The discovery of organic ligands that bind specifically to proteins is a central problem in chemistry, biology, and the biomedical sciences. The encoding of individual organic molecules with distinctive DNA tags, serving as amplifiable identification bar codes, allows the construction and screening of combinatorial libraries of unprecedented size, thus facilitating the discovery of ligands to many different protein targets. Fundamentally, one links powers of genetics and chemical synthesis. After the initial description of DNA-encoded chemical libraries in 1992, several experimental embodiments of the technology have been reduced to practice. This review provides a historical account of important milestones in the development of DNA-encoded chemical libraries, a survey of relevant ongoing research activities, and a glimpse into the future.

The widespread incidence of H5N1 influenza viruses in bird populations poses risks to human health. Although the virus has not yet adapted for facile transmission between humans, it can cause severe disease and often death. Here we report the generation of combinatorial antibody libraries from the bone marrow of five survivors of the recent H5N1 avian influenza outbreak in Turkey. To date, these libraries have yielded >300 unique antibodies against H5N1 viral antigens. Among these antibodies, we have identified several broadly reactive neutralizing antibodies that could be used for passive immunization against H5N1 virus or as guides for vaccine design. The large number of antibodies obtained from these survivors provide a detailed immunochemical analysis of individual human solutions to virus neutralization in the setting of an actual virulent influenza outbreak. Remarkably, three of these antibodies neutralized both H1 and H5 subtype influenza viruses.

Inhaled anesthetics are a chemically diverse collection of hydrophobic molecules that robustly activate TWIK-related K ⁺ channels (TREK-1) and reversibly induce loss of consciousness. For 100 y, anesthetics were speculated to target cellular membranes, yet no plausible mechanism emerged to explain a membrane effect on ion channels. Here we show that inhaled anesthetics (chloroform and isoflurane) activate TREK-1 through disruption of phospholipase D2 (PLD2) localization to lipid rafts and subsequent production of signaling lipid phosphatidic acid (PA). Catalytically dead PLD2 robustly blocks anesthetic TREK-1 currents in whole-cell patch-clamp recordings. Localization of PLD2 renders the TRAAK channel sensitive, a channel that is otherwise anesthetic insensitive. General anesthetics, such as chloroform, isoflurane, diethyl ether, xenon, and propofol, disrupt lipid rafts and activate PLD2. In the whole brain of flies, anesthesia disrupts rafts and PLD ^null flies resist anesthesia. Our results establish a membrane-mediated target of inhaled anesthesia and suggest PA helps set thresholds of anesthetic sensitivity in vivo.

Glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) agonists have emerged as treatment options for type 2 diabetes mellitus (T2DM). GLP-1R signals through G-protein-dependent, and G-protein-independent pathways by engaging the scaffold protein β-arrestin; preferential signalling of ligands through one or the other of these branches is known as ‘ligand bias’. Here we report the discovery of the potent and selective GLP-1R G-protein-biased agonist, P5. We identified P5 in a high-throughput autocrine-based screening of large combinatorial peptide libraries, and show that P5 promotes G-protein signalling comparable to GLP-1 and Exendin-4, but exhibited a significantly reduced β-arrestin response. Preclinical studies using different mouse models of T2DM demonstrate that P5 is a weak insulin secretagogue. Nevertheless, chronic treatment of diabetic mice with P5 increased adipogenesis, reduced adipose tissue inflammation as well as hepatic steatosis and was more effective at correcting hyperglycaemia and lowering haemoglobin A_1c levels than Exendin-4, suggesting that GLP-1R G-protein-biased agonists may provide a novel therapeutic approach to T2DM.

Antibodies that target both group 1 and group 2 influenza A viruses are valuable for therapeutic and vaccine development, but only a few have been reported to date. Here, we describe a new VH1-69 antibody 27F3 that broadly recognizes heterosubtypic hemagglutinins (HAs) from both group 1 and group 2 influenza A viruses. Structural characterization of 27F3 Fab with A/California/04/2009 (H1N1) hemagglutinin illustrates that 27F3 shares the key binding features observed in other VH1-69 antibodies to the HA stem. Compared to other VH1-69 antibodies, the 27F3 VH domain interacts with the HA stem in a distinct orientation, which alters its epitope and may have influenced its breadth. The diverse rotations of VH1-69 antibodies on the HA stem epitope highlight the different ways that this antibody family can evolve to broadly neutralize influenza A viruses. These results have important implications for understanding how to elicit broad antibody responses against influenza virus.

“… We envisioned an iterative system where a unique DNA tag identifier that encoded the event was appended to each newly formed molecule. These vast collections of molecules are known today as DNA‐ encoded chemical libraries (DECLs), and allow scientists to do selections on the benchtop that previously required access to large and complex high‐throughput screening centers …” Read more in the Guest Editorial by Richard A. Lerner and Sydney Brenner.