Dietary cholesterol consumption and intestinal cholesterol absorption contribute to plasma cholesterol levels, a risk factor for coronary heart disease. The molecular mechanism of sterol uptake from the lumen of the small intestine is poorly defined. We show that Niemann-Pick C1 Like 1(NPC1L1) protein plays a critical role in the absorption of intestinal cholesterol. NPC1L1 expression is enriched in the small intestine and is in the brush border membrane of enterocytes. Although otherwise phenotypically normal, NPC1L1-deficient mice exhibit a substantial reduction in absorbed cholesterol, which is unaffected by dietary supplementation of bile acids. Ezetimibe, a drug that inhibits cholesterol absorption, had no effect in NPC1L1 knockout mice, suggesting that NPC1L1 resides in an ezetimibe-sensitive pathway responsible for intestinal cholesterol absorption.

The contribution of seven known and nine predicted genes or operons associated with multidrug resistance to the susceptibility of Escherichia coli W3110 was assessed for 20 different classes of antimicrobial compounds that include antibiotics, antiseptics, detergents, and dyes. Strains were constructed with deletions for genes in the major facilitator superfamily, the resistance nodulation-cell division family, the small multidrug resistance family, the ATP-binding cassette family, and outer membrane factors. The agar dilution MICs of 35 compounds were determined for strains with deletions for multidrug resistance (MDR) pumps. Deletions in acrAB or tolC resulted in increased susceptibilities to the majority of compounds tested. The remaining MDR pump gene deletions resulted in increased susceptibilities to far fewer compounds. The results identify which MDR pumps contribute to intrinsic resistance under the conditions tested and supply practical information useful for designing sensitive assay strains for cell-based screening of antibacterial compounds.

Riboswitches are non-coding RNA structures located in messenger RNAs that bind endogenous ligands, such as a specific metabolite or ion, to regulate gene expression. As such, riboswitches serve as a novel, yet largely unexploited, class of emerging drug targets. Demonstrating this potential, however, has proven difficult and is restricted to structurally similar antimetabolites and semi-synthetic analogues of their cognate ligand, thus greatly restricting the chemical space and selectivity sought for such inhibitors. Here we report the discovery and characterization of ribocil, a highly selective chemical modulator of bacterial riboflavin riboswitches, which was identified in a phenotypic screen and acts as a structurally distinct synthetic mimic of the natural ligand, flavin mononucleotide, to repress riboswitch-mediated ribB gene expression and inhibit bacterial cell growth. Our findings indicate that non-coding RNA structural elements may be more broadly targeted by synthetic small molecules than previously expected.

Highlights d Specific compounds against P. falciparum Plasmepsin IX and X were identified d PMIX and PMX are modulators of parasite proteins for egress, invasion, and development d Anti-PMIX and anti-PMX compounds inhibit liver, blood, and mosquito stages of Plasmodium d One compound, WM382, can clear mouse models of P. berghei and P. falciparum parasites

Orphan G-protein-coupled receptors are a large class of receptors whose cognate ligands are unknown. SP9155 (also referred to as AQ27 and GPR103) is an orphan G-protein-coupled receptor originally cloned from a human brain cDNA library. SP9155 was found to be predominantly expressed in brain, heart, kidney, retina, and testis. Phylogenetic analysis shows that SP9155 shares high homology with Orexin, NPFF, and cholecystokinin (CCK) receptors, but identification of the endogenous ligand for SP9155 has not been reported. In this study, we have used a novel method to predict peptides from genome data bases. From these predicted peptides, a novel RF-amide peptide, P52 was shown to selectively activate SP9155-transfected cells. We subsequently cloned the precursor gene of the P52 ligand and characterized the activity of other possible peptides encoded by the precursor. This revealed an extended peptide, P518, which exhibited high affinity for SP9155 (EC 50 ‫؍‬ 7 nM). mRNA expression analysis revealed that the peptide P518 precursor gene is predominantly expressed in various brain regions, coronary arteries, thyroid and parathyroid glands, large intestine, colon, bladder, testes, and prostate. These results indicate the existence of a novel RF-amide neuroendocrine peptide system, and suggest that SP9155 is likely the relevant G-protein-coupled receptor for this peptide.G-protein coupled receptors (GPCRs) 1 are members of a large protein family that share a common structural motif of seven transmembrane domains (1, 2). GPCRs mediate a variety of physiological functions by interacting with extracellular ligands including small chemical molecules, peptides, and proteins, then transmitting the signal to intracellular second messengers via G proteins (1, 2). In recent years, the primary sequence of many GPCRs have been identified through searching the human genome sequence data base. Whereas these GPCRs have common structural motifs including seven transmembrane domains, often their cognate ligands and biological function are unknown (3-5). To understand the biological functions of these so called orphan receptors, and to enable identification of pharmacological agents active at these receptors, it is helpful to first identify their endogenous cognate ligands (3-5). Currently there are two main approaches generally used to identify orphan receptor ligands. One common approach has been to screen the orphan GPCRs against a collection of known or putative GPCR ligands. This approach has been used successfully to identify several ligand receptor pairings, including MCH, NMU, and P2Y13 etc. (6 -8). However, because ligand collections are somewhat limited, they often do not contain the appropriate ligand for the orphan receptor of interest. Another approach involves purification of the ligands from animal tissue extracts. This approach has also been successful in a number of cases including OFQ/Nociceptin, MCH, Orexin, and P2Y12 etc. (9 -13). However, purification of ligands from animal tissue extracts is labor-intensive and is c...