behavioral deficits are restored by anti-oxidant therapy