Loss of interferon alpha and interferon tau-induced antiviral protection in interferon regulatory factor-2 DNA-binding domain dominant negative mutants

Transcriptional regulation of the major HIV-1 coreceptor, CXCR4, by the kappa opioid receptor

Previous studies have demonstrated that KOR activation results in decreased susceptibility to infection by HIV-1 in human PBMCs. In the present studies, we have found this effect is, in part, a result of down-regulation of the major HIV-1 coreceptor, CXCR4. Using a combination of biochemical approaches, our results show that CXCR4 protein and mRNA levels were reduced significantly following KOR activation. We evaluated the nature of the signaling pathway(s), which were induced by KOR activation, using transcription factor-binding array analysis and comparing extracts from control and KOR-activated cells. We determined that the IRFs and STATs were induced following KOR activation, and these events were important for the inhibition of CXCR4 expression. Using chemical inhibitors and siRNA constructs, we determined that JAK2, STAT3, and IRF2 were critical members of this signal transduction pathway. Immediately following KOR activation, JAK2 was phosphorylated, and this was required for the phosphorylation/activation of STAT3. Moreover, IRF2 mRNA and protein expression were also up-regulated, and further studies using ChIP analysis showed that IRF2 was induced to bind in vivo to the CXCR4 promoter. This is the first report detailing the initiation of a KOR-induced JAK2/STAT3 and IRF2 signaling cascade, and these pathways result in substantial down-regulation of CXCR4 expression. The capacity of KOR to down-regulate CXCR4 expression may provide a strategy for the development of novel therapeutics for the inhibition of HIV replication.

The transcriptional response of human macrophages to murabutide reflects a spectrum of biological effects for the synthetic immunomodulator

The synthetic immunomodulator murabutide (MB) presents multiple biological activities with minimal toxicity in animals and in man. Although MB is known to target cells of the reticuloendothelial system and to regulate cytokine synthesis, the molecular mechanisms underlying several of its biological effects are still largely unknown. In an effort to define cellular factors implicated in the immunomodulatory and HIV-suppressive activities of MB, we have undertaken profiling the regulated expression of genes in human monocyte-derived macrophages (MDM) following a 6-h stimulation with this synthetic glycopeptide. Oligonucleotide microarray analysis was performed on RNA samples of differentiated MDM from four separate donors, using probe sets corresponding to 1081 genes. We have identified, in a reproducible fashion, the enhanced expression of 40 genes and the inhibition of 16 others in MB-treated MDM. These regulated genes belonged to different families of immune mediators or their receptors, transcription factors and kinases, matrix proteins and their inhibitors, ion channels and transporters, and proteins involved in cell metabolic pathways. Additional verification of the regulated expression of selected genes was carried out using Northern blots or the quantification of released proteins in MDM cultures. The profile of MB-regulated genes in MDM provides a molecular basis for some of its previously reported biological activities, and reveals new set of genes targeted by the immunomodulator suggesting potential application in novel therapeutic indications.