Cell surface proteins are major targets of biomedical research due to their utility as cellular markers and their extracellular accessibility for pharmacological intervention. However, information about the cell surface protein repertoire (the surfaceome) of individual cells is only sparsely available. Here, we applied the Cell Surface Capture (CSC) technology to 41 human and 31 mouse cell types to generate a mass-spectrometry derived Cell Surface Protein Atlas (CSPA) providing cellular surfaceome snapshots at high resolution. The CSPA is presented in form of an easy-to-navigate interactive database, a downloadable data matrix and with tools for targeted surfaceome rediscovery (http://wlab.ethz.ch/cspa). The cellular surfaceome snapshots of different cell types, including cancer cells, resulted in a combined dataset of 1492 human and 1296 mouse cell surface glycoproteins, providing experimental evidence for their cell surface expression on different cell types, including 136 G-protein coupled receptors and 75 membrane receptor tyrosine-protein kinases. Integrated analysis of the CSPA reveals that the concerted biological function of individual cell types is mainly guided by quantitative rather than qualitative surfaceome differences. The CSPA will be useful for the evaluation of drug targets, for the improved classification of cell types and for a better understanding of the surfaceome and its concerted biological functions in complex signaling microenvironments.

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We describe a single autoregulatory cassette that allows reversible induction of transgene expression in response to tetracycline (tet). This cassette contains all of the necessary components previously described by others on two separate plasmids that are introduced sequentially over a period of months [Gossen, M. & Bujard, H. (1992) Proc Studies of gene function in cultured cells, analyses of gene expression during mammalian development, and delivery of proteins via gene therapy would all greatly benefit from the ability to regulate gene expression in a temporal and quantitative manner. In cultured cells, a frequent approach to the study of genes is stable transfection of plasmids and isolation of constitutively expressing cells using a drug selectable marker, a procedure that is time consuming, labor intensive, and may result in loss of function of the gene of interest over time. In mouse development, the role of genes is typically studied by irreversible changes: for example, gene inactivation or gene augmentation in transgenic animals from the onset of embryogenesis or use of flp or cre recombinases later in development (1, 2). In gene therapy, only constitutive delivery of proteins has been achieved, yet constant expression levels are often not physiological and can even be life threatening. In each of these three cases, it would be highly advantageous if the gene of interest could be expressed during a particular window of time in a dose-dependent and reversible manner.Several inducible gene expression systems have been developed over the past decade in an attempt to meet the need for regulated gene expression. Most of the commonly used methods for inducing gene expression such as heat shock, steroids, or metallothionein, suffer from either high basal levels of gene expression under noninduced conditions, pleiotropic effects on host cell genes, or both (reviewed in refs. 3 and 4). Although usefully applied in a multitude of studies over the past decade, these inducible systems are frought with problems.Recently two systems have been developed that appear to overcome many of the problems associated with the first generation of inducible vectors in that the inducers are specific to the gene of interest and lead to low basal and high inducible levels of gene expression: the tetracycline (tet) and progesterone antagonist (RU486) regulatable systems (5, 6). Both systems use microbial proteins and microbial DNA response elements to drive the expression of a desired gene in heterologous cells. As a result, regulation is restricted to the gene of interest, host genes are not affected, and there appears to be no associated toxicity. In addition, gene expression can frequently be modulated over a broad range of levels during a defined temporal window.The two-plasmid systems described above (5, 6), represent theoretical milestones in the development of inducible systems, yet widespread application is severely hindered for several reasons. First, two sequential transfection steps are necessary to introduce e...

Videira, Sandy Sampaio, 1981-Estudo da comunidade de bactérias diazotróficas associada a plantas de capim-elefante / Sandy Sampaio Videira -2012. 105 f. : il.