RESUMO
Understanding cellular signaling mediated by cell surface receptors is key to modern biomedical research and drug development. The discovery of a growing number of potential molecular targets and therapeutic compounds requires downscaling and accelerated functional screening. Receptor-mediated cellular responses are typically investigated on single cells or cell populations. Here, we show how to monitor cellular signaling reactions at a yet unreached miniaturization level. On the basis of our observations, cytochalasin induces mammalian cells to extrude from their plasma membrane submicrometer-sized native vesicles. They comprise functional cell surface receptors correctly exposing their extracellular ligand binding sites on the outer vesicle surface and retaining cytosolic proteins in the vesicle interior. As a prototypical example, ligand binding to the ionotropic 5-HT(3) receptor and subsequent transmembrane Ca(2+) signaling were monitored in single attoliter vesicles. Thus, native vesicles are the smallest autonomous containers capable of performing cellular signaling reactions under physiological conditions. Because a single cell delivers about 50 native vesicles, which can be isolated and addressed as individuals, our concept allows multiple functional analyses of individual cells having a limited availability and opens new vistas for miniaturized bioanalytics.
Assuntos
Sinalização do Cálcio/fisiologia , Receptores 5-HT3 de Serotonina/fisiologia , Animais , Linhagem Celular , Membrana Celular/química , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Citocalasina B/farmacologia , Citosol/química , Citosol/metabolismo , Receptores ErbB/química , Receptores ErbB/metabolismo , Humanos , Rim/citologia , Ligantes , Camundongos , Microscopia Confocal , Microscopia de Fluorescência , Receptores 5-HT3 de Serotonina/química , Receptores 5-HT3 de Serotonina/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes de Fusão/fisiologiaRESUMO
In this study, the general suitability of quantum dot (QD)-DNA conjugates for the surface plasmon enhanced fluorescence spectroscopy technique is demonstrated. Furthermore, the QD-DNA system is transferred to the platform of surface plasmon enhanced fluorescence microscopy. Using this technique together with a microarray format, in which the sensor-bound single-stranded catcher probes are organized in individual surface spots, results in a simultaneous qualitative analysis of QD-conjugated analyte DNA strands as multicolor images. A clear decomposition of different QD(x)()-DNA(y)() mixtures can be achieved for sequential, as well as mixture injections. Besides this, the study describes the successful approach of measuring spectrally resolved surface plasmon enhanced fluorescence signals derived from catcher probe hybridized QD-DNA conjugates.