Gain-of-Function Somatic Cell Lines for Drug Discovery Applications Generated by Homologous Recombination

Very long-term memories may be stored in the pattern of holes in the perineuronal net

A hypothesis and the experiments to test it propose that very long-term memories, such as fear conditioning, are stored as the pattern of holes in the perineuronal net (PNN), a specialized ECM that envelops mature neurons and restricts synapse formation. The 3D intertwining of PNN and synapses would be imaged by serial-section EM. Lifetimes of PNN vs. intrasynaptic components would be compared with pulse-chase (15)N labeling in mice and (14)C content in human cadaver brains. Genetically encoded indicators and antineoepitope antibodies should improve spatial and temporal resolution of the in vivo activity of proteases that locally erode PNN. Further techniques suggested include genetic KOs, better pharmacological inhibitors, and a genetically encoded snapshot reporter, which will capture the pattern of activity throughout a large ensemble of neurons at a time precisely defined by the triggering illumination, drive expression of effector genes to mark those cells, and allow selective excitation, inhibition, or ablation to test their functional importance. The snapshot reporter should enable more precise inhibition or potentiation of PNN erosion to compare with behavioral consequences. Finally, biosynthesis of PNN components and proteases would be imaged.

Cellular models for disease exploring and drug screening

The biopharmaceutical industry has been greatly promoted by the application of drug and disease models, including both animal and cellular models. In particular, the emergence of induced pluripotent stem cells (iPSC) makes it possible to create a large number of disease-specific cells in vitro. This review introduces the most widely applied models and their specialties.

High-throughput screening assays for the identification of chemical probes

High-throughput screening (HTS) assays enable the testing of large numbers of chemical substances for activity in diverse areas of biology. The biological responses measured in HTS assays span isolated biochemical systems containing purified receptors or enzymes to signal transduction pathways and complex networks functioning in cellular environments. This Review addresses factors that need to be considered when implementing assays for HTS and is aimed particularly at investigators new to this field. We discuss assay design strategies, the major detection technologies and examples of HTS assays for common target classes, cellular pathways and simple cellular phenotypes. We conclude with special considerations for configuring sensitive, robust, informative and economically feasible HTS assays.

Human embryonic stem cells as a cellular model for human disorders

Human embryonic stem cells (HESCs) are pluripotent cell lines derived from the inner cell mass (ICM) of embryos at the blastocyst stage. These cells possess self renewal capacity and differentiation potential to all three embryonic germ layers. These unique characters made HESCs an attractive research tool for studying early human developmental processes as well as a potential therapeutic tool for various human diseases. Here, we focus on HESCs as a cellular model for human disorders. The advantages of such models as well as the various methodologies to achieve HESCs carrying a genetic defect will be discussed.