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 ability to program recombinant gene expression in cardiac myocytes in vivo holds promise for the treatment of many inherited and acquired cardiovascular diseases. In this report, we demonstrate that a recombinant P-galactosidase gene under the control of the Rous sarcoma virus promoter can be introduced into and expressed in adult rat cardiac myocytes in vivo by the injection of purified plasmid DNA directly into the left ventricular wall. Cardiac myocytes expressing recombinant /3-galactosidase were detected histochemically in rat hearts for at least 4 weeks after injection of the f3-galactosidase gene. These results demonstrate the potential of this method of somatic gene therapy for the treatment of cardiovascular disease. (Circulation 1990;82:2217-2221 Somatic gene therapy, the expression of recombinant genes in non-germ-line tissues of the adult organism, holds great promise for the treatment of many inherited and acquired human diseases (reviewed in Reference 1). The biological requirements for this type of gene therapy include the ability to introduce recombinant genes efficiently into the appropriate cells and tissues and to program the high-level and, in many cases, stable expression of these recombinant genes in vivo. In addition, it is necessary that the process of gene therapy itself not be harmful to the recipient organism, in particular, that the techniques used to introduce the recombinant genes do not result in persistent infection of the host or in deleterious mutations of the recipient cells. Two general approaches have proven useful in animal models of somatic gene therapy. In

A transcriptional enhancer element has been identified 4.5 kilobases 3' of C. (