NF-kappa B-dependent induction of the NF-kappa B p50 subunit gene promoter underlies self-perpetuation of human immunodeficiency virus transcription in monocytic cells.

The molecular mechanisms underlying the sustained nuclear translocation of NF-kappa B observed in U937 monocytic cells chronically infected with human immunodeficiency virus (HIV) were studied. The activity of the promoter regulating the synthesis of the p105 precursor of the NF-kappa B p50 subunit was enhanced in these cells. Deletions in this promoter indicated that this upregulation was mediated through the NF-kappa B- but not the AP-1-binding motif, by bona fide p50/p65 heterodimers. Analysis of cytosolic extracts indicated that NF-kappa B levels were increased in HIV-infected cells. In contrast to the transient NF-kappa B activation induced by phorbol ester, the permanent NF-kappa B translocation induced by HIV infection was not dependent on PKC isoenzymes alpha and beta as shown by the use of a specific inhibitor (GF 109203X). These observations indicate that during chronic HIV infection of U937 cells, continuous NF-kappa B (p50/p65) translocation results in p105 promoter upregulation with subsequent cytosolic NF-kappa B accumulation, ready for further translocation. This HIV-mediated mechanism results in a self-perpetuating loop of NF-kappa B production.     

Prostacyclin: a potent activator of human colonic adenylate cyclase activity.

Prostacyclin and its stable catabolite 6-keto-prostaglandin F1 alpha were tested on the human colonic mucosal adenylate cyclase which represents the key enzyme in the secretory process in this organ. Prostacyclin was able to activate dose-dependently the human cyclase system. Saturating concentrations of prostacyclin and 6-keto-prostaglandin F1 alpha (each 0.28 mM) increased the enzyme activity 2.5-fold and only 1.4-fold, respectively. The presence of prostacyclin receptor sites in human colonic mucosa suggests a physiological role of this novel prostaglandin in human colonic function.     

The human myometrium as a target for melatonin

The circadian timing of spontaneous human deliveries results in births occurring statistically more often during the nocturnal phase of the 24-h cycle. The neuroendocrine mechanisms underlying this physiological phenomenon are not understood. In an effort to test the hypothesis that melatonin may serve as an endocrine signal for coordinating myometrial events in the human, we determined the mRNA expression of both MT1 and MT2 melatonin receptor isoforms in pregnant as well as nonpregnant myometrial biopsies by means of RT-PCR and in situ hybridization histochemistry. Additionally, we could demonstrate specific, high affinity iodomelatonin binding to myometrial tissues of both pregnant and nonpregnant women. Primary cultures of myocytes responded differentially from melatonin in terms of cAMP signaling depending on the reproductive state. These results imply that melatonin may have the potential to modulate myometrial function in the human, a finding that could open up new possibilities for the development of novel therapeutic agents.     

Two human glutamate decarboxylases, 65-kDa GAD and 67-kDa GAD, are each encoded by a single gene.

We report the isolation and sequencing of cDNAs encoding two human glutamate decarboxylases (GADs; L-glutamate 1-carboxy-lyase, EC 4.1.1.15), GAD65 and GAD67. Human GAD65 cDNA encodes a Mr 65,000 polypeptide, with 585 amino acid residues, whereas human GAD67 encodes a Mr 67,000 polypeptide, with 594 amino acid residues. Both cDNAs direct the synthesis of enzymatically active GADs in bacterial expression systems. Each cDNA hybridizes to a single species of brain mRNA and to a specific set of restriction fragments in human genomic DNA. In situ hybridization of fluorescently labeled GAD probes to human chromosomes localizes the human GAD65 gene to chromosome 10p11.23 and the human GAD67 gene to chromosome 2q31. We conclude that GAD65 and GAD67 each derive from a single separate gene. The cDNAs we describe should allow the bacterial production of test antigens for the diagnosis and prediction of insulin-dependent diabetes mellitus.