Cloning and expression of a human ATP-citrate lyase cDNA

Correlation of ATP/citrate lyase activity with lipid accumulation in developing seeds of Brassica napus L

The temporal distribution of ATP/citrate lyase (ACL) activity in developing seeds of Brassica napus L. closely paralleled both that of acetyl-CoA carboxylase and the overall rate of lipid biosynthesis. Maximum ACL activities (250 nmol acetyl-CoA formed min-1.g fresh seed) were recorded between 35 to 42 d after pollination and, if the in vitro data could be extrapolated to the situation in vivo, could account for half of the acetyl-CoA required for the measured rate of fatty acid biosynthesis during seed development. The enzyme appeared to be localized in a subcellular compartment, which was clearly separated from mitochondria on a sucrose gradient and by differential centrifugation, and which corresponded to the chloroplast organelle.

ATP-citrate lyase as a target for hypolipidemic intervention. Design and synthesis of 2-substituted butanedioic acids as novel, potent inhibitors of the enzyme

ATP-citrate lyase is the primary enzyme responsible for the synthesis of cytosolic acetyl-CoA in many tissues. Inhibitors of the enzyme represent a potentially novel class of hypolipidemic agent, which are anticipated to have combined hypocholesterolemic and hypotriglyceridemic properties. A series of 2-substituted butanedioic acids have been designed and synthesized as inhibitors of the enzyme. The best compounds, 58, 68, 71, 74 have reversible Ki's in the 1-3 microM range against the isolated rat enzyme. As representative of this compound class, 58, has been shown to exert its inhibitory action through a mainly competitive mechanism with respect to citrate and a noncompetitive one with respect to CoA. None of the inhibitors were able to inhibit cholesterol and/or fatty acid synthesis in HepG2 cells. This has been attributed to the adverse physicochemical properties of the molecules leading to a lack of cell penetration. Despite this, a lead structural class of compound has been identified with the potential for modification into potent, cell-penetrant, and efficacious inhibitors of ATP-citrate lyase.

The Epstein-Barr virus nuclear protein 2 acidic domain forms a complex with a novel cellular coactivator that can interact with TFIIE

Epstein-Barr virus nuclear antigen 2 (EBNA 2) activates transcription of specific genes and is essential for B-lymphocyte transformation. EBNA 2 has an acidic activation domain which interacts with general transcription factors TFIIB, TFIIH, and TAF40. We now show that EBNA 2 is specifically bound to a novel nuclear protein, p100, and that p100 can coactivate gene expression mediated by the EBNA 2 acidic domain. The EBNA 2 acidic domain was used to affinity purify p100. cDNA clones encoding the p100 open reading frame were identified on the basis of peptide sequences of the purified protein. Antibody against p100 coimmunoprecipitated p100 and EBNA 2 from Epstein-Barr virus-transformed lymphocyte extracts, indicating that EBNA 2 and p100 are complexed in vivo. p100 overexpression in cells specifically augmented EBNA 2 acidic domain-mediated activation. The coactivating effect is probably mediated by p100 interaction with TFIIE. Bacterially expressed p100 specifically adsorbs TFIIE from nuclear extracts, and in vitro-translated p56 or p34 TFIIE subunit can independently bind to p100. p100 also appears to be essential for normal cell growth, since cell viability was reduced by antisense p100 RNA and restored by sense p100 RNA expression.

A physical map and candidate genes in the BRCA1 region on chromosome 17q12-21

We have constructed a physical map of a 4 cM region on chromosome 17q12-21 that contains the hereditary breast and ovarian cancer gene BRCA1. The map comprises a contig of 137 overlapping yeast artificial chromosomes and P1 clones, onto which we have placed 112 PCR markers. We have localized more than 20 genes on this map, ten of which had not been mapped to the region previously, and have isolated 30 cDNA clones representing partial sequences of as yet unidentified genes. Two genes that lie within a narrow region defined by meiotic breakpoints in BRCA1 patients have been sequenced in breast cancer patients without revealing any deleterious mutations. These new reagents should facilitate the identification of BRCA1.

Expression and functional characterisation of a synthetic version of the human D4 dopamine receptor in a stable human cell line

A synthetic version of the human D4 (hD4) dopamine receptor was prepared. The G/C content of the natural gene was reduced by 14% without altering the amino acid composition of the corresponding protein sequence. HEK293 cells were transfected with the synthetic hD4 gene and stable clones resistant to G418 selected. The hD4 receptor expressed from the synthetic gene had identical pharmacological characteristics to the native hD4 receptor [(1991) Nature 350, 610-619; (1992) Nature 358, 149-152]. Functional studies with cells expressing the synthetic hD4 gene indicated negative coupling of this receptor to adenylate cyclase.

Molecular cloning and functional characterization of a human liver vasoactive intestinal peptide receptor

We have isolated a cDNA from a human liver library which is 2349 base pairs in length and encodes a near-full length seven transmembrane receptor (432 amino acids), 85% homologous to the amino acid sequence for the rat vasoactive intestinal peptide (VIP) receptor. Northern blot analysis identifies a major species at 3.3 kb in lung, and to a lesser extent in brain, heart and liver. In order to confirm the identity of this human clone, double-stranded oligonucleotides encoding the signal peptide of the rat VIP receptor were constructed by polymerase chain reaction and attached to the 5' end of the human clone. COS cells transiently transfected with this human VIP receptor chimera, express a single binding site for 125I-VIP with a Kd of 9.2 +/- 2 nM. Related peptides displace 125I-VIP with a relative potency of VIP = PACAP > helodermin >> PHM > secretin, which is similar to the binding profile seen in human tissues. This human chimeric receptor is functionally coupled to the stimulation of adenylyl cyclase in transfected COS cells, as evidenced by a dose-dependent increase in intracellular cAMP accumulation. These studies indicate that this cDNA encodes a human liver VIP receptor which is functionally coupled to the activation of adenylyl cyclase.