Organ formation requires a delicate balance of positive and negative regulators. In Drosophila eye development, wingless (wg) is expressed at the lateral margins of the eye disc and serves to block retinal development. The T-box gene optomotor-blind (omb) is expressed in a similar pattern and is regulated by Wg. Omb mediates part of Wg activity in blocking eye development. Omb exerts its function primarily by blocking cell proliferation. These effects occur predominantly in the ventral margin. Our results suggest that the primary effect of Omb is the blocking of Jak/STAT signaling by repressing transcription of upd which encodes the Jak receptor ligand Unpaired.

G protein-coupled receptors (GPCRs) comprise the largest membrane protein family in humans and can respond to a wide variety of ligands and stimuli. Like other multi-pass membrane proteins, the biochemical properties of GPCRs are notoriously difficult to study because they must be embedded in lipid bilayers to maintain their native conformation and function. To enable an unbiased, high-throughput platform to profile biochemical activities of GPCRs in native conformation, we individually displayed 315 human non-odorant GPCRs (>85% coverage) in the envelope of human herpes simplex virus-1 and immobilized on glass to form a high-content Virion Display (VirD) array. Using this array, we found that 50% of the tested commercial anti-GPCR antibodies (mAbs) is ultra-specific, and that the vast majority of those VirD-GPCRs, which failed to be recognized by the commercial mAbs, could bind to their canonical ligands, indicating that they were folded correctly. Next, we used the VirD-GPCR arrays to examine binding specificity of two known peptide ligands and recovered expected interactions, as well as new off-target interactions, three of which were confirmed with real-time kinetics measurements. Finally, we explored the possibility of discovering novel pathogen targets by probing VirD-GPCR arrays with live group B Streptococcus (GBS), a commonGram-positive bacterium causing neonatal meningitis. Using cell invasion assays and a mouse model of hematogenous meningitis, we showed that inhibition of one of the five newly identified GPCRs, CysLTR1, greatly reduced GBS penetration in brain-derived endothelial cells and in mouse brains. Therefore, our work demonstrated that the VirD-GPCR array holds great potential for high-throughput, unbiased screening for small molecule drugs, affinity reagents, and deorphanization.

drug discovery is their immature state relative to the adult myocardium. In this research, 3D cardiac microtissues (CMTs) were generated using hiPSC-CMs to recapitulate the structural, functional and metabolic properties of normal and diseased adult ventricular myocardium. CMTs were treated with ontologically defined biochemical interventions (thyroid hormone, dexamethasone and insulin-like growth factor, TDI) to promote the maturation of hiPSC-CMs. The effects of TDI treatment on both structural and functional (biomechanical, Ca2þ handling and electrophysiology) properties at the tissue level were characterized. Also, the molecular correlates of maturation of the hiPSC-CMs in the CMTs were studied by gene expression, proteomics studies. Our data demonstrate that TDI treatment improves both the structure and function of CMTs. Structurally, the hiPSC-CMs show improved alignment and longer sarcomere length, as shown by immunofluorescence and confocal microscopy. Functionally, CMTs' static and dynamic force both increase following TDI treatment, and cardiac electrophysiology assessed by optical mapping showing that the CMTs are electrically coupled. TDI-treated CMTs exhibited both chronotropic and inotropic response to isoproterenol treatment. The enhanced functional properties that this maturation approach yields have the potential to yield improved hiPSC derived cardiac model systems that can advance both mechanistic studies and the development of new therapies for the treatment of cardiac diseases.

The ability to identify and characterize individual biomarker protein molecules in patient blood samples could enable diagnosis of diseases at an earlier stage, when treatment is typically more effective. Single-molecule imaging offers a promising approach to accomplish this goal. However, thus far single-molecule imaging methods have only been used to monitor protein molecules in solutions or cell lysates, and have not been translated into the clinical arena. Furthermore, the detection limit of these methods has been confined to the picomolar (10-12 M) range. In many diseases, the circulating concentrations of biomarker proteins fall several orders of magnitude below this range. Here we describe Single-Molecule Augmented Capture (SMAC), a single-molecule imaging technique to visualize, quantify, and characterize individual protein molecules of interest down to the subfemtomolar (<10-15 M) range, even in complex biologic fluids. We demonstrate SMAC in a wide variety of applications with human blood samples, including the analysis of disease-associated secreted proteins, membrane proteins, and rare intracellular proteins. Using ovarian cancer as a model, a lethal malignancy in which high-grade disease is driven almost universally by alterations in the TP53 gene and frequently only diagnosed at a late, incurable stage, we found that mutant pattern p53 proteins are released into the blood in patients at an early stage in disease progression. SMAC opens the door to the application of single-molecule imaging in non-invasive disease profiling and allows for the analysis of circulating mutant proteins as a new class of highly specific disease biomarkers. The SMAC platform can be adapted to multiplex or high-throughput formats to characterize heterogeneous biochemical and structural features of circulating proteins-of-interest.