Bacteria Engineered to Produce Serotonin Modulate Host Intestinal Physiology.

Bacteria in the gastrointestinal tract play a crucial role in intestinal motility, homeostasis, and dysfunction. Unraveling the mechanisms by which microbes impact the host poses many challenges due to the extensive array of metabolites produced or metabolized by bacteria in the gut. Here, we describe the engineering of a gut commensal bacterium, Nissle 1917, to biosynthesize the human metabolite serotonin for examining the effects of microbially produced biogenic amines on host physiology.

Hepatotoxic potential of therapeutic oligonucleotides can be predicted from their sequence and modification pattern.

Antisense oligonucleotides that recruit RNase H and thereby cleave complementary messenger RNAs are being developed as therapeutics. Dose-dependent hepatic changes associated with hepatocyte necrosis and increases in serum alanine-aminotransferase levels have been observed after treatment with certain oligonucleotides. Although general mechanisms for drug-induced hepatic injury are known, the characteristics of oligonucleotides that determine their hepatotoxic potential are not well understood.

RNA exosome depletion reveals transcription upstream of active human promoters.

Studies have shown that the bulk of eukaryotic genomes is transcribed. Transcriptome maps are frequently updated, but low-abundant transcripts have probably gone unnoticed. To eliminate RNA degradation, we depleted the exonucleolytic RNA exosome from human cells and then subjected the RNA to tiling microarray analysis.

The RNA exosome component hRrp6 is a target for 5-fluorouracil in human cells.

The drug 5-fluorouracil (5-FU) is a widely used chemotherapeutic in the treatment of solid tumors. Recently, the essential 3'-5' exonucleolytic multisubunit RNA exosome was implicated as a target for 5-FU in yeast. Here, we show that this is also the case in human cells.

A minimal uORF within the HIV-1 vpu leader allows efficient translation initiation at the downstream env AUG.

The HIV-1 Vpu and Env proteins are translated from 16 alternatively spliced bicistronic mRNA isoforms. Translation of HIV-1 mRNAs generally follows the ribosome scanning mechanism. However, by using subgenomic env expression vectors, we found that translation of glycoprotein from polycistronic mRNAs was inconsistent with leaky scanning.

The strength of the HIV-1 3' splice sites affects Rev function.

Background: The HIV-1 Rev protein is a key component in the early to late switch in HIV-1 splicing from early intronless (e.g. tat, rev) to late intron-containing Rev-dependent (e.

A bidirectional SF2/ASF- and SRp40-dependent splicing enhancer regulates human immunodeficiency virus type 1 rev, env, vpu, and nef gene expression.

The integrated human immunodeficiency virus type 1 (HIV-1) genome is transcribed in a single pre-mRNA that is alternatively spliced into more than 40 mRNAs. We characterized a novel bidirectional exonic splicing enhancer (ESE) that regulates the expression of the HIV-1 env, vpu, rev, and nef mRNAs. The ESE is localized downstream of the vpu-, env-, and nef-specific 3' splice site no.

A novel approach to describe a U1 snRNA binding site.

RNA duplex formation between U1 snRNA and a splice donor (SD) site can protect pre-mRNA from degradation prior to splicing and initiates formation of the spliceosome. This process was monitored, using sub-genomic HIV-1 expression vectors, by expression analysis of the glycoprotein env, whose formation critically depends on functional SD4. We systematically derived a hydrogen bond model for the complementarity between the free 5' end of U1 snRNA and 5' splice sites and numerous mutations following transient transfection of HeLa-T4+ cells with 5' splice site mutated vectors.